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Perioperative Maintenance of Normothermia Reduces the Incidence of Morbid Cardiac Events. A Randomized Clinical Trial
Abstract
To assess the relationship between body temperature and cardiac morbidity during the perioperative period.
Randomized controlled trial comparing routine thermal care (hypothermic group) to additional supplemental warming care (normothermic group).
Operating rooms and surgical intensive care unit at an academic medical center.
Three hundred patients undergoing abdominal, thoracic, or vascular surgical procedures who either had documented coronary artery disease or were at high risk for coronary disease.
The relative risk of a morbid cardiac event (unstable angina/ischemia, cardiac arrest, or myocardial infarction) according to thermal treatment. Cardiac outcomes were assessed in a double-blind fashion.
Mean core temperature after surgery was lower in the hypothermic group (35.4+/-0.1 degrees C) than in the normothermic group (36.7+/-0.1 degrees C) (P<.001) and remained lower during the early postoperative period. Perioperative morbid cardiac events occurred less frequently in the normothermic group than in the hypothermic group (1.4% vs 6.3%; P=.02). Hypothermia was an independent predictor of morbid cardiac events by multivariate analysis (relative risk, 2.2; 95% confidence interval, 1.1-4.7; P=.04), indicating a 55% reduction in risk when normothermia was maintained. Postoperative ventricular tachycardia also occurred less frequently in the normothermic group than in the hypothermic group (2.4% vs 7.9%; P=.04).
In patients with cardiac risk factors who are undergoing noncardiac surgery, the perioperative maintenance of normothermia is associated with a reduced incidence of morbid cardiac events and ventricular tachycardia.
... For cardiovascular outcomes and all-cause mortality, however, limited data were analyzed based on low-quality evidence. Current conclusions of active warming on postoperative cardiovascular risk reduction were mainly drawn from an RCT of 300 patients with high coronary artery risk [16]. Yet, the cardiac events in this trial were assessed based on 48-h electrocardiogram monitoring, which was insensitive and would miss most asymptomatic (no chest pain or other symptoms) myocardial injuries. ...
... Here are the results for primary outcomes. The two studies (5313 patients) [16,19] that assessed the risk of MACE showed no significant differences between active warming Fig. 3 Meta-analyses of perioperative cardiovascular complications. CI indicates confidence interval. ...
... number of events 59 vs. 70). All-cause mortality within 30 days was assessed in three trials (5513 patients) [16,19,29], and no statistically significant difference in risk of 30-day all-cause mortality was noted when active warming was compared with routine care or no active warming (RR 0.81, 95% CI 0.43-1.54, number of events 17 vs. ...
Purpose
The objective of this study was to provide an updated review on the active warming effects on major adverse cardiac events, 30-day all-cause mortality, and myocardial injury after noncardiac surgery.
Method
We systematically searched MEDLINE, EMBASE, CINAHL, Cochrane CENTRAL, Web of Science, and Chinese BioMedical Literature Database. We included randomized controlled trials of adult population undergoing noncardiac surgeries that concentrate on the comparison of active warming methods and passive thermal management. Cochrane Collaboration’s tool was applied for risk-of-bias assessment. We used trial sequential analysis to evaluate the possibility of false positive or negative results.
Results
A total of 13,316 unique records were identified, of which only 19 with reported perioperative cardiovascular outcomes were included in the systematic review and nine of them were included in final meta-analysis. No statistically significant difference between active warming methods and routine care was found in major adverse cardiac events (RR 0.56, 95% confidence interval (CI) 0.14–2.21, I ² = 71%, number of events 59 vs. 70), 30-day all-cause mortality (RR 0.81, 95% CI 0.43–1.54, I ² = 0%, number of events 17 vs. 21), and myocardial injury after noncardiac surgery (RR 0.61, 95% CI 0.17–2.22, I ² = 79%, number of events 236 vs. 234). Trial sequential analysis suggests that current trials did not reach the minimum information size regarding the major cardiovascular events.
Conclusions
Compared to routine perioperative care, we found that active warming methods are not necessary for cardiovascular prevention in patients undergoing noncardiac surgery.
... Yi et al. (2) reported that the incidence of intraoperative hypothermia was as high as 44.3%, and the rate of active warming remains low. Intraoperative hypothermia is associated with numerous adverse outcomes, including postoperative drug metabolism disorders (3,4), surgical site infections (5)(6)(7), perioperative bleeding and the need for transfusion (8,9), postoperative shivering, cardiovascular events (10,11), and even mortality (12). Intraoperative hypothermia also prolongs post-anesthesia care unit or intensive care unit stays (7,13,14), reduces patient satisfaction, and increases medical costs (5,15). ...
... We also found that the incidence of postoperative nonsurgical procedure-related complications was 9.1% in the routine management group and 6.0% in the aggressive warming group. This trend was consistent with large sample studies that have shown that perioperative thermal management is associated with adverse cardiovascular and cerebrovascular events (3)(4)(5)(6)(7)(8)(9)(10)(11)(12)(13)(14)(15). In our study, 1 patient in group R developed delirium. ...
... Active intraoperative temperature management is a modifiable condition, and its management can prevent increases in postoperative APACHE II scores. Our findings are consistent with those of cohort studies and numerous studies that support perioperative active warming (5)(6)(7)(8)(9)(10)(11)(12)(13)(14)(15). ...
Background:
Intraoperative hypothermia is related with postoperative complication, longer length of stay (LoS) and mortality. Acute Physiology and Chronic Health Evaluation II (APACHE II) it the most commonly used evaluation system for assessing the severity and clinical prognosis of patients. This study sought to examine the effect of intraoperative body temperature on postoperative APACHE II scores and the prognosis of high-risk patients undergoing thoracoscopic surgery.
Methods:
This study used the clinical data of patients from a multicenter randomized controlled trial who had undergone thoracoscopic surgery at our center (NCT03111875). In our center were randomly assigned (1:1) to receive either aggressive warming to a target core temperature of 37 ℃ or routine thermal management to a target of 35.5 ℃ during non-cardiac surgery. Randomisation was computer-generated. Eligible patients (aged ≥45 years) had at least one cardiovascular risk factor, were scheduled for inpatient noncardiac surgery expected to last 2-6 h with general anaesthesia. We retrieved medical information through the electronic medical record system. The primary outcome was the postoperative APACHE II scores, APACHE II score variation. The secondary outcome was Quality of Recovery-15 (QoR-15) scores, LoS in hospital, postoperative complications, infections, and deaths of the patients were recorded, and a logistic regression analysis was conducted to stratify the risk factors for the APACHE II score.
Results:
Group R comprised 121 patients and Group A comprised 84 patients. Group A had lower postoperative APACHE II scores (P=0.046) and a lower probability of a grade increase than Group R (P=0.005). However, no significant differences were found in terms of the QoR-15 scores, LoS, postoperative complications, infections, and deaths between the 2 groups. The logistic regression showed that aggressive warming, age, and the American Society of Anesthesiologists (ASA) grade were risk factors for the deterioration of postoperative APACHE II scores.
Conclusions:
The active adoption of various passive and aggressive warming strategies to keep the core body temperature ≥37 ℃ during thoracoscopic surgery significantly reduced increases in APACHE II scores, which is different from age and ASA grade, and was the only intervention factor.
... Upon review of the literature on hypothermia, it is observed that the studies between 1990 and 2005 focused on the clinical consequences of hypothermia in patients. [14][15][16][17][18] Nevertheless, since 2005 it is seen that evidence-based guidelines have been created that include interventions to prevent hypothermia in patients. 3,5,19,20 In the literature there are varying reports regarding the incidence of IPH according to countries, centers, and surgical procedures, but the incidence of hypothermia in the United States is approximately 4%-70%. ...
... This may cause adverse effects in patients with existing intrapulmonary shunting, limited lung reserve, and limited cardiac output. 9,15 Cardiac events • Activation of sympathetic (norepinephrine) and adrenomedullary systems with decrease in body temperature, resulting in increased release of catecholamine. 15 • Elevated serum catecholamine level increases cardiac output and heart rate and may lead to hypertension. ...
... 9,15 Cardiac events • Activation of sympathetic (norepinephrine) and adrenomedullary systems with decrease in body temperature, resulting in increased release of catecholamine. 15 • Elevated serum catecholamine level increases cardiac output and heart rate and may lead to hypertension. This may cause increased cardiac demand, ischemia, and morbidity. ...
Inadvertent perioperative hypothermia is defined as a decrease in core body temperature below 36°C (96.8°F) in patients undergoing surgery, starting from one hour before anesthesia induction in the preoperative period, during the intraoperative period, and in the postoperative period in intensive care unit, spanning 24 hours. Inadvertent perioperative hypothermia is a preventable complication that occurs during surgery and can occur due to factors, such as open skin and abdominal cavity, general or regional anesthesia, prolonged surgery duration, low ambient temperature, use of cold irrigation or intravenous fluids, and factors related to the patient. Morbid heart problems, delayed wound healing, increased blood loss and blood transfusion, surgical site infection, deterioration in drug metabolism, and prolonged intensive care and hospital stay are some of the complications that may result from hypothermia. There are several international evidence-based practice guidelines for the prevention and control of hypothermia in the perioperative period. Although the guidelines state that hypothermia can be prevented with some simple and cost-effective measures implemented during the perioperative process, the compliance rate with these practices may be poor in clinical practice. In this article, the practices of healthcare professionals in preventing inadvertent perioperative hypothermia will be discussed in line with evidence-based guidelines.
... In both patient groups, it is associated with a higher mortality and poor prognosis [60]. Post-operative ventricular tachycardia and perioperative morbid cardiac events were shown by Frank et al. to occur less frequently if normothermia is achieved perioperatively, especially in patients already bearing risk factors for cardiac diseases [61]. Furthermore, hypothermia has been shown to be associated with delayed wound-healing and a predisposition for wound infections [62] in general surgery. ...
... Hypothermia is a part of the aforementioned lethal triad not only in burn patients, but generally. Especially during general anaesthesia, hypothermia can lead to adverse cardiac events or to delayed wound healing [61,62]. Thus, adequate temperature management is not only an issue in burn patients. ...
Background:
In this systematic review, we summarize the aetiology as well as the current knowledge regarding thermo(dys)regulation and hypothermia after severe burn trauma and aim to present key concepts of pathophysiology and treatment options. Severe burn injuries with >20% total body surface area (TBSA) affected commonly leave the patient requiring several surgical procedures, prolonged hospital stays and cause substantial changes to body composition and metabolism in the acute and long-term phase. Particularly in severely burned patients, the loss of intact skin and the dysregulation of peripheral and central thermoregulatory processes may lead to substantial complications.
Methods:
A systematic and protocol-based search for suitable publications was conducted following the PRISMA guidelines. Articles were screened and included if deemed eligible. This encompasses animal-based in vivo studies as well as clinical studies examining the control-loops of thermoregulation and metabolic stability within burn patients.
Results:
Both experimental animal studies and clinical studies examining thermoregulation and metabolic functions within burn patients have produced a general understanding of core concepts which are, nonetheless, lacking in detail. We describe the wide range of pathophysiological alterations observed after severe burn trauma and highlight the association between thermoregulation and hypermetabolism as well as the interactions between nearly all organ systems. Lastly, the current clinical standards of mitigating the negative effects of thermodysregulation and hypothermia are summarized, as a comprehensive understanding and implementation of the key concepts is critical for patient survival and long-term well-being.
Conclusions:
The available in vivo animal models have provided many insights into the interwoven pathophysiology of severe burn injury, especially concerning thermoregulation. We offer an outlook on concepts of altered central thermoregulation from non-burn research as potential areas of future research interest and aim to provide an overview of the clinical implications of temperature management in burn patients.
... Inadvertent intraoperative hypothermia, defined as a core temperature <36.0°C at any point during the operation [1], is present in 4% to 90% of surgical patients [2,3]. Hypothermia can lead to numerous adverse outcomes, including postoperative infection [4,5], cardiovascular events [5,6], increased blood loss and transfusion requirement [7], and altered pharmacodynamics [8], with substantial costs [5,9]. Professional societies, such as the National Institute for Health and Care Excellence (NICE) and the American Society of PeriAnesthesia Nurses (ASPAN), have submitted some clinical guidelines [1,10] for the management of perioperative hypothermia and recommended forced-air warming as the most effective active warming [3,10]. ...
... b P value for trend from logistic regression. 6 International Journal of Clinical Practice conducted in several designated operating rooms, this narrow, single-centered cohort had a relatively young, thin, healthy (91% either ASA I or II) set of patients, mainly females, with an operative time of fewer than 2 hours, receiving only general anesthesia, which presents a risk of spectrum bias. Hence, the model could be used only with caution in clinical settings similar to ours after this validation [24]. ...
Objectives:
There have been no fully validated tools for the rapid identification of surgical patients at risk of intraoperative hypothermia. The objective of this study was to validate the performance of a previously established prediction model in estimating the risk of intraoperative hypothermia in a prospective cohort.
Methods:
In this observational study, consecutive adults scheduled for elective surgery under general anesthesia were enrolled prospectively at a tertiary hospital between September 4, 2020, and December 28, 2020. An intraoperative hypothermia risk score was calculated by a mobile application of the prediction model. A wireless axillary thermometer was used to continuously measure perioperative core temperature as the reference standard. The discrimination and calibration of the model were assessed, using the area under the receiver operating characteristic curve (AUC), Hosmer-Lemeshow goodness-of-fit test, and Brier score.
Results:
Among 227 participants, 99 (43.6%) developed intraoperative hypothermia, and 10 (4.6%) received intraoperative active warming with forced-air warming. The model had an AUC of 0.700 (95% confidence interval [CI], 0.632-0.768) in the overall cohort with adequate calibration (Hosmer-Lemeshow χ 2 = 13.8, P=0.087; Brier score = 0.33 [95% CI, 0.29-0.37]). We categorized the risk scores into low-risk, moderate-risk, and high-risk groups, in which the incidence of intraoperative hypothermia was 23.0% (95% CI, 12.4-33.5), 43.4% (95% CI, 33.7-53.2), and 62.7% (95% CI, 51.5-74.3), respectively (P for trend <0.001).
Conclusions:
The intraoperative hypothermia prediction model demonstrated possibly helpful discrimination and adequate calibration in our prospective validation. These findings suggest that the risk screening model could facilitate future perioperative temperature management.
... Perioperative hypothermia (a temperature less than 36 0 C) is associated with the risk of wound infection (RR 4.00, 95% CI 1.57, 10.19) ( National Collaborating Centre for Nursing and Supportive Care (NCCNSC), 2008 Updated 2016), surgical bleeding and blood transfusion (RR 1.33, 95% CI 1.06, 1.66) ( National Collaborating Centre for Nursing and Supportive Care (NCCNSC), 2008 Updated 2016), morbid cardiac events (RR 2.20, 95% CI 1.10, 4.70) ( Frank et al., 1997 ; National Collaborating Centre for Nursing and Supportive Care (NCCNSC), 2008 Updated 2016), increased recovery time and longer hospital stay ( Lenhardt et al., 1997 ). Despite knowledge of clinical sequelae and guideline recommendations, global prevalence of perioperative hypothermia remains high: reported rates of perioperative hypothermia in Australian surgical patients are between 32% to 54% ( Duff, Walker, Edward, Williams, & Sutherland-Fraser, 2014 ;Munday, Hines, & Chang, 2013 ). ...
... This disparity is longstanding: in 2007, the TEMPP study concluded a lack of attention to temperature monitoring was consistent for the entire European population ( Torossian, 2007 ). Earlier, in 1999, Frank and colleagues found that temperature monitoring during regional anaesthesia in the United States occurred only rarely ( Frank et al., 1997 ). More recently, Echeverry-Marin et al. warned of the risks of warming performed 'blindly' with no knowledge of temperature, even in PACU ( Echeverry-Marin et al., 2016 ). ...
Background
Patients undergoing surgery require accurate and consistent temperature monitoring to enable identification of thermal disturbances. Internationally, evidence indicates low rates of monitoring, but knowledge of Australian practices reported by the multidisciplinary team is lacking.
Aim
To investigate temperature monitoring practices as reported by multidisciplinary health care workers caring for patients receiving perioperative care.
Methods
A cross-sectional survey was distributed online via nursing, anaesthetic, and anaesthetic allied health practitioner professional colleges. Following low-risk ethical approval, data were collected via REDCap using a pre-piloted tool (November to December 2019). Data were analysed using IBM SPSS Statistics (Version 26). Binomial logistic regression assessed relationships between private or public facilities, location, profession, and factors influencing temperature monitoring practices.
Findings
Responses were received from 545 participants: registered or enrolled nurses comprised the largest proportion (n = 281/545, 52%) followed by anaesthetists (n = 219/545, 40%). Over half were unsure whether national guidelines for perioperative temperature monitoring existed (n = 273/500, 55%), 19% (n = 106/545) stated that decision-making was influenced by guidelines, and 24% (n = 129/545) were influenced by departmental policy. The odds of influence by national guidelines in decision-making among nurses was twice than for anaesthetists (OR 2.09, 95% CI 1.26, 3.46, p <0.01).
Discussion
Findings revealed a lack of awareness of perioperative temperature monitoring guidelines among all professions, but adequate availability of devices was reported. Disparities exist between reported uptake of monitoring, and existing observational evidence.
Conclusion
Low uptake of optimal perioperative temperature monitoring practices may be influenced by lack of awareness of guidelines and availability of accurate devices.
... A cardiovascular composite outcome was observed in 6·3% of the hypothermic patients versus 1·4% of those kept normothermic (p=0·02), with the composite being largely driven by electrocardiographic evidence of myocardial ischemia and ventricular tachycardia. 37 Because the trial was conducted before the troponin biomarker became available, diagnoses were primarily based on Holter electrocardiogram findings. The reported incidence of myocardial infarction was less than 1%, whereas the true incidence is at least 14% in patients who have vascular surgery. ...
... 38 In another trial of 100 patients having abdominal aortic surgery, again based on Holter monitoring, there was no difference in postoperative myocardial ischemia in hypothermic (35·6°C) and normothermic (36·4°C) patients. 39 Among PROTECT and relevant trials, 37,40,41 nearly all outcome events are from the current trial and clearly indicate that cardiovascular outcomes are similar at 35·5°C and 37°C. ...
Background
Moderate intraoperative hypothermia promotes myocardial injury, surgical site infections, and blood loss. Whether aggressive warming to a truly normothermic temperature near 37°C improves outcomes remains unknown. We aimed to test the hypothesis that aggressive intraoperative warming reduces major perioperative complications.
Methods
In this multicentre, parallel group, superiority trial, patients at 12 sites in China and at the Cleveland Clinic in the USA were randomly assigned (1:1) to receive either aggressive warming to a target core temperature of 37°C (aggressively warmed group) or routine thermal management to a target of 35·5°C (routine thermal management group) during non-cardiac surgery. Randomisation was stratified by site, with computer-generated, randomly sized blocks. Eligible patients (aged ≥45 years) had at least one cardiovascular risk factor, were scheduled for inpatient non-cardiac surgery expected to last 2–6 h with general anaesthesia, and were expected to have at least half of the anterior skin surface available for warming. Patients requiring dialysis and those with a body-mass index exceeding 30 kg/m² were excluded. The primary outcome was a composite of myocardial injury (troponin elevation, apparently of ischaemic origin), non-fatal cardiac arrest, and all-cause mortality within 30 days of surgery, as assessed in the modified intention-to-treat population. This study is registered with ClinicalTrials.gov, NCT03111875.
Findings
Between March 27, 2017, and March 16, 2021, 5056 participants were enrolled, of whom 5013 were included in the intention-to-treat population (2507 in the aggressively warmed group and 2506 in the routine thermal management group). Patients assigned to aggressive warming had a mean final intraoperative core temperature of 37·1°C (SD 0·3) whereas the routine thermal management group averaged 35·6°C (SD 0·3). At least one of the primary outcome components (myocardial injury after non-cardiac surgery, cardiac arrest, or mortality) occurred in 246 (9·9%) of 2497 patients in the aggressively warmed group and in 239 (9·6%) of 2490 patients in the routine thermal management group. The common effect relative risk of aggressive versus routine thermal management was an estimated 1·04 (95% CI 0·87–1·24, p=0·69). There were 39 adverse events in patients assigned to aggressive warming (17 of which were serious) and 54 in those assigned to routine thermal management (30 of which were serious). One serious adverse event, in an aggressively warmed patient, was deemed to be possibly related to thermal management.
Interpretation
The incidence of a 30-day composite of major cardiovascular outcomes did not differ significantly in patients randomised to 35·5°C and to 37°C. At least over a 1·5°C range from very mild hypothermia to full normothermia, there was no evidence that any substantive outcome varied. Keeping core temperature at least 35·5°C in surgical patients appears sufficient.
Funding
3M and the Health and Medical Research Fund, Food and Health Bureau, Hong Kong.
Translation
For the Chinese translation of the abstract see Supplementary Materials section.
... Therefore, the temperature drop during laparoscopic procedures does not differ essentially from that seen during open surgery. Even mild forms of intraoperative hypothermia can lead to a marked increase in morbidity and mortality [4,5]. The negative consequences of intraoperative hypothermia have been well researched and include disturbances of blood clotting with increased blood loss as well as increased rate of transfusions, myocardial dysfunction, arrhythmia and hypokalemia [5]. ...
... The negative consequences of intraoperative hypothermia have been well researched and include disturbances of blood clotting with increased blood loss as well as increased rate of transfusions, myocardial dysfunction, arrhythmia and hypokalemia [5]. In addition, delayed wound healing and wound infections occur more often, with prolonged hospitalization as a result [4][5][6]. ...
Background
Hypothermia is defined as a decrease in body core temperature to below 36 °C. If intraoperative heat-preserving measures are omitted, a patient’s temperature will fall by 1 – 2 °C. Even mild forms of intraoperative hypothermia can lead to a marked increase in morbidity and mortality. Using warm and humidified gas insufflation in laparoscopy may help in the maintenance of intraoperative body temperature.
Methods
In this prospective randomized controlled study, we investigated effects of temperature and humidity of the insufflation gas on intra- and postoperative temperature management. 150 patients undergoing gynecologic laparoscopic surgery were randomly assigned to either insufflation with non-warmed, non-humidified CO 2 with forced air warming blanket (AIR), humidified warm gas without forced air warming blanket (HUMI) or humidified warm gas combined with forced air warming blanket (HUMI+). We hypothesized that the use of warmed laparoscopic gas would have benefits in the maintenance of body temperature and reduce the occurrence of hypothermia.
Results
The use of warm and humidified gas insufflation alone led to more hypothermia episodes with longer duration and longer recovery times as well as significantly lower core body temperature compared to the other two groups. In the comparison of the AIR group and HUMI + group, HUMI + patients had a significantly higher body temperature at arrival at the PACU (Post Anaesthesia Care Unit), had the least occurrence of hypothermia and suffered from less shivering.
Conclusion
The use of warm and humidified gas insufflation alone does not sufficiently warm the patients. The optimal temperature management is achieved in the combination of external forced air warming and insufflation of warm and humidified laparoscopy gas.
... Hypothermia is associated with an increased risk of complications, some of which can be severe [4,5]. Several authors have reported an association with poor wound healing, cardiac dysrhythmias, and increased bleeding [4,6,7]. Even mild hypothermia of only 1-3 °C is associated with increased complications such as delayed wound healing, ventricular tachycardia, poor anesthetic drug clearance, coagulopathy, and susceptibility to infection [6,8,9]. ...
... Several authors have reported an association with poor wound healing, cardiac dysrhythmias, and increased bleeding [4,6,7]. Even mild hypothermia of only 1-3 °C is associated with increased complications such as delayed wound healing, ventricular tachycardia, poor anesthetic drug clearance, coagulopathy, and susceptibility to infection [6,8,9]. In contrast, maintenance of normothermia reduces hospital costs and death rates [10]. ...
Background
Perioperative hypothermia is a common occurrence, particularly with the elderly and pediatric age groups. Hypothermia is associated with an increased risk of perioperative complications. One method of preventing hypothermia is warming the infused fluids given during surgery. The enFlow™ intravenous fluid warmer has recently been reintroduced with a parylene coating on its heating blocks. In this paper, we evaluated the impact of the parylene coating on the new enFlow’s fluid warming capacity.
Methods
Six coated and six uncoated enFlow cartridges were used. A solution of 10% propylene glycol and 90% distilled H 2 O was infused into each heating cartridge at flow rates of 2, 10, 50, 150, and 200 ml/min. The infused fluid temperature was set at 4 °C, 20 °C, and 37 °C. Output temperature was recorded at each level. Data for analysis was derived from 18 runs at each flow rate (six cartridges at three temperatures).
Results
The parylene coated fluid warming cartridge delivered very stable output of 40 °C temperatures at flow rates of 2, 10, and 50 ml/min regardless of the temperature of the infusate. At higher flow rates, the cartridges were not able to achieve the target temperature with the colder fluid. Both cartridges performed with similar efficacy across all flow rates at all temperatures.
Conclusions
At low flow rates, the parylene coated enFlow cartridges was comparable to the original uncoated cartridges. At higher flow rates, the coated and uncoated cartridges were not able to achieve the target temperature. The parylene coating on the aluminum heating blocks of the new enFlow intravenous fluid warmer does not negatively affect its performance compared to the uncoated model.
... Perioperative hypothermia is de ned as a core body temperature of lower than 36 degrees Celsius (℃) at any point in the perioperative period [3]. Perioperative hypothermia is reported to occur in 50-90% of surgical cases [4,5] and to be a risk factor for shivering [6], blood coagulation disorder [7,8], surgical site infection [9] and myocardial ischemia [10]. ...
Perioperative hypothermia occurs in patients undergoing general anesthesia. Hypothermia is defined as a core body temperature of lower than 36℃. There are few reports on the relationship between patient body composition and occurrence of hypothermia. Therefore, this study was aimed to clarify the relationship between patient body composition and hypothermia.
Patients undergoing open gastrectomy were enrolled in the study. Patients whose bladder temperature was lower than 36℃ for more than 1 minute were allocated to the hypothermia group, and the other patients were allocated to the control group. The patient’s body composition was evaluated by the bioelectrical impedance analysis.
Of sixty-eight patients enrolled in this study, thirty-four patients were allocated to the hypothermia group. Body surface area per body weight was significantly high in the hypothermia group. Body composition factors such as total fat mass, skeletal muscle mass index, and basal metabolic rate were significantly lower (p < 0.05) in the hypothermia group. Body fat percentage and visceral fat mass were similar between the two groups. Multivariate analysis demonstrated total fat mass less than 11.2 kg (HR 4.51 (95%CI: 1.35–15.03), p = 0.014) and skeletal muscle mass index less than 10.06 kg/m² (HR 5.61 (95%CI: 1.86–16.93), p = 0.002) as independent risk factors for hypothermia.
Low total fat mass and low skeletal muscle mass index will be likely to be risk factors for perioperative hypothermia in open gastrectomy.
... In addition, intraoperative operations, such as disinfection, infusion, application of anesthetic drugs, and low-temperature environment in the operating room, will lead to the occurrence of hypothermia in patients, so there is a common phenomenon of body temperature imbalance in the perioperative period (Yi et al., 2015). Perioperative hypothermia may damage the coagulation function and immune function of patients, increase the postoperative infection rate of patients, and lead to cardiovascular function disorders and delayed recovery (Frank et al., 1997;Leslie & Sessler, 2003). ...
Objective
Our study aimed to investigate the correlation between intraoperative hypothermia and postoperative delirium (POD) in patients undergoing general anesthesia for gastrointestinal surgery.
Methods
The study comprised 750 participants from the Perioperative Neurocognitive Disorder Risk Factor and Prognosis (PNDRFAP) study database, which ultimately screened 510 individuals in the final analysis. Preoperative cognitive function was evaluated using the Mini‐Mental State Examination (MMSE). The occurrence of POD was determined using the Confusion Assessment Method, and the severity of POD was evaluated using the Memorial Delirium Assessment Scale. Logistic regression was employed to scrutinize the association between intraoperative hypothermia and the incidence of POD, and the sensitivity analysis was conducted by introducing adjusted confounding variables. Decision curves and a nomogram model were utilized to assess the predictive efficacy of intraoperative hypothermia for POD. Mediation analysis involving 10,000 bootstrapped iterations was employed to appraise the suggested mediating effect of numeric rating scale (NRS) scores at 24 and 48 h post‐surgeries. The receiver‐operating characteristic (ROC) was utilized to evaluate the effectiveness of intraoperative hypothermia in predicting POD.
Results
In the PNDRFAP study, the occurrence of POD was notably higher in the intraoperative hypothermia group (62.2%) compared to the intraoperative normal body temperature group (9.8%), with an overall POD incidence of 17.6%. Logistic regression analysis, adjusted for various confounding factors (age [40–90], gender, education, MMSE, smoking history, drinking history, hypertension, diabetes, and the presence of cardiovascular heart disease), demonstrated that intraoperative hypothermia significantly increased the risk of POD (OR = 4.879, 95% CI = 3.020–7.882, p < .001). Mediation analyses revealed that the relationship between intraoperative hypothermia and POD was partially mediated by NRS 24 h after surgery, accounting for 14.09% of the association (p = .002). The area under the curve of the ROC curve was 0.685, which confirmed that intraoperative hypothermia could predict POD occurrence to a certain extent. Decision curve and nomogram analyses, conducted using the R package, further substantiated the predictive efficacy of intraoperative hypothermia on POD.
Conclusion
Intraoperative hypothermia may increase the risk of POD, and this association may be partially mediated by NRS scores 24 h after surgery.
... The effects of intraoperative core body temperature on operative morbidity have previously been the subject of robust investigation in multiple surgical fields, with relative hypothermia associated with increased risk for prolonged length of stay, ischemic cardiac events, and blood loss. [17][18][19][20][21] Although studies have also evaluated temperature effect on the risk of thrombotic events, none have done so specifically in the setting of CAWR. We found that intraoperative core body temperature was not associated with VTE development as a standalone variable using univariable regression analysis or predictive of VTE development when controlling for covariates with multivariable regression. ...
Background
Venous thromboembolism (VTE) is a dangerous postoperative complication after abdominal wall reconstruction (AWR). Intraoperative core body temperature has been associated with thrombotic events in other surgical contexts. This study examines the effects of intraoperative temperature on VTE rate after AWR.
Methods
A retrospective study was performed on AWR patients. Cohorts were defined by postoperative 30-day VTE. Intraoperative core body temperature was recorded as the minimum, maximum, and mean intraoperative temperatures. Study variables were analyzed with logistic regression and cutoff analysis to assess for association with VTE.
Results
In total, 344 patients met inclusion criteria. Fourteen patients were diagnosed with 30-day VTE for an incidence of 4.1%. The VTE cohort had a longer median inpatient stay (8 days versus 5 days, P < 0.001) and greater intraoperative change in peak inspiratory pressure (3 mm H 2 O versus 1 mm H 2 O, P = 0.01) than the non-VTE cohort. Operative duration [odds ratio (OR) = 1.32, P = 0.01], length of stay (OR = 1.07, P = 0.001), and intraoperative PIP difference (OR = 1.18, P = 0.045) were significantly associated with 30-day VTE on univariable regression. Immunocompromised status (OR = 4.1, P = 0.023; OR = 4.0, P = 0.025) and length of stay (OR = 1.1, P < 0.001; OR = 1.1, P < 0.001) were significant predictors of 30-day VTE on two multivariable regression models. No significant associations were found between temperature metrics and 30-day VTE on cutoff point or regression analysis.
Conclusions
Intraoperative core body temperature did not associate with 30-day VTE after AWR, though operative duration, length of stay, immunocompromised status, and intraoperative PIP difference did. Surgeons should remain mindful of VTE risk after AWR, and future research is warranted to elucidate all contributing factors.
... Prevention of intraoperative hypothermia is important in RALP, similar to other operations. Intraoperative hypothermia is associated with greater intraoperative bleeding and blood transfusion, 2,3 prolonged recovery from anesthetics and muscle relaxants, 4,5 higher rate of major morbidity (cardiac, respiratory, infectious), [5][6][7] and prolonged hospital stay. 3,6 Maintenance of normothermia is one of the important elements in the guidelines for the prevention of surgical site infection and enhanced recovery and surgery (ERAS) protocol. ...
Purpose: The study aimed to investigate whether an under-body blanket is more effective than an over-body blanket in preventing intraoperative hypothermia in patients undergoing robot-assisted laparoscopic prostatectomy (RALP). Methods: This was a retrospective observational study. We analyzed the medical records of patients who underwent RALP between January 2014 and December 2015 at Nippon Medical School Hospital. The patients were divided into the following groups: under-body blanket group (n=89) and over-body blanket group (n=43). Results: The number of patients using the under-body blanket and the over-body blanket was 89 and 43, respectively. Intraoperative temperatures (at 3 h, 4 h, 5 h, and 6 h after induction of anesthesia, and at the end of the operation) and the postoperative temperature (on arrival in the ward and at 1 h, 2 h, 3 h, and 4 h after arrival in the ward) were significantly higher in the under-body than the over-body blanket group. The maximum and minimum temperatures of the patients and the serum creatinine levels were significantly higher in the under-body blanket group than in the over-body blanket group just after the operation, on postoperative day 1, and just before discharge. The postoperative course was not significantly different between the two groups. Conclusion: The under-body blanket was observed to be more effective in preventing intraoperative hypothermia in patients undergoing RALP than the over-body blanket.
... Inadvertent perioperative hypothermia, defined as a core temperature < 36.0 °C, is associated with various adverse outcomes, such as morbid cardiac events, delayed postanesthetic recovery, wound infection, and prolonged hospital stays [1][2][3]. During general anesthesia, the body's ability to produce heat is reduced by a lowered threshold for coldness [4]. ...
Background: Patients undergoing transurethral urologic procedures using bladder irrigation are at increased risk of perioperative hypothermia. Thirty minutes of prewarming prevents perioperative hypothermia. However, its routine application is impractical. We evaluated the effect of 10 minutes of prewarming combined with the intraoperative administration of warmed intravenous fluid on patients' core temperature.
Methods: Fifty patients undergoing transurethral bladder or prostate resection under general anesthesia were included in this study and were randomly allocated to either the control group or the prewarming group. Patients in the prewarming group were warmed for 10 minutes before anesthesia induction with a forced-air warming device and received warmed intravenous fluid during operations. The patients in control group did not receive preoperative forced-air warming and were administered room-temperature fluid. Participants' core body temperature was measured on arrival at the preoperative holding area (T0), on entering the operating room, immediately after anesthesia induction, and in 10-minute intervals from then on until the end of the operation (Tend), on entering PACU, and in 10-minute intervals during the postanesthesia care unit stay. The groups' incidence of intraoperative hypothermia, change in core temperature (T0 - Tend), and postoperative thermal comfort were compared.
Results: The incidence of hypothermia was 64% and 29% in the control group and prewarming group, respectively (P = 0.015). Change in core temperature was 0.93 ± 0.3 °C and 0.55 ± 0.4 °C in the control group and prewarming group, respectively (P = 0.0001). Thermal comfort was better in the prewarming group (P = 0.004).
Conclusions: Ten minutes of prewarming combined with warmed intravenous fluid significantly decreased the incidence of intraoperative hypothermia and resulted in better thermal comfort in patients undergoing transurethral urologic surgery under general anesthesia.
... Even moderate perioperative hypothermia can result in potentially serious complications [1]. These include increased mortality, cardiac complications such as arrhythmias and myocardial ischemia, coagulation disorders as well as increased transfusion requirements and oxygen consumption [2,3,4,5]. Postoperative shivering, changes in potassium serum concentrations and peripheral vasoconstriction are also relevant side effects of perioperative hypothermia [6]. ...
Background and study aims Perioperative hypothermia is associated with significant complications and can be prevented with forced-air heating systems (FAHS). Whether hypothermia occurs during prolonged endoscopic sedation is unclear and prevention measures are not addressed in endoscopic sedation guidelines. We hypothesized that hypothermia also occurs in a significant proportion of patients undergoing endoscopic interventions associated with longer sedation times such as endoscopic retrograde cholangiopancreaticography (ERCP), and that FAHS may prevent it.
Patients and methods In this observational study, each patient received two consecutive ERCPs, the first ERCP following current standard of care without FAHS (SOC group) and a consecutive ERCP with FAHS (FAHS group). The primary endpoint was maximum body temperature difference during sedation.
Results Twenty-four patients were included. Median (interquartile range) maximum body temperature difference was −0.9°C (−1.2; −0.4) in the SOC and −0.1°C (−0.2; 0) in the FAHS group ( P < 0.001). Median body temperature was lower in the SOC compared with the FAHS group after 20, 30, 40, and 50 minutes of sedation. A reduction in body temperature of > 1°C ( P < 0.001) and a reduction below 36°C ( P = 0.01) occurred more often in the SOC than in the FAHS group. FAHS was independently associated with reduced risk of hypothermia ( P = 0.006). More patients experienced freezing in the SOC group ( P = 0.004). Hemodynmaic and respiratory stability were comparable in both groups.
Conclusions Hypothermia occurred in the majority of patients undergoing prolonged endoscopic sedation without active temperature control. FAHS was associated with higher temperature stability during sedation and better patient comfort.
... [1] Perioperative hypothermia can cause problems associated with wound infection, such as prolonged hospital stay, [2] prolonged postanesthetic recovery, [3] coagulopathy, [4] and myocardial events. [5] Consequently, it is recommended to maintain the core body temperature above 36°C which is the cut off value of perioperative hypothermia during anesthesia. [6,7] The appropriate body temperature measurement sites and methods vary depending on their availability, invasiveness, accuracy, and reliability. ...
Thermoregulation is important for maintaining homeostasis in the body. It can be easily broken under anesthesia. An appropriate method for measuring core body temperature is needed, especially for elderly patients, because the efficiency of thermoregulation gradually decreases with age. Zero-heat-flux (ZHF) thermometry (SpotOn) is an alternative, noninvasive method for continuous temperature monitoring at the skin surface. The aim of this study was to examine the accuracy and feasibility of using the SpotOn sensor in lower extremity orthopedic surgery in elderly patients aged over 80 years by comparing a SpotOn sensor with 2 other reliable minimally invasive methods: a tympanic membrane thermometer and a bladder thermometer. This study enrolled 45 patients aged over 80 years who were scheduled to undergo lower extremity surgery. Body temperature was measured using a SpotOn sensor, a tympanic membrane thermometer and a bladder thermometer. Agreements between the SpotOn sensor and the other 2 methods were assessed using Bland and Altman plots for repeated measures adjusted for unequal numbers of measurements per patient. Compared with bladder temperature, bias and limits of agreement for SpotOn temperature were 0.07°C ± 0.58°C. Compared with tympanic membrane temperature, bias and limits of agreement for SpotOn temperature were −0.28°C ± 0.61°C. The 3M SpotOn sensor using the ZHF method for patients aged over 80 years undergoing lower extremity surgery showed feasible measurement value and sensitivity.
... 4 While the precise mechanism is unclear, hypothermia can trigger hypertension, tachycardia and shivering, which is linked to myocardial ischaemia, angina and reduced PaO2 post-operatively. 5 Surgical teams undertake many time-sensitive and life-saving actions and preventing perioperative hypothermia should be among them. ...
... Hypothermia, defined as core temperature <36.0°C, is a common perioperatively complication. [1] Previous studies for adults and elder children have demonstrated that inadvertent hypothermia is associated with numerous adverse outcomes, [2,3] including an increased incidence of postoperative cardiovascular events, [4,5] surgical site infections (SSIs), [6,7] perioperative hemorrhage, [8,9] increased postoperative length of stay, increased oxygen consumption, and shivering to lead to patient discomfort. [10] Hypothermia may also lead to prolonged retention time in the post-anesthesia care unit or intensive care unit (ICU), [11] and is associated with an increased rate of mortality and complications. ...
This study aimed to determine the incidence and evaluate the risk factors and outcomes of intraoperative hypothermia (IH) during general anesthesia in infants. Retrospective analysis of prospectively collected data. A total of 754 infants younger than 1 year old who underwent surgery under general anesthesia were included. Intraoperative body temperature fluctuations, surgical and anesthetic data, postoperative complications, and infant outcomes were recorded. Logistic regression algorithms were used to evaluate potential risk factors. Among the 754 infants, 47.88% developed IH (<36 °C) and 15.4% of them experienced severe hypothermia (<35 °C). The average lowest temperature in hypothermia patients was 35.06 ± 0.69°C with a duration of 82.23 ± 50.59 minutes. Neonates tended to experience hypothermia (37.7% vs 7.6%, P < .001) and prematurity was more common in patients with IH (29.4% vs 16.8%, P < .001). Infants with hypothermia experienced a longer length of stay in the post anesthesia care units and intensive care units, postoperative hospitalizations, and tracheal extubation as well as a higher rate of postoperative hemorrhage than those with normothermia (all P < .05). Several factors were proved to be associated with an increased risk of IH after multivariate analysis: neonate (odds ratio [OR] = 3.685, 95% CI 1.839–7.382), weight (OR = 0.599, 95% CI 0.525–0.683), American society of anesthesiologists (OR = 3.418, 95% CI 2.259–5.170), fluid > 20 mL/kg (OR = 2.380, 95% CI 1.389–4.076), surgery time >60 minutes (OR = 1.785, 95% CI 1.030–3.093), and pre-warming (OR = 0.027, 95% CI 0.014–0.052). This retrospective study found that neonates, lower weight, longer surgery times, more fluid received, higher American society of anesthesiologists stage, and no pre-warming were all significant risk factors for IH during general anesthesia in infants.
... 7 Perioperative hypothermia has been associated with delayed post-anesthetic recovery, increased blood loss during surgery with the need for transfusion, increased incidence of surgical wound infections, impairment of antibody-and cell-mediated immune defenses, and increased postoperative adverse myocardial events. [8][9][10][11][12][13] To reduce these events, current techniques to maintain normothermia include draping and covering the patient during surgery, active heating with forced air warming devices or heated water underbody pads, use of heated irrigation fluids in major body cavities, and warming of IV fluids as they are infused. 14 In particular, warmed IV fluids are used for avoidance of intraoperative hypothermia. ...
Objectives
Avoiding inadvertent hypothermia during surgery is important. Intravenous fluid warmers used intraoperatively are critical for maintaining euthermia. We sought to prospectively evaluate the performance of the parylene-coated enFlow™ intravenous fluid warmer in patients undergoing surgery.
Methods
This was a prospective two-center observational clinical trial performed in inpatient surgical services of two large academic hospital systems. After written informed consent, patients were enrolled in the trial. All patients were adults scheduled for a surgery that was expected to last for at least 1 h with the administration of at least 1 L of fluid warmed prior to infusion. Patient temperature was recorded in the preoperative unit, at the induction of anesthesia, and then every 15 or 30 min until the end of surgery. Temperature monitoring continued in the recovery unit. The parylene-coated enFlow™ intravenous fluid warmer was used in addition to the usual patient warming techniques. The primary outcome was the average core temperature, and secondary analyses assessed individual temperature measurements, temperature measurements during specific time periods, and rate of hypothermic events.
Results
In all, 50 patients (29 males) with a mean age of 64 years were included in the analysis. The mean surgical time was 195 min and patients received an average of 1142 mL of fluids. Core temperature dropped by only 0.3°C approximately 60 min after induction and recovered back to the baseline level approximately 60 min later. There was no correlation between flow rate and measured core body temperature.
Conclusions
The parylene-coated enFlow intravenous fluid warmer was able to warm fluids at all flow rates during prolonged surgery. The results showed that enFlow performed as expected.
... As a result of postoperative shivering, cardiac adverse events, coagulopathy and perioperative hypothermia can impede the quick healing process in this regard. [28][29][30] It is simpler to avoid physiological issues before they arise, as with all phases of anaesthesia. ...
Background: Under general anaesthesia, the core temperature may drop up to 6°C. Patients undergoing prolonged maxillofacial surgery frequently experience unintentional hypothermia that causes postanaesthetic shivering which is a common complication of anaesthesia that should be prevented. This study aimed to evaluate the role of warmed intravenous fluid in preventing intraoperative hypothermia and postoperative shivering. Methods: Between January 2022 and December 2022, 322 patients with American Society of Anesthesiologists (ASA) physical status I, II and the age group of 18 to 45 years old scheduled for elective major oral and maxillofacial surgery were evaluated under the Department of Anaesthesiology in Dhaka Dental College and Hospital. The patients were grouped into Room Temperature Group and Warmed Fluid Group. Results: 162 patients received warmed fluid, whereas 160 patients received fluid at room temperature. In Room Temperature Group, there were 89 male and 71 female patients, whereas Warmed Fluid group had 88 male and 74 female patients. At the end of the procedure, the basal core temperature was 36.7±0.2°C in the group receiving warmed fluid versus 35.9±0.2°C in the group receiving fluid at room temperature. The incidence of hypothermia (<36 °C) was much lower in Warmed Fluid Group (n=28, 17.28%) than Room Temperature Group (n=86, 53.75%). Shivering was more common in Room Temperature Group (n = 67, 41.86%) than in Warmed Fluid Group (n = 19, 11.73%) in the postanaesthetic care unit (PACU). Conclusions: The results of this study suggested that intraoperative hypothermia and postoperative shivering are less common when warmed fluid is infused.
... However, anesthesia can easily break such response and lead to hypothermia [1]. Perioperative hypothermia can cause some problems associated with wound infection, such as lengthened hospital stay [2], prolonged postanesthetic recovery [3], coagulopathy [4], and myocardial events [5]. ...
Thermoregulation is important for maintaining homeostasis of our body. It can be easily broken under anesthesia. An appropriate method to measure the core body temperature is needed, especially for elderly patients because the efficiency of thermoregulation gradually decreases with age. The aim of this study was to examine the accuracy and feasibility of using of SpotOn® sensor in lower extremity orthopedic surgery in elderly patients aged over 80 years by comparing a SpotOn® sensor with two other reliable minimal-invasive methods: a tympanic membrane thermometer and a bladder thermometer. This study enrolled 45 patients aged over 80 years who were scheduled to undergo a lower extremity surgery. Body temperature was measured using a SpotOn® sensor, tympanic membrane thermometer and bladder thermometer. Agreements between the SpotOn® sensor and the other two methods were assessed using Bland and Altman plots for repeated measures adjusted for unequal numbers of measurements per patient. Compared with TempBladder, bias and limits of agreement for TempZHF were 0.07℃ ± 0.58℃. Compared with TempTympanic, bias and limits of agreement for TempZHF were -0.28℃ ± 0.61℃. 3M SpotOn® sensor using ZHF method for patients aged over 80 years undergoing lower extremity surgery shows feasible measurement value and sensitivity.
... Thus, a 1997 trial randomizing patients to additional intraoperative warming or no warming found a reduced incidence of cardiac arrest, MI or unstable angina when normothermia was maintained intraoperatively. [66] More recently, the PROTECT (Aggressive intraoperative warming versus routine thermal management during non-cardiac surgery) trial found that aggressive warming to a target core temperature of 37 • C did not increase the incidence of a composite of non-fatal cardiac arrest, myocardial injury or mortality, compared to maintaining routine thermal management to a target of 35.5 • C. [67] Consequently, maintaining a body core temperature above 35.5 • C during surgery is sufficient. ...
Myocardial injury is a frequent complication of surgical patients after having non-cardiac surgery that is strongly associated with perioperative mortality. While intraoperative anesthesia-related deaths are exceedingly rare, about 1% of patients undergoing non-cardiac surgery die within the first 30 postoperative days. Given the number of surgeries performed annually, death following surgery is the second leading cause of death in the United States. Myocardial injury after non-cardiac surgery (MINS) is defined as an elevation in troponin concentrations within 30 days postoperatively. Although typically asymptomatic, patients with MINS suffer myocardial damage and have a 10% risk of death within 30 days after surgery and excess risks of mortality that persist during the first postoperative year. Many factors for the development of MINS are non-modifiable, such as preexistent coronary artery disease. Preventive measures, systematic approaches to surveillance and treatment standards are still lacking, however many factors are modifiable and should be considered in clinical practice: the importance of hemodynamic control, adequate oxygen supply, metabolic homeostasis, the use of perioperative medications such as statins, anti-thrombotic agents, beta-blockers, or anti-inflammatory agents, as well as some evidence regarding the choice of sedative and analgesic for anesthesia are discussed. Also, as age and complexity in comorbidities of the surgical patient population increase, there is an urgent need to identify patients at risk for MINS and develop prevention and treatment strategies. In this review, we provide an overview of current screening standards and promising preventive options in the perioperative setting and address knowledge gaps requiring further investigation.
... In spite of efforts to maintain normothermia, inadvertent perioperative hypothermia of patients is common [1,2]. Even moderate hypothermia increases blood loss [3], cardiovascular events [4] and wound infections [5] and may prolong hospitalization [5] and increase mortality [6]. Conventional core body temperature measurements, e.g., pulmonary artery, esophagus, nasopharynx, or tympanum, are invasive [1]. ...
Zero-heat-flux core temperature measurements on the forehead (ZHF-forehead) show acceptable agreement with invasive core temperature measurements but are not always possible in general anesthesia. However, ZHF measurements over the carotid artery (ZHF-neck) have been shown reliable in cardiac surgery. We investigated these in non-cardiac surgery. In 99 craniotomy patients, we assessed agreement of ZHF-forehead and ZHF-neck (3M™ Bair Hugger™) with esophageal temperatures. We applied Bland-Altman analysis and calculated mean absolute differences (difference index) and proportion of differences within ± 0.5 °C (percentage index) during entire anesthesia and before and after esophageal temperature nadir. In Bland-Altman analysis [mean (limits of agreement)], agreement with esophageal temperature during entire anesthesia was 0.1 (−0.7 to +0.8) °C (ZHF-neck) and 0.0 (−0.8 to +0.8) °C (ZHF-forehead), and, after core temperature nadir, 0.1 (−0.5 to +0.7) °C and 0.1 (−0.6 to +0.8) °C, respectively. In difference index [median (interquartile range)], ZHF-neck and ZHF-forehead performed equally during entire anesthesia [ZHF-neck: 0.2 (0.1–0.3) °C vs ZHF-forehead: 0.2 (0.2–0.4) °C], and after core temperature nadir [0.2 (0.1–0.3) °C vs 0.2 (0.1–0.3) °C, respectively; all p > 0.017 after Bonferroni correction]. In percentage index [median (interquartile range)], both ZHF-neck [100 (92–100) %] and ZHF-forehead [100 (92–100) %] scored almost 100% after esophageal nadir. ZHF-neck measures core temperature as reliably as ZHF-forehead in non-cardiac surgery. ZHF-neck is an alternative to ZHF-forehead if the latter cannot be applied.
... Hypothermia is an important concern after surgery [4] that leads to an increased risk in septic complication (respiratory failure, heart failure, kidney failure, etc.) and mortality [5]. It is linked to a number of harmful effects including increased cardiovascular complications [6]; perioperative bleeding [7]; higher infection rate [8]; drug metabolism alteration [9]; and prolonged hospital stay decreasing patient's comfort and an increased hospitalization cost [1]. Management of body temperature is emphasized during the surgical period, as perioperative hypothermia mostly arises from a combination of anesthesia-induced impairment of thermoregulatory control and surgical factors, leading to excessive heat loss [1]. ...
Hypothermia is a medical crisis which arises when a patient's body significantly loses heat rather than producing heat. It is a vital concern after surgery, exerting multiple effects such as impairment of innate immunity leading to an increase complication and mortality risk. Postoperative care received after a surgical procedure includes discharge destination whether the patient is to be delivered to an intensive care unit (ICU), to be delivered to the general hospital floor or the patient is already allowed to be sent home. Since postoperative hypothermia is a serious risk, discharge decision corresponds roughly to patient's body temperature measurements. In this paper, we discuss the utilization of extreme gradient boosting (XGBoost) algorithm-a variant of gradient boosted algorithm and an ensemble of classification and regression tree, for classifying patient's postoperative discharge destination. Patients' data, including core and surface temperatures, blood pressure, blood oxygen level, stability of patient's internal and surface temperatures, stability of patient's blood pressure and postoperative perceived comfort are used as input features in formulating the XGBoost model. Experimental results show high performance of the formulated XGBoost model (accuracy = 0.8947, kappa coefficient = 0.8407, f-score = 0.90) in classifying postoperative patients' discharge destination compared to the methods used as discussed in section II. A ranking of feature importance is presented in the latter part of this paper.
... Unplanned perioperative hypothermia involves a decrease in core temperature to ≤ 36°C. [1] It results in an increased rate of surgical site infection, hemorrhagic tendency, and ischemic heart disease, [2][3][4][5] making it a serious perioperative complication. Therefore, their occurrence should be prevented. ...
The perfusion index (PI) cutoff value before anesthesia induction and the ratio of PI variation after anesthesia induction remain unclear. This study aimed to clarify the relationship between PI and central temperature during anesthesia induction, and the potential of PI in individualized and effective control of redistribution hypothermia. This prospective observational single center study analyzed 100 gastrointestinal surgeries performed under general anesthesia from August 2021 to February 2022. The PI was measured as peripheral perfusion, and the relationship between central and peripheral temperature values was investigated. Receiver operating characteristic curve analysis was performed to identify baseline PI before anesthesia, which predicts a decrease in central temperature 30 minutes after anesthesia induction, and the rate of change in PI that predicts the decrease in central temperature 60 minutes after anesthesia induction. In cases with a central temperature decrease of ≥ 0.6°C after 30 minutes, the area under the curve was 0.744, Youden index was 0.456, and the cutoff value of baseline PI was 2.30. In cases with a central temperature decrease of ≥ 0.6°C after 60 minutes, the area under curve was 0.857, Youden index was 0.693, and the cutoff value of the PI ratio of variation after 30 minutes of anesthesia induction was 1.58. If the baseline PI is ≤ 2.30 and the PI 30 minutes after anesthesia induction is at least 1.58-fold the PI ratio of variation, there is a high probability of a central temperature decrease of at least 0.6°C within 30 minutes after 2 time points.
... Hypothermia induces shivering and potentially causes an imbalance between systemic O delivery and consumption. Non-cardiac surgery patients exposed to temperatures of <35°C showed an increased risk of myocardial ischaemia [90]. Active warming with heated infusions and forced air circulation is warranted, depending on the character and length of the procedure. ...
This book is a physiological and evidence-based reference guide to the principles and techniques of advanced echocardiography. Both transoesophageal and transthoracic echocardiography are addressed, where appropriate. The foundations of advanced echocardiography are outlined in Part 1, preceding specific assessment methods of critical care echo which are demonstrated and discussed in Part 2. In reality, most critically ill patients do not suffer only one clinical problem, so Part 3 integrates techniques learned in Part 2 to answer both common and unexpected critical care questions. The future use of echocardiography in critical care is explored in Part 4. Important reference values for clinical use can be accessed easily in the appendices. An appendix includes videos, cases, and multiple-choice questions that can be used to reinforce understanding.
... Hypothermia induces shivering and potentially causes an imbalance between systemic O delivery and consumption. Non-cardiac surgery patients exposed to temperatures of <35°C showed an increased risk of myocardial ischaemia [90]. Active warming with heated infusions and forced air circulation is warranted, depending on the character and length of the procedure. ...
Cardiovascular diseases (CVDs) are a major cause of premature death worldwide and a cause of loss of disability-adjusted life years. For most types of CVD early diagnosis and intervention are independent drivers of patient outcome. Clinicians must be properly trained and centres appropriately equipped in order to deal with these critically ill cardiac patients. This new updated edition of the textbook continues to comprehensively approach all the different issues relating to intensive and acute cardiovascular care and addresses all those involved in intensive and acute cardiac care, not only cardiologists but also critical care specialists, emergency physicians and healthcare professionals. The chapters cover the various acute cardiovascular diseases that need high quality intensive treatment as well as organisational issues, cooperation among professionals, and interaction with other specialities in medicine.
... postoperative complications [2][3][4]. Body temperature is monitored at various locations, such as the esophagus and nasopharynx [5]. In addition, the rectal and bladder temperatures reasonably estimate the core temperature. ...
Background
Body temperature is a vital sign, and temperature monitoring during liver transplantation is important. Tracheal temperature can be measured via an endotracheal tube with a temperature sensor on the cuff of the tube. This study aimed to investigate the accuracy and trending ability of tracheal temperature measurement compared to those of the core temperature measured at the esophagus and pulmonary artery (PA) in living donor liver transplant recipients.
Methods
Twenty-two patients who underwent living donor liver transplantation (LDLT) were enrolled. Patients were intubated using an endotracheal tube with a temperature sensor placed on the inner surface of the tube cuff. Tracheal, esophageal, and PA temperatures were recorded at five time points corresponding to the different phases of liver transplantation. The tracheal and esophageal, tracheal and PA, and esophageal and PA temperatures were compared using Bland–Altman analysis, four-quadrant plot/concordance analysis, and polar plot analysis.
Results
Bland–Altman analysis showed an overall mean bias (95% limits of agreement) between tracheal and esophageal temperatures of -0.10 °C (-0.37 °C to 0.18 °C), with a percentage error of 0.27%; between tracheal and PA temperatures, -0.05 °C (-0.91 °C to 0.20 °C), with a percentage error of -0.15%; and between esophageal and PA temperatures, 0.04 °C (-0.27 °C to 0.35 °C), with a percentage error of 0.12%. The concordance rates between tracheal and esophageal temperatures, tracheal and PA temperatures, and esophageal and PA temperatures were 96.2%, 96.2%, and 94.94%, respectively. The polar plot analysis showed a mean angular bias (radial limits of agreement) of 4° (26°), -3° (13°), and 2° (21°).
Conclusions
Monitoring core temperature at the inner surface of the endotracheal tube cuff is accurate in all phases of LDLT with good trending ability; thus, it can be an excellent alternative for monitoring during LDLTs.
... Prospective randomized data suggest that high-risk patients assigned to only 1.3°C core hypothermia were three times more likely to experience adverse myocardial. Marked increase in plasma catecholamine level is perhaps associated with highrisk cardiac complications [6]. ...
... [16] Hypothermia causes stress in the process of rewarming, thus resulting in adverse effects such as damage to the blood coagulation mechanism and leukocyte function and an increase in cardiovascular burden. [17] In addition, intraoperative and early postoperative heat preservation has been proven to reduce intraoperative bleeding, postoperative infection, and cardiac complications. [18] Therefore, all the patients were kept warm by an air heater during the operation in the ERAS group. ...
Few reports have focused on the use of enhanced recovery after surgery (ERAS) in laparoscopic common bile duct exploration (LCBDE) to promote the postoperative recovery of patients with choledocholithiasis. Therefore, this study aimed to explore the advantages and safety of ERAS in patients who underwent LCBDE. From December 2016 to February 2020, 86 and 84 patients were retrospectively enrolled in the control and ERAS groups, respectively. The perioperative insulin resistance index, perioperative C-reactive protein level, time of postoperative analgesic use, time of postoperative first flatus, time of abdominal drainage tube removal, time of liver function recovery, and postoperative complications were analyzed between the two groups. The insulin resistance index (1, 3, and 5 days postoperatively) and C-reactive protein level (1, 3, 5, and 7 days postoperatively) in the ERAS group were significantly lower than those in the control group (all P < .05). In terms of the postoperative rehabilitation efficacy, the time of postoperative activity of the patient, time of postoperative first flatus, time of postoperative analgesic use, time of abdominal drainage tube removal, time of postoperative T-tube closing, and length of postoperative hospital stay in the ERAS group were significantly shorter than those in the control group (all P < .05). Additionally, the overall incidence of postoperative complications in the ERAS group had a decreasing trend when compared with that in the control group (P = .05). ERAS can reduce the postoperative stress response and postoperative complications of patients undergoing LCBDE, promote rehabilitation and shorten the length of postoperative hospital stay and therefore has good social and economic benefits.
... Body temperature is a critical vital sign, and its measurement during surgery is an integral part of standard American Society of Anesthesiologists monitoring [1,2]. Intraoperative hypothermia has been associated with perioperative complications, such as surgical wound infections, cardiac morbidity, coagulopathy, impaired drug metabolism, and prolonged recovery [3][4][5][6][7]. Given its profound impact on postoperative outcomes, accurately accounting for intraoperative temperature in large perioperative database studies is of paramount importance. ...
Background
The automated acquisition of intraoperative patient temperature data via temperature probes leads to the possibility of producing a number of artifacts related to probe positioning that may impact these probes’ utility for observational research.
Objective
We sought to compare the performance of two de novo algorithms for filtering such artifacts.
Methods
In this observational retrospective study, the intraoperative temperature data of adults who received general anesthesia for noncardiac surgery were extracted from the Multicenter Perioperative Outcomes Group registry. Two algorithms were developed and then compared to the reference standard—anesthesiologists’ manual artifact detection process. Algorithm 1 (a slope-based algorithm) was based on the linear curve fit of 3 adjacent temperature data points. Algorithm 2 (an interval-based algorithm) assessed for time gaps between contiguous temperature recordings. Sensitivity and specificity values for artifact detection were calculated for each algorithm, as were mean temperatures and areas under the curve for hypothermia (temperatures below 36 C) for each patient, after artifact removal via each methodology.
Results
A total of 27,683 temperature readings from 200 anesthetic records were analyzed. The overall agreement among the anesthesiologists was 92.1%. Both algorithms had high specificity but moderate sensitivity (specificity: 99.02% for algorithm 1 vs 99.54% for algorithm 2; sensitivity: 49.13% for algorithm 1 vs 37.72% for algorithm 2; F-score: 0.65 for algorithm 1 vs 0.55 for algorithm 2). The areas under the curve for time × hypothermic temperature and the mean temperatures recorded for each case after artifact removal were similar between the algorithms and the anesthesiologists.
Conclusions
The tested algorithms provide an automated way to filter intraoperative temperature artifacts that closely approximates manual sorting by anesthesiologists. Our study provides evidence demonstrating the efficacy of highly generalizable artifact reduction algorithms that can be readily used by observational studies that rely on automated intraoperative data acquisition.
... Intraoperative hypothermia is known to be associated with complications [1][2][3] such as delayed recovery from anesthesia, higher incidence of surgical site infections, impaired coagulation, increased blood loss, and increased cardiac morbidity. Therefore, maintaining body temperature during surgery is closely related to postoperative outcomes. ...
Maintaining body temperature in pediatric patients is critical, but it is often difficult to use currently accepted core temperature measurement methods. Several studies have validated the use of the SpotOn sensor for measuring core temperature in adults, but studies on pediatric patients are still lacking. The aim of this study was to investigate the accuracy of the SpotOn sensor compared with that of esophageal temperature measurement in pediatric patients intraoperatively. Children aged 1–8 years with American Society of Anesthesiology Physical Condition Classification I or II scheduled to undergo elective ear surgery for at least 30 min under general anesthesia were enrolled. Body core temperature was measured every 15 min after induction till the end of anesthesia with an esophageal probe, axillary probe, and SpotOn sensor. We included 49 patients, providing a total 466 paired measurements. Analysis of Pearson rank correlation between SpotOn and esophageal pairs showed a correlation coefficient (r) of 0.93 (95% confidence interval [CI] 0.92–0.94). Analysis of Pearson rank correlation between esophageal and axillary pairs gave a correlation coefficient (r) of 0.89 (95% CI 0.87–0.91). Between the SpotOn and esophageal groups, Bland-Altman analysis revealed a bias (SD, 95% limits of agreement) of -0.07 (0.17 [-0.41–0.28]). Between the esophageal and axillary groups, Bland-Altman analysis showed a bias (SD, 95% limits of agreement) of 0.45 (0.22 [0–0.89]). In pediatric patients during surgery, the SpotOn sensor showed high correlation and agreement with the esophageal probe, which is a representative core temperature measurement method.
... IIH is one of the most prevalent events faced by anaesthesiologists, with a current prevalence of 20%-70%, 1-4 even up to 90% decades ago. 5,6 It is a risk factor for a series of postoperative complications, including bleeding and blood product transfusion, 7,8 cardiovascular events, 9,10 postoperative infection, 10,11 shivering, 12 drug metabolism disorder, 13 prolonged stay in the postanaesthetic recovery unit 14 and increased length of hospital stay, 10,11,15 etc. All of these unfavourable consequences lead to increased hospitalisation expense, [16][17][18] patient discomfort, and complains. ...
Purpose:
Inadvertent intraoperative hypothermia (IIH) is generally associated with several postoperative complications. Inspite of the existing guidelines, the global incidence of IIH remains unacceptably high. Understanding the conditions that influence temperature management is critical for developing future interventions to improve the postoperative patient outcomes. This study aimed to identify the major factors that hinder the implementation of IIH prevention practices.
Methods:
Through a literature research, pilot small-sample investigation, and expert suggestions, 11 factors that may hinder the implementation of IIH prevention practices were identified. A questionnaire was developed, and each question was used to assess each factor. After approval by the Research Ethics Board, the questionnaires were sent to the staff anaesthesiologists at two academic hospitals via WeChat. Each answer was coded according to the degree to which the factor was affected, as anticipated. Finally, the answers were analysed based on the 80/20 rule to identify the major barriers to effective temperature management.
Results:
We included 195 participants. Knowledge, memory, attention and decision processes, beliefs about consequences, and environmental context and resources were the major factors, with cumulative composition ratios of 24%, 43.4%, 57.7%, and 70.7%, respectively. Meanwhile, behavioural regulation and social influence were the secondary factors, with cumulative composition ratios of 80.4% and 87.5%, respectively. Reinforcement, confidence in capacity, duty realisation, skills, and intention were the general factors with cumulative composition ratios of 94.3%, 99.8%, 100%, 100%, and 100%, respectively.
Conclusion:
Four factors-knowledge, memory, attention and decision process, beliefs about consequences, and environmental context and resources-were the major factors that influence the effective hypothermia prevention practice.
Relevance to clinical practice:
These major factors will be used in further studies as a basis to develop the corresponding solutions and improve the patient outcomes in clinical practice.
... Unplanned perioperative hypothermia is de ned as the decrease of core temperature to 36°C or lower during the perioperative period [1]. Unplanned perioperative hypothermia results in an increased rate of surgical site infection, hemorrhagic tendency, and ischemic heart disease [2][3][4][5], making it a serious perioperative complication. Thus, its occurrence should be prevented as far as possible. ...
Background
The cut-off value of perfusion index (PI) before the induction of anesthesia and the ratio of PI variation after the induction of anesthesia, which is effective in preventing redistribution hypothermia, have not been clarified to date. This study aimed to clarify the relationship between PI and central temperature during the induction of anesthesia and PI potential for individualized and effective control of redistribution hypothermia.
Methods
This prospective observational single-center study analyzed 100 cases of general anesthesia gastrointestinal surgery in the operating room from August 2021 to February 2022. PI was measured as peripheral perfusion, and the relationship between central and peripheral temperature values was investigated. Receiver operating characteristic curve analysis was performed to identify the baseline PI before anesthesia that predicts the decrease in central temperature 30 min after anesthesia induction and the rate of change in PI that predicts the decrease in central temperature 60 min after anesthesia induction.
Results
PI had a significant association with peripheral (p < 0.01) and central temperatures (p < 0.01). In cases where the central temperature decreased by ≥ 0.6℃ after 30 min, the area under the curve (AUC) was 0.744, Youden’s index was 0.456, and cut-off value of baseline PI was 2.30. In cases in which the central temperature decreased by ≥ 0.6℃ after 60 min, the AUC was 0.857, Youden’s index was 0.693, and cut-off value of the ratio of variation in PI after 30 min of anesthesia induction was 1.58.
Conclusions
Our results indicate that if baseline PI is 2.30 or lower and the PI 30 min after induction of anesthesia is at least 1.58 times the PI ratio of variation, there is a high probability of the central temperature decreasing by at least 0.6℃ within 30 min after each timepoint.
... Development of hypothermia during surgery is associated with increased risks of surgical wound infection, blood loss, and cardiac events [29][30][31]. Strategies to maintain normothermia include forced air-warming, warming of intravenous fluids, and increasing the operating room temperature. ...
Enhanced recovery after surgery (ERAS) protocols for obstetrics are unique and include pathway elements for both the mother and the newborn. We compare the ERAS Society and the Society for Obstetrics and Perinatology (SOAP) recently published guidelines and discuss selected pre-, intra-, and post-cesarean pathway elements from both guidelines, presenting a systematic review of the literature.
... To the Editor-The American Society of Anesthesiologists practice guidelines recommend normothermia as a goal during anesthetic emergence and recovery 1 in part to reduce adverse cardiac events. 2 The Bair Hugger (3M, St Paul, MN) is a type of forced-air warming (FAW) device commonly used to maintain intraoperative normothermia; however, its use is not without the potential for harm. 3 Surgical site infection (SSI) is a major risk of any surgical procedure. ...
... We preferred to use multiple time points of static image acquisition for short durations under intermittent anesthesia over a longer duration of dynamic imaging under continuous anesthesia primarily because the CSF flow in the spinal SAS, the CSF clearance from spinal SAS to peripheral lymphatic, and the contractility of peripheral lymph vessels are significantly inhibited by isoflurane in comparison to the awake condition [75,76] which altogether can explain the 9-min post-injection image (Fig. 3) showing faint visualization of cranial and sacral SAS along with non-visualization of peripheral lymph nodes when the animal had been under continuous anesthesia for intrathecal access followed by the injection and then the image acquisition. Moreover, a 60-min period of isoflurane inhalation without thermal support can cause hypothermia [77] that may lead to potentially fatal cardiorespiratory dysregulation [78]. ...
Purpose Clearance of brain waste in the cerebrospinal fluid (CSF) through the meningeal lymphatic vessels (mLV) has been evaluated mostly through the fluorescent imaging which has inherent limitations in the context of animal physiology and clinical
translatability. The study aimed to establish molecular imaging for the evaluation of mLV clearance function.
Methods Radionuclide imaging after intrathecal (IT) injection was acquired in C57BL/6 mice of 2–9 months. The distribution of [99mTc]Tc-diethylenetriamine pentaacetate (DTPA) and [64Cu]Cu-human serum albumin (HSA) was comparatively evaluated.
Evans Blue and [64Cu]Cu-HSA were used to evaluate the distribution of tracer under various speed and volume conditions.
Results [
99mTc]Tc-DTPA is not a suitable tracer for evaluation of CSF clearance via mLV as no cervical lymph node uptake was
observed while it was cleared from the body. A total volume of 3 to 9 μL at an infusion rate of 300 to 500 nL/min was not
sufficient for the tracer to reach the cranial subarachnoid space and clear throughout the mLV. As a result, whole-body positron
emission tomography imaging using [64Cu]Cu-HSA at 700 nL/min, to deliver 6 μL of injected volume, was set for characterization of the CSF to mLV clearance. Through this protocol, the mean terminal CSF clearance half-life was measured to be
123.6 min (range 117.0–135.0) in normal mice.
Conclusions We established molecular imaging to evaluate CSF drainage through mLV using [64Cu]Cu-HSA. This imaging method is expected to be extended in animal models of dysfunctional meningeal lymphatic clearance and translational research
for disease-modifying therapeutic approaches.
A Hipotermia não intencional definida como temperatura sanguínea central menor que 36°C acontece frequentemente durante anestesia em cerca de 20% da população cirúrgica e aumenta até 90% quando se trata do período pós-operatório. Em pacientes oncológicos a situação é mais grave pois pode contribuir para recorrência ou metástases das neoplasias. A Fundação Centro de Controle de Oncologia do Estado do Amazonas (FCECON) é instituição de referência na pesquisa, diagnóstico e tratamento do câncer em toda a Amazônia Ocidental e inserida na rede de atendimento de alta complexidade, no entanto, ainda não se tinha estudo sobre hipotermia nos pacientes oncológicos que são submetidos a cirurgia eletiva. Desde modo, este estudo buscou avaliar a incidência de hipotermia perioperatória em pacientes oncológicos submetidos a cirurgia eletiva na FCECON. A pesquisa tem como objetivo analisar a hipotermia em pacientes oncológicos submetidos a cirurgias eletivas na FCECON através da determinação da incidência e identificação do perfil clínico epidemiológico dos pacientes. Trata-se de estudo qualitativo etnográfico prospectivo, com questionário semiestruturado para examinar a hipotermia em pacientes cirúrgicos oncológicos acima de 18 anos de idade na FCECON. A temperatura dos pacientes foi aferida em quatro momentos diferentes, classificados de acordo com a sua relação com o procedimento anestésico-cirúrgico. Foi observado a ocorrência de hipotermia em 21,8% dos pacientes em pelo menos um dos estágios para cirurgias eletivas na FCECON, com maior incidência nos pacientes idosos. A hipotermia perioperatória é um problema prevalente em pacientes oncológicos submetidos a cirurgias eletivas na FCECON. Mais de 20% dos pacientes avaliados evoluíram com hipotermia em pelo menos um dos estágios perioperatórios avaliados no estudo. Pacientes analisados apresentaram hipotermia principalmente no estágio intraoperatório, com maior incidência nos pacientes idosos. Os anestesiologistas apresentaram boa capacidade de resolução do quadro de hipotermia, principalmente no período de recuperação pós-anestésica. Estes achados têm potencial para influenciar protocolos clínicos e direcionar melhorias nas estratégias para uma assistência perioperatória mais segura e eficaz em pacientes oncológicos submetidos a procedimentos cirúrgicos.
Hasta Güvenliği: Neden Biz? Ne Durumdayız? Tuğhan UTKU Anestezide Hasta Güvenliği Dünden Bugüne Zuhal AYKAÇ Güvenlik Kültürü Nasıl Geliştirilir? Çiğdem SİZER, İnci KARA Hasta Güvenliğini Tehdit Edenlerden/Hatalardan Öğrenimler Serhan ÇOLAKOĞLU Hata ve Zararın Nitelik ve Ölçekleri Çiğdem SİZER, İnci KARA Hata Bildirim Sistemleri-Raporlama ve Öğrenme Sistemleri Dilek ÖMÜR Güvenlik Değerlendirme Kalite-Ölçüm Stratejileri Kerem ERKALP Güvenli Kuruluşlar Mine AKIN Sağlık Politikaları ve Hasta Güvenliği Özge KÖNER Hasta Güvenliğinde Teknik Olmayan Beceriler Nazan ATALAN Ameliyat Öncesi Teşhis Hataları - Preoperatif Değerlendirme Hataları ve Güvenlik Gülsen KESKİN Ameliyathanelerde Güvenlik Özcan PİŞKİN Anestezi Makine ve Ekipman Kullanımında Güvenlik Tuğba AŞKIN Hastaların Ameliyathaneye Transferleri ve Güvenlik Gamze KÜÇÜKOSMAN İntraoperatif Hatalar ve Güvenlik Özge KÖNER Termoregülasyon ve Perioperatif İstemsiz Hipotermi Hülya BİLGİN İlaç Hataları Ayşegül ÖZGÖK Rejyonal Anestezide Hasta Güvenliği Bengü AYDIN Anestezik Farmakolojide Hasta Güvenliği Volkan HANCI, Gözde GÜRSOY ÇİRKİNOĞLU Postoperatif Hatalar ve Güvenlik Hilal AYOĞLU Postoperatif Ağrı Kontrolünde ve Ağrı Tedavisinde Hasta Güvenliği Edip GÖNÜLLÜ Yoğun bakımda hasta güvenliği Volkan HANCI, Taner ÇALIŞKAN Hasta Transferleri ve Güvenlik Nilay BOZTAŞ Ameliyathane Dışı ve Günübirlik Anestezi Uygulamalarında Güvenlik Derya ARSLAN YURTLU Düşmeleri Önleme Bengü Gülhan AYDIN Bası Ülserlerini Önleme Bengü Gülhan AYDIN Deliryumu Önleme Nazan ATALAN Derin Ven Trombozu Proflaksisi Seval ÜRKMEZ, Tuğhan UTKU Zor / Başarısız Havayolu Hastanın Preoperatif Değerlendirilmesi ve Planlanması İpek EDİPOĞLU Anafilaksi Tolga SARAÇOĞLU Lokal Anestezik Toksisitesi Tolga SARAÇOĞLU Enfeksiyon Kontrolü Yetkin ÖZER Kayıtlarda ve Orderlarda Güvenlik ve Gizlilik Seyhan YAĞAR Pediatrik Hastalarda Güvenlik Yeşim ŞENAYLI Geriatrik Hastalarda Güvenlik Ayten SARAÇOĞLU Obstetrik Hastalarda Güvenlik İpek EDİPOĞLU Teknoloji ve Standardizasyon Tasarımı (Güvenlik Riskleri) Yetkin ÖZER Çevresel Etmenler ve Güvenlik Hilal AYOĞLU Eğitim ve Öğretim Yeşim ŞENAYLI Hasta Güvenliğinde Simülasyon Eğitimi ve Kriz Kaynak Yönetiminde Simülasyon Ayten SARAÇOĞLU Uzmanlık Öğrencisi Eğitiminde Hasta Güvenliği Ayşegül ÖZGÖK Klinik Araştırmalarda Katılımcıların (Hastaların, Sağlıklı Bireylerin) Güvenliğinin Sağlanması Seyhan YAĞAR Akreditasyon ve Düzenlemeler Aysun YILMAZLAR Hasta Güvenliğinde Yalın Uygulamalar Aysun YILMAZLAR
Objectives
To develop a consensus on evidence-based principles and recommendations for perioperative hypothermia prevention in the Australian context.
Design
This study was informed by CAN-IMPLEMENT using the ADAPTE process: (1) formation of a multidisciplinary development team; (2) systematic search process identifying existing guidance for perioperative hypothermia prevention; (3) appraisal using the AGREE II Rigor of Development domain; (4) extraction of recommendations from guidelines meeting a quality threshold using the AGREE-REX tool; (5) review of draft principles and recommendations by multidisciplinary clinicians nationally and (6) subsequent round of discussion, drafting, reflection and revision by the original panel member team.
Setting
Australian perioperative departments.
Participants
Registered nurses, anaesthetists, surgeons and anaesthetic allied health practitioners.
Results
A total of 23 papers (12 guidelines, 6 evidence summaries, 3 standards, 1 best practice sheet and 1 evidence-based bundle) formed the evidence base. After evidence synthesis and development of draft recommendations, 219 perioperative clinicians provided feedback. Following refinement, three simple principles for perioperative hypothermia prevention were developed with supporting practice recommendations: (1) actively monitor core temperature for all patients at all times; (2) warm actively to keep body temperature above 36°C and patients comfortable and (3) minimise exposure to cold at all stages of perioperative care.
Conclusion
This consensus process has generated principles and practice recommendations for hypothermia prevention that are ready for implementation with local adaptation. Further evaluation will be undertaken in a large-scale implementation trial across Australian hospitals.
Objective: This study was designed to evaluate the impact of different temperatures of intravenous fluids on the body. Study Design: Randomized Experiment. Setting: LRH Peshawar. Period: April 2022 to January 2023. Material & Methods: 600 individuals were scheduled for abdominal surgery to include them in the study. Two groups were made using sealed, opaque envelopes carrying randomly generated computer numbers. The patient's body temperature, O2 saturation,, heart rate, shivering, blood pressure and fluid intake were all monitored and recorded on two point i)when he was admitted to the PAR and ii) one and a half hour later. The classification developed by Crossley and Mahajan was used to determine the level of shivering. With SPSS 23, the t test and Mann-Whitney U test were used to evaluate data. Results: The mean age of the intervention group was 38.30 years, compared to 37.64 years for the control group. After 30 minutes, the average temperature difference among the two groups on admission to PAR was statistically significant. No discernible difference existed between the levels of pain of two groups. Time to return to work was reported to differ significantly. For factors like SpO2, systolic and diastolic blood pressure, and respiratory rate, no discernible difference was discovered. Conclusion: After administering warm fluids intravenously, there is a fall in the intervention group's shivering.
Introduction: Laparoscopic cholecystectomy remains the standardtreatment for cholelithiasis. Everincreasing number of patients with myriad of medical illness is being treated by this technique. However,significant concern prevails among the surgical community regarding its safety in patients with cardiacco-morbidity. Patients with diabetes, significant cardiac dysfunction and multiple co-morbidities wereprospectively evaluated. Patients were assessed by cardiologists and anesthesiologists and laparoscopiccholecystectomy was performed. Results: Patient demographics, details of peri-operative management and post-operative complicationswere studied.Between July 2014 and January 2018, 32 patients (M:F=24:08) with mean age of 55 years(range 36–78) and having significant cardiac dysfunction had undergone laparoscopic cholecystectomy.Of these, 24 patients were in NYHA class-II, while 8 belonged to class-III. Left ventricular ejection fraction,as recorded by transthoracic echocardiography, was20–30% in 08 (25%) patients and 30–40% in the rest24(75%). In addition, 21 (71%) patients had regional wall motion abnormalities, 11 (34%) patients hadcardiomyopathy while 09 (39%)patients had prior cardiac interventions. Following laparoscopiccholecystectomy, hypertension (21), tachyarrhythmia(4) and bradycardia (2) were the commonest eventsencountered.Two patients required dopamine in the immediate postoperative period but all other patientsmade an uneventful recovery. Conclusion: With appropriate cardiological support, laparoscopic cholecystectomy may be safely performedin patients with significant cardiac dysfunction. JBSA 2020; 33(2): 78-84
Purpose: Inadvertent perioperative hypothermia (IPH) is a common complication of anesthesia and surgical exposure. Although considerably increased attention has been paid to the role of IPH over the past decades, a systematical bibliometric analysis on this topic has not yet been performed. This study aimed to investigate current research hotspot and predict future trends in IPH research using bibliometric analysis.
Methods: The relevant literatures published from 2000 to 2022 were identified and selected from the Science Citation Index Expanded of Web of Science Core Collection (WoSCC). The VOSviewer and CiteSpace software were used to perform collaboration network analysis, co-citation analysis, co-occurrence analysis, and citation burst detection.
Results: 1685 publications (1450 articles and 235 reviews) from WoSCC were used for analysis and visualization. The United States has made the largest contribution in this field, with most publications (535, 31.8%), and closely collaborations with China and Canada. The most productive institution and scholar in this field were University of Sao Paulo (30, 1.8%) and Professor Braeuer (19, 1.13%), respectively. Anesthesia and Analgesia was the most productive journal. The top ten keywords based on the co-occurrence analysis are “hypothermia”, “cardiopulmonary bypass”, “body temperature, “anesthesia”, “surgery”, “cardiac surgery”, “damage control surgery”, “perioperative hypothermia”, “trauma”, “bleeding”. The emerging research hotspot might be “active warming “, “prewarming”, and “forced-air warming”.
Conclusion: This study analyzed the IPH using bibliometric and visual analysis. These results provide an instructive perspective on the current research and future directions and give a potential foundation for further research and clinical applications.
Background
Avoiding inadvertent hypothermia during surgery is important. Intravenous fluid warmers used intraoperatively are critical for maintaining euthermia. We sought to prospectively evaluate the performance of the parylene-coated enFlow™ intravenous fluid warmer in patients undergoing surgery.
Methods
This was a prospective two-center observational clinical trial performed in inpatient surgical services of two large academic hospital systems. After informed consent, patients were enrolled in the study. All patients were adults scheduled for a surgery that was expected to last for at least 1 h with the administration of at least one liter of fluid warmed prior to infusion. Patient temperature was recorded in the preoperative unit, at the induction of anesthesia, and then every 15 or 30 minutes until the end of surgery. Temperature monitoring continued in the recovery unit. The parylene-coated enFlow™ intravenous fluid warmer was used in addition to the usual patient warming techniques. The primary outcome was the average core temperature, and secondary analyses assessed individual temperature measurements, temperature measurements during specific time periods, and rate of hypothermic events.
Results
Fifty patients (29 male) with a mean age of 64 years were included in the analysis. The mean surgical time was 195 minutes and patients received an average of 1142 ml of fluids. Core temperature dropped by only 0.3°C approximately 60 minutes after induction and recovered back to the baseline level approximately 60 minutes later. There was no correlation between flow rate and measured core body temperature.
Conclusions
The parylene-coated enFlow intravenous fluid warmer was able to warm fluids at all flow rates during prolonged surgery. The results showed that enFlow performed as expected.
Trial registration
The trial was registered prior to patient enrollment at clinicaltrials.gov (NCT04709627, Principal investigator: Mikko Lax, MD, Date of registration: 14 January 2021.)
Oral nutritional intake impacts the postoperative course in surgical patients. The enhanced recovery after surgery (ERAS) concept embeds the early resumption of oral intake as a key item in all of its guidelines. Gynecological and obstetrics patients benefit from this methodology, especially for malnourished and underfed patients. Tailored feeding based on individual tolerance is key. Efforts and monitoring of nutritional intake should be pursued not only during the hospital stay but after leaving hospital as well.
Objective
To investigate whether the temperature recorded by an iThermonitor has better concordance with the core temperature than the bladder temperature recorded by a Foley catheter sensor in laparoscopic rectal surgery.
Methods
Eighty-two adults undergoing laparoscopic rectal surgery were enrolled. Temperatures were continuously measured by a distal oesophageal probe (the reference core temperature), axillary iThermonitor and Foley catheter sensor (bladder temperature) in each patient during surgery. Pairs of axillary and core temperatures or pairs of bladder temperature and core temperatures were compared and summarized using linear regression and the repeated-measured Bland–Altman method during the whole surgical period and pneumoperitoneum period.
Results
There were 3303 pairs of temperature measurements during the whole surgical period. The mean difference between iThermonitor and oesophageal was 0.05 °C ; the limits of agreement were − 0.48 to 0.56 °C. The mean difference between the oesophagus and bladder was 0.28 °C; the limits of agreement were − 0.39 to 0.94 °C (P < 0.001, F-test vs. iThermonitor). Ninety -five% of all iThermonitor values were within 0.5 °C of oesophageal temperature, whereas the proportion for oesophageal and bladder differences within 0.5 °C was only 84% (95% confidence interval 80–88%). Lin’s CCC for the iThermonitor and bladder measurements were 0.842 (95%CI: 0.831–0.851) and 0.688 (95%CI: 0.673–0.703) respectively. Similar results were found during the pneumoperitoneum period.
Conclusions
The temperature recorded by iThermonitor has better concordance with the core temperature than the bladder temperature recorded by Foley catheter sensor in laparoscopic rectal surgery.
Objectives
To identify and explore barriers that healthcare professionals working as prehospital care (PHC) providers at the University Hospital of North Norway experience with temperature monitoring and discover solutions to these problems.
Study design
Qualitative study using the modified nominal group technique.
Materials and methods
14 experienced healthcare professionals working in air and ground emergency medical services were invited to the study. Initially, each participant was asked to suggest through email topics of importance regarding barriers to prehospital thermometry. Afterwards, they received a list of all disparate topics and were asked to individually rank them by importance. The top-ranked topics were discussed in a consensus meeting. The meeting was audio-recorded and a transcript was written and then analysed through an inductive thematic analysis.
Results
13 participants accepted the invitation. 63 suggestions were reduced to 24 disparate topics after removal of duplicates. Twelve highly ranked topics were discussed during the consensus meeting. Thematic analysis revealed 47 codes that were grouped together into six overarching themes, of which four described challenges to monitoring and two described potential solutions: equipment dissatisfaction, little focus on patient temperature, fear of iatrogenic complications, thermometry subordinated, more focus on temperature and simplification of thermometry.
Conclusion
To increase the frequency of temperature measurement on correct indication, we suggest introducing PHC protocols that specify patients and conditions where an accurate temperature measurement should have high priority. Furthermore, there is a profound need for more suitable techniques for temperature monitoring in the prehospital setting.
Elderly surgical patients present a specific challenge to anaesthesiologists. This chapter elaborates on the risk to elderly patients during the perioperative period and how they may be managed in order to minimise postoperative morbidity and mortality in this potentially vulnerable patient group. The cardiovascular system undergoes significant age‐related changes. These changes have specific consequences for the patient when undergoing anaesthesia. The morbidity associated with anaesthesia and surgery in older patients most commonly takes the form of postoperative confusion (POC) or stroke. The risk factors for the development of POC are also listed. The physiological changes associated with ageing predispose older patients to respiratory complications after surgery and anaesthesia. Neurological complications are the most common surgical complication in the elderly population.
Intraoperative hypothermia increases perioperative morbidity and identifying patients at risk preoperatively is challenging. The aim of this study was to develop and internally validate prediction models for intraoperative hypothermia occurring despite active warming and to implement the algorithm in an online risk estimation tool. The final dataset included 36,371 surgery cases between September 2013 and May 2019 at the Vienna General Hospital. The primary outcome was minimum temperature measured during surgery. Preoperative data, initial vital signs measured before induction of anesthesia, and known comorbidities recorded in the preanesthetic clinic (PAC) were available, and the final predictors were selected by forward selection and backward elimination. Three models with different levels of information were developed and their predictive performance for minimum temperature below 36 °C and 35.5 °C was assessed using discrimination and calibration. Moderate hypothermia (below 35.5 °C) was observed in 18.2% of cases. The algorithm to predict inadvertent intraoperative hypothermia performed well with concordance statistics of 0.71 (36 °C) and 0.70 (35.5 °C) for the model including data from the preanesthetic clinic. All models were well-calibrated for 36 °C and 35.5 °C. Finally, a web-based implementation of the algorithm was programmed to facilitate the calculation of the probabilistic prediction of a patient’s core temperature to fall below 35.5 °C during surgery. The results indicate that inadvertent intraoperative hypothermia still occurs frequently despite active warming. Additional thermoregulatory measures may be needed to increase the rate of perioperative normothermia. The developed prediction models can support clinical decision-makers in identifying the patients at risk for intraoperative hypothermia and help optimize allocation of additional thermoregulatory interventions.
Seventeen male patients with angina pectoris, and a history of increased severity of angina in the cold, performed submaximal bicycle exercise tests in a normal (20°C) and a cold environment (-10°C, 2.2 m/s wind velocity) wearing standardised clothing. Observations were made during and after serial short-term exercise periods each starting at 50 W, with continuous load increase of 10 to 30 W per minute, separated by 30-minute rest intervals. In the group as a whole, maximal work load decreased by 7 per cent during exposure to cold. Heart rate, systolic blood pressure, and rate-pressure product were significantly higher during submaximal exercise in the cold, but at maximal work load there was no difference in heart rate, rate-pressure product, or magnitude of ST segment depression. The decrease in maximal work load exceeded 5 per cent (mean 11%) in 10 patients, who were described as cold-susceptible, while the decrease averaged 1 per cent in the seven non-susceptible patients. The cold-induced reduction in maximal work load showed a significant correlation with the increase in heart rate, blood pressure, and rate-pressure product during submaximal exercise. After exercise, heart rate was significantly lower and blood pressure and rate-pressure product significantly higher in the cold than at normal temperature in all patients. In cold-susceptible patients, blood pressure was significantly higher at two and four minutes after exercise, and rate-pressure product at two minutes after exercise, than in non-susceptible patients, but in spite of this angina disappeared more quickly in cold-susceptible patients. In conclusion, subjective cold intolerance was objectively demonstrated in 10 out of 17 patients with angina pectoris, by exercise in a room at -10°C. Susceptibility to cold was explained by a higher heart rate and blood pressure during exercise in the cold room, than during exercise in the room at normal temperature.
There are significant physiologic differences between spinal and epidural anesthesia. Consequently, these two types of regional anesthesia may influence thermoregulatory processing differently. Accordingly, in volunteers and in patients, we tested the null hypothesis that the core-temperature thresholds triggering thermoregulatory sweating, vasoconstriction, and shivering are similar during epidural and spinal anesthesia.
Six male volunteers participated on three consecutive study days: epidural or spinal anesthesia were randomly assigned on the 1st and 3rd days (approximately T10 level); no anesthesia was given on the 2nd day. On each day, the volunteers were initially warmed until they started to sweat, and subsequently cooled by central venous infusion of cold fluid until they shivered. Mean skin temperature was kept constant near 36 degrees C throughout each study. The tympanic membrane temperatures triggering a sweating rate of 40 g.m-2.h-1, a finger flow less than 0.1 ml/min, and a marked and sustained increase in oxygen consumption (approximately 30%) were considered the thermoregulatory thresholds for sweating, vasoconstriction, and shivering, respectively. Twenty-one patients were randomly assigned to receive epidural (n = 10) or spinal (n = 11) anesthesia for knee and calf surgery (approximately T10 level). As in the volunteers, the shivering threshold was defined as the tympanic membrane temperature triggering a sustained increase in oxygen consumption.
The thresholds and ranges were similar during epidural and spinal anesthesia in the volunteers. However, the sweating-to-vasoconstriction (inter-threshold) range, the vasoconstriction-to-shivering range, and the sweating-to-shivering range all were significantly increased by regional anesthesia. The shivering thresholds in patients assigned to epidural and spinal anesthesia were virtually identical.
Comparable sweating, vasoconstriction, and shivering thresholds during epidural and spinal anesthesia suggest that thermoregulatory processing is similar during each type of regional anesthesia. However, thermoregulatory control was impaired during regional anesthesia, as indicated by the significantly enlarged inter-threshold and sweating-to-shivering ranges.
Previous investigators have proposed that postoperative shivering may be poorly tolerated by patients with cardiopulmonary disease because of the associated significant increase in total-body oxygen consumption. However, the often-quoted 300-400% increase in oxygen consumption with shivering was derived from relatively few studies performed in a small number of younger persons specifically selected on the basis of clinically recognizable shivering. We hypothesized that the average elderly postoperative patient has a shivering response that is associated with a relatively small increase in total-body oxygen consumption.
One hundred eleven elderly patients (age > 60 yr) undergoing surgery were studied to assess the determinants of shivering and total-body oxygen consumption in the early postoperative period. Anesthetic technique, postoperative analgesia, and thermal management were controlled by protocol. The clinical variables associated with shivering and increased total-body oxygen consumption were determined by univariate and multivariate analyses.
Mean total-body oxygen consumption in shivering patients was 38% greater than in nonshivering patients. Regardless of whether data from shivering patients were included in the analysis, oxygen consumption was directly proportional to mean body temperature. Despite similar core temperatures, men had a greater incidence of clinically recognizable shivering and greater total-body oxygen consumption than did women.
The metabolic demands associated with postoperative shivering in elderly patients are less than those reported previously in younger persons. These findings suggest that if hypothermia predisposes to cardiovascular complications in the postoperative period, these complications are not likely to be mediated by shivering and increased metabolism.
Background: Hypothermia occurs commonly during surgery and can be associated with increased metabolic demands during rewarming in the postoperative period. Although cardiac complications remain the leading cause of morbidity after anesthesia and surgery, the relationship between unintentional hypothermia and myocardial ischemia during the perioperative period has not been studied.
Background: Surgical trauma elicits diffuse changes in hormonal secretion and autonomic nervous system activity. Despite studies demonstrating modulation of the stress response by different anesthetic/analgesic regimens, little is known regarding the determinants of catecholamine and cortisol responses to surgery.
Unintended hypothermia occurs frequently during surgery and may have adverse effects on the cardiovascular system. Although the mechanisms responsible for the cardiovascular manifestations of hypothermia are unclear, it is possible that they are sympathetically mediated. In this prospective study, relationships between body temperature, the neuroendocrine response, and hemodynamic changes in the perioperative period were examined.
Seventy-four elderly patients, undergoing abdominal, thoracic, or lower extremity vascular surgical procedures, were randomly assigned to either "routine care" (n = 37) or "forced-air warming" (n = 37) groups. Throughout the intraoperative and early postoperative periods, the routine care group received standard thermal care, and the forced-air warming group received forced-air skin-surface warming. Core temperature, forearm minus fingertip skin-surface temperature gradient, and plasma concentrations of epinephrine, norepinephrine, and cortisol were measured throughout the perioperative period, and the two groups were compared. In addition, heart rate and arterial blood pressure were compared between groups.
The routine care and forced-air warming groups did not differ with regard to age, sex, type of surgical procedures, anesthetic techniques, or postoperative analgesia. Mean core temperature was lower in the routine care group on admission to the postanesthetic care unit (routine care, 35.3 +/- 0.1 degree C; forced-air warming, 36.7 +/- 0.1 degree C; P = 0.0001) and remained lower during the early postoperative period. Forearm minus fingertip skin-surface temperature gradient (an index of peripheral vasoconstriction) was greater in the routine care group in the early postoperative period. The mean norepinephrine concentration (pcg/ml) was greater in the routine care group immediately after surgery (480 +/- 70 vs. 330 +/- 30, P = 0.02) and at 60 min (530 +/- 50 vs. 340 +/- 30, P = 0.002) and 180 min (500 +/- 80 vs. 320 +/- 30, P = 0.004) postoperatively. Mean epinephrine concentrations were not significantly different between groups. Mean cortisol concentrations were increased in both groups during the early postoperative period (P < 0.01), but the differences between groups were not significant. Systolic, mean, and diastolic arterial blood pressures were significantly higher in the routine care group.
Compared with patients in the forced-air warming group, patients receiving routine thermal care had lower core temperatures, a greater degree of peripheral vasoconstriction, higher norepinephrine concentrations, and higher arterial blood pressures in the early postoperative period. These findings suggest a possible mechanism for hypothermia-related cardiovascular morbidity in the perioperative period.
Background: Perioperative morbidity may be modifiable in high risk patients by the anesthesiologist's choice of either regional or general anesthesia. This clinical trial compared outcomes between epidural (EA) and general (GA) anesthesia/analgesia regimens In a group of patients at high risk for cardiac and other morbidity who were undergoing similarly stressful surgical procedures.
To assess possible coronary vasoconstriction in patients with ischemic heart disease, we measured coronary vascular resistance in 12 patients with normal hearts and 12 with coronary disease before and during the initial 50 seconds of cold pressor test, a stimulus known to produce systemic vasoconstriction. Control coronary vascular resistance was similar in the two groups, and although it did not change in patients with normal vessels, it rose by 27 per cent (P less than 0.005) in the group with coronary disease during the cold pressor test. In three of 12 patients with coronary disease coronary flow actually declined despite an increase in arterial pressure; in four, angina was precipitated. Phentolamine abolished increases in arterial pressure and coronary vascular resistance during the test in three patients with coronary disease. Adrenergically mediated coronary vascular tone may be an important determinant of coronary blood flow and may contribute to ischemia in patients with coronary disease.
A multiple testing procedure is proposed for comparing two treatments when response to treatment is both dichotomous (i.e., success or failure) and immediate. The proposed test statistic for each test is the usual (Pearson) chi-square statistic based on all data collected to that point. The maximum number (N) of tests and the number (m1 + m2) of observations collected between successive tests is fixed in advance. The overall size of the procedure is shown to be controlled with virtually the same accuracy as the single sample chi-square test based on N(m1 + m2) observations. The power is also found to be virtually the same. However, by affording the opportunity to terminate early when one treatment performs markedly better than the other, the multiple testing procedure may eliminate the ethical dilemmas that often accompany clinical trials.
Certain features of the relationship between 11 measurements of weekly temperature and the number of deaths from ischaemic heart disease (IHD) within age groups in Greater London between 1970 and 1974 are described. Firstly, the correlation coefficients between age-specific deaths from IHD and each of the temperature variables are of a similar order. Secondly, in contrast, the linear regression coefficients between deaths and temperature are more variable and depend upon the particular measurement of temperature chosen. Thirdly, the proportional changes in the number of deaths with the temperature variables are similar within specific age groups; consequently it is suggested that deaths from IHD and temperature may be directly related.
To determine the incidence and characteristics of ventricular dysrhythmias (premature ventricular contractions greater than 30/min, ventricular tachycardia greater than or equal to 3 beats, and ventricular fibrillation) and whether a relationship exists between ventricular tachycardia and myocardial ischemia in patients undergoing coronary artery bypass graft surgery, we continuously monitored 50 patients for 10 perioperative days using two-lead electrocardiography. Electrocardiographic changes consistent with ischemia were defined as a reversible ST depression greater than or equal to 1.0 mm, or ST elevation greater than or equal to 2.0 mm from baseline, lasting at least 1 minute. Ventricular dysrhythmias developed in 10% of patients preoperatively and in 16% intraoperatively before bypass surgery. The highest incidence occurred postoperatively, with ventricular dysrhythmias developing in 66% of patients (22% to 44% of patients on any postoperative day 0 to 7). Premature ventricular contractions were greater than 30/hr in 6% of patients preoperatively, in 8% intraoperatively before bypass, and in 34% postoperatively (6% to 23% of patients on any postoperative day). Twenty-nine patients (58%) developed 76 verified episodes of greater than or equal to 3 beats of ventricular tachycardia. Ventricular tachycardia occurred in 6% of patients preoperatively (four episodes), in 8% of patients intraoperatively prior to bypass (four episodes), and 54% of patients postoperatively (5% to 21% on any postoperative day). No patient developed ventricular fibrillation. All postoperative ventricular tachycardia episodes (after tracheal extubation) were asymptomatic. Postoperatively, 48% of patients developed ischemia, compared with 12% preoperatively and 10% intraoperatively before bypass surgery. Only 5 of 68 (7%) postoperative ventricular tachycardia episodes occurred within 3 hours of an ischemia episode.(ABSTRACT TRUNCATED AT 250 WORDS)
To compare the effectiveness of three commonly used intraoperative warming devices.
A randomized, prospective clinical trial.
The surgical suite of a university medical center.
Twenty adult patients undergoing kidney transplantation for end-stage renal disease.
Patients were assigned to one of four warming therapy groups: circulating-water blanket (40 degrees C), heated humidifier (40 degrees C), forced-air warmer (43 degrees C, blanket covering legs), or control (no extra warming). Intravenous fluids were warmed (37 degrees C), and fresh gas flow was 5 L/min for all groups. No passive heat and moisture exchangers were used.
The central temperature (tympanic membrane thermocouple) decreased approximately 1 degree C during the first hour of anesthesia in all groups. After three hours of anesthesia, the decrease in the tympanic membrane temperature from baseline (preinduction) was least in the forced-air warmer group (-0.5 degrees C +/- 0.4 degrees C), intermediate in the circulating-water blanket group (-1.2 degrees C +/- 0.4 degrees C), and greatest in the heated humidifier and control groups (-2.0 degrees C +/- 0.5 degrees C and -2.0 degrees C +/- 0.7 degrees C, respectively). Total cutaneous heat loss measured with distributed thermal flux transducers was approximately 35W (watts = joules/sec) less in the forced-air warmer group than in the others. Heat gain across the back from the circulating-water blanket was approximately 7W versus a loss of approximately 3W in patients lying on a standard foam mattress.
The forced-air warmer applied to only a limited skin surface area transferred more heat and was clinically more effective (at maintaining central body temperature) than were the other devices. The characteristic early decrease in central temperature observed in all groups regardless of warming therapy is consistent with the theory of anesthetic-induced heat redistribution within the body.
To elucidate the multifactorial nature of perioperative changes in body temperature, the influence of several clinical variables, including anesthetic technique, ambient operating room temperature, and age, were evaluated. Perioperative oral sublingual temperatures were measured in 97 patients undergoing lower extremity vascular surgery randomized to receive either general (GA) or epidural (EA) anesthesia. Surgery and anesthesia were performed in operating rooms (OR) with a relatively warm mean ambient temperature (24.5 +/- 0.4 degrees C) (GA, n = 30; EA, n = 33) or relatively cold mean ambient temperature (21.3 +/- 0.3 degrees C) (GA, n = 21; EA, n = 13). Patients were 35-94 yr old, with a mean age of 64.5 +/- 1.1 yr. A regression analysis was performed to determine the variables that correlated with intraoperative decrease in temperature and postoperative rewarming rate. The major correlates of greater intraoperative decrease in temperature were 1) GA (P = 0.003); 2) cold ambient OR temperature (P = 0.07); and 3) advancing patient age (P = 0.03). There was significant interaction between ambient OR temperature and type of anesthesia (P = 0.03): there was a greater intraoperative decrease in temperature with GA compared to EA in a cold OR but a similar decrease with GA and EA in a warm OR. The data also suggest an interaction between type of anesthesia and patient age (P = 0.06), showing a greater decrease in temperature with GA compared to EA in the younger patients, but a similar decrease between GA and EA in older patients.(ABSTRACT TRUNCATED AT 250 WORDS)
To evaluate physiologic responses to mild perianesthetic hypothermia, we measured tympanic membrane and skin-surface temperatures, peripheral vasoconstriction, thermal comfort, and muscular activity in nine healthy male volunteers. Each volunteer participated on three separate days: 1) normothermic isoflurane anesthesia; 2) hypothermic isoflurane anesthesia (1.5 degrees C decrease in central temperature); and 3) hypothermia alone (1.5 degrees C decrease in central temperature) induced by iced saline infusion. Involuntary postanesthetic muscular activity was considered thermoregulatory when preceded by central hypothermia and peripheral cutaneous vasoconstriction. Tremor was considered normal shivering when electromyographic patterns matched those produced by cold exposure in unanesthetized individuals. During postanesthetic recovery, central temperatures in hypothermic volunteers increased rapidly when residual end-tidal isoflurane concentrations were less than or equal to 0.3% but remained 0.5 degree C less than control values throughout 2 h of recovery. All volunteers were vasodilated during isoflurane administration. Peripheral vasoconstriction occurred only during recovery from hypothermic anesthesia, at end-tidal isoflurane concentrations of less than approximately 0.4%. Spontaneous tremor was always preceded by central hypothermia and peripheral vasoconstriction, indicating that muscular activity was thermoregulatory. Maximum tremor intensity during recovery from hypothermic anesthesia occurred when residual end-tidal isoflurane concentrations were less than or equal to 0.4%. Three patterns of postanesthetic muscular activity were identified. The first was a tonic stiffening that occurred in some normothermic and hypothermic volunteers when end-tidal isoflurane concentrations were approximately 0.4-0.2%. This activity appeared to be largely a direct, non-temperature-dependent effect of isoflurane anesthesia. In conjunction with lower residual anesthetic concentrations, stiffening was followed by a synchronous, tonic waxing-and-waning pattern and spontaneous electromyographic clonus, both of which were thermoregulatory. Tonic waxing-and-waning was by far the most common pattern and resembled that produced by cold-induced shivering in unanesthetized volunteers; it appears to be thermoregulatory shivering triggered by hypothermia. Spontaneous clonus resembled flexion-induced clonus and pathologic clonus and did not occur during hypothermia alone; it may represent abnormal shivering or an anesthetic-induced modification of normal shivering. We conclude that among the three patterns of muscular activity, only the synchronous, tonic waxing-and-waning pattern can be attributed to normal thermoregulatory shivering.
Adverse cardiac events are a major cause of morbidity and mortality after noncardiac surgery. It is necessary to determine the predictors of these outcomes in order to focus efforts on prevention and treatment. Patients undergoing noncardiac surgery sometimes have postoperative cardiac events. It would be helpful to know which patients are at highest risk.
We prospectively studied 474 men with coronary artery disease (243) or at high risk for it (231) who were undergoing elective noncardiac surgery. We gathered historical, clinical, laboratory, and physiologic data during hospitalization and for 6 to 24 months after surgery. Myocardial ischemia was assessed by continuous electrocardiographic monitoring, beginning two days before surgery and continuing for two days after.
Eighty-three patients (18 percent) had postoperative cardiac events in the hospital that were classified as ischemic events (cardiac death, myocardial infarction, or unstable angina) (15 patients), congestive heart failure (30), or ventricular tachycardia (38). Postoperative myocardial ischemia occurred in 41 percent of the monitored patients and was associated with a 2.8-fold increase in the odds of all adverse cardiac outcomes (95 percent confidence interval, 1.6 to 4.9; P less than 0.0002) and a 9.2-fold increase in the odds of an ischemic event (95 percent confidence interval, 2.0 to 42.0; P less than 0.004). Multivariate analysis showed no other clinical, historical, or perioperative variable to be independently associated with ischemic events, including cardiac-risk index, a history of previous myocardial infarction or congestive heart failure, or the occurrence of ischemia before or during surgery.
In high-risk patients undergoing noncardiac surgery, early postoperative myocardial ischemia is an important correlate of adverse cardiac outcomes.
Skin-surface temperature gradients (forearm temperature - fingertip temperature) have been used as an index of thermoregulatory peripheral vasoconstriction. However, they have not been specifically compared with total finger blood flow, nor is it known how long it takes fingertip temperature to fully reflect an abrupt change in finger blood flow. Steady-state skin-temperature gradients were compared with total fingertip blood flow in 19 healthy volunteers. There was an excellent correlation between steady-state skin-surface temperature gradients and total fingertip blood flow measured with venous-occlusion volume plethysmography: gradient = 0.2-5.7.log(flow), r = 0.98. The half-time for fingertip cooling after complete arterial obstruction (in 8 volunteers) was 6.6 +/- 1.2 min. The authors conclude that skin-temperature gradients are an accurate measure of thermoregulatory peripheral vasoconstriction.
In the heart, alpha-adrenergic agonists have long been known to produce a positive inotropic effect that is rate dependent and associated with action potential prolongation but is not accompanied by adenosine 3',5'-cyclic monophosphate (cAMP) elevation. The ionic mechanism of these effects is unknown. We report that a transient outward K+ current, a major determinant of plateau duration in rabbit and human atria, is strongly inhibited by norepinephrine and the alpha-adrenoceptor agonists methoxamine and phenylephrine. These effects of alpha-stimulation can be blocked by prazosin. The reduction in the transient outward current substantially slows action potential repolarization. These results can explain the regional and species-dependent positive inotropic effects of alpha-adrenergic stimulation in the heart and give important new insight into the autonomic regulation of cardiac function. In addition, reduction in this repolarizing current during the enhanced alpha-adrenergic responsiveness of myocardial ischemia may be a factor in the genesis of arrhythmias produced by catecholamines.
We studied the effects of alpha-adrenergic receptor stimulation and calcium on automaticity of isolated canine Purkinje fibers during simulated ischemia and reperfusion. Ischemia included acidosis (pH 6.7), hypoxia (PO2 = 10-25 mm Hg), hyperkalemia (10 mM K+), and either normal or elevated [Ca2+]o (2.7 or 10.8 mM). Control automatic rate and maximum diastolic potential were 18 +/- 2 beats/min and -94 +/- 1 mV, respectively. Simulated ischemia led to depolarization (to -60 +/- 1 mV), cessation of normal automaticity, and in 21% of fibers, bursts of an abnormal automatic rhythm. Phenylephrine, 5 X 10(-8) M, increased the incidence of the automatic rhythm during ischemia to 44%; this effect was blocked by prazosin but not by propranolol. During reperfusion after simulated ischemia at 2.7 mM [Ca2+]o, automatic rhythm and maximum diastolic potential returned toward control values; after simulated ischemia at 10.8 mM [Ca2+]o, automatic rates were greater than those seen after normal Ca2+ ischemia and were associated with sustained membrane depolarization. Phenylephrine (5 X 10(-8) M) at 2.7 mM [Ca2+]o rapidly restored membrane potential during reperfusion, an effect that was blocked by prazosin. At 10.8 mM [Ca2+]o, phenylephrine also restored membrane potential during reperfusion and blunted the increase in reperfusion rate induced by high [Ca2+]o alone. These effects were blocked by propranolol but not by prazosin. Our results show that the effects of phenylephrine on automatic rhythms during simulated ischemia are blocked by alpha-adrenergic receptor antagonists and that rhythms occurring during reperfusion have alpha- and beta-adrenergic receptor components.
To examine the role of chronic calcium entry blocking drug administration on perioperative myocardial ischemia and, specifically, the frequency of hemodynamically unrelated ischemia, the authors studied 444 patients undergoing coronary artery bypass operations. Before induction of anesthesia, 119 patients who chronically took calcium entry blocking drugs received nifedipine 20 mg or diltiazem 60 mg orally, 74 received calcium entry and beta adrenergic blocking drugs, 71 received beta blocking drugs only, and 180 received neither. New ischemia occurred in 208 (46.8%) patients; 55 at arrival to the operating room, 86 only after induction, and 67 separately during both periods. Two-thirds of all ischemia was not related to extremes of heart rate or blood pressure; this type was not less frequent in patients receiving calcium entry blocking drugs. Ischemia did occur less frequently in the two patient groups receiving beta adrenergic blocking drugs (34% vs. 53%), a result of less tachycardia both on arrival (3.4% vs. 15.4%) and during anesthesia, when peak heart rate exceeded 109 bpm in only one of 145 beta-blocked patients compared to 29 of 299 not receiving beta blocking drugs. While ischemia appeared during anesthesia in 34.5% of all patients, its incidence was doubled (63%) when heart rate was greater than or equal to 110 bpm. At lower heart rates, the incidence of ischemia did not differ among groups. With respect to all types of ischemia, patients receiving calcium entry blocking drugs only were indistinguishable from those receiving no antianginal therapy.(ABSTRACT TRUNCATED AT 250 WORDS)
Although suppression of thermoregulatory mechanisms by anesthetics is generally assumed, the extent to which thermoregulation is active during general anesthesia is not known. The only thermoregulatory responses available to anesthetized, hypothermic patients are vasoconstriction and non-shivering thermogenesis. To test anesthetic effects on thermoregulation, the authors measured skin-surface temperature gradients (forearm temperature--finger-tip temperature) as an index of cutaneous vasoconstriction in unpremedicated patients anesthetized with 1% halothane and paralyzed with vecuronium during elective, donor nephrectomy. Patients were randomly assigned to undergo maximal warming (warm room, humidified respiratory gases, and warm intravenous fluids; n = 5) or standard temperature management (no special warming measures; n = 5). Skin-surface temperature gradients greater than or equal to 4 degrees C were prospectively defined as significant vasoconstriction. Normothermic patients [average minimum esophageal temperature = 36.4 +/- 0.3 degrees C (SD)] did not demonstrate significant vasoconstriction. However, each hypothermic patient displayed significant vasoconstriction at esophageal temperatures ranging from 34.0 to 34.8 degrees C (average temperature = 34.4 +/- 0.2 degrees C). These data indicate that active thermoregulation occurs during halothane anesthesia, but that it does not occur until core temperature is approximately equal to 2.5 degrees C lower than normal. In two additional hypothermic patients, increased skin-temperature gradients correlated with decreased perfusion as measured by a laser Doppler technique. Measuring skin-surface temperature gradients is a simple, non-invasive, and quantitative method of determining the thermoregulatory threshold during anesthesia.
We have previously reported that the frequencies of myocardial infarction and of sudden cardiac death are highest during the period from 6 a.m. to noon. Since platelet aggregation may have a role in triggering these disorders, we measured platelet activity at 3-hour intervals for 24 hours in 15 healthy men. In vitro platelet responsiveness to either adenosine diphosphate (ADP) or epinephrine was lower at 6 a.m. (before the subjects arose) than at 9 a.m. (60 minutes after they arose). The lowest concentration of these agents required to produce biphasic platelet aggregation decreased (i.e., aggregability increased) from a mean +/- SEM of 4.7 +/- 0.6 to 3.7 +/- 0.6 microM (P less than 0.01) for ADP and from 3.7 +/- 0.8 to 1.8 +/- 0.5 microM (P less than 0.01) for epinephrine. The period from 6 to 9 a.m. was the only interval in the 24-hour period during which platelet aggregability increased significantly. We subsequently studied 10 subjects on alternate mornings after they arose at the normal time and after delayed arising. The morning increase in platelet aggregability was not observed when the subjects remained supine and inactive. Thus, there is a temporal association between increased platelet aggregability in the morning and an increased frequency of myocardial infarction and of sudden cardiac death. Demonstration of this association does not establish a cause--effect relation, but together with other evidence linking platelets to these disorders, it may provide insight into the mechanisms precipitating myocardial infarction and sudden cardiac death and aid in the design of more effective preventive measures.
The physiologic basis for the frequent complaint of worsening of symptoms in a cold environment was investigated in six patients with and five without coronary-artery disease, at rest and during identical levels of mild upright exercise at 25 and 15°C, with similar results. Significantly higher at the lower temperature were mean systemic arterial pressure (105 vs 92 mm of mercury at rest and 110 vs 92 during exercise; p less than 0.001), total peripheral resistance (1821 vs 1609 dynes-sec-cm-5 at rest, 1213 vs 993 during exercise; p less than 0.02) and left ventricular minute work (6.5 vs 5.7 kg-m at rest, 10.9 vs 9.0 during exercise; p less than 0.001). Exposure to cold did not change heart rate, cardiac output or stroke volume at rest or during exercise. These results indicate that a cold environment increases peripheral resistance at rest and during exercise. The consequent rise in arterial pressure, by augmenting myocardial oxygen requirements, would thus more readily provoke an attack of angina.
Alpha compared to beta adrenergic contributions to dysrhythmias induced by left anterior descending coronary occlusion and by reperfusion were assessed in chloralose-anesthetized cats (n = 96). Alpha receptor blockade with either phentolamine or prazosin significantly reduced the number of premature ventricular complexes during coronary reperfusion (321 +/- 62-14 +/- 10 premature ventricular complexes, P less than 0.001), abolished early ventricular fibrillation (from 25% in controls to 0%), and prevented the increase in idioventricular rate seen with coronary reperfusion. However, beta-receptor blockade was without effect. Ventricular dysrhythmias induced by coronary occlusion alone (without reperfusion) were attenuated markedly by alpha-receptor blockade under conditions in which perfusion (measured with radiolabeled microspheres) within ischemic zones was not affected. Alternative sympatholytic interventions including pretreatment with 6-hydroxydopamine to deplete myocardial norepinephrine from 8.8 +/- 1.4 to 0.83 +/- 0.2 ng/mg protein and render the heart unresponsive to tyramine (120 microgram/kg) attenuated dysrhythmias induced by both coronary occlusion and reperfusion in a fashion identical to that seen with alpha-receptor blockade. Although efferent sympathetic activation induced by left stellate nerve stimulation increased idioventricular rate from 66 +/- 6 to 144+/- 7 beats/min (P less than 0.01) before coronary occlusion, this response was blocked by propranolol but not by phentolamine. In contrast, during reperfusion the increase in idioventricular rate induced by left stellate nerve stimulation (to 203 +/- 14) was not inhibited by propranolol but was abolished by phentolamine (79 +/- 10). Intracoronary methoxamine (0.1 microM) in animals depleted of myocardial catecholamines by 6-hydroxydopamine pretreatment did not affect idioventricular rate before coronary occlusion. However, early after coronary reperfusion, methoxamine increased idioventricular rate from 33 +/- 7 to 123 +/- 21 beats/min (P less than 0.01). Thus, enhanced alpha-adrenergic responsiveness occurs during myocardial ischemia and appears to be primary mediator of the electrophysiological derangements and resulting malignant dysrhythmias induced by catecholamines during myocardial ischemia and reperfusion.
The authors undertook a prospective study of 30 patients undergoing halothane anesthesia for coronary-artery revascularization to ascertain which clinically monitored hemodynamic variables--or combination of variables--associated with myocardial oxygen supply and demand best predict myocardial ischemia. Simultaneous recordings of electrocardiogram (lead II and V5), systemic, central venous, pulmonary artery, and pulmonary artery occluded pressures were analyzed for correlation with ischemic episodes. Ischemia occurred with significant increases (P less than 0.0001) in heart rate, central venous pressure, and pulmonary artery occlusion pressure and with significant decreases (P less than 0.0001) in systolic and mean arterial blood pressure and in coronary perfusion pressure (mean arterial minus pulmonary artery occluded pressure). There was no correlation between ischemia and either hypertension (systolic blood pressures up to 200 mmHg) or the rate-pressure product. Systemic systolic blood pressure, systemic mean arterial blood pressure, and coronary perfusion pressure as single determinants were the most useful to monitor in avoiding myocardial ischemia. A combination of systemic arterial blood pressure (systolic or mean) and filling pressure (central venous or pulmonary artery occluded) was generally as useful but not more so than the preceding single variables in avoiding ischemia. Rate-pressure product was not of value in this regard. Patients were divided into three groups according to preoperative left ventricular (LV) function to determine whether pulmonary artery occluded pressure (PAOP) was more useful than central venous pressure (CVP) as either a predictor of ischemia or an index of cardiac filling: normal LV function (Group I), moderately abnormal LV function (Group II), and markedly abnormal LV function (Group III). PAOP offered no advantage over CVP for either purpose, except in some Group III patients.
Dipyridamole thallium imaging (DTI) and ambulatory electrocardiography (AEGC) have been advocated as means to stratify risk before vascular surgery. The purpose of this study was to compare the predictive value of both tests in noncardiac surgery patients for perioperative cardiac morbidity and long-term mortality.
One hundred eighty patients were referred to the nuclear cardiology laboratory for DTI before noncardiac surgery. In patients with normal electrocardiograms and who consented, an ambulatory electrocardiogram was recorded for 24 h. DTI results were classified as negative, positive, or strongly positive (included in positive). Patients were assessed for a minimum of 12 months, and Kaplan-Meier cardiovascular survival curves were constructed with a log-rank statistic of equality with P < 0.05 significant.
One hundred nine patients had both tests and then underwent surgery, sustaining 10 perioperative cardiac events (cardiac death, myocardial infarction, or symptomatic ischemia). The positive predictive values for DTI (18%) and AECG (25%) were similar, as were the likelihood ratios for positive tests (DTI = 2.1, AECG = 3.3). The likelihood ratios of a negative test were also similar (DTI = 0.45, AECG = 0.48). A strongly positive thallium defect had a somewhat greater likelihood ratio (3.5) for in-hospital events and was the only test result associated with a significantly worse long-term cardiac survival.
AECG and DTI demonstrated a similar, although lower than initially reported, ability to stratify risk and predict short-term outcome. Only quantitative dipyridamole thallium also had predictive value for long-term prognosis.
Background:
The contribution of mean skin temperature to the thresholds for sweating and active precapillary vasodilation has been evaluated in numerous human studies. In contrast, the contribution of skin temperature to the control of cold responses such as arteriovenous shunt vasoconstriction and shivering is less well established. Accordingly, the authors tested the hypothesis that mean skin and core temperatures are linearly related at the vasoconstriction and shivering thresholds in men. Because the relation between skin and core temperatures might vary by gender, the cutaneous contribution to thermoregulatory control also was determined in women.
Methods:
In the first portion of the study, six men participated on 5 randomly ordered days, during which mean skin temperatures were maintained near 31, 34, 35, 36, and 37 degrees C. Core hypothermia was induced by central venous infusion of cold lactated Ringer's solution sufficient to induce peripheral vasoconstriction and shivering. The core-temperature thresholds were then plotted against skin temperature and a linear regression fit to the values. The relative skin and core contributions to the control of each response were calculated from the slopes of the regression equations. In the second portion of the study, six women participated on three randomly ordered days, during which mean skin temperatures were maintained near 31, 35, and 37 degrees C. At each designated skin temperature, core hypothermia sufficient to induce peripheral vasoconstriction and/or shivering was again induced by central venous infusion of cold lactated Ringer's solution. The cutaneous contributions to control of each response were then calculated from the skin- and core-temperature pairs at the vasoconstriction and shivering thresholds.
Results:
There was a linear relation between mean skin and core temperatures at the response thresholds in the men: r = 0.90 +/- 0.06 for vasoconstriction and r = 0.94 +/- 0.07 for shivering. Skin temperature contributed 20 +/- 6% to vasoconstriction and 19 +/- 8% to shivering. Skin temperature in the women contributed to 18 +/- 4% to vasoconstriction and 18 +/- 7% to shivering, values not differing significantly from those in men. There was no apparent correlation between the cutaneous contributions to vasoconstriction and shivering in individual volunteers.
Conclusions:
These data indicate that skin and core temperatures contribute linearly to the control of vasoconstriction and shivering in men and that the cutaneous contributions average approximately 20% in both men and women. The same coefficients thus can be used to compensate for experimental skin temperature manipulations in men and women. However, the cutaneous contributions to each response vary among volunteers; furthermore, the contributions to the two responses vary within volunteers.
Background:
The range of core temperatures not triggering thermoregulatory responses ("interthreshold range") remains to be determined in humans. Although the rates at which perioperative core temperatures vary typically range from 0.5 to 2 degrees C/h, the thermoregulatory contribution of different core cooling rates also remains unknown. In addition, sweating in women is triggered at a slightly greater core temperature than in men. However, it is unknown whether the vasoconstriction and shivering thresholds are comparably greater in women, or if women tolerate a larger range of core temperatures without triggering thermoregulatory responses. Accordingly, the authors sought to (1) define the interthreshold range; (2) test the hypothesis that, at a constant skin temperature, the vasoconstriction and shivering thresholds are greater during rapid core cooling than during slowly induced hypothermia; and (3) compare the sweating, vasoconstriction, and shivering thresholds in men and women.
Methods:
Eight men and eight women participated. The men participated on 2 separate days; no anesthesia or sedatives were administered. On each day, they were cutaneously warmed until sweating was induced and then were cooled by a central venous infusion of cold fluid. The cooling rates were 0.7 +/- 0.1 degrees C/h on 1 day and 1.7 +/- 0.4 degrees C/h on the other, randomly ordered. Skin temperature was maintained near 36.7 degrees C throughout each trial. The women were studied only once, in the follicular phase of their menstrual cycles, at the greater cooling rate.
Results:
The interthreshold range was approximately 0.2 degrees C in both men and women, but all thermoregulatory response thresholds were approximately 0.3 degrees C higher in women. All thresholds were virtually identical during slow and fast core cooling.
Conclusions:
Our findings confirm the existence of an interthreshold range and document that its magnitude is small. They also demonstrate that the interthreshold range does not differ in men and women, but that women thermoregulate at a significantly higher temperature than do men. Typical clinical rates of core cooling do not alter thermoregulatory responses.
In-vitro studies indicate that platelet function and the coagulation cascade are impaired by hypothermia. However, the extent to which perioperative hypothermia influences bleeding during surgery remains unknown. Accordingly, we tested the hypothesis that mild hypothermia increases blood loss and allogeneic transfusion requirements during hip arthroplasty.
Blood loss and transfusion requirements were evaluated in 60 patients undergoing primary, unilateral total hip arthroplasties who were randomly assigned to normothermia (final intraoperative core temperature 36.6 [0.4] degrees C) or mild hypothermia (35.0 [0.5] degrees C). Crystalloid, colloid, scavenged red cells, and allogeneic blood were administered by strict protocol.
Intra- and postoperative blood loss was significantly greater in the hypothermic patients: 2.2 (0.5) L vs 1.7 (0.3) L, p < 0.001). Eight units of allogeneic packed red cells were required in seven of the 30 hypothermic patients, whereas only one normothermic patient required a unit of allogeneic blood (p < 0.05 for administered volume). A typical decrease in core temperature in patients undergoing hip arthroplasty will thus augment blood loss by approximately 500 mL.
The maintenance of intraoperative normothermia reduces blood loss and allogeneic blood requirements in patients undergoing total hip arthroplasty.
Mild perioperative hypothermia, which is common during major surgery, may promote surgical-wound infection by triggering thermoregulatory vasoconstriction, which decreases subcutaneous oxygen tension. Reduced levels of oxygen in tissue impair oxidative killing by neutrophils and decrease the strength of the healing wound by reducing the deposition of collagen. Hypothermia also directly impairs immune function. We tested the hypothesis that hypothermia both increases susceptibility to surgical-wound infection and lengthens hospitalization.
Two hundred patients undergoing colorectal surgery were randomly assigned to routine intraoperative thermal care (the hypothermia group) or additional warming (the normothermia group). The patient's anesthetic care was standardized, and they were all given cefamandole and metronidazole. In a double-blind protocol, their wounds were evaluated daily until discharge from the hospital and in the clinic after two weeks; wounds containing culture-positive pus were considered infected. The patients' surgeons remained unaware of the patients' group assignments.
The mean (+/- SD) final intraoperative core temperature was 34.7 +/- 0.6 degrees C in the hypothermia group and 36.6 +/- 0.5 degrees C in the normothermia group (P < 0.001) Surgical-wound infections were found in 18 of 96 patients assigned to hypothermia (19 percent) but in only 6 of 104 patients assigned to normothermia (6 percent, P = 0.009). The sutures were removed one day later in the patients assigned to hypothermia than in those assigned to normothermia (P = 0.002), and the duration of hospitalization was prolonged by 2.6 days (approximately 20 percent) in hypothermia group (P = 0.01).
Hypothermia itself may delay healing and predispose patients to wound infections. Maintaining normothermia intraoperatively is likely to decrease the incidence of infectious complications in patients undergoing colorectal resection and to shorten their hospitalizations.