Trendelenburg positioning after cardiac surgery: Effects on intrathoracic blood volume index and cardiac performance

ArticleinEuropean Journal of Anaesthesiology 20(1):17-20 · February 2003with 130 Reads
Abstract
The efficacy of the Trendelenburg position, a common first step to treat suspected hypovolaemia, remains controversial. We evaluated its haemodynamic effects on cardiac preload and performance in patients after cardiac surgery. Twelve patients undergoing mechanical ventilation of the lungs who demonstrated left ventricular 'kissing papillary muscles' by transoesophageal echocardiography, thus suggesting hypovolaemia, were positioned 30 degrees head down for 15 min immediately after cardiac surgery. Cardiac output by thermodilution, central venous pressure, pulmonary artery occlusion pressure, left ventricular end-diastolic area by transoesophageal echocardiography and intrathoracic blood volume by thermo- and dye dilution were determined before, during and after this Trendelenburg manoeuvre. Trendelenburg's manoeuvre was associated with increases in central venous pressure (9 +/- 2 to 12 +/- 3 mmHg) and pulmonary artery occlusion pressure (8 +/- 2 to 11 +/- 3 mmHg). The intrathoracic blood volume index increased slightly (dye dilution from 836 +/- 129 to 872 +/- 112 mL m(-2); thermodilution from 823 +/- 129 to 850 +/- 131 mL m(-2)) as did the left ventricular end-diastolic area index (7.5 +/- 2.1 to 8.1 +/- 1.7 cm2 m(-2)), whereas mean arterial pressure and the cardiac index did not change significantly. After supine repositioning, the cardiac index decreased significantly below baseline (3.0 +/- 0.6 versus 3.5 +/- 0.8 L min(-1) m(-2)) as did mean arterial pressure (76 +/- 12 versus 85 +/- 11 mmHg), central venous pressure (8 +/- 2 mmHg) and pulmonary artery occlusion pressure (6 +/- 4 mmHg). The intrathoracic blood volume index and left ventricular end-diastolic area index did not differ significantly from baseline. Trendelenburg's manoeuvre caused only a slight increase of preload volume, despite marked increases in cardiac-filling pressures, without significantly improving cardiac performance.
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    To review the literature on use of the Trendelenburg position as a position for resuscitation of patients who are hypotensive. PubMed online, cited bibliographies, critical care textbooks, and Advanced Cardiac Life Support guidelines were searched for information on the position used for resuscitation. Because of the heterogeneity of the data, only pertinent articles and chapters were summarized. Eight peer-reviewed publications on the position used for resuscitation were found. Pertinent information from 2 critical care textbooks and from the Advanced Cardiac Life Support guidelines was included in the review. Literature on the position was scarce, lacked strength, and seemed to be guided by "expert opinion." The general "slant" of the available data seems to indicate that the Trendelenburg position is probably not a good position for resuscitation of patients who are hypotensive. Further clinical studies are needed to determine the optimal position for resuscitation.
  • Article
    Background Breath‐hold diving has increasingly established itself within the leisure sector as near‐natural sport. In parallel, a number of competitive disciplines have developed. To reach greater depths various breathing maneuvers are employed one of them being glossopharyngeal insufflation (GI), for which air is repetitively “pumped” into the lungs in order to increase the intrathoracic air volume. As intrapulmonary pressure is considerable increased in parallel, venous return is impeded, leading to incomplete filling of the cardiac chambers. In this case study, the assumption will be addressed that after GI and breath‐holding cardiac filling can become entirely incomplete, such that kissing papillary muscle occurs. Participant/Methods An elite breath‐hold diver was examined using cardiovascular magnetic resonance (CMR). The corresponding images were analyzed via calculating end‐diastolic and end‐systolic left ventricular volumes together with their related wall volumes before and at the end of breath‐holding and approximating the left ventricular volume on the basis of an ellipsoid of rotation. Results The estimates of left ventricular volume suggest that GI and 2‐min breath‐holding can lead to end‐systolic volumes in the range of zero milliliters. Summary/Conclusion CMR imaging combined with mathematical modelling of ventricular volume supports the notion that GI can lead to kissing papillaries. It remains open, however, whether ECG changes observed after lung packing and breath‐holding in other studies are the result of such unphysiological contractions or of a reduced subendocardial oxygen supply. The pulmonary and cardiovascular consequences of this breathing maneuver sound a clear note of caution. This article is protected by copyright. All rights reserved.
  • Article
    Previous studies have failed to demonstrate that the head-down tilt position confers benefits in hypovolaemic hypotensive patients. The aim of this study was to evaluate the haemodynamic effect and vasopressor use by this position in hypotensive patients after the induction of general anaesthesia. This prospective randomised study involved 98 patients scheduled for elective cardiac surgery and 40 patients (40.1%) developed hypotension after anaesthesia induction. Upon occurrence of hypotension, patients were randomly allocated to the supine (n = 19) or head-down tilt (n = 21) groups (15° head-down tilt position). Blood pressure, heart rate, cardiac index and stroke volume index were recorded at 1-min interval for 10 min from the occurrence of hypotension. Vasopressors were administered to treat hypotension in both groups. No haemodynamic difference was observed between the supine and head-down tilt groups except for SBP changes from baseline at 1 min (-3.98 ± 6.31 vs. 1.84 ± 8.25%, P = 0.004) and 2 min (1.51 ± 14.34 vs. 9.37 ± 10.57%, P = 0.032). The number of vasopressor administrations and percentage of the patients requiring vasopressors in the supine group were greater than that in the head-down tilt group [median 1 (range 1-5) vs. median 0 (range 0-2), P = 0.002, 19/19 (100%) vs. 10/21 (47.6%), P < 0.001]. The head-down tilt position in hypotensive patients following anaesthesia induction reduced vasopressor requirement by almost one third. Minimal haemodynamic effect may be caused by different vasopressor administrations. This result suggests that the head-down tilt position may enable more stable anaesthesia induction in patients undergoing elective coronary artery bypass graft or valvular heart surgeries.
  • Article
    Purpose: Trendelenburg positioning is commonly used to temporarily treat intraoperative hypotension. The Trendelenburg position improves cardiac output in normovolemic or anesthetized patients, but not hypovolemic or non-anesthetized patients. Therefore, the response to Trendelenburg positioning may vary depending on patient population or hemodynamic conditions. We thus tested the hypothesis that the effectiveness of the Trendelenburg position, as indicated by an increase in cardiac output, improves after replacement of a stenotic aortic valve. Secondarily, we evaluated whether measurements of left ventricular preload, systolic function, or afterload were associated with the response to Trendelenburg positioning. Methods: This study is a secondary analysis of a clinical trial which included patients having aortic valve replacement (AVR) who were monitored with pulmonary artery catheters (NCT01187329). We examined changes in thermodilution cardiac output with Trendelenburg positioning before and after AVR. We also examined whether echocardiographic and hemodynamic measurements of preload, afterload, and systolic function were associated with changes in cardiac output during Trendelenburg positioning. Results: Thirty-seven patients were included. The median [IQR] cardiac output change with Trendelenburg positioning was -3% [-10%, 5%] before AVR versus +4% [-4%, 15%] after AVR. Estimated median difference in cardiac output with Trendelenburg was 5% (95% CI 1, 15%, P = 0.04) greater after AVR. The response to Trendelenburg positioning was largely independent of hemodynamic conditions. Conclusion: The response to Trendelenburg positioning improved following AVR, but by a clinically unimportant amount. The response to Trendelenburg positioning was independent of hemodynamic conditions.
  • Article
    Objective The subclavian vein (SCV) is usually used to inject the indicator of cold saline for a transpulmonary thermodilution (TPTD) measurement. The SCV catheter being misplaced into the internal jugular (IJV) vein is a common occurrence. The present study explores the influence of a misplaced SCV catheter on TPTD variables. Methods Thirteen severe acute pancreatitis (SAP) patients with malposition of the SCV catheter were enrolled in this study. TPTD variables including cardiac index (CI), global end-diastolic volume index (GEDVI), intrathoracic blood volume index (ITBVI), and extravascular lung water index (EVLWI) were obtained after injection of cold saline via the misplaced SCV catheter. Then, the misplaced SCV catheter was removed and IJV access was constructed for a further set of TPTD variables. Comparisons were made between the TPTD results measured through the IJV and misplaced SCV accesses. Results A total of 104 measurements were made from TPTD curves after injection of cold saline via the IJV and misplaced SCV accesses. Bland-Altman analysis demonstrated an overestimation of +111.40 ml/m2 (limits of agreement: 6.13 and 216.70 ml/m2) for GEDVI and ITBVI after a misplaced SCV injection. There were no significant influences on CI and EVLWI. The biases of +0.17 L/(min·m2) for CI and +0.17 ml/kg for EVLWI were revealed by Bland-Altman analysis. Conclusions The malposition of an SCV catheter does influence the accuracy of TPTD variables, especially GEDVI and ITBVI. The position of the SCV catheter should be confirmed by chest X-ray in order to make good use of the TPTD measurements.
  • Article
    Full-text available
    Background: Hypovolaemia is generally believed to induce centralization of blood volume. Therefore, we evaluated whether induced hypo- and hypervolaemia result in changes in central blood volumes (pulmonary blood volume (PBV), intrathoracic blood volume (ITBV)) and we explored the effects on the distribution between these central blood volumes and circulating blood volume (Vd circ). Methods: Six anaesthetized, spontaneously breathing Foxhound dogs underwent random blood volume alterations in steps of 150 ml (mild) to 450 ml (moderate), either by haemorrhage, retransfusion of blood, or colloid infusion. PBV, ITBV and Vd circ were measured using (transpulmonary) dye dilution. The PBV/Vd circ ratio and the ITBV/Vd circ ratio were used as an assessment of blood volume distribution. Results: 68 blood volume alterations resulted in changes in Vdcirc ranging from -33 to +31%. PBV and ITBV decreased during mild and moderate haemorrhage, while during retransfusion, PBV and ITBV increased during moderate hypervolaemia only. The PBV/Vd circ ratio remained constant during all stages of hypo- and hypervolaemia (mean values between 0.20-0.22). This was also true for the ITBV/Vd circ ratio, which remained between 0.31 and 0.32, except for moderate hypervolaemia, where it increased slightly to 0.33 (0.02), P<0.05. Conclusions: Mild to moderate blood volume alterations result in changes of Vd circ, PBV and ITBV. The ratio between the central blood volumes and Vd circ generally remained unaltered. Therefore, it could be suggested that in anaesthetized spontaneously breathing dogs, the cardiovascular system maintains the distribution of blood between central and circulating blood volume.
  • Article
    Measuring cardiac output accurately during anesthesia is thought to be helpful for safely controlling hemodynamics. Several minimally invasive methods to measure cardiac output have been developed as alternatives to thermodilution with pulmonary artery catheterization. We evaluated the reliability of a novel pulse wave transit time method of cardiac output assessment to trend with thermodilution cardiac output in patients undergoing partial hepatectomy. Thirty-one patients (ASA physical status II or III) undergoing partial hepatectomy under general anesthesia were evaluated. Cardiac output measurements by pulse wave transit time method and by thermodilution were recorded after induction of anesthesia, after a change in body positioning to 20° head up, after a change to 20° head down, after volume challenge with 10 mL·kg hydroxyethyl starch 6%, during the Pringle maneuver, and immediately after Pringle maneuver release. Trending was assessed using Bland-Altman analysis and concordance analysis. The direction of change between consecutive pulse wave transit time measurements and the corresponding thermodilution measurements showed a concordance rate of 96.0% (lower 95% confidence interval = 64%), with limits of agreement -1.51 and 1.61 L·min. The pulse wave transit time method had good concordance but fairly wide limits of agreement with regard to trending in patients with changes in preload and systemic vascular resistance. There are potential inaccuracies when vasopressors are used to treat hypotension associated with decreased systemic vascular resistance. The study limitations are that the cardiac output data were collected in a nonblinded fashion, and an existing intraarterial catheter was used, although the system requires only routine, noninvasive cardiovascular monitors. This is a promising technique that currently has limitations and will require further improvements and clinical assessment.
  • Article
    Full-text available
    To review the literature on use of the Trendelenburg position or variations of it to determine whether this position has an impact on hemodynamic status. A search strategy to locate the most relevant indexed articles was developed. Representative textbooks and manuals on emergency medicine were also consulted. Twenty-two articles of reasonable quality were selected. The literature on this subject is scant and studies have considerable design limitations. Fourteen studies question the benefit of the Trendelenburg position. The review of textbooks and manuals showed great diversity of therapeutic indications. Current evidence is too inconsistent to allow us to state that the Trendelenburg position is beneficial in hemodynamically compromised patients.
  • Article
    To assess the effects of norepinephrine on cardiac preload, cardiac index, and preload dependency during septic shock. Prospective interventional study. Medical Intensive Care Unit. We included 25 septic shock patients (62 ± 13 yrs old, Simplified Acute Physiology Score II 53 ± 12, lactate 3.5 ± 2.1 mmol/L, all receiving norepinephrine at baseline at 0.24 [25%-75% interquartile range: 0.12-0.48] μg/kg/min) with a positive passive leg raising test (defined by an increase in cardiac index ≥ 10%) and a diastolic arterial pressure ≤ 40 mm Hg. We performed a passive leg raising test (during 1 min) at baseline. Immediately after, we increased the dose of norepinephrine (to 0.48 [0.36-0.71] μg/kg/min) and, when the hemodynamic status was stabilized, we performed a second passive leg raising test (during 1 min). We finally infused 500 mL saline. Increasing the dose of norepinephrine significantly increased central venous pressure (+23% ± 12%), left ventricular end-diastolic area (+9% ± 6%), E mitral wave (+19% ± 23%), and global end-diastolic volume (+9% ± 6%). Simultaneously, cardiac index significantly increased by 11% ± 7%, suggesting that norepinephrine had recruited some cardiac preload reserve. The second passive leg raising test increased cardiac index to a lesser extent than the baseline test (13% ± 8% vs. + 19% ± 6%, p < .05), suggesting that norepinephrine had decreased the degree of preload dependency. Volume infusion significantly increased cardiac index by 26% ± 15%. However, cardiac index increased by <15% in four patients (fluid unresponsive patients) while the baseline passive leg raising test was positive in these patients. In three of these four patients, the second passive leg raising test was also negative, i.e., the second passive leg raising test (after norepinephrine increase) predicted fluid responsiveness with a sensitivity of 95 [76-99]% and a specificity of 100 [30-100]%. In septic patients with a positive passive leg raising test at baseline suggesting the presence of preload dependency, norepinephrine increased cardiac preload and cardiac index and reduced the degree of preload dependency.
  • Article
    Background: We elucidated the effects of various body positions on the agreement of cardiac output (CO) measurement between pulse contour analysis with the PiCCO monitor and thermodilution with pulmonary artery catheterization. Methods: Fifteen anesthetized and mechanically ventilated pigs (40 ± 2 kg) were sequentially placed in various positions to facilitate simultaneous CO measurement. Between-methods agreement was assessed using the Bland-Altman method. Trending ability was assessed using Pearson product-moment correlation coefficient analysis. Results: In supine, reverse Trendelenburg, Trendelenburg, and left lateral decubitus (lateral) positions, CO measured by these two methods was comparable (4.9 ± 1.5 versus 4.6 ± 1.6 L/min, 4.6 ± 2.2 versus 4.8 ± 1.8 L/min, 5.1 ± 2.1 versus 4.9 ± 2.1 L/min, and 5.4 ± 1.8 versus 5.0 ± 1.6 L/min; all P > 0.05). Mean bias between methods and limits of agreement (percentage error) were 0.3 ± 2.9 L/min (61%), -0.3 ± 3.3 L/min (71%), 0.1 ± 4.1 L/min (77%), and 0.5 ± 3.7 L/min (71%). Directional changes of paired CO revealed 66% (reverse Trendelenburg), 57% (Trendelenburg), and 66% (lateral) concordance. The correlation coefficient (r(2)) was 0.199, 0.127, and 0.108. For paired CO ≤6 L/min, mean bias between methods and limits of agreement (percentage error) were 0.2 ± 1.0 L/min (25%), -0.1 ± 1.0 L/min (28%), 0.2 ± 1.1 L/min (29%), and 0.5 ± 0.9 L/min (23%). Directional changes of paired CO revealed 84% (reverse Trendelenburg), 76% (Trendelenburg), and 65% (lateral) concordance. The correlation coefficient (r2) was 0.583, 0.626, and 0.213. Conclusions: The mean CO measured by pulse contour analysis and thermodilution did not agree well in various body positions. Moreover, the measurements tended to trend differently in response to positional changes. For paired CO ≤6 L/min, however, the between-methods agreement and the trending ability improved significantly.
  • Article
    Objective: The objective was to evaluate whether passive leg raising during cardiopulmonary resuscitation in a porcine model of prolonged ventricular fibrillation improves hemodynamics, return of spontaneous circulation, 24-hour survival, and neurological outcome. Methods: Ventricular fibrillation was induced in 20 healthy Landrace/Large White piglets, which were subsequently left untreated for 8 minutes. Ten animals were randomly assigned into the control group and were resuscitated according to the 2005 European Resuscitation Council guidelines, and 10 piglets were assigned into the passive leg raising group and were resuscitated with the legs passively raised at 45° with the aid of a special purpose-made metallic device. End points were either return of spontaneous circulation or asystole. Results: Return of spontaneous circulation was observed in 6 and 9 animals from the control and the passive leg raising group, respectively (P = .121; odds ratio = 0.16; 95% confidence interval, 0.01-1.87). Just prior to the first defibrillation attempt, coronary perfusion pressure was significantly higher in the passive leg raising group (22.8 ± 9.5 vs 10.6 ± 6.5 mm Hg, P < .004); but no subsequent significant differences were observed. Although all animals that restored spontaneous circulation survived for 24 hours, neurologic alertness score was significantly better in the animals treated with passive leg raising (90 ± 10 vs 76.6 ± 12.1, P = .037). Conclusions: Passive leg raising during cardiopulmonary resuscitation significantly increased coronary perfusion pressure in the minute prior to the first shock. Return of spontaneous circulation and 24-hour survival rate were comparable between groups. However, the animals in the passive leg raising group exhibited significantly higher neurological scores.
  • Chapter
    Hemodynamic assessment is of primary importance in guiding volume therapy and vasoactive drug administration to optimize organ perfusion and to avoid fluid overload with lung edema in critically ill patients [1, 2]. Clinical examination has been shown to be of minimal value in detecting inadequate cardiac preload [3]. Several methods for preload determination, such as central venous pressure (CVP) and pulmonary artery occlusion pressure (PAOP), have been widely used [4]. Cardiac filling pressures are not always accurate indicators of ventricular preload because of erroneous readings of pressure tracings, discrepancy between measured and transmural pressures, and changes in ventricular compliance [5]. In recent years, right ventricular end-diastolic volume (RVEDV) evaluated by fast response pulmonary artery catheters (PACs), left ventricular end-diastolic area (LVEDA) measured by echocardiography, and the intrathoracic blood volume (ITBV) evaluated by the transpulmonary indicator dilution technique, have been proposed to assess cardiac preload at the bedside [6–8].
  • Article
    Background Cardiac index obtained by arterial pulse contour analysis (CIPC) demonstrated good agreement with arterial or pulmonary arterial thermodilution derived cardiac index (CITD, CIPA) in cardiac surgical or critically ill patients. However as the accuracy of pulse contour analysis during changes of the aortic impedance is unclear, we compared CIPC, CITD and CIPA during changes of preload and the aortic impedance as occurring during sternotomy. Patients and methods CIPC und CITD, were compared in 28 patients, (and CIPA in 6 patients) undergoing elective coronary artery bypass grafting, before and after sternotomy. The relative changes ΔCIPC und ΔCIPC were calculated. Results Sternotomy resulted in a significant increase in CI in 25 out of 28 patients. Regression analysis was performed between CIPC and CITD before and after sternotomy (r2 = 0.87, p<0.0001, r2 = 0.88, p<0.0001) as well as between CIPC and CIPA, before and after sternotomy (r2 = 0.85, p<0.0001, r2 = 0.93, p<0.01) and between ΔCIPC and ΔCITD (r2 = 0.72, p<0.0001). Bland Altman-Analysis for determining bias (m) and precision (2SD) between CIPC and CITD before and after sternotomy and between ΔCIPC and ΔCITD resulted in m = –0.03 L/min/m2, 2SD = –0.34 to 0.28 L/min/m2, m = –0.06 L/min/m2, 2SD = –0.45 to 0.33 L/min/m2 and m = –0.02 L/min/m2, SD = –0.47 to 0.44 L/min/m2. Conclusion Pulse contour analysis derived CIPC accurately reflects thermodilution derived CITD or CIPA during changes of preload and the aortic impedance as occurring during sternotomy.
  • Article
    Full-text available
    For excellence in practice to be the standard for care, critical care nurses must embrace evidence-based practice as the norm. Nurses cannot knowingly continue a clinical practice despite research showing that the practice is not helpful and may even be harmful to patients. This article is based on 2 presentations on evidence-based practice from the American Association for Critical-Care Nurses' 2009 and 2010 National Teaching Institute and addresses 7 practice issues that were selected for 2 reasons. First, they are within the realm of nursing, and a change in practice could improve patient care immediately. Second, these are areas in which the tradition and the evidence do not agree and practice continues to follow tradition. The topics to be addressed are (1) Trendelenburg positioning for hypotension, (2) use of rectal tubes to manage fecal incontinence, (3) gastric residual volume and aspiration risk, (4) restricted visiting policies, (5) nursing interventions to reduce urinary catheter-associated infections, (6) use of cell phones in critical care areas, and (7) accuracy of assessment of body temperature. The related beliefs, current evidence, and recommendations for practice related to each topic are outlined.
  • Based on maximisation of cardiac stroke volume (SV), peri-operative individualised goal-directed fluid therapy improves patient outcome. It remains, however, unknown how fluid therapy by this strategy relates to filling of the heart during supine rest as reference for the anaesthetised patient and whether the heart becomes distended. To answer these questions, this study related SV to the diastolic filling of the heart while varying central blood volume (CBV) between hypo- and hyper-volaemia, simulating bleeding, and fluid loading, respectively, when exposing healthy human subjects to head-up (HUT) and head-down tilt (HDT). Twelve healthy volunteers underwent graded tilt from 20 degrees HDT to 30 degrees HUT. The end-diastolic dimensions of the heart were assessed by transthoracic echocardiography with independent evaluation of SV by Modelflow. The CBV was monitored by thoracic electrical admittance, central venous oxygenation and pressure, and arterial plasma atrial natriuretic peptide. Also, muscle and brain oxygenation were assessed by near infrared spectroscopy (n=7). The HUT reduced the mentioned indices of CBV, the end-diastolic dimensions of the heart, and SV. Conversely, HDT-enhanced tissue oxygenation and the diastolic filling of the heart, but not SV. In healthy supine humans, the heart is provided with a volume that is sufficient to secure a maximal SV without distending the heart. The implication for individualised goal-directed fluid therapy is that when a maximal SV is established for patients, cardiac pre-load is comparable to that of supine healthy subjects.
  • Article
    A newly developed test for the assessment of psychomotor recovery--the perceptive accuracy test (PAT)--is described. Seventy-four subjects who performed the test though that it was easy to perform and some were motivated to try it on a number of occasions. Eight persons performed the test on different days and at different periods of time; the results were consistent and reproducible. Eight more persons were then asked to do the test 4 times at 15-min intervals; no 'learning' was seen with this test. A randomized, prospective study was then performed in two groups of 15 patients, undergoing arthroscopic procedures of the knee. Anaesthesia was induced with propofol and maintained with an infusion of propofol 12 mg/kg/h for the first 15 min, followed by 8 mg/kg/h subsequently in the propofol group. In the isoflurane group, anaesthesia was also induced with propofol, but isoflurane (0.5-2%) was used to maintain anaesthesia. Alfentanil was the analgesic used in both groups of patients. Results were compared with a third group of unanaesthetised controls, who were asked to perform psychomotor tests including choice reaction time and PAT at 30-min intervals for 2.5 h. There was a significant difference (P less than 0.01) in psychomotor recovery on the PAT-200 between the propofol group and control groups, but not in the isoflurane and control groups at 30 min. Both groups had returned to baseline values at 60 min in the PAT-60 and PAT-200. The choice reaction time showed no significant difference in either group 30 min after the anaesthetic.(ABSTRACT TRUNCATED AT 250 WORDS)
  • Article
    Upper oesophageal sphincter pressure has been measured in 24 patients with a sleeve device. The median sphincter pressure when awake was 38 mmHg, and when anaesthetized and paralysed was 6 mmHg. After tracheal intubation, cricoid pressure was applied at measured values between 5 and 50 N using a hand-held cricoid yoke while the sphincter pressure was recorded in two head and neck positions: with and without a standard intubating pillow with neck support. A cricoid force of 40 N increased sphincter pressure to above 38 mmHg in all the patients and the use of the pillow did not alter this effect. With the application of cricoid pressure, operating department assistants raised sphincter pressure to above 38 mmHg in only 50% of patients. Laryngoscopy made little difference to the effect of cricoid pressure except in one patient in whom it reduced the sphincter pressure by 27 mmHg.
  • Article
    Dependence of left ventricular (LV) relaxation on cardiac systolic load is a function of myocardial contractility. The authors hypothesized that, if a tight coupling would exist between LV contraction and relaxation, the changes in relaxation rate with an increase in cardiac systolic load would be related to the changes in LV contraction. Coronary surgery patients (n = 120) with preoperative ejection fraction >40% were included. High-fidelity LV pressure tracings (n = 120) and transgastric transesophageal echocardiographic data (n = 40) were obtained. Hearts were paced at a fixed rate of 90 beats/min. Effects on contraction were evaluated by analysis of changes in dP/dt(max) and stroke area. Effects on relaxation were assessed by analysis of R (slope of the relation between tau and end-systolic pressure). Correlations were calculated with linear regression analysis using Pearson's coefficient r. Baseline LV end-diastolic pressure was 10+/-3 mm Hg (mean +/- SD). During leg raising, systolic LV pressure increased from 93+/-9 to 107+/-11 mm Hg. The change in dP/dt(max) was variable and ranged from -181 to +254 mm Hg/s. A similar variability was observed with the changes in stroke area, which ranged from -2.0 to +5.5 cm2. Changes in dP/dt(max) and in stroke area were closely related to individual R values (r = 0.87, P<0.001; and r = 0.81, P<0.001, respectively) and to corresponding changes in LV end-diastolic pressure (r = 0.81, P< 0.001; and r = 0.74, P<0.001, respectively). A tight coupling was observed between contraction and relaxation. Leg raising identified patients who developed a load-dependent impairment of LV performance and increased load dependence of LV relaxation.
  • Article
    Purpose To observe the changes in EEG bispectral index (BIS), 95% spectral edge frequency (95% SEF) and median frequency (MF) with haemodynamic changes to intubation during induction with propofol or propofol and 2 μg· kg−1 fentanyliv. Methods Twenty four ASA 1–11 patients were randomized to receive either propofol infusion preceded by normal saline (group P, n= 12) or propofol preceded by 2 μg· kg−1 fentanyl (group PF, n= 12). Intubation was performed five minutes after maintenance of BIS within 45 ± 5. EEG and haemodynamic variables were recorded at before induction, and before and after intubation. Results Haemodynamic responses to intubation were greater in group P than in group PF (P < 0.05). Postintubation SBP, DBP and HR increased, compared with preinduction values, more in group P than in group PF Postintubation BIS values increased from 45.5 ± 3.5 and 44.2 ± 4.1 to 51.1 ± 4.1 and 50.9 ± 5.3 in groups P and PF, respectively, compared with preintubation values. The BIS values were not different between treatment groups before and after intubation, and 95% SEF and MF values did not increase after intubation. Conclusion Fentanyl, 2 μg· kg−1iv, blunted the haemodynamic responses to intubation, but failed to attenuate the arousal of cerebral cortical activity. The different haemodynamic responses postintubation but similar BIS and 95% SEF changes in the two groups suggest that BIS or 95% SEF cannot predict the haemodynamic responses to intubation during anaesthesia induction with propofol and fentanyl.
  • Article
    Previous studies reported that complications associated with removal of the laryngeal mask were more frequent in awake patients than in anaesthetised patients; however, these studies did not comply with the method described in the manufacturer's instruction manual. The reported incidences of regurgitation during the use of the laryngeal mask also differ considerably between studies. We studied these factors in 66 patients in whom the method described in the manual was used. After induction of anaesthesia, the laryngeal mask and a pH probe were inserted and the cuff of the mask was inflated with a minimum volume of air. Anaesthesia was maintained with nitrous oxide and isoflurane in oxygen. At the end of the operation, we randomly allocated patients to one of two groups and the laryngeal mask was removed either while they were still deeply anaesthetised or after they had regained consciousness. No apparent regurgitation occurred in any patient during operation, but one patient in the anaesthetised group regurgitated immediately after removal of the mask. The incidence of complications during or after removal of the laryngeal mask was significantly greater in the anaesthetised group than that in the awake group (p < 0.001; difference [95% CI]: 48.5 [30.5-66.5]%). Therefore, the laryngeal mask can be safely left in place until the patient has regained consciousness after emergence from anaesthesia.
  • Article
    The aims of the study were to evaluate costs and clinical characteristics of desflurane-based anaesthetic maintenance versus propofol for outpatient cholecystectomy. All 60 patients received ketamine 0.2 mg kg(-1), fentanyl 2 microg kg(-1) and propofol 2 mg kg(-1) for induction. Ketorolac 0.4 mg kg(-1) and ondansetron 0.05 mg kg(-1) +droperidol 20 microg kg(-1) was given as prophylaxis for postoperative pain and emesis, respectively. The patients were randomly assigned into Group P with propofol maintenance and opioid supplements, or Group D with desflurane in a low-flow circuit system. All the patients were successfully discharged within 8 h without any serious complications. Emergence from anaesthesia was more rapid after desflurane; they opened their eyes and stated date of birth at mean 6.4 and 8.4 min respectively, compared with 9.6 and 12 min in the propofol group (P<0.05). Nausea and pain were more frequent in Group D, 40% and 80% respectively; versus 17% and 50% in Group P (P<0.05). By telephone interview at 24 h and 7 d after the procedure, there was no major difference between the groups. With desflurane, drug costs per case were 10 $ lower than with propofol. We conclude that desflurane is cheaper and has a more rapid emergence than propofol for outpatient cholecystectomy. However, propofol results in less pain and nausea in the recovery unit. Despite ondansetron and droperidol prophylaxis, there was still a substantial amount of nausea and vomiting after desflurane.
  • Article
    The effect of the Trendelenburg position on systemic and pulmonary hemodynamics in critically ill patients is not generally appreciated. This study examined the hemodynamoc effect of 15-20 degrees head-down tilt in 61 normotensive and 15 hypotensive patients with acute cardiac illness or sepsis. In normotensive patients, the head-down tilt increased the preload of both right and left ventricles, increased cardiac output slightly, decreased systemic vascular resistance, and did not change the mean arterial pressure. This effect was probably mediated by baroreceptor stimulation. In hypotensive patients, the Trendelenburg position did not increase preload, slightly increased afterload, and decreased cardiac output. This study failed to document any beneficial hemodynamic effect of the Trendelenburg position in critically ill normo- or hypotensive patients.
  • Article
    Several technical modifications of the various perivascular techniques of brachial plexus block have been advocated but their efficacy has never been documented. The present study used injections of radiopaque anesthetic solutions to illustrate the effect of various technical maneuvers on the flow of the solutions injected into the sheath at several levels. Axillary block studies indicated that solutions injected through a needle placed high in the axilla and centrally directed achieve a higher level than similar volumes injected through a needle that is perpendicular to the neurovascular bundle at the more traditional lower level. Furthermore, the studies demonstrate that a rubber tourniquet applied around the arm distal to the needle is unable to prevent retrograde flow of the injected solution, especially when the usual volumes utilized clinically are injected. Firm digital pressure applied immediately distal to the needle, on the other hand, is effective in preventing retrograde flow and, in so doing, enhances central flow. Bringing the arm to the side while maintaining digital pressure results in even further central spread by removing the obstacle provided by the head of the abducted humerus. Studies carried out using the infraclavicular technique indicate that because the direction of the properly placed needle is lateral, most of the injected solution passes distally out along the sheath. Again, firm digital pressure high in the axilla occludes the sheath, preventing distal flow and causing the solution to move centrally. Studies carried out using the interscalene technique show that with the usual technique the injected solution moves cephalad into the cervical portion of the sheath as well as caudad into the brachial portion. Firm digital pressure applied superior to the needle prevents cephalad flow and thus forces all of the injected solution to move caudally as far as the dome of the lung and laterally into the axillary sheath.
  • Article
    Full-text available
    A stabilometer has been used to measure changes in the activity of postural muscles during the later stages of recovery from anaesthesia. It is concluded that stabilometry might be a useful tool with which to measure and record the extent of recovery andthat this might be especially useful for use after out-patient sugery.
  • Article
    A review of the anatomy of the cervical plexus and surrounding structures suggests a single-injection technic which simplifies anesthesia of the cervical plexus and increases the margin of safety in this procedure. Used by the authors, the technic has been successful in 97 percent of over 100 cases.
  • Article
    This study prospectively evaluated the efficacy of oral ketamine in alleviating procedure-related distress in pediatric oncology patients. Ketamine (10 mg/kg) was administered orally to 35 children and adolescents, ranging in age from 14 months to 17 years (mean = 6.5 years). Procedure-related distress was evaluated by using parent/clinician ratings and the Observational Scale of Behavioral Distress (OSBD-R). Eighty-seven percent of children were sedated within 45 minutes. Clinician and parent ratings were similar, with 77% rating procedural distress as low (0 to 3). The OSBD-R scores were low throughout all phases of the study. Although this study was neither randomized nor placebo-controlled, statistical comparison of the OSBD-R scores of the patients who received oral ketamine with those of historical controls (from a study previously performed at the same institution but using intravenous midazolam) showed significantly less distress (P < .001) during the procedure in children who received oral ketamine. Additionally, OSBD-R scores of the patients who received oral ketamine were significantly lower (P < .001) during all phases than those of the saline placebo group in the other study. No cardiorespiratory side effects related to ketamine were noted. The majority of patients showed recovery from sedation within 2 hours following the procedure. In conclusion, oral ketamine effectively alleviated procedure-related distress in pediatric oncology patients.
  • Article
    We have noted that tracheal intubation can be accomplished in many patients after induction of anesthesia with propofol and alfentanil without the simultaneous use of muscle relaxants. This study was designed to evaluate airway and intubating conditions after administration of propofol and alfentanil in 75 ASA physical status I or II outpatients with Mallampati class I airways undergoing various surgical procedures. The patients were randomly assigned to one of five groups for induction of anesthesia. All patients received midazolam 1 mg IV before induction of anesthesia. Group I patients (n = 15) received d-tubocurarine 3 mg, thiamylal 4 mg/kg, and succinylcholine 1 mg/kg IV. Groups II-V patients (n = 15 each) received alfentanil 30, 40, 50, or 60 micrograms/kg followed by propofol 2 mg/kg IV. No muscle relaxants were given to patients in groups II-V. Airway management was performed by one of the authors who was blinded as to the dose of alfentanil administered. After loss of consciousness, patients' lungs were ventilated via face mask, and the ease of ventilation was recorded. Jaw mobility was also assessed. Ninety seconds after administration of the propofol or thiamylal, laryngoscopy was performed and exposure of the glottis and position of the vocal cords were noted. Intubation of the trachea was performed and patient response was noted. Heart rate and arterial blood pressure were also recorded before induction of anesthesia, after induction, and then again after intubation of the trachea. The lungs of all patients were easily ventilated via mask, and the jaw was judged to be relaxed in all patients.(ABSTRACT TRUNCATED AT 250 WORDS)
  • Article
    The efficacy of cricoid pressure was studied in 10 adult cadavers. The oesophageal pressure that would result in regurgitation during measured values of cricoid pressure was determined. Oesophageal pressure, recorded by a 2 mm diameter oesophageal tube, was increased by oesophageal distension with saline, and incremental levels of cricoid force, 20, 30 and 40 Newtons, were applied with a cricoid yoke. With each 10 Newton increment of cricoid force there was a significant rise in the oesophageal pressure required to provoke regurgitation (p < 0.01). Thirty Newtons of cricoid force prevented regurgitation of saline in all cadavers with oesophageal pressures of up to 40 mmHg. Rupture of the oesophagus occurred in three cadavers: one at 30 and two at 40 Newtons of cricoid force, but there was no rupture at 20 Newtons of cricoid force. In the other seven cadavers oesophageal pressures were also studied with a 4.6 mm diameter (14 FG) oesophageal tube, which did not reduce the efficacy of cricoid pressure in preventing regurgitation.
  • Article
    This study compares psychomotor recovery following induction of anaesthesia with either thiopentone or propofol in 30 healthy, unpremedicated patients undergoing outpatient arthroscopic procedures of the knee. A battery of tests including simple reaction time (SRT), choice reaction time (CRT), perceptive accuracy test (PAT) and digit symbol substitution test (DSST) were done before anaesthesia. The patients were randomly divided into two groups: Group 1 was induced with thiopentone 5-6 mg/kg while Group 2 was induced with propofol 2-3 mg/kg. Anaesthesia was then maintained with isoflurane (0.5-2%) in oxygen and air, and supplements of alfentanil were given for analgesia during spontaneous respiration with a face mask. Psychomotor recovery assessed every 30 min postoperatively for 120 min showed that patients in Group 1 had not returned to baseline values until 120 min after the operation on the PAT, while those in Group 2 had returned to baseline values at 60 min. No patient had any significant side effects. The SRT, CRT and DSST proved to be relatively insensitive in the detection of residual effects of anaesthesia and had a significant learning effect. This study suggests that induction of anaesthesia with propofol followed by maintenance with isoflurane in oxygen and air during spontaneous ventilation is associated with rapid psychomotor recovery and is a suitable method for ambulatory surgery. The PAT is sensitive and not associated with some of the problems found with other commonly used tests.
  • Article
    We conducted a randomized, double-blind trial to compare the efficacy of preincisional and postincisional wound infiltration with 1% lidocaine (40 mL) on the postoperative pain of 37 patients scheduled for elective inguinal herniotomy. The demand for additional postoperative analgesics occurred earlier in those who received lidocaine infiltration after incision (165 min) than in those who received preincisional lidocaine (225 min, P less than 0.05). The preincisional lidocaine infiltration group also had fewer patients requiring supplemental analgesics (58%) than the postincisional group (94%) (P less than 0.05). We conclude that preincisional infiltration of the surgical wound with lidocaine is a more effective method of providing postoperative analgesia than is postincisional infiltration.
  • Article
    Quantitative measurements of coordination ability and performance speed were carried out on 76 female day-case patients undergoing minor gynaecological operations. The women were assigned at random to the anaesthetic agent used, propofol 2.5 mg/kg or thiopentone 4 mg/kg. Spacing control, timing control and performance speed were recorded using a newly developed computerized coordination ability test system. The patients were tested once before the operation and 0.5, 1 and 2 h after awakening. Postoperatively the initial impairment and the subsequent regression towards preoperative test results were very similar whether the anaesthetic agent was propofol or thiopentone. Although the test apparatus was able to detect even minor differences, no postoperative test showed statistically significant differences between the two groups. We find it reasonable to conclude that there is no difference in recovery of coordination ability following propofol- or thiopentone-induced anaesthesia.
  • Article
    Fifty unpremedicated patients scheduled for outpatient restorative dentistry and/or oral surgery lasting 2 to 4 h were anaesthetized with either propofol infusion or isoflurane inhalation. Before induction of anaesthesia with propofol (2.5 mg.kg-1), all patients were given 75 mg of diclofenac and 0.01 mg.kg-1 vecuronium intravenously. Intubation was facilitated with suxamethonium (1.5 mg.kg-1) and anaesthesia was maintained in random order either with propofol infusion (12 mg.kg-1.h-1 for the first 20 min, 9 mg.kg-1.h-1 for the next 20 min, and 6 mg.kg-1.h-1 for the rest of the anaesthesia) or with isoflurane (inspired concentration 1-2.5%), both with nitrous oxide and oxygen (30%). The patients breathed spontaneously using a non-rebreathing circuit. Patients given propofol infusion became re-orientated faster (11.0 +/- 5.5 min vs. 16.5 +/- 7.5 min; P less than 0.01) and at 30 min walked along a straight line better (P less than 0.01). At 60 min, none of the propofol patients displayed an unsteady gait, whereas 11 of the 25 isoflurane patients did (P less than 0.001). None of the patients receiving propofol had emesis at the clinic, compared with 10 of the 25 patients receiving isoflurane (P less than 0.001). The overall incidence of emesis was 2 of 25 and 14 of 25 in the propofol and isoflurane groups, respectively (P less than 0.01). Patients receiving propofol were discharged home earlier than patients receiving isoflurane (80 +/- 14 min and 102 +/- 32 min, respectively; P less than 0.01). It is concluded that propofol allows early discharge of patients, even after long anaesthesias.
  • Article
    The present study compares the effectiveness of 0.25% ropivacaine and 0.25% bupivacaine in 44 patients receiving a subclavian perivascular brachial plexus block for upper extremity surgery. The patients were assigned to two equal groups in this randomized, double-blind study; one group received ropivacaine 0.25% (112.5 mg) and the other, bupivacaine 0.25% (112.5 mg), both without epinephrine. Onset times for analgesia and anesthesia in each of the C-5 through T-1 brachial plexus dermatomes did not differ significantly between the two groups. The mean onset time for analgesia ranged from 11.2 to 20.2 min, and the mean onset time for anesthesia ranged from 23.3 to 48.2 min. The onset of motor block differed only with respect to paresis in the hand, with bupivacaine demonstrating a shorter onset time than ropivacaine. The duration of sensory and motor block also was not significantly different between the two groups. The mean duration of analgesia ranged from 9.2 to 13.0 h, and the mean duration of anesthesia ranged from 5.0 to 10.2 h. Both groups required supplementation with peripheral nerve blocks or general anesthesia in a large number of cases, with 9 of the 22 patients in the bupivacaine group and 8 of the 22 patients in the ropivacaine group requiring supplementation to allow surgery to begin. In view of the frequent need for supplementation noted with both 0.25% ropivacaine and 0.25% bupivacaine, we do not recommend using the 0.25% concentrations of these local anesthetics to provide brachial plexus block.
  • Article
    This study was undertaken to compare desflurane with propofol anesthesia in outpatients undergoing peripheral orthopedic surgery. Data were combined from two institutions participating in a multicenter study. Ninety-one patients, ASA physical status I or II, were each randomly assigned to one of four groups. After administration of fentanyl (2 micrograms/kg) and d-tubocurarine (3 mg), intravenous propofol was administered to induce anesthesia in groups I and II and desflurane in groups III and IV. Maintenance was provided by desflurane/N2O in groups I and III, propofol/N2O in group II, and desflurane/O2 in group IV. Emergence and recovery variables, psychometric test results, and side effects were recorded by observers unaware of the experimental treatment. Patients in group II experienced less nausea than other groups (P = 0.002) despite this group having required more intraoperative fentanyl supplementation than groups III and IV (P = 0.01). Time to emergence, discharge, and psychometric test results were similar in all groups. Desflurane appears to be comparable with propofol as an outpatient anesthetic, facilitating rapid recovery and discharge home.
  • Article
    We studied 114 female patients (ASA 1 or 2) who were within 20% of ideal body weight and who were scheduled to undergo gynaecological laparoscopy which required supplementation with an opioid (groups IA and PA), or dental procedures which did not require opioid supplementation (groups IO and PO). A computerised package of psychomotor tests was performed before surgery. Anaesthesia was induced with propofol 2.5 mg.kg-1 and all patients received atracurium 0.3 mg.kg-1 and 67% nitrous oxide in oxygen. Patients in group IA received isoflurane 1% (inspired), and alfentanil 10 micrograms.kg-1 as a bolus and 10 micrograms.kg-1.h-1 as an infusion. Patients in group PA received propofol 9 mg.kg-1.h-1 as an infusion, decreasing to 6 mg.kg-1.h-1 after 15 min, together with alfentanil 10 micrograms.kg-1.h-1. Patients in groups IO and PO received isoflurane and propofol in the regimens described for groups IA and PA, but without alfentanil. Recovery was assessed by a blinded observer who recorded times to awakening (eye opening) and orientation (giving date of birth), and who repeated the psychomotor tests at 1, 3 and 5 h. Linear analogue scales of mood, nausea and pain were obtained and other side effects were noted in the succeeding 48 h. A matched control group of 25 females (who were not anaesthetised) underwent psychomotor testing on four occasions in order to assess the 'learning effect' of repeated recovery testing. The analysis of recovery tests did not assume a normal distribution.(ABSTRACT TRUNCATED AT 250 WORDS)
  • Article
    This study was designed to determine whether greater diversion of bile and pancreatic secretions away from the functional gastrointestinal tract would produce greater weight loss in superobese patients (greater than or equal to 200 pounds overweight) in comparison with conventional Roux-en-Y gastric bypass (RYGB). During the past 7 years, two modifications of RYGB were prospectively compared in 45 superobese patients: RYGB-1, in which the length of defunctionalized jejunum measured 75 cm, and RYGB-2, in which the defunctionalized jejunum measured 150 cm. Respective mean preoperative weight/body mass indexes were 393 pounds/63.4 for 22 RYGB-1 patients and 404 pounds/61.6 for 23 RYGB-2 patients. Two patients (5%) had nonfatal early complications. There were six late incisional hernias. There were no cases of protein deficiency, hepatic dysfunction, or diarrhea after operation. Mean follow-up was 43 +/- 17 months. Postoperative weight loss in pounds and daily calorie intake were compared at 6-month intervals. Weight loss stabilized by 24 months at a mean 50% excess weight lost in RYGB-1 patients and 64% excess weight lost in RYGB-2 patients. Nineteen of 23 RYGB-2 patients achieved at least 50% excess weight lost versus 11 of 22 RYGB-1 patients (p less than or equal to 0.03). Weight loss was significantly greater at 24 through 36 months in RYGB-2 versus RYGB-1 patients (p less than 0.02). There was no significant difference in either calorie intake or incidence of iron and vitamin B-12 deficiency between the two groups. These data show that gastric restriction and biliopancreatic diversion without intestinal exclusion resulted in significantly greater weight loss than conventional RYGB but did not cause additional metabolic sequelae or diarrhea. This long-limb modification of Roux-en-Y gastric bypass is a safe and effective procedure in patients who are 200 pounds or more overweight.
  • Article
    Propofol, the new intravenous anesthetic agent, is generally used in outpatient anesthesia with expectations of fast recovery. We assessed recovery from anesthesia in a double-blind, crossover, controlled manner in 12 healthy volunteers using clinical tests during the first hour and several psychomotor tests 0.5, 1, 3, 5, and 7 h after brief anesthesia with propofol (2.5 mg/kg and 1.0 mg/kg 3 min later) or thiopental (5.0 mg/kg and 2.0 mg/kg 3 min later). Subjects were able to respond to command, sit, and stand steadily significantly faster (P less than 0.05) after propofol (time until standing steadily 33 +/- 7 min; mean +/- SD) when compared to thiopental anesthesia (time until standing steadily 62 +/- 29 min; mean +/- SD). Psychomotor performance remained significantly worse (P less than 0.05 to P less than 0.001) compared to control for 1 h after propofol and for 5 h after thiopental anesthesia. We conclude that the rapid and complete recovery makes propofol a suitable anesthetic for patients undergoing brief ambulatory surgery.
  • Article
    Full-text available
    Preoperative transfusions are frequently given to prevent perioperative morbidity in patients with sickle cell anemia. There is no consensus, however, on the best regimen of transfusions for this purpose. We conducted a multicenter study to compare the rates of perioperative complications among patients randomly assigned to receive either an aggressive transfusion regimen designed to decrease the hemoglobin S level to less than 30 percent (group 1) or a conservative regimen designed to increase the hemoglobin level to 10 g per deciliter (group 2). Patients undergoing a total of 604 operations were randomly assigned to group 1 or group 2. The severity of the disease, compliance with the protocol, and the types of operations were similar in the two groups. The preoperative hemoglobin level was 11 g per deciliter in group 1 and 10.6 g per deciliter in group 2. The preoperative value for hemoglobin S was 31 percent in group 1 and 59 percent in group 2. The most frequent operations were cholecystectomies (232), head and neck surgery (156), and orthopedic surgery (72). With the exception of transfusion-related complications, which occurred in 14 percent of the operations in group 1 and in 7 percent of those in group 2, the frequency of serious complications was similar in the two groups (31 percent in group 1 and 35 percent in group 2). The acute chest syndrome developed in 10 percent of both groups and resulted in two deaths in group 1. A history of pulmonary disease and a higher risk associated with surgery were significant predictors of the acute chest syndrome. A conservative transfusion regimen was as effective as an aggressive regimen in preventing perioperative complications in patients with sickle cell anemia, and the conservative approach resulted in only half as many transfusion-associated complications.
  • Article
    The purpose of this study was to determine the influence of timing and concomitant administration of atropine and/or meperidine on the perioperative effects of oral midazolam in children. In 154 healthy children, 1-8 yr old, we studied six oral preanesthetic medication regimens according to a randomized, double-blind protocol. Group A (placebo) received 5 mL of apple juice. The other five groups received medication with apple juice to a total volume of 5 mL, 20-60 min before induction of anesthesia. Group B received atropine (0.02 mg/kg); group C received midazolam (0.5 mg/kg); group D received midazolam (0.5 mg/kg) and atropine (0.02 mg/kg); group E received meperidine (1.5 mg/kg) and atropine (0.02 mg/kg); and group F received meperidine (1.5 mg/kg), atropine (0.02 mg/kg), and midazolam (0.5 mg/kg). The sedative effect of midazolam was maximal 30 min after oral administration. Ninety-five percent of the children who were separated from their parents within 45 min after oral midazolam administration (with or without atropine) had satisfactory separation scores (vs 66% of those separated after 45 min; P less than 0.02). Midazolam-treated patients were more cooperative with a mask induction of anesthesia compared with non-midazolam-treated children (83% vs 56%). Neither atropine nor meperidine appeared to significantly improve the effectiveness of oral midazolam. No preoperative changes in heart rate, respiratory rate, or hemoglobin oxygen saturation were noted in any of the treatment groups. Finally, oral midazolam did not prolong recovery even after outpatient procedures lasting less than 30 min. In conclusion, midazolam (0.5 mg/kg) given orally 30-45 min before induction of anesthesia is safe and effective without delaying recovery after ambulatory surgery.
  • Article
    This study examined the relationship among pseudo-steady-state (constant) serum thiopental concentrations, clinical anesthetic depth as assessed by several perioperative stimuli, and the electroencephalogram (EEG). Twenty-six ASA physical status 1 or 2 patients participated in the study. Two constant serum thiopental concentrations were maintained in each patient using a computer-controlled infusion pump. The first randomly assigned target serum concentration of 10-30 micrograms/ml was maintained for 5 min to allow serum:brain equilibration. Then the following stimuli were applied at 1-min intervals: verbal command, tetanic nerve stimulation, trapezius muscle squeeze, and laryngoscopy. A second, higher, randomly assigned target serum concentration of 40-90 micrograms/ml was then achieved and maintained by the computer-controlled infusion pump. The previously described stimuli were reapplied, after which laryngoscopy and intubation was performed. A positive response was recorded if purposeful extremity movement or coughing was observed. Using the quantal movement or cough response and the measured constant serum thiopental concentration, the probability of no movement to each stimulus was characterized using logistic regression. The serum thiopental concentrations that produced a 50% probability of no movement response for the clinical stimuli were as follows: 15.6 micrograms/ml for verbal command, 30.3 micrograms/ml for tetanic nerve stimulation, 39.8 micrograms/ml for trapezius muscle squeeze, 50.7 micrograms/ml for laryngoscopy, and 78.8 micrograms/ml for laryngoscopy followed by intubation. The EEG was analyzed using aperiodic waveform analysis to derive the number of waves per second. A biphasic relationship between constant serum thiopental concentration and the EEG number of waves per second was observed. Loss of responsiveness to verbal stimulation occurred when the EEG was activated at 15-18 waves/s.(ABSTRACT TRUNCATED AT 250 WORDS)
  • Article
    A prospective, double-blind study was conducted to compare postoperative recovery after either total i.v. anaesthesia (TIVA: propofol and alfentanil) or an inhalation technique (propofol and alfentanil followed by nitrous oxide and isoflurane) in 50 patients undergoing day-case gynaecological surgery. Psychomotor performance was assessed at 1 and 2 h after surgery using the Critical Flicker Fusion Threshold (CFFT), Simple Reaction Time (SRT) and Choice Reaction Time (CRT). Subjective recovery and side effects after discharge from hospital were assessed using a postal questionnaire. Recovery occurred significantly earlier in the TIVA group as assessed by CFFT and SRT (P < 0.01 ); there were no significant differences (P > 0.05) between the two groups in CRT, subjective duration of recovery or side effects.
  • Article
    Full-text available
    Spinal and epidural anaesthesia were compared in 65 patients undergoing hip arthroplasty, with regard to the degree of sensory and motor blockade, cardiovascular effects, operating conditions, the dose of propofol required to produce satisfactory hypnosis, and complications. Epidural anaesthesia was successful in 30 patients using an initial dose of 15 ml of 0.5% bupivacaine, and spinal anaesthesia in 32 patients, using 4 ml 0.5% isobaric bupivacaine. The two techniques were similar with regard to the level of sensory blockade (T8), degree of hypotension and perioperative haemorrhage. Differences occurred in the degree of motor blockade (mean Bromage score of 1 in the spinal group vs 3.86 in the epidural group) (P less than 0.05), time to achieve maximal cephalad spread (13 min in the spinal group vs 21 min in the epidural group) (P less than 0.05) and the dose of propofol required to produce adequate hypnosis (1.95 mg.kg-1.hr-1 in the spinal group vs 2.89 mg.kg-1.hr-1 in the epidural group) (P less than 0.05). Only seven patients required urethral catheterization in this spinal group compared with 14 in the epidural group (P less than 0.05). Spinal anaesthesia also proved advantageous by providing better operating conditions for the surgeon, with a lower incidence of patient movement.
  • Article
    Positive pressure ventilation in patients with acute respiratory failure (ARF) may render the interpretation of central venous pressure (CVP) or pulmonary wedge pressure (PCWP) difficult as indicators of circulating volume. The preload component of cardiac (CI) and stroke index (SI) is also influenced by the increased intrathoracic pressures of positive pressure ventilation. Moreover CI and SI do not indicate volume status exclusively but also contractility and afterload. We investigated whether intrathoracic blood volume (ITBV) more accurately reflects blood volume status and the resulting oxygen transport (DO2). CVP, PCWP, cardiac (CI) and stroke index (SI) were measured, oxygen transport index (DO2I) and oxygen consumption index (VO2I) were calculated in 21 ARF-patients. Ventilatory patterns were adjusted as necessary. CI, SI and intrathoracic blood volume index (ITBVI) were derived from thermal dye dilution curves which were detected with a 5 F fiberoptic thermistor femoral artery catheter and fed into a thermal-dye-computer. All data were collected in intervals of 6 h. There were 224 data sets obtained. Linear regression analysis was performed between absolute values as well as between the 6 changes (prefix delta).(ABSTRACT TRUNCATED AT 250 WORDS)
  • Article
    The authors sought to define a dose of oral ketamine that would facilitate induction of anesthesia without causing significant side effects. Forty-five children (ASA Physical Status 1 and 2; aged 1-7 yr) were assigned randomly in a prospective, double-blind fashion to three separate groups that received either 3 mg/kg, 6 mg/kg, or no ketamine mixed in 0.2 ml/kg cola-flavored soft drink. They also were evaluated preoperatively and postoperatively for acceptance of oral ketamine as a premedicant, reaction to separation from parents, emotional state, and emergence phenomena. The authors detected no episodes of respiratory depression, tachycardia, or arterial hemoglobin desaturation before, during, or after surgery. The 6 mg/kg dose was well accepted; provided uniform, predictable sedation within 20-25 min; and allowed calm separation from parents and good induction conditions. The 3 mg/kg dose did not always cause sedation and calm separation from parents. Neither dose of ketamine increased the incidence of laryngospasm, prolonged recovery times, or caused emergence phenomena. The authors conclude that an oral dose of 6 mg/kg ketamine is easily administered and well accepted in young children and provides predictable, satisfactory premedication without significant side effects.
  • Article
    Two pre-operative tests for the prediction of difficult intubation are assessed. A modified Mallampati test and a measurement of thyromental distance were performed at the pre-operative visit of 244 patients whose tracheas were subsequently intubated under general anaesthesia. Patients in whom the posterior pharyngeal wall could not be visualised below the soft palate, who also had a distance of less than 7 cm between the prominence of the thyroid cartilage and the bony point of the chin proved significantly more likely to present difficulty with intubation. The performance of these two simple tests on all patients before operation should allow the majority of cases of difficult intubation to be anticipated.
  • Article
    Forty-three mothers who had requested regional anaesthesia for elective Caesarean section were allocated randomly to receive either extradural anaesthesia with pH-adjusted 2% lignocaine with 1/200 000 adrenaline, or incremental spinal anaesthesia using a 32-gauge catheter with 0.5% plain bupivacaine. Increments of lignocaine or bupivacaine were given with the aim of achieving a block from T4 to S5. The spinal catheter was quicker to place (median 3 min, range 1–45 min, compared with median 10 min, range 1.5–50 min) and spinal anaesthesia was quicker to establish (median 20 min, range 10–46 min compared with median 48 min, range 15–59 min) compared with the extradural technique. The maximum height of the spinal block was significantly higher (median T3–4, range T5–T3) than the extradural group (median T5, range T6–T3). The total dose of intrathecal 0.5% bupivacaine was unpredictable, with a mean dose of 2.7 ml and a range between 1.5 ml and 7.4 ml. Haemodynamic stability and the quality of the block were similar between the groups. There were two mild spinal headaches in the spinal group. All the spinal catheters were removed intact.
  • Article
    Desflurane's induction and recovery characteristics were compared to those of propofol-nitrous oxide in outpatients undergoing laparoscopic procedures. Ninety-two healthy patients were randomized to receive either: 1) propofol induction and propofol-nitrous oxide maintenance (control), 2) propofol induction and desflurane-nitrous oxide maintenance, 3) desflurane-nitrous oxide, or 4) desflurane alone for induction and maintenance of anesthesia. Inhalation induction with desflurane-nitrous oxide was faster than with desflurane alone (100 +/- 35 vs. 124 +/- 43 s). Inhalation inductions were associated with a high incidence of apnea (17 and 26%), breath-holding (26 and 39%), and coughing (30 and 22%) in groups 3 and 4, respectively. The emergence time after discontinuation of desflurane in oxygen (4.5 +/- 2.1 min.) was significantly less than that after propofol-nitrous oxide (7.3 +/- 3.9 min.). However, times from arrival in the recovery room until the patients were judged fit for discharge were similar for all four treatment groups. Digit-symbol substitution test results and sedation visual analogue scores also were similar during the first 2 h in the recovery room. A lower incidence of moderate-to-severe nausea was reported in group 1 (15% vs. 52, 52, and 59% in groups 2, 3, and 4, respectively). In conclusion, induction of anesthesia with desflurane was rapid but is associated with a high incidence of airway irritation. Emergence and recovery profiles after maintenance of anesthesia with desflurane compared favorably to a propofol-nitrous oxide combination. However, propofol was associated with a lower incidence of nausea than was desflurane after outpatient anesthesia for laparoscopic surgery.
  • Article
    We have seen a marked decrease in maternal and perinatal morbidity and mortality among pregnant patients with sickle cell disease. This has been the result of coordinated efforts with the obstetric and hematologic teams. Patients are counseled prior to pregnancy regarding the risks and are given the opportunity to modify their life style to prepare for the additional metabolic burden of gestation. Once pregnant, they are instructed in the techniques to recognize and avoid complications. They are observed frequently for the appearance of pain crisis and other medical and obstetric complications. If complications are identified, they should be treated aggressively. Transfusion therapy is important in the management of patients; however, prophylactic transfusion does not change outcome. Although significant laboratory techniques aid in fetal and maternal supervision, the universal fundamentals of good clinical perinatal care provided through the combined efforts of the obstetrician and hematologist contribute to the framework for the modern management and successful outcome of patients with sickle cell disease during pregnancy.
  • Article
    Recovery and psychomotor performance were studied in 80 ASA physical status I-III adult patients undergoing outpatient surgery. Patients were divided into four equal groups: thiopental induction of anesthesia followed by desflurane in nitrous oxide and oxygen (Th-DES-N2O/O2), thiopental induction of anesthesia followed by isoflurane in nitrous oxide and oxygen (Th-ISO-N2O/O2), thiopental induction of anesthesia followed by desflurane in oxygen (Th-DES-O2), and desflurane inhaled induction followed by desflurane in oxygen (DES-DES-O2). Patients were excluded from analysis if they required opioids or antiemetics postoperatively. The use of desflurane was associated with more rapid awakening compared with isoflurane (time to eye opening 9.45 +/- 0.67 min [Th-DES-N2O/O2] and 13.8 +/- 1.59 min [Th-ISO-N2O/O2], P less than 0.05). Psychomotor performance was measured using the choice reaction time and critical flicker fusion threshold. At 30 min after discontinuing anesthesia, five patients in the Th-ISO-N2O/O2 group and one patient in the Th-DES-N2O/O2 group were too sleepy to perform psychomotor tests. In addition, five patients who received Th-DES-O2 and one patient who received the inhaled induction and maintenance of anesthesia with desflurane in oxygen were too sleepy to perform tests at 30 min. Patients receiving Th-DES-N2O/O2 showed less impairment of choice reaction time than those receiving Th-ISO-N2O/O2. Critical flicker fusion threshold, however, showed no difference between groups. The use of thiopental was associated with delayed recovery. Compared with isoflurane, desflurane anesthesia is associated with more rapid initial awakening and less impairment of choice reaction time.
  • Article
    Fifty-seven patients undergoing minor out-patient gynaecological procedures were allocated to one of two total intravenous anaesthesia regimes: propofol and alfentanil or thiopentone and alfentanil. Diazepam was given orally as premedication. To assess objectively the quality of recovery, the patients underwent a number of tests pre-operatively and two hours post-operatively. The time to opening of eyes and orientation was equal in both groups, as was the recovery of the tested cognitive and psychomotor functions after 2 h, when the score in both groups had returned to baseline. We conclude that the use of propofol instead of thiopentone for shorter surgical procedures gives no advantage as regards length of stay in hospital.
  • Article
    The laryngeal mask airway is an important addition to the anaesthetist's armamentarium, but its use is not without the possibility for misfortune. We encountered an unusual and potentially serious complication. A patient's epiglottis became trapped between the pliable grates in the mask portion of the laryngeal mask and partially obstructed his airway. Should this problem occur and remain unnoticed, in addition to the problem of airway obstruction during the anaesthetic, the oedematous epiglottis could be severely injured upon removal of the laryngeal mask. This, in turn, could result in airway obstruction requiring emergency treatment.
  • Article
    Four cases of severely mentally handicapped young adults requiring day care dental treatment are reported. All had required varying degrees of restraint during previous dental treatments, which had been distressing for the patient, the relatives and the ward staff. In all cases, administration of oral ketamine 10 mg/kg, 30-60 minutes before the procedure, facilitated subsequent induction of anaesthesia.
  • Article
    Desflurane is an ether halogenated exclusively with fluorine. It has a blood/gas partition coefficient of 0.42 (cf. isoflurane 1.40 and nitrous oxide 0.46). This characteristic suggests that it should provide both a fast induction of anaesthesia and a rapid recovery from anaesthesia. To assess this, 60 patients were entered into a study and allocated at random to one of four groups receiving either desflurane or propofol for induction and maintenance of anaesthesia. Desflurane caused loss of consciousness in approximately 2 minutes during gaseous inductions. The psychomotor scores in the patients who received propofol for induction and maintenance of anaesthesia were significantly worse compared with those who were given desflurane for either induction and maintenance or for maintenance only. There was also a tendency for other recovery parameters to be faster in the patients receiving desflurane although this did not reach statistical significance. This suggests that desflurane would be a suitable agent for day case anaesthesia providing for a rapid recovery.
  • Article
    Breathing through an endotracheal tube and a demand valve may increase the work performed by the respiratory muscles. Inspiratory pressure support (PS) is known to reduce this work and might therefore compensate for this increased requirement. To test this hypothesis, we measured the work of breathing (WOB) in 11 patients whose tracheas were intubated. Five had no intrinsic lung disease, but six had chronic obstructive lung disease. We compared WOB measurements taken under several sets of conditions: during assisted breathing at four levels of PS, during unassisted breathing and connection to a T-piece, and after extubation of the trachea. During unassisted breathing via the ventilator circuit (PS set at 0 cmH20), the WOB per minute was greater than that after extubation, with a mean increase (+/- standard deviation) of 68 +/- 38% (10.3 +/- 5.1 vs. 6.5 +/- 3.7 J.min-1, P less than 0.01). While breathing through the T-piece, the WOB was 27 +/- 18% greater than after tracheal extubation (8.2 +/- 5.1 vs. 6.5 +/- 3.7 J.min-1, P less than 0.05). The principal reason why inspiratory work decreased after extubation was that the ventilatory requirement decreased. For each patient, we determined retrospectively, after extubation, the level of PS that had reduced WOB to its postextubation value and obtained levels ranging from 3.4 to 14.4 cmH2O. The PS level at which additional WOB was compensated for, was greater in patients with chronic lung disease than in those free of lung disease (12.0 +/- 1.9 vs. 5.7 +/- 1.5 cm H2O, P less than 0.05).(ABSTRACT TRUNCATED AT 250 WORDS)
  • Article
    A prospective study of unexpected, difficult laryngoscopy was carried out. During a 7-month period, all general surgery patients in whom the trachea was intubated were assessed; only those with obvious neck pathology were excluded. Ease or difficulty of laryngoscopy was graded by a standard method. There were no grade 4 cases and no failed intubations in a total of 1387 cases. There were significant differences in the results recorded by different individuals; this did not correlate with seniority or with the type of surgery. Four factors have been identified which help to explain these discrepancies. These findings are analysed in relation to the training of junior staff, with particular reference to obstetric anaesthesia.
  • Article
    Thirty-eight healthy outpatients undergoing elective surgical procedures lasting 1-3 h were randomly assigned to receive either desflurane 3% (approximately 0.5 MAC) or isoflurane 0.6% (approximately 0.5 MAC) for maintenance of general anesthesia with nitrous oxide 60% in oxygen after a standardized induction sequence consisting of fentanyl 3 micrograms.kg-1, thiopental 4 mg.kg-1, and succinylcholine 1-1.5 mg.kg-1, intravenously. Although anesthetic conditions were similar during operations in the two treatment groups, significant differences were noted in the recovery profiles as measured by elimination kinetics, psychometric testing, and visual analog scales (to assess subjective feelings). The time required for the end-tidal concentration to decrease by 50% was 2.5 +/- 0.8 min for desflurane vs. 9.5 +/- 3.4 min for isoflurane (mean +/- standard deviation [SD]). Times to awakening and ability to follow simple commands were significantly shorter after desflurane than after isoflurane (5.1 +/- 2.4 vs. 10.2 +/- 7.7 min 6.5 +/- 2.3 min vs. 11.1 +/- 7.9 min, respectively). Postoperatively, patients who received desflurane exhibited less impairment of cognitive function (as measured using the Digit-Symbol Substitution Test) than did those who received isoflurane. Furthermore, visual analog scores indicated that patients receiving desflurane experienced significantly less discomfort (pain), drowsiness, fatigue, clumsiness, and confusion in the early postoperative period. We conclude that desflurane may offer clinical advantages over isoflurane when used for maintenance of anesthesia during outpatient surgical procedures.
  • Article
    This study compared the effectiveness of 0.5% ropivacaine and 0.5% bupivacaine for brachial plexus block. Forty-eight patients received a subclavian perivascular brachial plexus block for upper-extremity surgery. One group (n = 24) received ropivacaine 0.5% (175 mg) and a second group (n = 24) received bupivacaine 0.5% (175 mg), both without epinephrine. Onset times for analgesia and anesthesia in each of the C5 through T1 brachial plexus dermatomes did not differ significantly between groups. Duration of analgesia and anesthesia was long (mean duration of analgesia, 13-14 h; mean duration of anesthesia, 9-11 h) and also did not differ significantly between groups. Motor block was profound, with shoulder paralysis as well as hand paresis developing in all of the patients in both groups. Two patients in each group required supplemental blocks before surgery. Ropivacaine 0.5% and bupivacaine 0.5% appeared equally effective in providing brachial plexus anesthesia.
  • Article
    A prospective study of routine premedication management was carried out at a large teaching hospital. Many patients received their premedication at times inappropriate for it to be effective. Several patients receiving regular medication had this suddenly stopped pre-operatively. Prolonged fasting occurred in both elective and emergency groups of patients. Benzodiazepines and opioids were prescribed most frequently and drying agents were used widely. Antacids, H2-blockers and agents to promote gastric emptying were used very little despite the potential of aspiration in many groups of patients. This audit of activity has revealed several areas of practice that can either be improved immediately or warrant detailed investigation.
  • Article
    Recovery was assessed over 48 hours after anaesthesia with propofol or thiopentone as sole anaesthetic agent in 36 unpremedicated gynaecological patients. Immediate recovery, as measured by the Steward scale, was shown to be quicker for the patients given propofol. At one hour postoperatively the thiopentone group showed impaired visual-motor coordination on the aiming test (p less than 0.01) and dexterity task (p less than 0.05), and a slowing of reaction time (p less than 0.01). Patients given propofol showed only an increase in reaction time (p less than 0.05). By 2 hours the thiopentone group showed impairment only in the aiming task (p less than 0.05). No further significant impairment was detected at 4, 24 or 48 hours. However, patients reported symptoms throughout the 48 hours indicative of residual drug effects. There was a substantial practice effect with some tests which may have obscured impairment. It can be argued therefore that the better recovery profile after propofol is still evident at 24 hours.
  • Article
    Postanesthetic nausea and vomiting can delay discharge of outpatients and can cause occasional admissions to hospital. Nitrous oxide (N2O) has been thought to increase this frequency, but previous studies have been indecisive. One hundred eighty-five unpremedicated outpatients undergoing laparoscopic tubal ligation were studied to determine the effect of N2O on postanesthetic nausea and vomiting. The patients were divided by registration number, intubated, and given mixtures of either N2O-O2 enflurane or air-O2 enflurane. Intravenous (IV) lidocaine, administered initially prior to intubation to control bucking, was later omitted in randomly chosen cases to determine its effect. The overall prevalence of nausea and vomiting was 29.2% with N2O and 9.3% with air (p less than 0.001). While the lidocaine subseries was small, it appeared to prevent nausea and vomiting, particularly when N2O was omitted. Further study is justified. Fentanyl, given postoperatively for pain, did not increase the prevalence of nausea and vomiting. It was concluded that N2O is associated with an increased prevalence of nausea and vomiting.
  • Article
    A randomized, prospective study was performed to compare recovery characteristics in 41 ASA physical status I-II patients scheduled for ambulatory surgery with either propofol or thiopentone-isoflurane anaesthesia. Particular attention was focused on the recovery time needed to meet discharge criteria. The propofol group received propofol 2 mg.kg-1 for induction followed by propofol infusion (6-9 mg.kg-1.h-1) 1 min after intubation. The thiopentone-isoflurane group received thiopentone 4 mg.kg-1 for induction followed by isoflurane (0.5-2%) 1 min after endotracheal intubation. Other drugs administered during or after anaesthesia were similar between the groups. The propofol group had significantly (P less than 0.05) faster clinical recovery than the isoflurane group with respect to times to response to commands, eye opening, orientation, ability to stand and void, tolerance to oral fluids, "home-readiness", and recovery of perceptual speed. Patients in the propofol group had significantly less (P less than or equal to 0.05) emesis than the patients given isoflurane. We conclude that in patients undergoing ambulatory surgery propofol infusion is preferable to thiopentone-isoflurane anaesthesia, because it may allow faster discharge home.
  • Article
    A new local anaesthetic, ropivacaine hydrochloride, was used in a concentration of 0.5 per cent in 32 patients receiving a subclavian perivascular block for upper extremity surgery. One group (n = 15) received 0.5 per cent ropivacaine without epinephrine and a second group (n = 17) received 0.5 per cent ropivacaine with epinephrine in a concentration of 1:200,000. Anaesthesia was achieved in 87 per cent of the patients in both groups in all of the C5 through T1 brachial plexus dermatomes. Motor block was profound with 100 per cent of patients in both groups developing paresis at both the shoulder and hand and 100 per cent developing paralysis at the shoulder. There was a rapid initial onset of sensory block (a mean of less than four minutes for analgesia) with a prolonged duration (a mean of greater than 13 hr of analgesia). The addition of epinephrine did not significantly affect the quality or onset of sensory or motor block. The duration of sensory block was reduced by epinephrine at T1 for analgesia and at C7, C8, and T1 for anaesthesia. The duration of sensory block in the remaining brachial plexus dermatomes as well as the duration of motor block was not effected by epinephrine. There was no evidence of cardiovascular or central nervous system toxicity in either group with a mean dose of 2.5-2.6 mg.kg-1 ropivacaine.