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Preoperative screening and perioperative care of the patient with sleep-disordered breathing
Abstract
Emerging data are raising concerns that patients with known or suspected obstructive sleep apnea (OSA) are at increased risk for a myriad of perioperative complications. Strategies to identify patients preoperatively with OSA, or at risk for OSA, are being advocated. In addition, approaches to identify patients most at risk for OSA-related postoperative complications have been described. While lacking solid evidence, a number of perioperative management strategies have been proposed for the care of these patients.
Recent studies utilizing different methodologies have provided additional evidence regarding the impact that OSA can have on postoperative outcomes, including increased risk of difficult intubations, adverse pulmonary outcomes, and delirium. Tools, such as the STOP-Bang questionnaire and limited channel monitoring, have been investigated with regards to their utility to identify not only patients at risk for OSA but also those at risk for more severe OSA. Consensus-based guidelines for the perioperative care of OSA patients have recently been published.
OSA is quite common in patients presenting for elective surgery and has been linked to increased perioperative complications. Attempts to identify these patients preoperatively appear prudent. Protocols on how best to manage these patients are available, although validation of their effectiveness is needed.
... eine Atemdepression prädisponieren können in einer Phase, in der die Patienten unter Umständen nicht adäquat überwacht sind (vor bzw. während des Transports in den OP) [29]. ...
... Zu bevorzugen sind deshalb intravenöse und inhalative Anästhetika sowie Opioide mit vorteilhafter Pharmakokinetik, d. h. möglichst gut steuerbarer Elimination [29]. ...
... Neben einer erhöhten Häufigkeit an schwierigen Intubationen bei OSAPatienten kann auch die Maskenbeatmung erschwert sein [29]. Außer einer optimierten Körperposition sollten deshalb auch adäquate Instrumente zur Beherrschung eines schwierigen Atemweges entsprechend des ASA-Algorithmus unmittelbar verfügbar sein [44]. ...
Die obstruktive Schlafapnoe (OSA) ist eine im Schlaf auftretende Atmungsstörung mit zunehmender Prävalenz, bei der es trotz fortbestehender Atemanstrengung zu einer sich wiederholenden, teilweisen oder vollständigen Verlegung des pharyngealen Atemweges kommt. In Abhängigkeit vom Schweregrad der Erkrankung kann dies zu Schlafunterbrechungen, einer Gasaustauschstörung sowie kardiovaskulären und metabolischen Folgeerkrankungen führen.
Chirurgische Patienten mit einer OSA, welche präoperativ in den meisten Fällen nicht diagnostiziert ist, haben ein erhöhtes Risiko für das perioperative Auftreten von pulmonalen, kardiovaskulären und weiteren Komplikationen.
Spezielle Maßnahmen können dazu beitragen, die Sicherheit der Patienten in dieser Phase zu erhöhen. Dazu zählen präoperativ die frühzeitige Erkennung und Einschätzung einer OSA und eventuell bestehender Begleiterkrankungen, intraoperativ die Auswahl eines geeigneten Anästhesie- und Überwachungsverfahrens sowie postoperativ die Aufrechterhaltung einer ausreichend langen Überwachungsdauer mit der Möglichkeit intensivmedizinischer Behandlungsmaßnahmen. Das konkrete Vorgehen sollte sich dabei nach dem individuellen Risikoprofil des einzelnen Patienten richten, das u. a. vom Schweregrad der OSA, der Invasivität des operativen Eingriffes und vom postoperativen Opioidbedarf sowie dem Auftreten kritischer Ereignisse in der frühen postoperativen Phase abhängt.
Auf Initiative und im Auftrag der Deutschen Gesellschaft für Hals-, Nasen-, Ohren-Heilkunde, Kopf- und Hals-Chirurgie sollen nachfolgend auf der Grundlage der bestehenden Literatur und bereits existierender Leitlinien anderer Fachgesellschaften Empfehlungen für das perioperative Management von erwachsenen Patienten mit OSA bei HNO-ärztlichen Eingriffen vorgestellt werden.
... This implies that with proper preventive strategies postoperative pulmonary complications can be reduced in severe OSA also [37]. Recent survey by Auckley and Bolden has shown that large number of surgical patients (24-41%) are at risk of undiagnosed OSA during perioperative period [39]. Patients with sleep apnoea are at risk of development respiratory impairment leading to hypoxaemia, hypercapnia, negative pressure pulmonary oedema etc. ...
... Patients with sleep apnoea are at risk of development respiratory impairment leading to hypoxaemia, hypercapnia, negative pressure pulmonary oedema etc. These patients are also at risk for aspiration pneumonia and ARDS [39]. ...
Postoperative pulmonary complications such as Pneumonia, Acute Lung Injury (ALI), Acute Respiratory Distress Syndrome (ARDS) substantially increases the risk of morbidity, mortality, length of hospitalisation and financial burden. Risk factors can be broadly categorized into patient related, procedure related, anaesthesia related and post procedural care related. The prevention of postoperative ALI requires a comprehensive approach that includes preoperative risk stratification and optimizations, intra-operative lung protective strategies that includes lung protective ventilation, regional analgesia technique, avoiding excessive fluid, minimising blood and blood product transfusion, control oxygen therapy. Postoperative part is equally important and required multidisciplinary multi-model approach that includes-fast tracking protocol for enhanced recovery, good analgesia using multi-model therapy to minimised systemic opioid, vigilance monitoring, physiotherapy and lung expansion manoeuvres including use of non-invasive ventilation in selected patients and other supportive care such as nutritional support, glycemic control, selective naso-gastric drainage, thrombo-prophylaxis and early empirical antibiotic therapy in suspected infection and sepsis. or Acute Respiratory Distress Syndrome (ARDS) accounting for up to 7% in thoracic surgery [1]. Postoperative pulmonary complication not only leads to increased hospital stay, it accounts for substantial increase in morbidity and mortality in relation to anaesthesia and surgical outcome [2-5]. Proper preoperative optimization of the clinical conditions and satisfactory employment of intra operative proposed strategies have considerably reduced the post operative lung injuries. In the immediate post operative period primary form of ALI strictly depends upon the systemic inflammatory response induced by the surgical and anesthetic events which should be distinguished from a secondary ALI, usually delayed and showing an onset from 3 to 12 days after surgery. The secondary ALI is triggered by several postoperative complications including sepsis, pulmonary embolism, gastric content aspiration, and pneumonia [6]. It is essential to understand that although ALI is a diffuse & heterogeneous process, and not all lung units are affected equally: normal and diseased tissue may exist side-by-side. The patho-physiology of postoperative ALI/ ARDS involves alveolar-capillary endothelial injury or dysfunction with alteration in innate immune system, generation of reactive oxygen radicals, activation of coagulation etc. [7,8] resulting in fluid flooding into alveoli impairing gas exchange leading to hypoxaemia and respiratory failure. Postoperative ALI/ARDS has high mortality rate exceeding 45% in certain surgical populations [4,5]. Importantly patient co-existing pathology, surgical injury, medications and various perioperative health care delivery factors such as ventilator strategy, fluid-balance, physiotherapy, transfusion therapy might play crucial rule in many form of postoperative ALI [8,9]. The preventive aspect of ALI has been largely neglected or not emphasised in literatures, rather focused on cause and treatment of ALI. This might be because studies on ALI are typically performed in the critical care setting with already established lung injury and are beyond the potential preventive strategy. The peri-operative period is an important and attractive period where many clinical and therapeutic strategy can be applied as preventive approach for postoperative ALI. Early diagnosis
... Obstructive Sleep Apnea (OSA) is a known perioperative risk factor, where despite being highly prevalent, it remains under-diagnosed in the surgical setting [1][2][3]. OSA impacts many physiologic functions including cardiac, respiratory and neurological functions [4], and is associated with an increased risk of complications including difficult airway, adverse cardiopulmonary outcomes, and delirium [5][6][7]. Polysomnography (PSG) is the gold standard diagnostic test for OSA [8], however, it has many shortcomings including significant cost, inaccessibility, poor tolerance due to interference with patients' sleep, pain and discomfort in the perioperative setting. Multiple wearable sensors interfere with oxygen delivery devices, and access devices such as intravenous or invasive monitoring lines [9][10][11]. ...
Study objective: Obstructive Sleep Apnea (OSA) is associated with increased perioperative cardiac, respiratory and neurological complications. Pre-operative OSA risk assessment is currently done through screening question- naires with high sensitivity but poor specificity. The objective of this study was to evaluate the validity and diagnostic accuracy of portable, non-contact devices in the diagnosis of OSA as compared with polysomnography.
Design: This study is a systematic review of English observational cohort studies with meta-analysis and risk of bias assessment.
Setting: Pre-operative, including in the hospital and clinic setting.
Patients: Adult patients undergoing sleep apnea assessment using polysomnography and an experimental non- contact tool.
Interventions: A novel non-contact device, which does not utilize any monitor that makes direct contact with the patient’s body, in conjunction with polysomnography.
Measurements: Primary outcomes included pooled sensitivity and specificity of the experimental device in the diagnosis of obstructive sleep apnea, in comparison to gold-standard polysomnography.
Results: Twenty-eight of 4929 screened studies were included in the meta-analysis. A total of 2653 patients were included with the majority being patients referred to a sleep clinic (88.8%). Average age was 49.7(SD±6.1) years, female sex (31%), average body mass index of 29.5(SD±3.2) kg/m2, average apnea-hypopnea index (AHI) of 24.7(SD±5.6) events/h, and pooled OSA prevalence of 72%. Non-contact technology used was mainly video, sound, or bio-motion analysis.
Pooled sensitivity and specificity of non-contact methods in moderate to severe OSA diagnosis (AHI > 15) was 0.871 (95% CI 0.841,0.896, I2 0%) and 0.8 (95% CI 0.719,0.862), respectively (AUC 0.902). Risk of bias assessment showed an overall low risk of bias across all domains except for applicability concerns (none were conducted in the perioperative setting).
Conclusion: Available data indicate contactless methods have high pooled sensitivity and specificity for OSA diagnosis with moderate to high level of evidence. Future research is needed to evaluate these tools in the perioperative setting.
... Patients were followed by respiratory therapists affiliated with RMBSP and the SMS to ensure OSA control. Based on the interpretation of OSA severity and level of control, BMI, and number of comorbidities, the SMS sent a recommendation to the preoperative clinic for the patient's postoperative bed location (Table 1) [18]. Accordingly, at the preoperative clinic assessment, the anesthesiologist or internist booked a postoperative bed for the patient in either the surgical ward, telemetry unit, HAU, or ICU, based on these recommendations. ...
Background
Postoperative bariatric management often includes high-intensity monitoring for respiratory complications since > 70% of patients have obstructive sleep apnea. Given the increasing number of bariatric surgeries, there is a need to determine safe and cost-effective processes for postoperative care.The objective of this study was to determine if a novel triage and perioperative management guideline reduces postoperative monitoring and costs following bariatric surgery.
Methods
Using a pre-post design, this is a retrospective analysis of 501 patients who had bariatric surgery. Half the patients were managed with usual care, and the other half received obstructive sleep apnea screening and treatment of moderate/severe obstructive sleep apnea with perioperative continuous positive airway pressure. The intervention group was triaged preoperatively to a postoperative nursing location based on risk factors.
Results
There were no significant differences in demographics, comorbidities, frequency, or severity of OSA between groups. In the intervention group, there were fewer admissions to the intensive care unit (2.0% vs 9.1%; p < 0.01) and high acuity unit (9.6% vs 18.3%; p < 0.01). The length of stay was shorter in the intervention group (1.3 vs 2.3 days; p < 0.01) with a 50% reduction in costs. There were no statistically significant differences in the incidence of postoperative respiratory and non-respiratory complications between the two groups.
Conclusions
Most postoperative bariatric surgery patients can be safely managed on the surgical ward with monitoring of routine vitals alone if patients with moderate/severe obstructive sleep apnea receive perioperative continuous positive airway pressure.
Graphical abstract
... Ovome doprinose promene u mehanici grudnog koša koje su deo fiziološkog procesa starenja (smanjenje FEV1, povećanje closing volume), ali i mikroembolizacija pluća nakon preloma dugih kostiju 1 . Gojazni pacijenti i oni sa opstruktivnom sleep apneom su pod visokim rizikom od nastanka postoperativnih respiratornih komplikacija 12 . ...
Ay anesthesia for orthopedic surgery is challenging for anesthesiologist from the patient's perspective, the type of surgery as well as the patient's position during the surgery. Patients may be old with numerous comorbidities but also young, healthy trauma patients who have associated injuries that can have a significant impact on the type of anesthesia. Therefore, it is imperative that the anesthesiologist in orthopedic surgery examine the entire patient and not just focus on the area of surgery, but also to make an adequate preoperative assessment and preparation. In the preoperative preparation of orthopedic patients cardiological, pulmological and neurological evaluation is most often needed, nasal screening and decolonization, preoperative skin preparation, glycemic control and the use of antibiotic prophylaxis. Patients undergoing major orthopedic surgery are at highest risk for venous thromboembolism both during and after surgery, so that the timing of thromboprophylaxis as well as its continuation in orthopedic patients is of exceptional importance. For the optimal use of adequate thromboprophylaxis there are several published guidelines with clear recommendations for daily clinical practice. Understanding the type and course of the surgery as the patient position during surgery provide adequate working conditions with minimal blood loss and complications. Reduction of bleeding, as intraoperatively and postoperatively have been achieved by normovolemic hypotension, tourniquet, but also by topical or systemic application of tranexamic acid.As a surgery with high postoperative requirements in analgesia within the multimodal approach, besides the peripheral nerve blocks, the periarticular injection of local anesthetics is increasingly used in everyday work. Knowing the specificity and requirements of an orthopedic surgery with adequate preoperative preparation, selection of anesthesia type and intraoperative plan in order to reduce intraoperative bleeding requires adapting to each patient individually.
... Overall, there is a clinical trend responding to a perceived risk of undiagnosed and untreated OSA in the perioperative setting leading to more pre-operative screening being incorporated into clinical practice [28,29]. The American Society of Anesthesiology (ASA) have published recommendations, updated in 2016 [29], to help guide the assessment and management of OSA in the perioperative setting. ...
Purpose
The purpose of this study is to establish if obstructive sleep apnoea (OSA) predicted by the STOP-BANG questionnaire would be associated with higher rates of post-operative cardiac, respiratory or neurological complications among a selected high-risk population with established major comorbidities undergoing major surgery. We hypothesise that a cohort selected for major comorbidities will show a higher post-operative complication rate that may power any potential association with co-existent OSA and identify an important target group for OSA screening and treatment pathways in preparation for major surgery.
Methods
Patients attending a high-risk preadmission clinic prior to major surgery from May 2015 to November 2015 were prospectively screened for OSA using the STOP-BANG questionnaire. Patients with treated OSA were excluded. Patient data and complications were attained from the pre-admission clinic and subsequent inpatient medical record at discharge.
Results
Three-hundred-and-ten patients were included in the study (age 68.6 ± 13.1 years, body mass index [BMI] 30.6 ± 7.4 kg/m²; 52.9% female). Sixty-four patients (20.6%) experienced 82 post-operative complications. Seventy-five percent of the cohort had a STOP-BANG ≥ 3. There was no association between the STOP-BANG score (unadjusted and adjusted for comorbidity) with the development of post-operative complications.
Conclusions
OSA predicted by the STOP-BANG score was not associated with higher rates of post-operative complications in patients with major comorbidities undergoing high-risk surgery. As the findings from this cohort contrast with other observational studies, more definitive studies are required to establish a causative link between OSA and post-operative complications and determine whether treating OSA reduces this complication rate.
... It was the aim of this study to evaluate the impact of a high risk of OSAS on the postoperative cognitive dysfunction after intravenous anesthesia. Patients susceptible for a high risk of OSAS were identified using the STOP BANG questionnaire, which is recommended for screening patients with moderate to severe risk for OSAS [20][21][22]. Recently, Kim and co-workers published [27]. ...
Background:
The obstructive sleep apnea syndrome (OSAS) is characterized by temporary cerebral hypoxia which can cause cognitive dysfunction. On the other hand, hypoxia induced neurocognitive deficits are detectable after general anesthesia. The objective of this study was to evaluate the impact of a high risk of OSAS on the postoperative cognitive dysfunction after intravenous anesthesia.
Methods:
In this single center trial between June 2012 and June 2013 43 patients aged 55 to 80 years with an estimated hospital stay of at least 3 days undergoing surgery were enrolled. Patients were screened for a high risk of OSAS using the STOP-BANG test. The cognitive function was assessed using a neuropsychological test battery, including the DemTect test for cognitive impairment and the RMBT test for memory, the day before surgery and within 36 h after extubation.
Results:
Twenty-two of the 43 analyzed patients were identified as patients with a high risk of OSAS. Preoperatively, OSAS patients showed a significant worse performance only for the DemTect (p = 0.0043). However, when comparing pre- and postoperative test results, the OSAS patients did not show a significant loss in any test but significantly improved in RMBT test, whereas the control group showed a significant worse performance in three of eight tests. In five tests, we found a significant difference between the two groups with respect to the change from pre- to postoperative cognitive function.
Conclusion:
Patients with a high risk of OSAS showed a less impairment of memory function and work memory performance after intravenous anesthesia. This might be explained by a beneficial effect of intrinsic hypoxic preconditioning in these patients.
... 17 Patients at risk of obstructive sleep apnoea should be identified and referred to an ear, nose, and throat surgeon for assessment and early management. 18 The need for ICU admission and prolonged LOS may be eliminated if medical conditions are optimised before TKR. ...
Introduction:
The demand for total knee replacement in Hong Kong places tremendous economic burden on our health care system. Shortening hospital stay reduces the associated cost. The aim of this study was to identify perioperative predictors of length of hospital stay following primary total knee replacement performed at a high-volume centre in Hong Kong.
Methods:
We retrospectively reviewed all primary total knee replacements performed at Yan Chai Hospital Total Joint Replacement Centre from October 2011 to October 2015. Perioperative factors that might influence length of stay were recorded.
Results:
A total of 1622 patients were identified. The mean length of hospital stay was 6.8 days. Predictors of prolonged hospital stay following primary total knee replacement were advanced age, American Society of Anesthesiologists physical status class 3, bilateral total knee replacement, in-patient complications; and the need for blood transfusion, postoperative intensive care unit admission, and urinary catheterisation.
Conclusions:
Evaluating factors that can predict length of hospital stay is the starting point to improve our current practice in joint replacement surgery. Prediction of high-risk patients who will require a longer hospitalisation enables proactive discharge planning.
... Furthermore, in the review by Zaremba, it was estimated that over 75% of the subpopulation of morbidly obese surgical patients may be affected by OSA (7). Although OSA patients have the propensity of hypoventilation and hypoxia after surgery, the majority of OSA cases remain undiagnosed prior to surgery (8,9). For this reason, several screening tools, such as the STOP-Bang, ASA checklist, sleep apnea clinical score, and Berlin questionnaire, were developed to assess the possible existence of an undiagnosed OSA and to provide risk stratification of OSA in surgical patients (10)(11)(12). ...
Obstructive sleep apnea (OSA) is one of the important risk factors contributing to postoperative airway complications. OSA alters the respiratory physiology and increases the sensitivity of muscle tone of the upper airway after surgery to residual anesthetic medication. In addition, the prevalence of OSA was reported to be much higher among surgical patients than the general population. Therefore, appropriate monitoring to detect early respiratory impairment in postoperative extubated patients with possible OSA is challenging. Based on the comprehensive clinical observation, several equipment have been used for monitoring the respiratory conditions of OSA patients after surgery, including the continuous pulse oximetry, capnography, photoplethysmography (PPG), and respiratory volume monitor (RVM). To date, there has been no consensus on the most suitable device as a recommended standard of care. In this review, we describe the advantages and disadvantages of some possible monitoring strategies under certain clinical conditions. According to the literature, the continuous pulse oximetry, with its high sensitivity, is still the most widely used device. It is also cost-effective and convenient to use but has low specificity and does not reflect ventilation. Capnography is the most widely used device for detection of hypoventilation, but it may not provide reliable data for extubated patients. Even normal capnography cannot exclude the existence of hypoxia. PPG shows the state of both ventilation and oxygenation, but its sensitivity needs further improvement. RVM provides real-time detection of hypoventilation, quantitative precise demonstration of respiratory rate, tidal volume, and MV for extubated patients, but no reflection of oxygenation. Altogether, the sole use of any of these devices is not ideal for monitoring of extubated patients with or at risk for OSA after surgery. However, we expect that the combined use of continuous pulse oximetry and RVM may be promising for these patients due to their complementary function, which need further study.
... Patients on positive airway pressure therapy (PAP) at home, either continuous PAP (CPAP) or bilevel PAP, should be encouraged to bring their PAP devices with them to the medical facility, as this may well facilitate compliance in the postoperative period [40]. Reassessment by a sleep medicine physician may be indicated in patients who have defaulted follow-up, been non-compliant to treatment, have had recent exacerbation of symptoms, or have undergone upper airway surgery to relieve OSA symptoms. ...
Obstructive sleep apnea (OSA) has been linked to a myriad of chronic diseases with physically serious and economically draining consequences. There has been a substantial increase in its prevalence over the last two decades and up to one-quarter of the elective surgical patients have been found to be at high risk for OSA. These patients are at an increased risk for perioperative adverse events such as cardiac and pulmonary complications as well as postoperative delirium. This review addresses the screening methods such as the STOP-Bang questionnaire for the undiagnosed and the preoperative management of the known and at-risk patients. Recommendations for the evaluation of the systemic complications and its management are included. Recent suggestions for the intraoperative management and risk mitigation methods are reviewed, such as the role of regional anesthesia and non-opioid analgesics. Special focuses on postoperative issues such as pain control, oxygenation, positioning, and patient disposition are also included.
Study objectives:
Patients with obstructive sleep apnea (OSA) have a disproportionate increase in post-operative complications and medical emergency team activation (META). We previously introduced DOISNORE50 (D-diseases, O-observed apnea, I-insomnia, S-snoring, N-neck circumference > 18 inches, O-obesity with BMI > 32, R-are you male, E-excessive daytime sleepiness, 50-age ≥ 50) from sleep questionnaire ISNORED (IS) using features associated with increased odds of META in perioperative patients. Performance of DOISNORE50 (DOISNORE) had yet to be tested.
Methods:
The performance of DOISNORE was tested along with IS and STOP-Bang (SB) questionnaires among 300 out of 392 participants without known OSA referred to the sleep lab. In study 2, the performance of DOISNORE was tested among 64,949 lives screened in perioperative assessment clinic from 2016 to 2020.
Results:
Receiver operating characteristic (ROC) curve demonstrated that best performance was achieved with DOISNORE ≥ 6, with area under curve (AUC) of 0.801. DOISNORE's predictability of OSA risk remained stable from 2016-2020 with AUC of 0.78 and a Cronbach alpha of 0.65. Patients at High Risk for OSA (DOISNORE ≥ 6) were associated with an increase of META (OR 1.30, 95% CI 1.12 - 1.45). Higher relative risk was noted among patients with congestive heart failure and hypercapnia.
Conclusions:
DOISNORE is predictive of OSA and postoperative META. Perioperative strategies against META should consider DOISNORE questionnaire and focused screening among patients with heart failure and hypercapnia.
Importance:
Obstructive sleep apnea syndrome (OSAS) is a common medical condition in the United States and affects gynecologic surgical outcomes.
Objective:
The aim of this review was to improve perioperative diagnosis and management of OSAS in patients presenting for gynecologic surgery and ultimately improve perioperative outcomes. The role of preoperative evaluation and screening is also addressed.
Evidence acquisition:
Medical databases were queried for publications pertaining to OSAS complications, risk factors, screening, and perioperative management. Pertinent articles were reviewed by the study authors.
Results:
Obstructive sleep apnea syndrome is underdiagnosed in the preoperative surgical population. Obesity and other risk factors for OSAS are prevalent in patients with gynecologic issues but are not fully assessed with screening prior to surgery. Effective treatment modalities, such as continuous positive airway pressure, and perioperative management strategies are available to improve patient outcomes.
Conclusions and relevance:
Increased diagnosis and treatment for OSAS in the perioperative period can improve perioperative outcomes, surgical outcomes, and long-term patient outcomes. Strategies to increase effective management in patients presenting for gynecologic surgery are needed.
: Obstructive sleep apnoea (OSA) is a common breathing disorder of sleep with a prevalence increasing in parallel with the worldwide rise in obesity. Alterations in sleep duration and architecture, hypersomnolence, abnormal gas exchange and also associated comorbidities may all feature in affected patients.The peri-operative period poses a special challenge for surgical patients with OSA who are often undiagnosed, and are at an increased risk for complications including pulmonary and cardiovascular, during that time. In order to ensure the best peri-operative management, anaesthetists caring for these patients should have a thorough understanding of the disorder, and be aware of the individual's peri-operative risk constellation, which depends on the severity and phenotype of OSA, the invasiveness of the surgical procedure, anaesthesia and also the requirement for postoperative opioids.The objective of this review is to educate clinicians in the epidemiology, pathogenesis and diagnosis of OSA in adults and also to highlight specific tasks in the preoperative assessment, namely to select a suitable intra-operative anaesthesia regimen, and manage the extent and duration of postoperative care to facilitate the best peri-operative outcome.
A significant proportion of patients undergoing ambulatory procedures is at risk for sleep-disordered breathing (SDB). Obstructive sleep apnea is the most common diagnosis, but other types such as opioid-related central apnea are important variants. Long-term cardiovascular, neurologic, and related sequelae of untreated SDB are significant such that screening at-risk patients with low-tech bedside tools such as STOP-BANG is warranted. Patients with presumptive SDB should be educated about the disease and referred for specialty evaluation and formal diagnosis. Those with known or presumptive moderate-to-severe disease warrant a special clinical pathway that may include sedation by an anesthesia provider with airway rescue experience and familiarity with a broader range of sedative-hypnotic medications, the availability of respiratory therapy support for periprocedural use of continuous positive airway pressure devices, and heightened vigilance and monitoring in the recovery suite.
Sleep-disordered breathing (SDB) disorders include: central sleep apnoea (Cheyne-Stokes respiration), obstructive sleep apnoea and mixed or complex sleep apnoea. Obstructive sleep apnoea (OSA) is the most common of these three disorders and is defined as airway obstruction during sleep, accompanied by at least five episodes of apnoea or hypopnoea per hour. Each episode is often associated with a decrease in arterial oxygen saturation of > 4%.
In recent years, more elderly patients with gastrointestinal cancers have been undergoing surgery. As one of main postoperative complications, postoperative delirium (POD) is harmful and difficult to prevent and treat. Prevention, diagnosis and treatment to POD properly and ptomptly can promote the patient's overall recovery. However, health care providers still have many problems for POD to face in elderly,with gastrointestinal cancers during the clinical care. In this paper, Etiology, damages, prevention, diagnosis and treatment of POD in elderly with gastrointestinal cancer were reviewed, and the prospect of POD was also discussed.
Obstructive sleep apnea (OSA) is a common sleep related breathing disorder with an increasing prevalence. Most surgical patients with OSA have not been diagnosed prior to surgery and are at an increased risk of developing perioperative complications. Preoperative identification of these patients is important in order to take appropriate measures concerning a safe perioperative management. While the level of scientific evidence for single measures is still low, several steps seem prudent: Preoperatively, sedating medications should only be applied with extreme caution. Anesthetic management should focus on regional anesthetic techniques and reduction of systemic opioids. In the case of general anesthesia, an increased risk of a patient presenting with a difficult airway should be appreciated. The extent and duration of postoperative continuous monitoring has to be determined on an individual basis. A preoperatively existing therapy with continuous positive airway pressure should be continued postoperatively as soon as possible. Patients with OSA may be managed on an outpatient basis if certain requirements are met.
© Georg Thieme Verlag Stuttgart · New York.
Undiagnosed obstructive sleep apnea (OSA) is a highly prevalent breathing disorder. The purpose of this study was to determine the effects of preoperative screening and subsequent treatment for OSA on the health of patients.
We conducted a two-year follow-up study of patients previously enrolled in a large prospective study in which patients were given the STOP questionnaire for OSA screening (n = 2,467). All patients who underwent a polysomnography were considered eligible (n = 211) and were asked to complete a paper-based mailed questionnaire. The severity of OSA, comorbidities, and treatment modalities and their effects were evaluated from the returned questionnaire. Research ethics board approval was obtained and returning the questionnaire implied informed patient consent.
The response rate was 67%. One hundred twenty-eight (82%) of the 156 patients who responded had OSA established by polysomnography. Among these 128 patients with OSA, 88 (69%) were prescribed continuous positive airway pressure (CPAP) therapy and 40 (31%) were prescribed other (non-CPAP) treatment. Among those 88 patients receiving CPAP, 40 (45%) were compliant and 48 (55%) were non-compliant. The CPAP compliant patients had a greater reduction in medication for comorbidities than the CPAP non-compliant or the other treatment group (38% vs 3% vs 0%, respectively; P < 0.001). A significant improvement in snoring, sleep quality, and daytime sleepiness was reported by CPAP compliant users compared with CPAP non-compliant or other treatment groups (P < 0.001).
The preoperative patients who were identified to have OSA and were compliant with CPAP use may have health benefits in terms of improved snoring, sleep quality, and daytime sleepiness. Timely diagnosis and treatment compliance may reduce symptoms of OSA and severity of associated comorbidities along with a reduction in medications.
The aim of this study was to evaluate prevalence of obstructive sleep apnea among patients undergoing bariatric surgery and the predictive value of various clinical parameters: body mass index (BMI), neck circumference (NC) and the Epworth Sleepiness Scale (ESS). We performed a prospective, multidisciplinary, single-center observational study including all patients on the waiting list for bariatric surgery between June 2009 and June 2010, irrespective of history or clinical findings. Patients visited our ENT outpatient clinic for patient history, ENT and general examination and underwent a full night polysomnography, unless performed previously. As much as 69.9% of the patients fulfilled the criteria for OSA (mean BMI 44.2 ± SD 6.4 kg/m(2)); 40.4% of the patients met the criteria for severe OSA. The regression models found BMI to be the best clinical predictor, while the ROC curve found the NC to be the most accurate predictor of the presence of OSA. The discrepancy of the results and the poor statistical power suggest that all three clinical parameters are inadequate predictors of OSA. In conclusion, in this large patient series, 69.9% of patients undergoing BS meet the criteria for OSA. More than 40% of these patients have severe OSA. A mere 13.3% of the patients were diagnosed with OSA before being placed on the waiting list for BS. On statistical analysis, increased neck circumference, BMI and the ESS were found to be insufficient predictors of the presence of OSA. Polysomnography is an essential component of the preoperative workup of patients undergoing BS. When OSA is found, specific perioperative measures are indicated.
The STOP-Bang questionnaire is used to screen patients for obstructive sleep apnoea (OSA). We evaluated the association between STOP-Bang scores and the probability of OSA.
After Institutional Review Board approval, patients who visited the preoperative clinics for a scheduled inpatient surgery were approached for informed consent. Patients answered STOP questionnaire and underwent either laboratory or portable polysomnography (PSG). PSG recordings were scored manually. The BMI, age, neck circumference, and gender (Bang) were documented. Over 4 yr, 6369 patients were approached and 1312 (20.6%) consented. Of them, 930 completed PSG, and 746 patients with complete data on PSG and STOP-Bang questionnaire were included for data analysis.
The median age of 746 patients was 60 yr, 49% males, BMI 30 kg m(-2), and neck circumference 39 cm. OSA was present in 68.4% with 29.9% mild, 20.5% moderate, and 18.0% severe OSA. For a STOP-Bang score of 5, the odds ratio (OR) for moderate/severe and severe OSA was 4.8 and 10.4, respectively. For STOP-Bang 6, the OR for moderate/severe and severe OSA was 6.3 and 11.6, respectively. For STOP-Bang 7 and 8, the OR for moderate/severe and severe OSA was 6.9 and 14.9, respectively. The predicted probabilities for moderate/severe OSA increased from 0.36 to 0.60 as the STOP-Bang score increased from 3 to 7 and 8.
In the surgical population, a STOP-Bang score of 5-8 identified patients with high probability of moderate/severe OSA. The STOP-Bang score can help the healthcare team to stratify patients for unrecognized OSA, practice perioperative precautions, or triage patients for diagnosis and treatment.
The objective of this review is to determine the effects of perioperative sedatives and anesthetics in surgical patients with obstructive sleep apnea (OSA) on respiratory events, medication requirements, hemodynamics, pain, emergence, and hospital stay. We searched The Cochrane CENTRAL Register of Controlled Trials, Medline, Embase, and Cochrane Database of Systematic Reviews from 1950 to June 2010 for relevant articles. All prospective and retrospective studies were eligible for inclusion if the effects of perioperative administration of sedation and anesthetics on medication requirements, pain, emergence, hemodynamics, respiratory events, and length of hospital stay in OSA patients were reported. T0 he search strategy yielded 18 studies of 1467 patients. Of these, 456 patients were documented as having OSA. Few adverse respiratory effects were reported. Eight out of 700 (1.14%) patients undergoing middle ear surgery with midazolam and fentanyl had impaired upper airway patency and were retrospectively diagnosed as having OSA by polysomnography. Also, intraoperative snoring causing uvular edema in the postoperative period was described in an OSA patient undergoing upper limb surgery when propofol was administered with midazolam and fentanyl for sedation. A decrease in oxygen saturation in the postoperative period was described with propofol and isoflurane in 21 OSA patients undergoing uvulo-palato-pharyngoplasty and tonsillectomy surgery (P
An important requirement during functional endoscopic sinus surgery is to maintain a clear operative field to improve visualization during surgery and to minimize complications.
We compared total intravenous anesthesia using propofol with inhalational anesthesia using isoflurane for controlled hypotension in functional endoscopic sinus surgery. It was a prospective study in a tertiary hospital in India. Forty ASA physical status I and II adult patients (16-60 years) were randomly allocated to one of two parallel groups (isoflurane group, n = 20; propofol group, n = 20). The primary outcome was to know whether total intravenous anesthesia using propofol was superior to inhalational anesthesia using isoflurane for controlled hypotension. The secondary outcomes measured were intraoperative blood loss, duration of surgery, surgeon's opinion regarding the surgical field and the incidence of complications.
The mean (±SD) time to achieve the target mean blood pressure was 18 (±8) minutes in the isoflurane group and 16 (±7) minutes in the propofol group (P = 0.66). There was no statistically significant difference (P = 0.402) between these two groups in terms of intraoperative blood loss and operative field conditions (P = 0.34).
Controlled hypotension can be achieved equally and effectively with both propofol and isoflurane. Total intravenous anesthesia using propofol offers no significant advantage over isoflurane-based anesthetic technique in terms of operative conditions and blood loss.
Unrecognized obstructive sleep apnea (OSA) is associated with unfavorable perio-perative outcomes among patients undergoing noncardiac surgery (NCS).
The study population was chosen from 39,771 patients who underwent internal medicine preoperative assessment between January 2002 and December 2006. Patients undergoing NCS within 3 years of polysomnography (PSG) were considered for the study, whereas those < 18 years of age, with a history of upper airway surgery, or who had had minor surgery under local or regional anesthesia were excluded. Patients with an apnea-hypopnea index (AHI) ≥ 5 were defined as OSA and those with an AHI < 5 as control subjects. For adjusting baseline differences in age, sex, race, BMI, type of anesthesia, American Society of Anesthesiology class, and medical comorbidities, the patients were classified into five quintiles according to a propensity score.
Out of a total of 1,759 patients who underwent both PSG and NCS, 471 met the study criteria. Of these, 282 patients had OSA, and the remaining 189 served as control subjects. The presence of OSA was associated with a higher incidence of postoperative hypoxemia (OR, 7.9; P = .009), overall complications (OR, 6.9; P = .003), and ICU transfer (OR, 4.43; P = .069), and a longer hospital length of stay (LOS), (OR, 1.65; P = .049). Neither an AHI nor use of continuous positive airway pressure at home before surgery was associated with postoperative complications (P = .3 and P = .75, respectively) or LOS (P = .97 and P = .21, respectively).
Patients with OSA are at higher risk of postoperative hypoxemia, ICU transfers, and longer hospital stay.
The objective of this study was to determine if primary care providers (PCPs) screen for sleep disorders during clinical evaluation of new patients, and to compare this to likely sleep diagnoses as assessed by validated questionnaires.
Adult patients evaluated as new patients in a primary care clinic at a tertiary care center were included in a prospective study. Following their appointment, patients completed the Cleveland Sleep Habits questionnaire (CSHQ), Berlin questionnaire, Epworth Sleepiness Scale (ESS), and STOP questionnaire. The encounters were subsequently reviewed for elements of a sleep history, sleep review of systems, and/or sleep workup.
101 patients participated in the study. Demographics: 58 (52%) females, mean age 38 ± 12.9 years, body mass index (BMI) 29.5 ± 8.3 kg/m² (BMI > 30 kg/m² in 44%), 46% Caucasian, 38% African American, 11% Hispanic, and 5% other. House staff evaluated 57.4%; faculty evaluated the remainder. The ESS was > 10 in 28% of subjects. High risk for obstructive sleep apnea (OSA) risk was found in 33% (Berlin) and 34% (STOP) (24.8% by both). The CSHQ suggested possible diagnoses of insomnia in 30% and restless legs syndrome in 22%. In the clinic encounters, a limited sleep history was found in 24.8%, documentation of a sleep disorder in 8.9%, referral to sleep clinic in 2%, and referral to psychiatry clinic in 6.9%.
Symptoms suggestive of sleep disorders are common but are not routinely screened for in the primary care setting. Validated questionnaires can efficiently identify patients at risk for common sleep disorders in this setting.
The aims of this study were to: (a) assess the prevalence of diagnosed OSA and symptoms of undiagnosed OSA in a cohort of ambulatory surgical patients, and (b) characterize the frequency of postoperative complications in outpatients with a diagnosis of or a propensity to OSA.
Patients presenting for ambulatory surgery completed a self-administered questionnaire. Using a previously validated prediction model, the probability for OSA was determined. Patients with > or = 70% propensities were considered to be at high risk of having the disorder. Relevant perioperative data and complications were tracked and recorded, and differences in median estimated propensities for OSA were considered by these data.
Three-thousand five hundred fifty-three patients 'completed the preoperative survey. A total of 2139 patients had perioperative data and estimated propensity scores. Ninety-four of the 2139 (4.4%) patients gave a self-reported prior diagnosis of OSA. One hundred three (4.8%) patients were found to be at high risk of OSA based on the survey and prediction model. Seventy-five percent of the patients with > 70% propensity for OSA had not yet been diagnosed. There was no association between OSA propensity scores and unplanned hospital admission, however there was an association of increased propensity with difficult intubation, intraoperative use of pressors, and postoperative oxygen saturation in the PACU.
The results of this study suggest that undiagnosed OSA may be relatively common in an ambulatory surgical population. There was no relationship between unplanned hospital admission and diagnosis of or increased risk of OSA. However, there was an association of increased perioperative events requiring additional anesthetic management in patients with a diagnosis of, or with a higher propensity to OSA.
Obstructive sleep apnea (OSA) is defined by repetitive partial or complete upper airway obstruction characterized by episodes of breathing cessation during sleep. It is the most prevalent of sleep disorders, seen in about one in four males and one in ten females. We reviewed current literature, collated expert opinion, and synthesized protocols from several institutions to present practical principles and functional algorithms to assist the anesthesiologist in the perioperative management of known and suspected OSA.
Patients with OSA may have an increase in postoperative adverse respiratory events, sustained arrhythmias, hypertension, and other cardiovascular events. The gold standard for the diagnosis of OSA is polysomnography. The Berlin questionnaire and the American Society of Anesthesiologists OSA checklist are useful screening tools, while the STOP and the STOP-Bang questionnaires are easy to use in adults. Patients scheduled for elective major surgery, who are at high risk of OSA with significant comorbidities, may be referred for preoperative polysomnography. Perioperative precautions, such as anticipation of a possible difficult airway, use of short-acting anesthetic agents, avoidance of opioids, and extubation in a non-supine position, should be undertaken for known or suspected high-risk OSA patients. Postoperative disposition of the OSA patient should be based on the severity of the sleep disorder, recurrent postanesthesia care unit respiratory events, and the need for opioid analgesia.
With adequate screening and vigilance in the preoperative period, risk stratification should be undertaken for known and suspected OSA patients, and care should be individualized. Practical algorithms based on current best evidence and expert opinion may be useful in the perioperative management.
This review summarizes the recent literature on the epidemiology of adult obstructive sleep apnea (OSA) from various population-based studies. Despite methodologic differences, comparisons have yielded similar prevalence rates of the OSA syndrome in various geographic regions and amongst a number of ethnic groups. Risk factors for OSA including obesity, aging, gender, menopause, and ethnicity are analyzed. We also provide discussion on adverse medical conditions associated with OSA including hypertension, stroke, congestive heart failure, coronary artery disease, cardiovascular mortality, insulin resistance, and neurocognitive dysfunction. Finally with the progression of the global obesity epidemic, we focus on the economic health care burden of OSA and the importance of recognizing the largely undiagnosed OSA population with emphasis on strategies to improve access to diagnostic resources.
The use of portable respiratory monitoring (PM) has been proposed for the diagnosis of obstructive sleep apnea syndrome (OSAS), but most studies that validate PM accuracy have not followed the best standards for diagnostic test validation. The objective of the present study was to evaluate the accuracy of PM performed at home to diagnose OSAS and its outcomes after first validating PM in the laboratory setting by comparing it to polysomnography (PSG).
Patients with suspected OSAS were submitted, in random order, to PM at the sleep laboratory concurrently with PSG (lab-PM) or at home-PM. The diagnostic performance was assessed by sensitivity, specificity, positive and negative predictive values, positive likelihood ratio (+LR), negative likelihood ratio (-LR), intraclass correlation coefficients, kappa statistic, and Bland-Altman plot.
One hundred fifty-seven subjects (73% men, mean age +/- SD, 45 +/- 12 yr) with an apnea-hypopnea index (AHI) of 31 (SD +/- 29) events/h were studied. Excluding inadequate recordings, 149 valid comparisons with lab-PM and 121 with unattended home-PM were obtained. Compared to PSG for detecting AHI > 5, the lab-PM demonstrated sensitivity of 95.3%, specificity of 75%, +LR of 3.8, and -LR of 0.11; the home-PM exhibited sensitivity of 96%, specificity of 64%, +LR of 2.7, and -LR of 0.05. Kappa statistics indicated substantial correlation between PSG and PM results. Bland-Altman plot showed smaller dispersion for lab-PM than for home-PM. Pearson product moment correlation coefficients among the three AHIs and clinical outcomes were similar, denoting comparable diagnostic ability.
This study used all available comparison methods to demonstrate accuracy of PM in-home recordings similar to that of repeated PSGs. PM increases the possibility of correctly diagnosing and effectively treating OSAS in populations worldwide.
Anesthetic, sedative, and analgesic drugs have been shown in animals and humans to selectively impair upper airway muscle activity. In patients with an already compromised upper airway, these drugs may further jeopardize upper airway patency, especially during sleep. Thus, patients with obstructive sleep apnea syndrome (OSAS) are at high risk for surgery because of the use of the aforementioned drugs in the perioperative period. It has been recommended that such drugs should be avoided or used with extreme caution in patients with OSAS submitted to surgery. We report herein on 16 adult patients with documented OSAS undergoing various types of surgical procedures, including coronary artery bypass surgery. Anesthesia was carried on with the usual type of drugs for each type of surgery. Postoperative opioid analgesia and sedation were not restricted. The first patient, whose OSAS was diagnosed but not treated, died after various complications, including a respiratory arrest in the ward. The second patient experienced serious postoperative complications until a treatment for OSAS with nasal continuous positive airway pressure (N-CPAP) was instituted, and thereafter he made an uneventful recovery. The 14 following patients were started on N-CPAP before surgery, were put on N-CPAP as soon as extubated, on a near-continuous basis, for 24 to 48 h and thereafter for all sleep periods. None of them had major complications. The intensive care unit and hospital stays were the normal ones for each type of surgery in our institution. We conclude that N-CPAP started before surgery and resumed immediately after extubation allowed us to safely manage a variety of surgical procedures in patients with OSAS, and to freely use sedative, analgesic, and anesthetic drugs without major complications. Every effort should be made to identify patients with OSAS and institute N-CPAP therapy before surgery.
Some preventable deaths in hospitalized patients are due to unrecognized deterioration. There are no publications of studies that have instituted routine patient monitoring postoperatively and analyzed impact on patient outcomes.
The authors implemented a patient surveillance system based on pulse oximetry with nursing notification of violation of alarm limits via wireless pager. Data were collected for 11 months before and 10 months after implementation of the system. Concurrently, matching outcome data were collected on two other postoperative units. The primary outcomes were rescue events and transfers to the intensive care unit compared before and after monitoring change.
Rescue events decreased from 3.4 (1.89-4.85) to 1.2 (0.53-1.88) per 1,000 patient discharges and intensive care unit transfers from 5.6 (3.7-7.4) to 2.9 (1.4-4.3) per 1,000 patient days, whereas the comparison units had no change.
Patient surveillance monitoring results in a reduced need for rescues and intensive care unit transfers.
The American Society of Anesthesiologists Task Force on Management of the Difficult Airway presents a systematically developed set of recommendations based on analysis of the current literature and a synthesis of expert opinion.
Maintenance of the pharyngeal airway is an essential task assigned to anesthesiologists for patients’ oxygenation and ventilation during the perioperative period. Based on preoperative identification of risk factors of pharyngeal obstruction such as obstructive sleep apnea (OSA), optimal positioning of the head, neck, mandible, and body is the key for accomplishment of this task. In this context, accumulated knowledge on changes of pharyngeal closing pressures in response to various positional interventions is helpful for determining airway management strategy. Combination of the triple airway maneuver (mandible advancement, head extension, and mouth opening) with sniffing position in the Fowler’s (semi-sitting) position is optimal for anesthesia induction in morbidly obese patients with severe OSA. Disturbance of any one of the elements of the triple airway maneuver indicates tracheal intubation during wakefulness in these patients. Sitting or lateral position is advantageous over supine position for pharyngeal airway maintenance, whereas nasal CPAP should be applied in severe OSA patients.
In February 2013 the Committee of the American Society of Anesthesiologists (ASA) Task Force published the amended version of the "Practice guidelines for management of the difficult airway" which replace the recommendations from 2003. The amended version re-evaluated the recommendations from 2003 in 2011, evaluated recently published studies and recommendations and included them in the new practice guidelines. In particular, new technical developments, such as the recently established video-assisted intubation procedure were taken into consideration. Despite the many publications in the field of airway management the evidence resulting from the data obtained from recent publications is so low that the new information does not necessitate any amendments to the existing guidelines. In short, the current guidelines basically correspond to the previous version published 10 years ago but are, however, more than twice as extensive. This article summarizes and comments on the cornerstones of the guidelines.
Patients with obstructive sleep apnea (OSA) are at increased risk to sustain adverse events during the perioperative period including difficulty with airway control, hypoxemia, airway obstruction requiring reintubation, arrhythmias, myocardial ischemia, and death. Numerous factors appear to be responsible for these consequences, including the effects of anesthetic agents, narcotics, postoperative supine positioning and, in some cases, the surgical intervention itself. The situation is complicated by the fact that most patients with OSA are undiagnosed and there is often insufficient time for adequate evaluation prior to surgery. Perioperative care providers need to maintain a high index of suspicion for OSA and should consider guidelines to help with the recognition and management of these patients. This review will discuss the available literature regarding the preoperative, intraoperative and postoperative evaluation and management of patients with known or suspected OSA undergoing surgery.
To test the utility of an integrated clinical pathway for obstructive sleep apnea (OSA) diagnosis and continuous positive airway pressure (CPAP) treatment using portable monitoring devices.
Randomized, open-label, parallel group, unblinded, multicenter clinical trial comparing home-based, unattended portable monitoring for diagnosis and autotitrating CPAP (autoPAP) compared with in-laboratory polysomnography (PSG) and CPAP titration.
Seven American Academy of Sleep Medicine (AASM) accredited sleep centers.
Consecutive new referrals, age 18 yr or older with high probability of moderate to severe OSA (apnea-hypopnea index [AHI] ≥ 15) identified by clinical algorithm and Epworth Sleepiness Scale (ESS) score ≥ 12.
Home-based level 3 testing followed by 1 wk of autoPAP with a fixed pressure CPAP prescription based on the 90% pressure from autotitration of PAP therapy (autoPAP) device (HOME) compared with attended, in-laboratory studies (LAB).
CPAP acceptance, time to treatment, adherence at 1 and 3 mo; changes in ESS, and functional outcomes.
Of 373 participants, approximately one-half in each study arm remained eligible (AHI ≥ 15) to continue in the study. At 3 mo, PAP usage (nightly time at pressure) was 1 hr greater: 4.7 ± 2.1 hr (HOME) compared with 3.7 ± 2.4 hr (LAB). Adherence (percentage of night used ≥ 4 hr) was 12.6% higher: 62.8 ± 29.2% compared with 49.4 ± 36.1% in the HOME versus LAB. Acceptance of PAP therapy, titration pressures, effective titrations, time to treatment, and ESS score change did not differ between arms.
A home-based strategy for diagnosis and treatment compared with in-laboratory PSG was not inferior in terms of acceptance, adherence, time to treatment, and functional improvements.
http://www.ClinicalTrials.gov; Identifier: NCT: 00642486.
Obstructive sleep apnea syndrome (OSAS) is a common sleep related breathing disorder. Its prevalence is estimated to be between 2% and 25% in the general population. However, the prevalence of sleep apnea is much higher in patients undergoing elective surgery. Sedation and anesthesia have been shown to increase the upper airway collapsibility and therefore increasing the risk of having postoperative complications in these patients. Furthermore, the majority of patients with sleep apnea are undiagnosed and therefore are at risk during the perioperative period. It is important to identify these patients so that appropriate actions can be taken in a timely fashion. In this review article, we will discuss the epidemiology of sleep apnea in the surgical population. We will also discuss why these patients are at a higher risk of having postoperative complications, with the special emphasis on the role of anesthesia, opioids, sedation, and the phenomenon of REM sleep rebound. We will also review how to identify these patients preoperatively and the steps that can be taken for their perioperative management.
It is impractical to perform polysomnography (PSG) in all surgical patients suspected of having sleep disordered breathing (SDB). We investigated the role of nocturnal oximetry in diagnosing SDB in surgical patients.
All patients 18 years and older who visited the preoperative clinics for scheduled inpatient surgery were approached for study participation. Patients expected to have abnormal electroencephalographic findings were excluded. All patients underwent an overnight PSG at home with a portable device and a pulse oximeter. The PSG recordings were scored by a certified sleep technologist. The oximetry recordings were processed electronically.
Four hundred seventy-five patients completed the study: 217 males and 258 females, aged 60 ± 11 years, and body mass index 31 ± 7 kg/m(2). The apnea-hypopnea index (AHI), the average number of episodes of apnea and hypopnea per hour of sleep, was 9.1 (2.8 to 21.4) [median (interquartile range)] and 64% patients had AHI >5. There was a significant correlation between oxygen desaturation index (ODI, hourly average number of desaturation episodes) and cumulative time percentage with SpO(2) <90% (CT90) from nocturnal oximetry, with the parameters measuring sleep breathing disorders from PSG. Compared to CT90, ODI had a stronger correlation and was a better predictor for AHI. The area under receiver operator characteristics curve for ODI to predict AHI >5, AHI >15, and AHI >30 was 0.908 (CI: 0.880 to 0.936), 0.931 (CI: 0.090 to 0.952), and 0.958 (CI: 0.937 to 0.979), respectively. The cutoff value based on the maximal accuracy for ODI to predict AHI >5, AHI >15, and AHI >30 was ODI >5, ODI >15, and ODI >30. The accuracy was 86% (CI: 83%-88%), 86% (CI: 83%-89%), and 94% (CI: 92%-96%), respectively. The ODI >10 demonstrated a sensitivity of 93% and a specificity of 75% to detect moderate and severe SDB.
ODI from a high-resolution nocturnal oximeter is a sensitive and specific tool to detect undiagnosed SDB in surgical patients.
Postoperative delirium, a common complication in the elderly, can occur following any type of surgery and is associated with increased morbidity and mortality; it may also be associated with subsequent cognitive problems. Effective therapy for postoperative delirium remains elusive because the causative factors of delirium are likely multiple and varied.
Patients 65 yr or older undergoing elective knee arthroplasty were prospectively evaluated for postoperative Diagnostic and Statistical Manual of Mental Disorders-IV delirium. Exclusion criteria included dementia, mini-mental state exam score less than 24, delirium, clinically significant central nervous system/neurologic disorder, current alcoholism, or any serious psychiatric disorder. Delirium was assessed on postoperative days 2 and 3 using standardized scales. Patients' preexisting medical conditions were obtained from medical charts. The occurrence of obstructive sleep apnea was confirmed by contacting patients to check their polysomnography records. Data were analyzed using Pearson chi-square or Wilcoxon rank sum tests and multiple logistic regressions adjusted for effects of covariates.
Of 106 enrolled patients, 27 (25%) developed postoperative delirium. Of the 15 patients with obstructive sleep apnea, eight (53%) experienced postoperative delirium, compared with 19 (20%) of the patients without obstructive sleep apnea (P = 0.0123, odds ratio: 4.3). Obstructive sleep apnea was the only statistically significant predictor of postoperative delirium in multivariate analyses.
This is the first prospective study employing validated measures of delirium to identify an association between preexisting obstructive sleep apnea and postoperative delirium.
To provide an update on the connection between obstructive sleep apnea (OSA) and cardiovascular disease.
Large prospective studies have established that OSA is associated with an increased incidence of hypertension and, in men, of coronary disease, stroke, and heart failure. Advances in understanding the pathophysiologic basis for these associations include identification of a role for OSA in inducing abnormalities in hepatic lipid-metabolizing enzymes, endothelial dysfunction, and upregulation of pro-inflammatory and pro-thrombotic mediators. A large body of data implicates OSA as playing a significant role in the occurrence and resistance to treatment of atrial fibrillation. Clinical trials have shown small-to-modest improvements in blood pressure associated with continuous positive airway pressure (CPAP) use, with smaller or uncontrolled studies suggesting that CPAP may improve cardiovascular outcomes or intermediate markers.
OSA and cardiovascular disease commonly co-aggregate. Multiple studies indicate that OSA contributes to or exacerbates cardiovascular disease, and thus may be a novel target for cardiovascular risk reduction. Although the evidence supports screening and treatment of OSA in patients at risk for cardiovascular disease, it also underscores a need for well powered clinical trials to examine the role of CPAP and other therapies in these populations.
Nurse-administered propofol sedation (NAPS) is now in widespread use. The safety profile of NAPS for routine endoscopic procedures in patients with obstructive sleep apnea (OSA) is unknown.
To compare outcomes of patients with and without OSA undergoing routine endoscopic procedures with NAPS and standard conscious sedation (CS) with benzodiazepines and narcotics.
Retrospective cohort study.
A total of 215 patients were placed in one of four groups: OSA patients undergoing endoscopy with NAPS, OSA patients undergoing endoscopy with standard CS, non-OSA patients undergoing endoscopy with NAPS, and non-OSA patients undergoing endoscopy with standard CS. Procedures were generally accomplished faster with NAPS. There was no statistically significant difference in complication rates or overall outcomes in patients with OSA when compared to non-OSA patients when either NAPS or CS was utilized.
Routine endoscopic procedures using NAPS are safe in patients with documented OSA, with complication rates comparable to when using CS. NAPS helped to decrease procedure times in general.
Due to the presumed higher risk of cardiopulmonary complications in patients with obstructive sleep apnea (OSA), many endoscopy centers consider OSA a contraindication to using conscious sedation. We evaluated the safety of conscious sedation during endoscopy for patients with OSA in a veteran population, and compared this to patients without OSA.
Polysomnography studies were reviewed from 2004 to 2009 to identify 200 patients with OSA who had undergone endoscopy. Controls included the last 200 consecutive endoscopies in this institution for patients without OSA. Sixty-three upper endoscopies, 136 colonoscopies, and one enteroscopy were included in the OSA group. Sixty-five upper endoscopies, 133 colonoscopies, one sigmoidoscopy, and one endoscopic ultrasound comprised the control group. Data obtained included demographics, medications prescribed, and any complication noted in the procedure report.
No complications occurred in the control group. In the OSA group, a patient experienced oxygen desaturation during an upper endoscopy and required oxygen supplementation. The procedure was completed and did not require an extended stay in the endoscopy suite.
This study demonstrated that endoscopy can be safely done in OSA patients using conscious sedation, and the complication rate is not significantly different than patients without OSA.
Obstructive sleep apnea (OSA) is the most common breathing disorder, with a high prevalence in both the general and surgical populations. OSA is frequently undiagnosed, and the initial recognition often occurs during medical evaluation undertaken to prepare for surgery. Adverse respiratory and cardiovascular outcomes are associated with OSA in the perioperative period; therefore, it is imperative to identify and treat patients at high risk for the disease. In this review, we discuss the epidemiology of OSA in the surgical population and examine the available data on perioperative outcomes. We also review the identification of high-risk patients using clinical screening tools and suggest intraoperative and postoperative treatment regimens. Additionally, the role of continuous positive airway pressure in perioperative management of OSA and a brief discussion of ambulatory surgery in patients with OSA is provided. Finally, an algorithm to guide perioperative management is suggested.
Although patients with sleep apnea (SA) are considered to be at increased risk for postoperative complications, evidence supporting increased risk of perioperative pulmonary morbidity is limited. The objective of this study, therefore, was to analyze perioperative demographics and pulmonary outcomes of patients with SA after orthopedic and general surgical procedures using a population-based sample. We hypothesized that SA is an independent risk factor for perioperative pulmonary complications, thus providing a basis for an increase in the utilization of resources, including intensive monitoring and development of strategies to prevent and treat these events.
National Inpatient Sample data for each year between 1998 and 2007 were accessed. Orthopedic and general surgical procedures were included and discharges with a diagnosis code for SA were identified. Patients with the diagnosis of SA were matched to those without the disease based on demographic variables using the propensity scoring method. Aspiration pneumonia, adult respiratory distress syndrome (ARDS), pulmonary embolism (PE), and the need for intubation and mechanical ventilation were the primary outcomes. Odds ratio (OR) and absolute risk reduction along with 95% confidence interval were reported.
We identified 2,610,441 entries for orthopedic and 3,441,262 for general surgical procedures performed between 1998 and 2007. Of those, 2.52% and 1.40%, respectively, carried a diagnosis of SA. Patients with SA developed pulmonary complications more frequently than their matched controls after both orthopedic and general surgical procedures, respectively (i.e., aspiration pneumonia: 1.18% vs 0.84% and 2.79% vs 2.05%; ARDS: 1.06% vs 0.45% and 3.79% vs 2.44%; intubation/mechanical ventilation: 3.99% vs 0.79% and 10.8% vs 5.94%, all P values <0.0001). Comparatively, PE was more frequent in SA patients after orthopedic procedures (0.51% vs 0.42%, P = 0.0038) but not after general surgical procedures (0.45% vs 0.49%, P = 0.22). SA was associated with a significantly higher adjusted OR of developing pulmonary complications after both orthopedic and general surgical procedures, respectively, with the exception of PE (OR for aspiration pneumonia: 1.41 [1.35, 1.47] and 1.37 [1.33, 1.41]; for ARDS: 2.39 [2.28, 2.51] and 1.58 [1.54, 1.62]; for PE: OR 1.22 [1.15, 1.29] and 0.90 [0.84, 0.97]; for intubation/mechanical ventilation: 5.20 [5.05, 5.37] and 1.95 [1.91, 1.98]).
SA is an independent risk factor for perioperative pulmonary complications. Our results may be used for hypothesis generation for clinical studies targeted to improve perioperative outcomes in this patient population.
To determine whether high risk scores on preoperative STOP-BANG (Snoring, Tiredness during daytime, Observed apnea, high blood Pressure, Body mass index, Age, Neck circumference, Gender) questionnaires during preoperative evaluation correlated with a higher rate of complications of obstructive sleep apnea syndrome (OSAS).
Historical cohort study.
Thomas Jefferson University Hospital, Philadelphia, Pennsylvania.
Adult patients undergoing elective surgery at a tertiary care center who were administered the STOP-BANG questionnaire for 3 consecutive days in May 2008.
Number and types of complications.
A total of 135 patients were included in the study, of whom 56 (41.5%) had high risk scores for OSAS. The mean (SD) age of patients was 57.9 (14.4) years; 60 (44.4%) were men. Patients at high risk of OSAS had a higher rate of postoperative complications compared with patients at low risk (19.6% vs 1.3%; P < .001). Age, American Society of Anesthesiologists class of 3 or higher, and obesity were associated with an increased risk of postoperative complications. On multivariate analysis, high risk of OSAS and American Society of Anesthesiologists class 3 or higher were associated with higher odds of complications.
The STOP-BANG questionnaire is useful for preoperative identification of patients at higher than normal risk for surgical complications, probably because it identifies patients with occult OSAS.
Anesthesia and sleep both predispose to upper airway obstruction through state-induced reductions in pharyngeal dilator muscle activation and lung volume. The tendencies are related in patients with obstructive sleep apnea commonly presenting with difficulties in airway management in the perioperative period. This is a period of great potential vulnerability for such patients because of compromise of the arousal responses that protect against asphyxiation during natural sleep. Careful preoperative evaluation and insightful perioperative observation are likely to identify patients at risk. A significant proportion of patients will have previously undiagnosed obstructive sleep apnea and anesthesiologists are well placed to identify this potential. Patients with known or suspected obstructive sleep apnea need careful postoperative management, particularly while consciousness and arousal responses are impaired. Specific follow-up of suspected cases is needed to ensure that the sleep-related component of the problem receives appropriate care.
Among patients undergoing advanced endoscopy, unrecognized obstructive sleep apnea (OSA) could predict sedation-related complications (SRCs) and the need for airway maneuvers (AMs). By using an OSA screening tool, we sought to define the prevalence of patients at high risk for OSA and to correlate OSA with the frequency of AMs and SRCs.
We enrolled 231 consecutive patients undergoing endoscopic retrograde cholangiopancreatography (ERCP) (n = 176) and endoscopic ultrasound (n = 55). Propofol-based sedation and patient monitoring were performed by a nurse anesthetist and an anesthesiologist. A previously validated screening tool for OSA (STOP-BANG) was used to identify patients at high risk for OSA (score, > or =3 of 8; SB+) or low risk (SB-). AMs were defined as a chin lift, modified mask ventilation, nasal airway, bag-mask ventilation, and endotracheal intubation. SRCs were defined as any duration of pulse oximetry less than 90%, systolic blood pressure less than 90 mm Hg, apnea, or early procedure termination.
The prevalence of SB+ was 43.3%. The frequency of hypoxemia was significantly higher among patients with SB+ than SB- (12.0% vs 5.2%; relative risk [RR], 1.83; 95% confidence interval [CI], 1.32-2.54). The rate of AMs was also significantly higher among SB+ (20.0%) compared with SB- (6.1%) patients (RR, 1.8; 95% CI, 1.3-2.4). These rates remained significant after adjusting for American Society of Anesthesiologists class 3 or higher (RR, 1.70; 95% CI, 1.28-2.2 for AMs; RR, 1.63; 95% CI, 1.19-2.25 for hypoxemia). Each element of the STOP-BANG was reported more commonly in SB+ patients (P < .0001 for each comparison).
A significant number of patients undergoing advanced endoscopic procedures are at risk for OSA. AMs and hypoxemia occur at an increased frequency in these patients.
Patients with obstructive sleep apnea (OSA) have an increased risk of perioperative complications.
The purpose of this study is to assess whether OSA increases the risk of cardiorespiratory complications in patients undergoing endoscopic procedures.
A retrospective study was performed. We identified all patients who had undergone both an endoscopic procedure under conscious sedation and a sleep study from January 2001 to May 2008. Patients were divided into four groups: OSA negative (apnea-hypopnea index (AHI) < 5/h), OSA positive; mild: AHI 5-15/h, moderate: AHI 15.1-30/h, and severe: AHI > 30/h. Minor and major complications were identified. The minor ones were hypertension, hypotension, bradycardia, tachycardia, oxygen desaturation (<90%), and bradypnea. Major complications included chest pain, respiratory distress, cardiorespiratory arrest, or any minor complication that required intervention.
Procedures were performed in 639 patients: colonoscopies 68.5%, upper endoscopies 20.2%, and combined procedures 11.3%. The mean age was 60.5 years, mean body mass index 33.7, and 93% were males. Sleep study results: 130 negative, 509 positive; 135 mild, 125 moderate, and 249 severe. Of the patients, 19% had minor complications, while 7% had major complications. There was no significant difference between the patients with and without OSA in the rate of minor complications (odds ratio 1.17, 95% confidence interval 0.70-1.92) or major complications (odds ratio 1.19, 95% confidence interval 0.54-2.63). The odds ratio was also not significantly increased when a cutoff value of 10 or 15/h was used to delineate a positive sleep study.
For patients undergoing endoscopy procedures under conscious sedation, the presence of OSA does not clearly increase the risk of cardiorespiratory complications.
Morbid obesity (MO), obstructive sleep apnea (OSA), and neck circumference (NC) are widely believed to be independent risk factors for difficult tracheal intubation. In this study, we sought to determine whether these factors were associated with increased risk of difficult intubation in patients undergoing bariatric surgery. The predictive factors tested were OSA and its severity, as determined by apnea-hypopnea index (AHI), gender, NC, and body mass index (BMI).
All sequentially enrolled MO patients underwent preoperative polysomnography. Severity of OSA was quantified using AHI and the American Society of Anesthesiologists' OSA severity scale. All patients had a standardized anesthetic that included positioning in the "ramped position" for direct laryngoscopy.
One hundred eighty consecutive patients were recruited, 140 women and 40 men. The incidence of OSA was 68%. The mean BMI was 49.4 kg/m(2). The mean AHI was 31.3 (range, 0-135). All the patients' tracheas were intubated successfully without the aid of rescue airways by anesthesiology residents. Six patients required three or more intubation attempts, a difficult intubation rate of 3.3%. There was an 8.3% incidence of difficult laryngoscopy, defined as a Cormack and Lehane Grade 3 or 4 view. There was no relationship between NC and difficult intubation (odds ratio 1.02, 95% confidence interval 0.93-1.1), between the diagnosis of OSA and difficult intubation (P = 0.09), or between BMI and difficult intubation (odds ratio 0.99, 95% confidence interval 0.92-1.06, P = 0.8). There was no relationship between number of intubation attempts and BMI (P = 0.8), AHI (P = 0.82), or NC (P = 0.3). Mallampati Grade III or more predicted difficult intubation (P = 0.02), as did male gender (P = 0.02). Finally, there was no relationship between Cormack and Lehane grade and BMI (P = 0.88), AHI (P = 0.93), or OSA (P = 0.6). Increasing NC was associated with difficult laryngoscopy but not difficult intubation (P = 0.02).
In MO patients undergoing bariatric surgery in the "ramped position," there was no relationship between the presence and severity of OSA, BMI, or NC and difficulty of intubation or laryngoscopy grade. Only a Mallampati score of 3 or 4 or male gender predicted difficult intubation.
Patients with obstructive sleep apnea are at risk for perioperative morbidity. The authors used a screening prediction model for obstructive sleep apnea to generate a sleep apnea clinical score (SACS) that identified patients at high or low risk for obstructive sleep apnea. This was combined with postanesthesia care unit (PACU) monitoring with the aim of identifying patients at high risk of postoperative oxygen desaturation and respiratory complications.
In this prospective cohort study, surgical patients with a hospital stay longer than 48 h who consented were enrolled. The SACS (high or low risk) was calculated; all patients were monitored in the PACU for recurrent episodes of bradypnea, apnea, desaturations, and pain-sedation mismatch. All patients underwent pulse oximetry postoperatively; complications were documented. Chi-square, two-sample t test, and logistic regression were used for analysis. The oxygen desaturation index (number of desaturations per hour) was calculated. Oxygen desaturation index and incidence of postoperative cardiorespiratory complications were primary endpoints.
Six hundred ninety-three patients were enrolled. From multivariable logistic regression analysis, the likelihood of a postoperative oxygen desaturation index greater than 10 was increased with a high SACS (odds ratio = 1.9, P < 0.001) and recurrent PACU events (odds ratio = 1.5, P = 0.036). Postoperative respiratory events were also associated with a high SACS (odds ratio = 3.5, P < 0.001) and recurrent PACU events (odds ratio = 21.0, P < 0.001).
Combination of an obstructive sleep apnea screening tool preoperatively (SACS) and recurrent PACU respiratory events was associated with a higher oxygen desaturation index and postoperative respiratory complications. A two-phase process to identify patients at higher risk for perioperative respiratory desaturations and complications may be useful to stratify and manage surgical patients postoperatively.
Obstructive sleep apnea (OSA) affects approximately 20% of US adults, of whom about 90% are undiagnosed. While OSA may increase risk of perioperative complications, its prevalence among surgical patients is unknown. We tested the feasibility of screening surgical patients for OSA and determined the prevalence of undiagnosed OSA.
In a prospective, observational study adult surgical patients were screened for OSA in an academic hospital. Patients without an OSA diagnosis who screened high-risk were offered a home sleep study to determine if they had OSA. The results were compared with polysomnography (PSG) when available. Charts of high-risk patients were examined for postoperative complications. High-risk patients received targeted interventions as part of a hospital safety initiative.
There were 2877 patients screened; 661 (23.7%) screened high-risk for OSA, of whom 534 (81%) did not have diagnosed OSA. The portable sleep study detected OSA in 170/207 (82%) high-risk patients without diagnosed OSA. Twenty-six PSGs confirmed OSA in 19 of these patients. Postoperatively there were no respiratory arrests, two unanticipated ICU admissions, and five documented respiratory complications.
Undiagnosed OSA is prevalent in adult surgical patients. Implementing universal screening is feasible and can identify undiagnosed OSA in many surgical patients. Further investigation is needed into perioperative complications and their prevention for patients with undiagnosed OSA.
Upper airway abnormalities carry the risk of obstructive sleep apnea (OSA) and difficult tracheal intubations. Both conditions contribute to significant clinical problems and have increased perioperative morbidity and mortality. We hypothesized that patients who presented with difficult intubation would have a very high prevalence of OSA and that those with unexpected difficult intubation may require referral to sleep clinics for polysomnography (PSG).
Patients classified as a grade 4 Cormack and Lehane on direct laryngoscopic view, and who required more than two attempts for successful endotracheal intubation, were referred to the study by consultant anesthesiologists at four hospitals. Apnea-hypopnea index (AHI) data and postoperative events were collected. Patients with AHI >5/h were considered positive for OSA. Clinical and PSG variables were compared using t-tests and chi(2) test.
Over a 20-mo period, 84 patients with a difficult intubation were referred into the study. Thirty-three patients agreed to participate. Sixty-six percent (22 of 33) had OSA (AHI >5/h). Of the 22 OSA patients, 10 patients (64%) had mild OSA (AHI 5-15), 6 (18%) had moderate OSA (AHI >15/h), and 6 (18%) had severe OSA (AHI >30/h). Of the 33 patients, 11 patients (33%) were recommended for continuous positive airway pressure treatment. Between the OSA group and the non-OSA group, there were significant differences in gender, neck size, and the quality of sleep, but there were no significant differences in age and body mass index.
Sixty-six percent of patients with unexpected difficult intubation who consented to undergo a sleep study were diagnosed with OSA by PSG. Patients with difficult intubation are at high risk for OSA and should be screened for signs and symptoms of sleep apnea. Screening for OSA should be considered by referral to a sleep clinic for PSG.
A retrospective review of 135 patients surgically treated for obstructive sleep apnea syndrome (OSAS) from 1982 to 1987 was performed to identify perioperative complications and potential risk factors. The incidence of complications was 13% (18/135). Airway problems comprised 77% (14/18) of these complications, resulting in one death. There were three postoperative hemorrhages and one postoperative arrhythmia. Comparison of the complication group versus the noncomplication group showed a statistically significant difference in the minimum oxygen saturation (66% vs. 79%) and apnea index (75 vs. 57) on the pre-operative sleep study and in the amount of narcotic administered intraoperatively. Patients with intubation complications tended to be heavier, whereas patients with extubation complications received significantly more narcotic analgesia intraoperatively. Risk for a perioperative complication was not related to age, type of obstructive symptoms, medical problems, or concurrent septoplasty/tonsillectomy. A protocol for perioperative airway management is presented.
The respiratory effects of two postoperative analgesic regimens were compared in two groups of 16 patients each, recovering from general anesthesia and major surgery. One group received a pain-relieving dose of iv morphine (mean, 18.1 mg), with the same dose repeated as a continuous intravenous infusion over the subsequent 24 h. The other group received regional anesthesia using bupivacaine. The patients were monitored for 16 h after surgery. The two analgesic regimens provided patients with comparable analgesia throughout the study period, but there were quite different respiratory effects in the two groups. Ten patients receiving morphine infusions had a total of 456 episodes of pronounced oxygen desaturation (SaO2 less than 80%). These occurred only while the patients were asleep, and all were associated with disturbances in ventilatory pattern, namely, obstructive apnea (144 episodes in eight patients), paradoxic breathing (275 episodes in six patients), and period of slow ventilatory rate (37 episodes in one patient). In contrast, in patients receiving regional anesthesia, oxygen saturation never decreased below 87%. Central apnea, obstructive apnea, and paradoxic breathing occurred more frequently in patients in the morphine group (12, 10, and 10 patients, respectively) than patients in the regional anesthesia group (4, 3, and 5 patients, respectively). The interaction of sleep and morphine analgesia produced disturbances in ventilatory pattern, causing profound oxygen destruction. These results suggest that postoperative pain relief using regional anaesthesia has a greater margin of safety in terms of respiratory side effects than does the continuous administration of opiates.
The immediate reduction in VC and the delayed decrease in FRC (18 to 24 hours) following abdominal surgery are the important mechanical abnormalities. The time for full recovery of VC to preoperative values is unknown, but appears to be in excess of 3 weeks, FRC returns to normal within 2 weeks. Since complete pain relief neither prevents the loss of VC nor fully restores it once lost, pain must be but one of several active factors. The chest wall lesion, plus the effects of rapid shallow breathing, without periodic sighs, lead to the fall in FRC. Small airway closure with trapping of gas beyond closed airways will, in some patients, be an additional mechanism leading to loss of lung volume and a further reduced FRC. Secondary to the limited VC (or more specifically inspiratory capacity), impairment of the cough mechanism occurs. This in turn leads to retention of secretions, producing airway obstruction or a focus for infection. The mechanisms of gas exchange abnormalities although not proven, relate best to the reduced FRC, and the relationship of FRC to the closing capacity. Breathing at low lung volumes leads to an increased frequency of low V̇/Q̇ ratios and to enlargement of the right to left shunts. Identification of FRC as the single most important lung volume in the postoperative patient provides a specific goal for therapy. Any technique that maintains or improves FRC can be expected to be beneficial. Since total prevention does not seem to be possible, an appropriate objective of treatment is to limit the extent of the pulmonary function abnormalities. Effective pain relief, without respiratory depression, is the ideal. VC and FRC are partially restored and gas exchange improved.
We hypothesized that upper airway mechanoreceptors contribute to the arousal stimulus that occurs with upper airway occlusion in obstructive sleep apnea (OSA). If so, upper airway anesthesia (UAA) should reduce the arousal stimulus and impair the arousal response. To test this hypothesis, we studied the effects of UAA on apnea duration and the esophageal pressure deflection before arousal in a group of patients with severe OSA. On two study nights separated by one week, subjects were monitored for 2 h after lights out. They were then awakened and either 5 cc of 4% lidocaine or saline (random order) was dripped into the upper airway via the nose over 10 min. Another 2 h of monitoring was then performed. Variables on the first and second parts of the control (C1 and C2) and lidocaine nights (L1 and L2) were compared during non-rapid eye movement sleep using the analysis of variance. With lidocaine, the mean (+/- SEM) apnea duration increased from 24.2 +/- 2.6 (L1) to 30.7 +/- 2.3 (L2) s but with saline the apnea length was unchanged from 23.3 +/- 1.5 (C1) to 23.4 +/- 1.6 (C2) (L2 > [L1, C1, C2], p < 0.01). In addition, the maximum esophageal pressure deflection (cm H2O) before arousal increased after lidocaine from 63.6 +/- 14.5 (L1) to 84.1 +/- 14.7 (L2) but after saline was unchanged from 62.1 +/- 15.4 (C1) to 60.0 +/- 15.2 (C2), (L2 > [L1, C1, C2], p < 0.05). We conclude that UAA impairs the arousal response to airway occlusion. This suggests that input from upper airway mechanoreceptors during obstructive events contributes to the total arousal stimulus in patients with OSA.
It was our impression that the respiratory parameters in obstructive sleep apnea (OSA) worsened as the night progressed. To confirm this, we review polysomnographic studies from 66 patients with apnea-hypopnea indices (AHI) of 40 to 125 events per hour, dividing bed time into equal quartiles. As the night progressed, the mean apnea duration (MAD) increased from 27.2 s to 34.6 s (p < 0.0001), mainly from increases during NREM sleep. The proportion of time spent in apnea increased from 54 to 71% (p < 0.0001) due to increases in both MAD and the proportion of REM sleep (from 2.8 to 14.7% of the total sleep time). The AHI did not change significantly between quartiles. Even though preapneic oxygen saturation did not change and apnea duration increased as the night progressed, the end-apneic saturation did not decrease, hence the rate of oxygen desaturation decreased. Also, it was found that patients with an AHI greater than 65 events per hour increased their proportion of time spent in apnea significantly more than those with an AHI smaller than 65, as the night progressed. In the patients with an AHI greater than 85, this was due to both an increase in MAD and AHI. In conclusion, in patients with an AHI greater than 40 events per hour, the severity of apnea increased as the night progressed due to lengthening of MAD, increased proportion of REM sleep, and in the most severe patients, also an increase in AHI. Even though the exact pathophysiologic mechanisms for the observed changes are unknown, a decrease in respiratory muscle effort with consequent decrease in oxygen consumption may explain both the lengthening of the apneas and the decrease in the rate of oxygen desaturation.