Postoperative obstructive sleep apnoea. Haemodynamic effects of treatment with nasal CPAP

Sleep study measures on post-operative night one following expansion pharyngoplasty for obstructive sleep apnea

PURPOSE

To examine the changes in measures of sleep apnea severity and hypoxemia on the first post-operative night (PON1) following expansion pharyngoplasty as a means to assess the safety of same day discharge after surgery.

MATERIALS AND METHODS

Prospective cohort study of subjects with moderate-severe obstructive sleep apnea who underwent expansion pharyngoplasty at a single academic sleep surgical practice. A WatchPAT study was performed on the night immediately following surgery (PON1) and comparisons were made to baseline sleep testing.

RESULTS

Twenty subjects who had a mean age of 45.7 ± 10.8 years old and a mean body-mass index (BMI) of 31.4 ± 3.2 kg/m² were enrolled. Patients had baseline severe OSA with mean apnea hypopnea index (AHI) 39.4 ± 19.5/h, O2 nadir 80.8 ± 6.1 % and time with oxygen saturation below 88 % (T88) 12.3 ± 13.2 min. Measures of sleep apnea and nocturnal hypoxemia were not significantly different on PON1. AHI was increased by >20 % in 11 (55.0 %) patients. One patient demonstrated a >10 % worsening in O2 nadir, and 8 patients (45.0 %) demonstrated a >20 % worsening in T88. BMI over 32 was associated with elevated odds of worsening in T88, and anesthesia involving ketamine was associated with lower odds of a 20 % worsening in AHI or T88.

CONCLUSIONS

On PON1 following expansion pharyngoplasty, AHI and nocturnal hypoxemia are stable overall but variable on an individual basis. The decision for admission should therefore be made on a case-by-case basis. Further research is need to elucidate definitive predictors of worsening measures on PON1.

Sleep Study Measures on Postoperative Night 1 Following Implantation of the Hypoglossal Nerve Stimulator

OBJECTIVE

To examine the changes in measures of sleep apnea severity and hypoxemia on the first postoperative night following implantation of the hypoglossal nerve stimulator.

STUDY DESIGN

This was a single-arm prospective cohort study.

SETTING

A single academic sleep surgical practice.

METHODS

Subjects with moderate to severe obstructive sleep apnea underwent implantation of the hypoglossal nerve stimulator (HGNS) and were discharged to home the same day as surgery. A single-night WatchPAT study was performed on the night immediately following surgery (PON 1) and was compared to baseline sleep testing.

RESULTS

Twenty subjects who were an average of 58.6 ± 2.5 years old, were 25% female, and had a mean body mass index of 28.1 ± 0.9 kg/m² completed the study. Mean O₂ nadir at baseline was 79.6% ± 1.1% compared to 82.7% ± 0.9% (P = .013) on PON 1. One patient demonstrated a >10% worsening in O₂ nadir. Only 2 additional patients demonstrated a worsening in O₂ nadir on PON 1, each by only 1 percentage point. Neither mean time spent below SpO₂ 88% nor oxygen desaturation index (ODI) worsened postoperatively (mean time spent below oxygen saturation of 88%, 27.8 ± 7.85 vs 11.2 ± 5.2, P = .03; mean ODI, 29.6 ± 5.2/h vs 21.0 ± 5.4/h, P = .10). Mean obstructive apnea hypopnea index (AHI) was no worse (40.6 ± 4.7/h to 28.7 ± 4.2/h, P = .02), with only 2 patients experiencing an obstructive AHI >20% more severe than baseline. Only 1 patient demonstrated a clinically meaningful increase in central AHI on PON 1.

CONCLUSIONS

Overall, AHI and measures of nocturnal hypoxemia are stable, if not improved, on PON 1 following HGNS implantation. These findings support the safety of same-day discharge following implantation of the hypoglossal nerve stimulator.

Perioperative sleep apnea: a real problem or did we invent a new disease?

Depending on the subpopulation, obstructive sleep apnea (OSA) can affect more than 75% of surgical patients. An increasing body of evidence supports the association between OSA  and perioperative complications, but some data indicate important perioperative outcomes do not differ between patients with and without OSA. In this review we will provide an overview of the pathophysiology of sleep apnea and the risk factors for perioperative complications related to sleep apnea. We also discuss a clinical algorithm for the identification and management of OSA patients facing surgery.

Obstructive Sleep Apnea: A Risk Factor for Surgical Site Infection following Colectomy

BACKGROUND

Obstructive sleep apnea (OSA) is associated with increased systemic oxidative stress, endothelial dysfunction, and activation of pro-inflammatory cascades, which increase host susceptibility to infection. OSA has not been evaluated as a risk factor for surgical site infection (SSI) following colectomy. We hypothesized that OSA increases the risk for SSI after colectomy.

METHODS

We performed a retrospective review of 507 colectomies that took place between August 2011 and September 2013. Forty-two patients carried the diagnosis of OSA prior to surgery. These 42 patients were matched to 68 patients with no OSA for age, body mass index (BMI), diabetes mellitus (DM), reason for surgery and surgical approach.

RESULTS

The rate of SSI was 28.6% (12 of 42) in the patients with and 10.3% (7 of 68) in the patients without OSA (p=0.03). Using logistic regression, the predictors of SSI following colectomy were found to be OSA (odds ratio [OR] of 3.98, 95% confidence interval [CI]=1.29-12.27), and DM (OR of 7.16, 95% CI=2.36-21.96). The average hospital stay after colectomy for patients with OSA complicated with SSI was 16.7 d whereas patients with OSA without SSI stayed 7.4 d (p<0.001). The rate of organ space infections was 9.5% (4 of 42) in the patients with OSA compared with 0 (p=0.02) in patients without OSA.

CONCLUSIONS

OSA is an independent risk factor for SSI following colectomy. Patients with OSA have substantially greater rates of organ space SSI and longer hospital stay.

[Cardiac surgery in underlying chronic pulmonary disease. Prognostic implications and efficient preoperative evaluation]

Cardiac surgery in patients with chronic pulmonary diseases carries a high risk of postoperative pulmonary complications (ppc) because both are known to cause ppc. Autopsy studies have revealed ppc as the main cause of mortality in approximately 5-8% of patients after cardiac surgery. Not all pulmonary diseases are high risk comorbidities in cardiac surgery: whereas chronic obstructive pulmonary disease (COPD) and obstructive sleep apnea significantly increase the risk of ppc, a well controlled asthma does not carry an additional risk of ppc. A thorough preoperative risk stratification is crucial for risk estimation and some validated risk calculators, such as the Canet risk score exist. Surprisingly the additional value of pulmonary function testing beyond a thorough patient history and physical examination is low. No validated thresholds exist in pulmonary function testing below which cardiac surgery should be denied if clearly indicated. Perioperative strategies for risk reduction should be applied to all patients whenever possible.

Perioperative Auto-titrated Continuous Positive Airway Pressure Treatment in Surgical Patients with Obstructive Sleep Apnea

Background:

Obstructive sleep apnea (OSA) may worsen postoperatively. The objective of this randomized open-label trial is to determine whether perioperative auto-titrated continuous positive airway pressure (APAP) treatment decreases postoperative apnea hypopnea index (AHI) and improves oxygenation in patients with moderate and severe OSA.

Methods:

The consented patients with AHI of more than 15 events/h on preoperative polysomnography were randomized into the APAP or control group (receiving routine care). The APAP patients received APAP for 2 or 3 preoperative, and 5 postoperative nights. All patients were monitored with oximetry for 7 to 8 nights (N) and underwent polysomnography on postoperative N3. The primary outcome was AHI on the postoperative N3.

Results:

One hundred seventy-seven OSA patients undergoing orthopedic and other surgeries were enrolled (APAP: 87 and control: 90). There was no difference between the two groups in baseline data. One hundred six patients (APAP: 40 and control: 66) did polysomnography on postoperative N3, and 100 patients (APAP: 39 and control: 61) completed the study. The compliance rate of APAP was 45%. The APAP usage was 2.4–4.6 h/night. In the APAP group, AHI decreased from preoperative baseline: 30.1 (22.1, 42.5) events/h (median [25th, 75th percentile]) to 3.0 (1.0, 12.5) events/h on postoperative N3 (P &lt; 0.001), whereas, in the control group, AHI increased from 30.4 (23.2, 41.9) events/h to 31.9 (13.5, 50.2) events/h, P = 0.302. No significant change occurred in the central apnea index.

Conclusions:

The trial showed the feasibility of perioperative APAP for OSA patients. Perioperative APAP treatment significantly reduced postoperative AHI and improved oxygen saturation in the patients with moderate and severe OSA.

Respiratory perioperative management of patients with obstructive sleep apnea

Obstructive sleep apnea (OSA) has become a major public health problem in the United State and Europe. However, perioperative strategies regarding diagnostic options and management of untreated OSA remain inadequate. Preoperative screening and identification of patients with undiagnosed OSA may lead to early perioperative interventions that may alter cardiopulmonary events associated with surgery and anesthesia.(1) Hence, clinicians need to become familiar with the preoperative screening and diagnosis of OSA. Perioperative management of a patient with OSA should be modified and may include regional anesthesia and alternative analgesic techniques such as nonsteroidal anti-inflammatory drugs that may reduce the need for systemic opioids. Additionally, supplemental oxygen and continuous pulse oximetry monitoring should be utilized to maintain baseline oxygen saturation. Postoperatively patients should remain in a semi-upright position and positive pressure therapy should be used in patients with high-risk OSA.

Perioperative care of patients with obstructive sleep apnea

OPINION STATEMENT

It has been demonstrated that patients undergoing surgical procedures are at increased risk for complications if they have obstructive sleep apnea. It is believed that this increase in risk is related to more difficult intubations, use of ventilatory depressant medications, and perhaps body positioning. Although identifying patients with a preexisting diagnosis of sleep apnea is important so they can be triaged appropriately during the perioperative period, a bigger challenge is trying to identify patients who require a surgical procedure and may have undiagnosed sleep apnea. Hospitals and surgical centers should have policies in place to assist in such identification preoperatively, with a protocol on how to manage such patients perioperatively. Such guidelines exist, but many institutions do not have such protocols in place or fail to ensure that they are consistently followed. The key to the perioperative management is close observation of these high-risk patients. In ambulatory surgery populations, these patients should be observed for an extended period before being discharged to home. In inpatient settings, the observation can be tailored to the patient's postoperative risks based on the type of surgery and the severity of his or her sleep apnea. Patients undergoing bariatric surgery are at particularly high risk. These patients have a very high prevalence of sleep apnea and comorbid conditions. Screening this population for obstructive sleep apnea is mandatory, and a plan for postoperative observation should be in place in all institutions performing such surgery.

Prevalence of comorbid obstructive sleep apnea and metabolic syndrome: syndrome Z and maxillofacial surgery implications

PURPOSE

To determine the prevalence of the recently identified syndrome Z (SZ), which is the co-occurrence of obstructive sleep apnea (OSA; hypoxia, systemic and pulmonary hypertension, nocturnal arrhythmias) and metabolic syndrome (MetS; increased abdominal girth, hypertriglyceridemia, decreased high-density lipoprotein, hypertension, increased fasting glucose), which places the surgical patient at heightened risk of perioperative complications (myocardial infarction, stroke, pneumonia, wound infection).

MATERIALS AND METHODS

Electronic medical records of 296 male veterans were assessed for the presence of SZ using the American Academy of Sleep Medicine definition of OSA and a modified Adult Treatment Panel III definition of MetS, where obesity was defined by a body mass index of at least 30 kg/m(2) rather than by waist circumference.

RESULTS

SZ was diagnosed in 59% of patients. These individuals commonly exhibited severe OSA and least commonly mild OSA. The more severe the OSA, the more likely (60%) that patients manifested moderate (4 risk markers) or severe (5 risk markers) MetS. Furthermore, with increasing apnea-hypopnea index values, the more severe were the MetS elements.

CONCLUSIONS

The results of this study demonstrate the high prevalence rate of MetS in patients with OSA seeking treatment. Given the risk of perioperative complications, it is suggested that all patients scheduled for maxillofacial surgical procedures to treat OSA be evaluated for SZ.

Obstructive sleep apnoea and anaesthesia

Obstructive sleep apnoea (OSA) correlates positively with obesity and age, both of which are becoming increasingly prevalent. Obstructive sleep apnoea occurs much more frequently in clinical practice than formerly diagnosed, and that this condition represents complex challenges for difficulty in mask ventilation, laryngoscopic intubation, accelerated arterial desaturation, postoperative monitoring and discharge status. In this review article pathophysiology, diagnosis, and perioperative management of this group of patients have been discussed in detail.

Obesity and obstructive sleep apnea-hypopnea syndrome

Obstructive sleep apnea-hypopnea syndrome involves recurring episodes of total obstruction (apnea) or partial obstruction (hypopnea) of airways during sleep. Obstructive sleep apnea-hypopnea syndrome affects mainly obese individuals and it is defined by an apnea-hypopnea index of five or more episodes per hour associated with daytime somnolence. In addition to anatomical factors and neuromuscular and genetic factors, sleep disorders are also involved in the pathogenesis of sleep apnea. Obesity affects upper airway anatomy because of fat deposition and metabolic activity of adipose tissue. Obstructive sleep apnea-hypopnea syndrome and metabolic syndrome have several characteristics such as visceral obesity, hypertension and insulin resistance. Inflammatory cytokines might be related to the pathogenesis of sleep apnea and metabolic syndrome. Sleep apnea treatment includes obesity treatment, use of equipment such as continuous positive airway pressure, drug therapy and surgical procedures in selected patients. Currently, there is no specific drug therapy available with proven efficacy for the treatment of obstructive sleep apnea-hypopnea syndrome. Body-weight reduction results in improvement of sleep apnea, and obesity treatment must be emphasized, including lifestyle changes, anti-obesity drugs and bariatric surgery.

Association of sleep-disordered breathing with postoperative complications

BACKGROUND

Obstructive sleep apnea (OSA) is associated with increased perioperative risk, but the incidence of postoperative complications and the severity of OSA associated with increased risk have not been established. We investigated the relationship between intermittent hypoxemia measured by home nocturnal oximetry with the occurrence of postoperative complications in patients with clinical signs of OSA identified during preoperative assessment for elective surgery.

METHODS

This study was performed at a tertiary care hospital. Home nocturnal oximetry was performed on elective surgical patients with clinical features of OSA. The number of episodes per hour of oxygen desaturation (or oxygen desaturation index) of > or = 4% (ODI4%) was determined. Subjects with five or more desaturations per hour (ODI4% > or = 5) were compared to those with less than five desaturations per hour (ODI4% < 5). Hospital records were reviewed to assess the incidence and type of postoperative complications.

RESULTS

A total of 172 patients were investigated as part of this study. No significant differences were observed between groups in terms of age, body mass index, number of medical comorbidities, or smoking history. Patients with an ODI4% > or = 5 had a significantly higher rate of postoperative complications than those with ODI4% < 5 (15.3% vs 2.7%, respectively [p < 0.01]; adjusted odds ratio, 7.2; 95% confidence interval, 1.5 to 33.3 [p = 0.012]). The complication rate also increased with increasing ODI severity (patients with an ODI4% of 5 to 15 events per hour, 13.8%; patients with an ODI4% of > or = 15 events per hour, 17.5%; p = 0.01) Complications were respiratory (nine patients), cardiovascular (five patients), GI (one patient), and bleeding (two patients). The hospital length of stay was similar in both groups.

CONCLUSION

An ODI4%> or = 5, determined by home nocturnal oximetry, in patients with clinical features of OSA is associated with an increased rate of postoperative complications.

Challenges in pulmonary risk assessment and perioperative management in bariatric surgery patients

Bariatric surgery has serious associated medical comorbidity and procedure-related risks and is, thus, considered an intermediate-to-high-risk non-cardiac surgery. Altered respiratory mechanics, obstructive sleep apnea (OSA), and less often, pulmonary hypertension and postoperative pulmonary embolism are the major contributors to poor pulmonary outcomes in obese patients. Attention to posture and positioning is critical in patients with OSA. Suspected OSA patients requiring intravenous narcotics should be kept in a monitored setting with frequent assessments and naloxone kept at the bedside. Use of reverse Tredelenburg position, preinduction, maintenance of positive end-expiratory pressure, and use of continuous positive airway pressure can help improve oxygenation in the perioperative period.

Unrecognized sleep apnea in the surgical patient: implications for the perioperative setting

Anesthesia and surgery both affect the architecture of sleep. Aside from the postoperative effects of anesthesia and surgery, sleep deprivation and fragmentation have been shown to produce apneas or desaturations even in patients without presumed sleep apnea. Recent epidemiologic data have placed the prevalence of obstructive sleep apnea syndrome (OSAS) at about 5% among Western countries. The problem is further hindered by the difficulty in diagnosing OSAS, as patients with OSAS may present for surgery without a prior diagnosis. Clinical suspicion for OSAS may first be recognized intraoperatively. Adverse surgical outcomes appear to be more frequent in OSAS patients. Immediate postoperative complications may intuitively be attributed to the negative effects of sedative, analgesic, and anesthetic agents, which can worsen OSAS by decreasing pharyngeal tone, and the arousal responses to hypoxia, hypercarbia, and obstruction. Later events are, however, more likely to be related to postoperative rapid eye movement (REM) sleep rebound. In the severe OSAS patient, REM sleep rebound could conceivably act in conjunction with opioid administration and supine posture to aggravate sleep-disordered breathing. REM sleep rebound has also been suggested to contribute to mental confusion and postoperative delirium, myocardial ischemia/infarction, stroke, and wound breakdown. Although the data to guide the perioperative management of patients with moderate-to-severe OSAS is scarce, heightened awareness is recommended. The selected use of therapy with nasal continuous positive airway pressure before surgery and after extubation may be beneficial.

LEARNING OBJECTIVES

1. Identify common sleep architectures affected by anesthesia and surgery in the perioperative period. 2. State a perioperative complication in Obstructive Sleep Apnea Syndrome patients. 3. Identify perioperative interventions and management techniques that best facilitate improved obstructive sleep apnea syndrome patient care.

[Anesthesia and sleep apnea syndrome]

The perioperative risk for patients with obstructive sleep apnea syndrome and the optimal anaesthesiological management of these patients have not been well elucidated. The prevalence of obstructive sleep apnea with significant symptoms is estimated to be 4% in men and 2% in women. However, in 80-95% of patients this syndrome is not sufficiently diagnosed. Thus identification of patients at risk and a thorough multidisciplinary diagnostic approach are essential for optimal perioperative management. The risk of perioperative complications, like cardiopulmonary compromise, and difficulties in airway management is elevated. The most important aspects of perioperative management include evaluation of intubating conditions, careful search for cardiopulmonary morbidity, permanent control of patient airways, sensible use of anaesthetics, sedatives, and narcotics, and strict monitoring of vital signs. If ambulatory nasal continuous positive airway pressure (CPAP) therapy has been established preoperatively, this should be continued in the perioperative period. Postoperative monitoring should be performed in an intensive care or intermediate care unit. Controlled clinical studies on the best perioperative management of patients with obstructive sleep apnea are urgently required.

Perioperative treatment of patients with obstructive sleep apnea

PURPOSE OF REVIEW

Obstructive sleep apnea is a common disorder. Despite reports of its role as a risk factor for postoperative morbidity and mortality, only a few investigators have examined the optimal treatment of patients during this vulnerable period. Recognition of obstructive sleep apnea during conscious sedation or in the perioperative period is important to prevent the occurrence of adverse outcomes. This review discusses the influence of sedative, anesthetic, and analgesic agents and other factors during the perioperative period on patients with obstructive sleep apnea. The aim of this article is to emphasize the importance of recognizing and appropriately treating surgical patients with obstructive sleep apnea.

RECENT FINDINGS

Sedative, analgesic, and anesthetic agents used perioperatively play a major role in the development of sleep-disordered breathing during the postoperative period. Postoperative apneic episodes frequently occur even after surgery remote from the upper airway. Sleep apnea predisposes patients to a greater than normal risk for postsurgical complications. Adequate screening of patients preoperatively and initiation of continuous positive airway pressure therapy perioperatively could prevent serious complications, including hypoxemia, arrhythmias, myocardial infarction, and respiratory arrest.

SUMMARY

Obstructive sleep apnea places a significant proportion of surgical patients at increased risk of perioperative complications. Obstructive sleep apnea can be induced, unmasked, or exacerbated by the effects of sedative, analgesic, and anesthetic agents regardless of the site of surgery. The role of sleep apnea as a risk factor for development of postoperative complications needs greater emphasis. Increased awareness of the risk posed by an obstructed upper airway and appropriate management are important to optimize the perioperative care of patients with obstructive sleep apnea.

Relationship between nocturnal hypoxaemia, tachycardia and myocardial ischaemia after major abdominal surgery

BACKGROUND

Episodic hypoxaemia, cardiac arrhythmias, and myocardial ischaemia may be related after major abdominal surgery.

METHODS

We studied 52 patients on the second and third nights after major abdominal operations, using continuous pulse oximetry and Holter ECG. We recorded the amount of time spent with oxygen saturation values less than 90, 85, and 80% during the night, and noted episodes of hypoxaemia, tachycardia, bradycardia, and ST-segment changes.

RESULTS

In 87 study nights there were 2403 (individual range 1-229) episodes of hypoxaemia, 3509 (individual range 1-234) episodes of tachycardia, and 265 (individual range 1-73) episodes of ST segment deviation. Of the 52 patients, 50 had episodes of hypoxaemia and tachycardia, and 19 patients had one or more episodes of ST segment deviation. For 38% of the episodes of ST deviation, there was an episode of hypoxaemia at the same time and in 16% there was an episode of tachycardia. ST deviation was only noted in 4% of the episodes of hypoxaemia and in 1% of the episodes of tachycardia.

CONCLUSION

Episodes of hypoxaemia and tachycardia frequently occur together after surgery but are rarely associated with ST deviation. Hypoxaemia or tachycardia is often present at the same time as ST deviation occurs.

Molecular mechanisms in male determination and germ cell differentiation

Sex determination and gametogenesis are key processes in human reproduction, and any defect can lead to infertility. We describe here the molecular mechanisms of male sex determination and testis formation; defects in sex determination lead to a female phenotype despite the presence of a Y chromosome, more rarely to a male phenotype with XX chromosomes, or to intersex phenotypes. Interestingly, these phenotypes are often associated with other developmental malformations. In testis, spermatozoa are produced from renewable stem cells in a complex differentiation process called spermatogenesis. Gene expression during spermatogenesis differs to a surprising degree from gene expression in somatic cells, and we discuss here mechanistic differences and their effect on the differentiation process and male fertility.

Uvulopalatopharyngoplasty for sleep apnea in mentally retarded obese 14-year-old: an anaesthetic challenge

Anaesthetic management of patients with obstructive sleep apnea for upper airway surgery has always been a challenging task. We report our anaesthetic approach for a young, mentally retarded obese patient with documented obstructive sleep apnea undergoing uvulopalatopharyngoplasty. The therapeutic intervention before, during and after operation is discussed.

Obstructive sleep apnea in the adult obese patient: implications for airway management

Adult obese patients with suspected or sleep test confirmed OSA present a formidable challenge throughout the perioperative period. Life-threatening problems can arise with respect to tracheal intubation, tracheal extubation, and providing satisfactory postoperative analgesia. Tracheal intubation and extubation decisions in obese patients with either a presumptive and/or sleep study diagnosis of OSA must be made within the context that there may be excess pharyngeal tissue that cannot be visualized by routine examination, and the literature indicates an increased risk of intubation difficulty. Regional anesthesia for postoperative pain control is desirable (although such management is not necessary or possible for many of these patients). If opioids are used for the extubated postoperative patient, then one must keep in mind an increased risk of pharyngeal collapse and consider the need for continuous visual and electronic monitoring. The exact management of each sleep apnea patient with regard to intubation, extubation, and pain control requires judgment and is a function of many anesthesia, medical, and surgical considerations.

Risk factors for airway complications during general anaesthesia in paediatric patients

BACKGROUND

Although airway complications are a frequent problem during paediatric anaesthesia, no study has prospectively identified risk factors for adverse respiratory events during airway management when LMA trade mark (laryngeal mask airway), face mask (FM) or a tracheal tube (TT) are used.

METHODS

A prospective study was performed at a university hospital's paediatric centre. Preoperative information included recent history of respiratory infection and type of surgery. Intraoperative information included the identification of the device user, the duration of anaesthesia and the type of airway device used. Adverse respiratory events during the perioperative and postoperative periods were registered. One thousand nine hundred and ninety-six patients were included (mean age 6.45 +/- 2.9 years).

RESULTS

Airway complications occurred in 10.2% of the patient for LMA (72/704), 4.7% for FM (19/401) and 7.4% (66/891) for TT. Using a stepwise logistic regression, three independent risk factors were identified: age < 6 years, odds ratio (OR) 1.84, 95% CI (1.21-2.80); use of LMA, OR 2.32, 95% CI (1.29-4.17); presence of respiratory infections (RI) before the procedure, OR 3.72, 95% CI (2.3-5.99).

CONCLUSIONS

Age < 6 years, recent RI and the use of the LMA were identified as independent factors associated with an increased risk of airway complications.

Sleep apnea syndrome in patients undergoing total joint arthroplasty

Sleep apnea syndrome (SAS) is a condition of repeated episodes of apnea and hypopnea during sleep. It can cause life-threatening morbidities, including cardiac arrhythmia and ischemia, hypertension, and respiratory arrest, and even death. In a retrospective study at our institution of patients who underwent hip or knee total joint arthroplasty (TJA) with a diagnosis of SAS, we hypothesized that avoiding factors that exacerbate SAS in the perioperative period would minimize adverse outcomes. There were 19 patients with a preoperative diagnosis of moderate or severe SAS; 15 patients received continuous positive airway pressure or bilevel positive airway pressure noninvasive ventilation, 1 patient experienced respiratory arrest secondary to intraoperative propafol, and 2 patients developed postoperative respiratory depression. Avoidance of opioids and sedative drugs, awareness of the possibility of acute airway obstruction, and close monitoring during and after surgery are vital in patients with SAS.

Postoperative complications in patients with obstructive sleep apnea syndrome undergoing hip or knee replacement: a case-control study

OBJECTIVE

To identify and assess the impact of postoperative complications in patients with unrecognized or known obstructive sleep apnea syndrome (OSAS) undergoing hip replacement or knee replacement compared with control patients undergoing similar operations. Although OSAS is a risk factor for perioperative morbidity, data quantifying the magnitude of the problem in patients undergoing non-upper airway operations are limited.

PATIENTS AND METHODS

This retrospective, case-control study from a single academic medical institution included patients diagnosed as having OSAS between January 1995 and December 1998 and undergoing hip or knee replacement within 3 years before or anytime after their OSAS diagnosis. Patients with OSAS were subcategorized as having the diagnosis either before or after the surgery and also, regardless of time of diagnosis, by whether they were using continuous positive airway pressure (CPAP) prior to hospitalization. Matched controls were patients without OSAS undergoing the same operation. Interventions were defined specifically as administration of a particular treatment in the context of each complication, eg, supplemental oxygen, implementation of additional monitoring such as oximetry for hypoxemia, or transfer to the intensive care unit (ICU) for cardiac ischemia concerns. Postoperative complications were assessed for all patients in the different categories and included respiratory events such as hypoxemia, acute hypercapnia, and episodes of delirium. Serious complications were noted separately, including unplanned ICU days, reintubations, and cardiac events. The length of hospital stay was also tabulated.

RESULTS

There were 101 patients with the diagnosis of OSAS in this study and 101 matched controls. Thirty-six patients had their joint replacement before OSAS was diagnosed, and 65 had surgery after OSAS was diagnosed. Of the latter 65 patients, only 33 were using CPAP at home preoperatively. Complications were noted in 39 patients (39%) in the OSAS group and 18 patients (18%) in the control group (P=.001). Serious complications occurred in 24 patients (24%) in the OSAS group compared with 9 patients (9%) in the control group (P=.004). Hospital stay was significantly longer for the OSAS patients at a mean +/- SD of 6.8 +/- 2.8 days compared with 5.1 +/- 4.1 days for the control patients (P<.007).

CONCLUSION

Adverse postoperative outcomes occurred at a higher rate in patients with a diagnosis of OSAS undergoing hip or knee replacement compared with a group of matched control patients.

Overnight pulse oximetry for sleep-disordered breathing in adults: a review

Pulse oximetry is a well-established tool routinely used in many settings of modern medicine to determine a patient's arterial oxygen saturation and heart rate. The decreasing size of pulse oximeters over recent years has broadened their spectrum of use. For diagnosis and treatment of sleep-disordered breathing, overnight pulse oximetry helps determine the severity of disease and is used as an economical means to detect sleep apnea. In this article, we outline the clinical utility and economical benefit of overnight pulse oximetry in sleep and breathing disorders in adults and highlight the controversies regarding its limitations as presented in published studies.

Obstructive sleep apnea in the adult obese patient: implications for airway management

Obstructive sleep apnea in the adult obese patient may be due, in part, to an increased amount of pharyngeal tissue. Therefore, there is an increased risk of intubation and extubation difficulties and pain management can be expected to be complicated by opioid/sedative-induced pharyngeal collapse.

Anaesthetic management of patients with sleep apnoea syndrome

PURPOSE

Sleep apnoea syndrome (SAS) is a relatively common, potentially fatal, disorder. Patients with SAS exhibit repetitive, often prolonged episodes of apnoea during sleep, with serious nocturnal and diurnal physiologic derangements. Several anecdotal reports and clinical studies have documented anaesthetic-related occurrence of fatal and near-fatal respiratory complications in these patients. The purpose of this article is to outline the potential problems encountered in anaesthetic management of adult SAS patients, and to suggest a practical approach for anaesthesia both for incidental and specific procedures.

PRINCIPAL FINDINGS

SASs have many implications for the anaesthetist. First, SAS patients are exquisitely sensitive to all central depressant drugs, with upper airway obstruction or respiratory arrest occurring even with minimal doses. Thus sedative and opioid premedication should be omitted as should the intra and postoperative use of opioids be limited or avoided. All anaesthetic drugs should be administered by titration to desired effect, preferably using short-acting drugs. When feasible, continuous regional anaesthesia using a catheter is the technique of choice. Where possible nonopioid analgesics or local anaesthetics should be used for postoperative analgesia. Perioperative monitoring for apnoea, desaturation, and dysrhythmias is essential. Secondly, SAS patients have a potentially difficult airway. Awake intubation is the safest approach to airway control. Extubation should only be tried in the fully conscious patient with intact upper airway function and under controlled situations. Thirdly, the cardiorespiratory complication of SAS and the presence of associated diseases can adversely influence anaesthetic management.

CONCLUSION

Perioperative risks attending SAS patients emphasize the importance of their detection, perioperative evaluation and planning.

Nasal continuous positive airway pressure in the perioperative management of patients with obstructive sleep apnea submitted to surgery

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.

Circadian variation in unexpected postoperative death

Unexpected deaths still occur following major surgical procedures. The cause is often unknown but may be cardiac or thromboembolic in nature. Postoperative ischaemia, infarction and sudden cardiac death may be triggered by episodic or constant arterial hypoxaemia, which increases during the night. This study examined the circadian variation of sudden unexpected death following abdominal surgery between 1985 and 1989 inclusive. Deaths were divided into those occurring during the day (08.00-16.00 hours), evening (16.00-24.00 hours) and night (24.00-08.00 hours). Twenty-three deaths were considered to have been totally unexpected. Of 16 such patients undergoing autopsy, pulmonary embolism was the cause of death in five. In the remaining 11 patients, death occurred at night in eight (P < 0.005). Five of the seven patients without an autopsy died at night (P < 0.04); overall, 13 of 18 unexpected deaths occurred at night-time. These results suggest a need for further studies of sleep- and respiration-related effects on postoperative nocturnal cardiac function. The efficacy of monitoring during this apparent high-risk period should be evaluated.