Postoperative complications associated with obstructive sleep apnea: time to wake up!

• Volume 118 • Number 2 www.anesthesia-analgesia.org 251 Copyright © 2014 International Anesthesia Research Society DOI: 10.1213/ANE.0000000000000067 Obstructive sleep apnea (OSA) is a prevalent disorder characterized by recurrent episodes of complete or partial collapse of the upper airway during sleep, leading to intermittent hypoxemia and hypercapnia and sleep fragmentation. A recent community-based study reported an increasing prevalence of OSA in parallel with the obesity epidemic.1 Concurrently, the number of surgical cases performed globally is increasing. In fact, Weiser et al.2 estimated that 234 million major surgeries were performed in 2004 worldwide. Although the reported prevalence of OSA in presurgical cohorts has varied, undoubtedly most anesthesiologists are bound to encounter patients with OSA in their daily clinical practice.3–7 This is of clinical relevance since sedatives, narcotics, and anesthetics can exacerbate upper airway collapsibility and blunt the arousal response. Several single-institution studies have reported an association between OSA and a myriad of adverse postoperative outcomes.8–11 In the absence of large-scale, well-controlled, prospective studies, analysis of administrative databases can shed some light on the association between OSA and postoperative outcomes and provide data that are more generalizable than single-center smaller studies. This is of importance because implementation of systematic screening for OSA and initiating treatment in the perioperative period for those patients at risk would impose a significant cost burden, particularly in the setting of large surgical volumes. Accordingly, the study by Memtsoudis et al.12 in this issue of Anesthesia & Analgesia is a timely contribution to the field of perioperative medicine. In an observational study performed using the Premier Perspective database, these investigators extracted data on 530,089 patients who underwent total hip or total knee arthroplasty between 2006 and 2010 in nearly 400 hospitals in the United States. OSA was present in 8.4% of the cohort based on the International Classification of Diseases, 9th Revision, Clinical Modification (ICD-9-CM) diagnostic codes. With robust statistical methodology and after adjusting for important confounders, they found that OSA was independently associated with increased odds ratio (OR) for the composite outcome of major postoperative adverse events (OR 1.47; 95% confidence interval [CI], 1.39–1.55). Not surprisingly, the association was stronger with pulmonary complications (OR 1.86; 95% CI, 1.65–2.09) than cardiac complications (OR 1.59; 95% CI, 1.48–1.71) with the risk of cardiac complications mainly due to atrial fibrillation. It is interesting to note that this type of arrhythmia has been strongly associated with OSA in nonsurgical cohorts as well.13 The risk of emergent reintubation was significantly increased in patients with OSA (OR 10.26; 95% CI, 9.01–11.69). OSA patients without hypertension and chronic obstructive pulmonary disease were 14 times more likely to receive mechanical ventilation and 46 times more likely to undergo noninvasive ventilation (NIV) than non-OSA patients. OSA was also independently associated with escalation of care, increased health care resource utilization, and length of stay.12 The types of complications associated with OSA reported by Memtsoudis et al. are similar to the findings from a recent analysis of the Nationwide Inpatient Sample.14,15 Mokhlesi et al.14,15 examined a cohort of 1,058,710 hospitalized adult patients undergoing 4 categories of elective procedures (orthopedic, prostate, abdominal, and cardiovascular cases) and a cohort of 91,028 adult patients undergoing bariatric surgeries between 2004 and 2008. Similar to the Premier Perspective database, OSA was independently associated with significantly increased odds of emergent intubation and mechanical ventilation, NIV, respiratory failure, and atrial fibrillation. A recent meta-analysis of 13 single-center studies also demonstrated a higher incidence of respiratory failure, cardiac events, and intensive care unit transfers in patients with OSA.8 In the study by Memtsoudis et al.,12 despite the increased rates of complications, there was no significant increase in the risk of in-hospital mortality in patients with OSA. In patients undergoing elective surgeries and bariatric surgeries, OSA was also found not to be associated with increased in-hospital mortality.14,15 D’Apuzzo and Browne16 examined a cohort of 258,488 patients undergoing revision total hip arthroplasty or total knee arthroplasty surgeries between 2006 and 2008. Contrary to these studies, OSA was associated with increase in-hospital mortality (OR 1.9; 95% CI, 1.3–2.8) with a mortality of 0.2% in patients without OSA Postoperative Complications Associated with Obstructive Sleep Apnea: Time to Wake Up!