May 2015 • Volume 120 • Number 5 www.anesthesia-analgesia.org 1013 Copyright © 2015 International Anesthesia Research Society DOI: 10.1213/ANE.0000000000000634 O bstructive sleep apnea (OSA) is a common sleep- breathing disorder, and its prevalence is increasing throughout the world. In the general population, the prevalence ranges from 9% to 25%. 1 Its prevalence, however, is greater in the surgical population. 2,3 In bariat- ric surgical patients, the prevalence of OSA may be >70%. 4,5 Furthermore, the majority of surgical patients with OSA may not have been diagnosed or treated before their surgery. 6 OSA may have serious implications for anes- thetic management because of its association with several comorbid conditions, such as cardiovascular disease, heart failure, arrhythmias, hypertension, stroke, and metabolic syndrome. 7–10 OSA has been independently associated with an increased incidence of perioperative adverse events. 11–15 Among the different treatment modalities available, con- tinuous positive airway pressure (CPAP) is the most effective and the most widely used. It is highly effective in controlling symptoms of OSA in the general population, such as reducing nocturnal events and providing subjective beneits of improve- ment in daytime sleepiness, cognitive function, and well- being. 16,17 CPAP also has been shown to decrease arterial blood pressure in OSA patients with hypertension and to improve glucose control in diabetic patients with severe OSA. 18,19 Liao et al. 20 have recently reported that newly diag- nosed OSA patients can be effectively treated with auto- titrated continuous positive airway pressure (APAP) in the perioperative period. OSA patients without APAP treat- ment had more hypoxemia and greater Apnea-Hypopnea Index (AHI) scores postoperatively versus OSA patients receiving APAP treatment. 20 Surgical patients identiied to have OSA in the preoperative clinic who were adher- ent to CPAP therapy were shown to have long-term health beneits, including better sleep quality and less daytime sleepiness. 21 Timely diagnosis of OSA before surgery and BACKGROUND: Obstructive sleep apnea (OSA) is a commonly encountered comorbid condition in patients undergoing surgery and is associated with a greater risk of postoperative adverse events. Our objective in this review was to investigate the effectiveness of continuous positive airway pressure (CPAP) in reducing the risk of postoperative adverse events in patients with OSA undergoing surgery, the perioperative Apnea-Hypopnea Index (AHI), and the hospital length of stay (LOS). METHODS: We performed a systematic search of the literature databases. We reviewed the studies that included the following: (1) adult surgical patients (>18 years old) with information available on OSA; (2) patients using either preoperative and/or postoperative CPAP or no-CPAP; (3) available reports on postoperative adverse events, preoperative and postoperative AHI, and LOS; and (4) all published studies in English including case series. RESULTS: Six studies that included 904 patients were eligible for the meta-analysis. The meta- analysis for postoperative adverse events was performed in 904 patients (CPAP: n = 471 vs no-CPAP: n = 433; adverse events: 134 vs 133; P = 0.19). There was no signiicant difference in the postoperative adverse events between the 2 groups. The preoperative baseline AHI with- out CPAP was reduced signiicantly with postoperative use of CPAP (preoperative AHI versus postoperative AHI, 37 ± 19 vs 12 ± 16 events per hour, P < 0.001). LOS showed a trend toward signiicance in the CPAP group versus the no-CPAP group (4.0 ± 4 vs 4.4 ± 8 days, P = 0.05). CONCLUSIONS: Our review suggests that there was no signiicant difference in the postopera- tive adverse events between CPAP and no-CPAP treatment. Patients using CPAP had signiicantly lower postoperative AHI and a trend toward shorter LOS. There may be potential beneits in the use of CPAP during the perioperative period. (Anesth Analg 2015;120:1013–23) The Effects of Continuous Positive Airway Pressure on Postoperative Outcomes in Obstructive Sleep Apnea Patients Undergoing Surgery: A Systematic Review and Meta-Analysis Mahesh Nagappa, MD, DNB, MNAMS,* Babak Mokhlesi, MD, MSc,† Jean Wong, MD, FRCPC,‡ David T. Wong, MD,* Roop Kaw, MD,§ and Frances Chung, MD, FRCPC‖ From the *Department of Anesthesiology, Toronto Western Hospital, University Health Network, University of Toronto, Toronto, Ontario, Canada; †Department of Medicine, Sleep Disorders Center and the Section of Pulmonary and Critical Care, University of Chicago, Chicago, Illinois; ‡Department of Anesthesiology, Toronto Western Hospital, University Health, Toronto, Ontario, Canada; §Department of Hospital Medicine and Department of Outcomes Research (Anesthesiology), Cleveland Clinic, Cleveland, Ohio; and ║Department of Anesthesia, Toronto Western Hospital, Women’s College Hospital, University Health Network, University of Toronto, Toronto, Ontario, Canada. Accepted for publication November 14, 2014. Funding: Supported by Department of Anesthesia, Toronto Western Hospital, University Health Network, University of Toronto. The authors declare no conlicts of interest. Reprints will not be available from the authors. Address correspondence to Frances Chung, MD, FRCPC, Department of An- esthesia, Toronto Western Hospital, Women’s College Hospital, University Health Network, University of Toronto 399, Bathurst St., Toronto, ON M5T 2S8, Canada. Address e-mail to Frances.Chung@uhn.ca. Section Editor: Tong J. Gan Society for Ambulatory Anesthesiology E REVIEW ARTICLE