Preoperative oximetry-derived hypoxemia predicts postoperative cardiovascular events in surgical patients with unrecognized obstructive sleep apnea

Study objective: Obstructive sleep apnea (OSA) is known to be associated with postoperative cardiovascular events in patients undergoing major non-cardiac surgery. The objective of the study is to determine whether preop-erative oximetry-derived hypoxemia predicts postoperative cardiovascular events in surgical patients with un-recognized obstructive sleep apnea. Design and setting: The study was a planned post hoc analyses of a multicenter prospective cohort study. Patients: The inclusion criteria were patients >= 45 years old undergoing major non-cardiac surgery with car-diovascular risk factors. Interventions and measurements: All patients underwent pre-operative pulse oximetry (PULSOX-300i, Konica-Minolta Sensing, Inc). The severity of OSA was classified based on oxygen desaturation index (ODI) (mild: >= 5 to <15, moderate: >= 15 to <30, and severe OSA: >= 30 events/h). The 30 days cardiovascular events were a composite of myocardial injury, cardiac death, congestive heart failure, thromboembolism, atrial fibrillation, and stroke. Main results: For 1218 patients with mild, moderate, or severe OSA (mean age: 67.2 +/- 9.3 years; body mass index: 27.0 +/- 5.3 kg/m(2)), the rate of postoperative cardiovascular events was 16.4%, 25.2%, and 29.8% respectively. The multivariable analysis showed that preoperative oxygen desaturation index (ODI) >= 30 events per hour {adjusted hazard ratio (aHR) 1.63 [95% confidence interval (CI): 1.05-2.53]}, and cumulative time spent during sleep with oxygen saturation below 80% (CT80) >= 10 min {aHR 1.79 [95% CI: 1.28-2.50]} were independent predictors of 30-day postoperative cardiovascular events. Conclusions: Preoperative ODI >30 events per hour and CT80 > 10 min are associated with increased risk of postoperative cardiovascular events. Preoperative screening using oximetry helps in risk stratification for unrecognized sleep apnea.