Prior research indicates an association between obstructive sleep apnea and unfavorable long-term cardiovascular outcomes in the general population. Studies assessing this association in perioperative patients have been mostly retrospective and from database reviews, leaving a need for high-quality and non-conflicting evidence. With the majority of perioperative patients presenting for surgery being largely unrecognized and untreated for OSA, if present, “The Postoperative Vascular Complications in Unrecognized OSA (POSA) group embarked on a large sample size, multicenter prospective study from 2012 to 2017 to determine the association between the diagnosis and severity of OSA based on preoperative home sleep apnea testing and 30-day postoperative cardiovascular outcomes among adult 1,218 patients (45 years and older) with at least one risk factor for postoperative cardiovascular events undergoing major noncardiac surgery in five countries,” explains Edwin Seet, MBBS, MMed.

The primary outcome of interest was a composite measure consisting of myocardial injury, heart failure, thromboembolism, atrial fibrillation, stroke and cardiac death. Secondary outcomes included unplanned tracheal intubation or postoperative lung ventilation, readmission to the intensive care unit, and infections.

The study team observed a high rate or unrecognized OSA—approximately 11% of patients had severe OSA, 19% had moderate OSA, and 37% had mild OSA. “Severe OSA was associated with a higher rate of postoperative cardiovascular events (adjusted hazard ratio 2.23),” explains Dr. Seet. “It is therefore important to identify those patients with severe OSA and implement measures to reverse the hypoxia associated with OSA after surgery. Perioperative physicians should recognize that OSA (along with its concomitant disease processes) is a major perioperative risk factor.”

Dr. Seet notes the logistic and financial constraints that prevent routine polysomnography sleep studies and even home sleep apnea tests preoperatively and suggests that patients, therefore be routinely assessed with the STOP-Bang screening tool “According to the results of the POSA study, patients with a STOP-Bang score of 5 or higher are at a higher risk of postoperative cardiovascular complications (1.7-fold),” he says. “These higher-risk patients should be monitored closely after surgery, and measures should be instituted to prevent severe oxygen desaturation.”