Evidence supporting routine polysomnography before bariatric surgery

Obstructive sleep apnea (OSA) is common in morbidly obese patients, with a reported prevalence from 12 to 40%. Preoperative diagnosis of OSA is important for both perioperative airway management and the prevention of postoperative pulmonary complications. BMI has been reported to be an independent risk factor, and has been used recently in scoring systems to help predict OSA. Our hypothesis was that OSA is highly prevalent in patients presenting for bariatric surgery, and that BMI alone is not a good predictor of the presence or absence of sleep apnea.

A cross-sectional study was undertaken of the last 170 consecutive patients presenting for bariatric surgery in a single surgeon's practice. Clinical and demographic data were available from our prospective database, and polysomnography results were reviewed retrospectively. Sleep apnea was noted as present or absent, and graded from mild to severe. The patient population was stratified by BMI into severely obese (BMI 35-39.9), morbidly obese (BMI 40-49.9), super-obese (BMI 50-59.9), and super-super-obese (BMI >or= 60).

OSA had been diagnosed before surgical consultation in 26 of the 170 patients (15.3%). Sleep studies were not available in 7 patients (4.1%). The remaining 137 patients (80.6%) had sleep data available, and 105 (76.6%) had sleep apnea (based on American Board of Sleep Medicine criteria). There was no correlation of sleep apnea with BMI. The overall prevalence of OSA in this cohort was 77% (131/170).

In this large patient cohort, sleep apnea was prevalent (77%) independent of BMI, and most cases were not diagnosed before bariatric surgical consultation. These data support the use of routine screening polysomnography before bariatric surgery.