Obstructive sleep apnea and pulmonary function in patients with severe obesity before and after bariatric surgery: a randomized clinical trial

Background: The increasing prevalence of obesity in both developed and developing countries is one of the most serious public health problems and has led to a global epidemic. Obesity is one of the greatest risk factors of obstructive sleep apnea (OSA), which is found in 60 to 70% of obese patients mainly due to the buildup of fat tissue in the upper portion of the thorax and neck. The aim of the present randomized clinical trial is to assess daytime sleepiness, sleep architecture and pulmonary function in patients with severe obesity before and after bariatric surgery.

Methods: This randomized, controlled trial, was designed, conducted, and reported in accordance with the standards of The CONSORT (Consolidated Standards of Reporting Trials) Statement. Patients were divided into a bariatric surgery group and control group. The clinical evaluation was performed at the Sleep Laboratory of the Nove de JulhoUniversity (Sao Paulo, Brazil) and consisted of the collection of clinical data, weight, height, body mass index (BMI), measurements of neck and abdomen circumferences, spirometry, maximum ventilatory pressure measurements, standard overnight polysomnography (PSG) and the administration of the Berlin Questionnaire and Epworth Sleepiness Scale.

Results: Fifty-two patients participated in the present study and performed PSG. Out of these, 16 underwent bariatric surgery. After surgery, mean BMI decreased from 48.15 ± 8.58 to 36.91 ± 6.67 Kg/m(2). Significant differences were found between the preoperative and postoperative periods regarding neck (p < 0.001) and waist circumference (p < 0.001), maximum inspiratory pressure (p = 0.002 and p = 0.004) and maximum expiratory pressure (p = 0.001 and p = 0.002) for women and men, respectively, as well as sleep stage N3 (p < 0.001), REM sleep (p = 0.049) and the apnea-hypopnea index (p = 0.008).

Conclusions: Bariatric surgery effectively reduces neck and waist circumference, increases maximum ventilatory pressures, enhances sleep architecture and reduces respiratory sleep disorders, specifically obstructive sleep apnea, in patients with severe obesity.

Trial registration: THE PROTOCOL FOR THIS STUDY WAS REGISTERED WITH THE WORLD HEALTH ORGANIZATION (UNIVERSAL TRIAL NUMBER: U1111-1121-8873) and Brazilian Registry of Clinical Trials - ReBEC (RBR-9k9hhv).