A pilot study investigating the effects of continuous positive airway pressure treatment and weight-loss surgery on autonomic activity in obese obstructive sleep apnea patients

Background: We have previously demonstrated that severity of obstructive sleep apnea (OSA) as measured by the apnea-hypopnea index (AHI) is a significant independent predictor of readily-computed time-domain metrics of short-term heart rate variability (HRV). Methods: We aimed to assess time-domain HRV measured over 5-min while awake in a trial of obese subjects undergoing one of two OSA therapies: weight-loss surgery (n = 12, 2 males, median and interquartile range (IQR) for BMI 43.7 [42.0, 51.4] kg/m(2), and AHI 18.1 [16.3, 67.5] events/h) or continuous positive airway pressure (CPAP) (n = 15, 11 males, median BMI 33.8 [31.3, 37.9] kg/m(2), and AHI 36.5 [24.7, 77.3] events/h). Polysomnography was followed by electrocardiography during wakefulness; measurements were repeated at 6 and 12-18 months post-intervention. Results: Despite similar measurements at baseline, subjects who underwent surgery exhibited greater improvement in short-term HRV than those who underwent CPAP (p = 0.04). Conclusions: Our data suggest a possible divergence in autonomic function between the effects of weight loss resulting from bariatric surgery, and the amelioration of obstructive respiratory events resulting from CPAP treatment. Randomized studies are necessary before clinical recommendations can be made. (C) 2014 Elsevier Inc. All rights reserved.