Exercise tolerance in obstructive sleep apnea-hypopnea (OSAH), before and after CPAP treatment: Effects of autonomic dysfunction improvement

Abstract

Background: Obstructive sleep apnea hypopnea (OSAH) is associated with decreased exercise tolerance and autonomic abnormalities and represents a risk for cardiovascular diseases. The aim of the study was to evaluate the effects of CPAP on cardiovascular autonomic abnormalities and exercise performance in patients with OSAH without changes in lifestyle and body weight during treatment.

Methods: Twelve overweight subjects with OSAH underwent anthropometric measures, autonomic cardiovascular and incremental symptom-limited cardio-respiratory exercise tests before and after two months of treatment with CPAP.

Results: Lower frequency component of power spectrum of heart rate variability (59.5±24.2 msec² vs 43.2±25.9 msec²; p<0.05) and improvements of maximal workload (99.3±13.5 vs 108.3±16.8%pred.; p<0.05) and peak oxygen consumption (95.3±7.6 vs 105.5±7.9%pred.; p<0.05) were observed in these patients after CPAP, being their BMI unchanged.

Conclusions: CPAP-induced decrease of sympathetic hyperactivity is associated with better tolerance to the effort in OSAH patients that did not change their BMI and lifestyle, suggesting that OSAH limits per se the exercise capacity.

Keywords: Autonomic assessment; CPAP; Cardio-pulmonary exercise test (CPET); Obstructive sleep apnea hypopnea; Sleep study.