Obstructive sleep apnea syndrome (OSAS) patients are at risk of cardiovascular complications. The aim of this study was to assess the effect of treatment with continuous positive airway pressure (CPAP) on the response to symptom limited exercise test.
Methods: twenty nine OSAS patients (1 F, 28 M), mean age 50.7+/-9.7 yrs with body mass index of 32.6+/-4.5 kg/m2 participated in the study. OSAS was diagnosed by overnight polysomnography. Incremental cardiopulmonary exercise test (CPET) on a treadmill was performed twice: before and after 2-3 weeks of regular treatment with CPAP.
Results: mean apnea + hypopnea index (AHI) before therapy was 57.6+/-12 h(-1). CPAP treatment did not change peak oxygen consumption (VO2max) (38.3+/-9.0 vs. 38.9+/-6.9 mlO2/kg/min, p=ns) or peak heart rate (153.4+/-21 min- vs. 155.5+/-22 min(-1), p=ns). There were no significant changes in ventilation or gas exchange variables. However, a decrease in peak systolic blood pressure from 194.5+/-24 mmHg to 186.7+/-27.9 mmHg (p<0.05) with CPAP treatment was found. During recovery a decrease in heart rate (at 1st minute and minutes 3 - 6) and mean arterial pressure (MAP) (minutes 4-7) with CPAP treatment was observed. Significant correlations between VO2max and AHI (r=-0,38, p<0,05); MAP at peak exercise and: AHI, mean oxygen saturation (SaO2) during sleep, minutes of sleep with SaO2<90% (T90); MAP at recovery (minutes 3-8) and T90 before CPAP treatment were also noted.
Conclusions: OSAS patients are not limited on exercise. Treatment with nasal CPAP attenuates circulatory response to incremental exercise on a treadmill.