The effects of positive airway pressure therapy on exercise parameters ın patients with obstructive sleep apnea syndrome

Obstructive Sleep Apnea Syndrome (OSAS) is common in adult population; that may cause many adverse clinical results, particularly cardiovascular complications. Positive airway pressure (PAP) therapy has been shown to reduce the heart rate and mean blood pressure in hypertensive OSAS patients. It also improves right and left ventricular function and reduces the pulmonary artery pressure. In this study we aimed to investigate possible changes in cardiopulmonary exercise capacity in OSAS patients after positive airway pressure treatment .Sixty five sleep clinic patients diagnosed with OSAS by polysomnography and in whom PAP therapy was indicated clinically were included in the study. Patients were older than 18 years, had no obstructive, restrictive lung disease or heart-failure with no orthopedic problems precluding cycling.Cardiopulmonary exercise capacity was assessed by bicycle ergometry during the diagnosis and at least 4 weeks later. Carbon dioxide production (VCO2), oxygen uptake (VO2), anaerobic threshold (AT), cardiac rhythm (HR), tidal volume (VT), HR-VO2 relationship, VE/VCO2, VE/VO2, work rate (WR), heart rate reserve (HRR), respiratory reserve (RR), oxygen pulse, minute ventilation (VE) parameters were evaluated.Patients were grouped with respect to compliance with PAP therapy for statistical analysis. Among the cases 57 (87.7 %) were males, and mean age was 45.29±10.57 years, apnea-hypopnea index 38.02±23.19 events/hour, body mass index 31.72±4.87 kg/m2.There was a significant difference between the groups according to age (p=0.006) and hence age-adjusted repeated measures analysis of variance was used for statistical analysis.While VO2 max/kg was protected in the group using the device (n=33) (22.52±6.62 ml/min/kg to 21.32±5.26 ml/min/kg; p=0.111), in the group not using the device, VO2 max decreased (21.31±5.66 ml/dk/kg to 19.92±5.40 ml/dk/kg; p=0.050).Work rate increased from 84.03%±16.31 to 85.03%±14.60 in the group using PAP therapy. It decreased from 79.56%±17.86 to 77.06%±17.76 in the noncompliant group (p=0.041).In the group that used the device, the rate of VE/VCO2 at anaerobic threshold declined from 28.42 to 27.36, on the other hand, it increased from 27.41 to 27.81 in the group which did not used the device (p=0.033).In conclusion, the decline in exercise capacity was prevented in patients with OSAS after 4 weeks of PAP therapy. The changes in VE/VCO2 at AT suggest that reversal of pathophysiologic changes in OSAS with PAP therapy may improve cardiac function and cause more efficient ventilation by reducing dead space ventilation and/or pulmonary artery pressure.