Cardiopulmonary exercise testing in patients with obstructive sleep apnea

Background The cardiopulmonary exercise testing (CPET) is a noninvasive process aiming to evaluate the respiratory and cardiovascular system during exercise. Aim To study the effect of obstructive sleep apnea (OSA) on cardiovascular system and exercise capacity and to correlate the severity of OSA with CPET parameters. Patients and methods Fifty patients (30 males and 20 females) were enrolled in this study, diagnosed as OSA based on polysomnography (apnea–hypopnea index ≥5). All patients were given a thorough medical history, a thorough physical examination, an arterial blood gas analysis before and after exercise, a pulmonary-function test, polysomnography, and a CPET. Results Patients with mild/moderate OSA had significantly higher oxygen consumption (VO 2 ) at peak (ml/min) and predicted value. Predicted VO 2 /kg was significantly higher among patients with mild/moderate OSA. Also, patients with mild/moderate OSA had significantly higher LT. Out of enrolled patients, three (6%), 15 (30%), and 32 (64%) patients had mild, moderate, and severe exercise impairment, respectively. Majority (90%) of the patients with severe OSA had severe exercise impairment, while majority (70%) of those with mild/moderate OSA had moderate exercise impairment. Conclusions OSA causes exercise impairment, which has a positive correlation with the severity of the disease.