Cardiopulmonary exercise testing in obstructive sleep apnea syndrome.

To investigate whether cardiac dysfunction or abnormal measurements on cardiopulmonary exercise testing (CPET) are present in patients with obstructive sleep apnea syndrome (OSAS) and what factors are responsible for exercise limitation in these patients. We enrolled 20 patients with moderate or severe OSAS in the OSA group and 20 subjects without OSAS in the control group. All subjects underwent a sleep study and cardiac evaluation by radionuclide scanning and CPET. There was no difference in left ventricular ejection fraction (VEF) between the two groups, but the OSA group had a lower right VEF. Patients in the OSA group had a lower VO2(peak), VO2(peak/kg) and workpeak than the control group. The OSA group had a higher breathing reserve and a greater decrease in anaerobic threshold (AT) and oxygen pulse. In conclusion, patients with moderate to severe OSAS had abnormal CPET results. These abnormalities may be due to cardiac disease, pulmonary vascular disease, or possible lack of fitness.