RESUMEN
STUDY OBJECTIVES: The aim of this study was to evaluate cardiopulmonary exercise performance in lean and obese patients with obstructive sleep apnea (OSA) compared with controls. DESIGN: Case-control study. SETTING: The study was carried out in Sao Paulo Sleep Institute, Sao Paulo, Brazil. PATIENTS AND PARTICIPANTS: INDIVIDUALS WITH SIMILAR AGES WERE ALLOCATED INTO GROUPS: 22 to the lean OSA group, 36 to the lean control group, 31 to the obese OSA group, and 26 to the obese control group. INTERVENTIONS: The participants underwent a clinical evaluation, polysomnography, a maximum limited symptom cardiopulmonary exercise test, two-dimensional transthoracic echocardiography, and spirometry. MEASUREMENTS AND RESULTS: The apnea-hypopnea index, arousal index, lowest arterial oxygen saturation (SaO2) and time of SaO2 < 90% were different among the groups. There were differences in functional capacity based on the following variables: maximal oxygen uptake (VO2max), P < 0.01 and maximal carbon dioxide production (VCO2max), P < 0.01. The obese patients with OSA and obese controls presented significantly lower VO2max and VCO2max values. However, the respiratory exchange ratio (RER) and anaerobic threshold (AT) did not differ between groups. Peak diastolic blood pressure (BP) was higher among the obese patients with OSA but was not accompanied by changes in peak systolic BP and heart rate (HR). When multiple regression was performed, body mass index (P < 0.001) and male sex in conjunction with diabetes (P < 0.001) independently predicted VO2max (mL/kg/min). CONCLUSIONS: The results of this study suggest that obesity alone and sex, when associated with diabetes but not OSA, influenced exercise cardiorespiratory function.