Oxygen uptake efficiency slope in patients with metabolic syndrome and obstructive sleep apnea

Abstract

Patients with metabolic syndrome (MetS) and obstructive sleep apnea (OSA) have increased cardiovascular risk. Besides decreased peak oxygen consumption peak (VO2peak), the decreased on Oxygen uptake efficiency slope (OUES) during cardiopulmonary exercise testing (CPET) can be used as a marker submaximal of worst prognosis. Therefore, we tested the hypotheses that: 1) OUES is decreased in MetS patients and the association of MetS; 2) OSA causes further decreased on OUES; and 3) The MetS risk factors are associated with OUES. Seventy eight MetS sedentary patients (ATP‐III) without the use of drugs were divided into: MetS+OSA (n=39, 50±1 yrs) and MetS‐OSA (n=33, 45±1 yrs). A control group (C; n=21, 46±1 yrs) was also studied. OSA was determined by apnea/hypopnea index (AHI>15events/h‐polysomnography). The OUES was obtained through the CPET by linear regression analysis of the relation between relative oxygen uptake (ml/kg/min) and the logarithm of VE (l/min), from the 1st min up to maximum effort (OUES100%). Besides, we analyzed the OUES in relation to lean mass body (LMB) (OUES100% LMB). The LMB was obtained by bioimpedance. The MetS+OSA and MetS‐OSA were similar, and both presented lower levels than C regarding OUES100% (25.3± 0,8, 25.3±0,9 and 32.3± 1,7 ml/kg/min/log, respectively p<0.001). Similar results were found to OUES100% LMB (36.8± 1.0, 38.2± 1.1 and 44.2± 2.7 ml/kg/min/log, p=0.003) and to VO2peak (21.7±0.9 vs. 21.8± 0.7 vs. 28±1.4 ml/kg/min, p<0.001). MetS groups have similar MetS risk factors and in body mass index (BMI) and greater than C. Regarding LMB, no difference was observed among groups. Further analysis showed that there were no association between the MetS risk factors or apnea/hypopnea index with OUES. Only BMI was associated with OUES 100% (r=−0,31, p=0.002). MetS patients have impaired cardiorespiratory efficiency during exercise independently of the presence of OSA. The excess body fat seems to be the main cause of this impairment in MetS patients.Support or Funding InformationThis study was supported by Fundação de Amparo à Pesquisa do Estado de São Paulo (FAPESP# 2011/17533‐6 ) and, in part, by Fundação Zerbini. Jefferson C Carvalho was supported by Coordenação de Aperfeiçoamento de Pessoal de Nível Superior, Felipe X Cepeda was supported by FAPESP# 2015/03274‐0,Sara Rodrigues was supported by FAPESP# 2013/15323‐0, Akothirene CB Dutra‐Marques was supported by Coordenação de Aperfeiçoamento de Pessoal de Nível Superior, Edgar Toschi‐Dias was supported by FAPESP# 2013/07651‐7.