Respiratory Muscle Endurance in Obesity Hypoventilation Syndrome

BACKGROUND: An increase in respiratory work load and resistance to respiration cause a decrease in respiratory muscle endurance (RME) in patients with obesity hypoventilation syndrome (OHS). We aimed to evaluate and compare RME in subjects with OHS and a control group using an incremental load test and compare the RME of subjects with OHS in whom noninvasive ventilation (NIV) was and was not used. METHODS: Forty subjects with OHS (divided according to body mass index [BMI] as group I: 30-40 kg/m(2); and group II: 6 40 kg/m(2)) and 20 subjects with obesity (control group: 30-40 kg/m(2)) were included in the study. RME was evaluated using the incremental load test, and respiratory muscle strength (RMS) was evaluated using mouth pressure measurements. The 6-min walk test, Epworth Sleepiness Scale (ESS), Pittsburgh Sleep Quality Index (PSQI), Fatigue Severity Scale (FSS), EQ-5D Health-Related Quality of Life Questionnaire (EQ-5D), and the Obesity and Weight-Loss Quality of Life Instrument (OWLQOL) were performed. RESULTS: RME and RMS (%) in group I were lower than the control group (P=.001, P=.005, and P=.001, respectively). No significant difference was found between the 3 groups in terms of 6-min walk distance (6MWD) percentage predicted values (P=.98). RME in the NIV user group was higher than the non-user group (P 5.006). ESS, total PSQI, and FSS scores in the control group were less than group I (P=.01, P=.009, and P=.005, respectively) and group II (P 5.01, P <.001, and P <.001, respectively). The EQ-5D scores of the control group were higher than group II only (P=.005 and P=.005, respectively). There were no differences in OWLQOL between the groups (P=.053). CONCLUSIONS: RME was low in subjects with OHS but higher in those who used NIV. The incremental load test could be performed easily and safely in a clinic setting.