Efeitos da pressão positiva expiratória sobre a tolerância ao exercício e na hiperinsuflação dinâmica em indivíduos com doença pulmonar obstrutiva crônica

Abstract

The EPAP (Expiratory Positive Airway Pressure) has been used as an auxiliary therapy in various respiratory illness in order to contribute for secretion removal and increase alveolar ventilation. Considering this latter function, we have come up with a hypothesis that the use of EPAP, before a physical activity, could improve the dynamic hyperinflation (DH) and optimize the ventilatory function of patients with chronic obstructive pulmonary disease (COPD) contributing to the increase of the intensity and/or duration of the exercise. Therefore, the purpose of this study was to evaluate the immediate effects of the previous use of EPAP in exercise tolerance and in DH in individuals with COPD, specifically concerning the parameters: time of exercise, inspiratory capacity (IC), dyspnea, lower limb fatigue (LLF) and peripheral arterial oxygen saturation of hemoglobin (SpO-2). A transversal study was performed, enrolling 12 patients with the diagnosis of moderate to very severe COPD, according to the Global Strategy for the Diagnosis, Management, and Prevention of Chronic Obstructive Pulmonary Disease criteria. Initially, volunteers were submitted to a maximum incremental cycle ergometer test to determine the target workload to be used in the constant-load test, obtained from 75% of the maximal load reached. This test was performed after the random use of EPAP with 5 cmH2O or placebo during 15 minutes with the purpose of identifying the maximum exercise time. In order to evaluate the hyperinflation, basal IC measurements were taken (before the use of EPAP or placebo), after the exercise and 2 minutes after recovery. The other variables were evaluated during these same periods. The DH was evaluated, besides the previous moments, every 2 minutes during the exercise. The normal distribution of the data was confirmed by the Kolmogorov Smirnov method. For the evaluation of the IC before and after the use of EPAP and the exercise time difference after the use of EPAP or placebo Students pared t test was used. For analysis of the variables mixed ANOVA with repeated measures was carried out, considering factors such as intervention (EPAP x placebo) and the different moments, followed by the Least Significance Difference (LSD) test. In all tests, p<0.05 was considered significant. As expected, there was an increase in the average exercise time (40.82%) after use of EPAP from 321.25 (407.85) seconds (p=0.020) in relation to the time after the use of placebo. With the use of placebo there was a significant decrease of the IC comparing the situation before and after the exercise (p=0.002) which was not observed with the use of EPAP (p=0.31), although without significant difference comparing the groups. Differences in the other variables were not observed: Borg as for dyspnea as for LLF and SpO2. These results show that the use of EPAP immediately before the exercise may contribute to the increase of tolerance to the exertion and control of the DH.