O teste do degrau de seis minutos avalia a capacidade funcional aeróbia de pacientes com Doença Pulmonar Obstrutiva Crônica?

Abstract

Objective: To assess the six-minute step test (6MST) in terms of its ability to evaluate the aerobic functional capacity of COPD patients. In addition to compare, correlate and verify if there is an agreement between the metabolic (oxygen uptake-VO2), ventilatory (minute ventilation-VE) and cardiovascular variables (heart rate-HR), and perceived exertion of the 6MST and the incremental cardiopulmonary exercise test (ICPET). Methods: Metabolic and ventilatory variables, heart rate, dyspnea and lower limb (LL) fatigue were recorded from 18 COPD patients (five had mild COPD, five moderate, six severe and two very severe) performing the 6MST and the submaximal ICPET on cycle ergometer (work rate was increased by 5-10 watts) on different and not consecutive days. Results: There were no significant differences between VO2, HR, VE, dyspnea and LL fatigue mean values at the peak of both tests. Moderate correlations were found between the 6MST performance and ICPET s VO2 (r=0.49;p=0.05) and performance (r=0.63;p=0.005), high correlations were found between both VO2 (L/min and mL/kg/min) (r=0.76 and r=0.77;p=0.001), and moderate correlations were found between HR (r=0.68;p=0.002) and LL fatigue (r=0.59;p=0.011) between the tests. There was no agreement between VO2, HR and LL fatigue values between the tests. Conclusion: The 6MST has the ability to assess aerobic functional capacity and presents cardiorespiratory responses and perceived exertion similar to the ICPET in magnitude, however it cannot replace the ICPET, since the 6MST assesses and demands greater and more localized work from peripheral muscles, thus not reflecting the same ICPET cardiorespiratory capacity.