Behavior of Oxygen Consumption During a Cardiac Rehabilitation Session

pp 234-238

Abstract

Objective: The aim of this study was to analyze the response of oxygen consumption in patients with dilated cardiomyopathy during a cardiac rehabilitation session.

Methods: This was an observational, cross-sectional, relational analytical study. Ten male patients with dilated cardiomyopathy and moderate to severe ventricular dysfunction were included in the study. Patients were evaluated in the laboratory and during a rehabilitation session using a Medgraphics VO 2000 portable gas analyzer. The rehabilitation session consisted in 10 minutes of stationary bike exercises, step, coordinaton stairs, and muscle strength using dumbbells for biceps and shoulder, a quadriceps stretcher and a dorsal muscle machine.

Results: Mean age was 57.4 ± 14.6 years, weight 91.4 ± 22.2 kg and height 168.1 ± 6.2 cm. In the laboratory, VO2 max was 21.8 ± 7.3 ml/kg/min, respiratory exchange rate (RER) (VCO2/VO2) 1.05 ± 0.09, ventilated volume 65.7 ± 18.5 L/min and heart rate in VO2 max 127.8 ± 23.8 beats/min. Rehabilitation session duration was 37.5 ± 10 min with peakVO2 14.6 ± 3 ml kg/min (69.9 ± 16.7 % VO2 max). The correlation coefficient between VO2 max and time with VO2 <50% VO2 max(min) was 0.662 (p = 0.037) and between peakVO2 in rehabilitation and time in RER between 0.85-1 (min) was 0.787 (p = 0.007). Patients with better fitness exercised in the low-intensity zone. As exercise increased, the minutes in moderate intensity also increased.

Conclusion: The study showed that patients reached peakVO2 in sessions below the maximum values obtained in the laboratory. Even though any dose of training in these patients was more beneficial than physical inactivity, cardiac rehabilitation session design and planning, taking into account intrasession exercise intensities, could generate greater impact on mortality, rehospitalizations and quality of life.