Abstract
PURPOSE: Cardiopulmonary exercise testing is a common prognostic tool in heart failure, yet it is not standardized. The purpose of this study was to evaluate a means of standardizing oxygen consumption (VO2) measurement and to evaluate the ability to predict peak VO2 from submaximal exercise.
METHODS: Fifty consecutive exercise tests with a respiratory exchange ratio >=1.10 were evaluated. VO2 was graphed against respiratory exchange ratio and the peak VO2 was determined with logarithmic, linear, power, and exponential regression lines. To predict a peak VO2, each patient's submaximal exercise data (respiratory exchange ratio <=0.98) were fitted to each regression line. The mean of the last 30 seconds of unaveraged breath-by-breath data was used as the reference value. Peak VO2 assessments are also provided from the metabolic cart, a rolling time average, and the graphical method.
RESULTS: Logarithmic regression best standardized peak VO2. Mean absolute bias (mL[middle dot]kg-1[middle dot]min-1) was 0.60 +/- 0.44 for logarithmic, 0.61 +/- 0.47 for linear, 0.85 +/- 0.67 for power, and 1.44 +/- 2.22 for exponential. The mean absolute bias between the peak logarithmic predicted VO2 and the reference peak VO2 was 1.62 +/- 1.20 mL[middle dot]kg-1[middle dot]min-1 (9.5% of the peak VO2).
CONCLUSION: Among the methods studied, logarithmic regression analysis was the best method to standardize and predict peak VO2 in this cohort of patients with heart failure.