Oxygen Uptake Kinetics and Functional Status Issues in Congestive Heart Failure: A Pilot Report

Abstract

Collection of peak oxygen consumption (V02) data provides valuable information with respect to prognosis and activity guidelines in the congestive heart failure (CHF) population. This pilot study examines the relationship between Duke Activity Status Index (DASI) score, calculated peak oxygen consumption (V02), and measured peak VO2. Six subjects, 3 males and 3 females, with stable CHF completed the DASI and underwent a symptom-limited ramp treadmill test. A metabolic cart was used to measure VO2 during testing. Mean measured VO2, calculated V02, and DASI score were 11.49 ± 3.86 m1O2/kg/min-1, 19.48 (6.24 mlO2/kg/min-1, and 20.09 ± 3.38 mlO2/kg/min-1 respectively. A Friedman two-way analysis of variance by ranks found no significant difference between DASI score and calculated VO2. However, a significant difference did exist between measured V02 and DASI scores as well as measured V02 and calculated V02 (p < 0.0085). These preliminary findings suggest that subjects with stable CHF can attain a calculated aerobic intensity level in excess of their measured V02. Interestingly, their perceived functional capacity is more closely related to calculated rather than measured V02. If confirmed by expansion of the subject pool, these findings have implications for future research endeavors, and clinicians interpreting V02 data for exercise and physical activity counseling in CHF patients.