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Relationship between ventilatory expired gas and cardiac parameters during symptom-limited exercise testing in
1Department of Physical Therapy, Box 980224, Virginia Commonwealth University, Medical College of Virginia, Health Sciences Campus, Richmond, VA 23298-0224, USA. raarena@gateway.net
Purpose:
This study investigates the relationship between ventilatory expired gas and cardiac parameters measured during exercise testing in patients with heart failure.
Methods:
Twenty-five subjects (12 male, 13 female) diagnosed with compensated heart failure underwent symptom-limited exercise testing with ventilatory expired gas analysis. Metabolic and cardiac measures of interest were collected during testing.
Results:
Mean peak oxygen consumption (VO2), minute ventilation/carbon dioxide production (VE/VCO2) slope, percentage of age predicted maximal heart rate achieved during exercise testing (%APMHR), and peak respiratory exchange ratio were 14.7 +/- 4.7 mL O2/kg/min-1, 33.8 +/- 9.8, 76% +/- 15%, and 1.1 +/- 0.11, respectively. The VE/VCO2 slope was significantly correlated with the following: %APMHR (r = -0.81, P < 0.001), peak VO2 (r = -0.83, P < 0.001), VO2 at ventilatory threshold (r = -0.70, P < 0.001), and the dead space to tidal volume ratio (VD/Vt) (r = 0.65, P < 0.001). The ability of peak VO2 and %APMHR to predict the VE/VCO2 slope was significant (r = 0.86, r2 = 0.72, P < 0.0001).
Conclusion:
This study demonstrates the importance of analyzing multiple exercise test parameters, including metabolic measures, in patients with heart failure.