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Date of Graduation
Bachelor of Science (BS)
Department of Kinesiology
Trent A. Hargens
Michael J. Saunders
Christopher J. Womack
Repeatability of Impedance Cardiography Hemodynamic Variables During Treadmill Exercise
Purpose To analyze the day to day repeatability of cardiac hemodynamic measurements using a Physio Flow 07 Enduro during treadmill submaximal exercise.
Methods 21 male subject ages 18 and older were studied. Two graded treadmill exercise tests consisting of two 5-minute steady state stages (Moderate and Vigorous intensity) were performed using the PhysioFlow device at least 48 hours apart. Cardiac hemodynamic measurements were compared between stages and trials using repeated measures ANOVA, intraclass correlations, and Bland-Altman plots.
Results Oxygen consumption (VO2) and respiratory exchange ratio (RER), were not different between the two trials for either Moderate or Vigorous intensities. There was a main effect for intensity for all variables with the exception early diastolic filling ratio (EDFR) and ejection fraction (EF%). Intraclass correlation coefficients between exercise trials were > 0.7 for all hemodynamic variables except for ventricular ejection time (VET) (Moderate and Vigorous Intensity stages), and EDFR (Moderate Intensity Stage). Coefficient of Variation between exercise trials were0.05) for all hemodynamic measures except heart rate (HR) (P = 0.018 and 0.019 for Moderate Intensity Stage and Vigorous Intensity Stage, respectively), left cardiac work index (LCWi) (Vigorous Intensity Stage, P = 0.000), and systemic vascular resistance index (SVRi) (Vigorous Intensity Stage, P = 0.000).
Conclusion Measurements from the PhysioFlow was repeatable, with no statistical differences across trials and reasonably strong reliability coefficients for most relevant hemodynamic variables, apart from VET and Low Intensity Stage EDFR, during moderate and vigorous intensity treadmill exercise.
Keywords: PhysioFlow, Impedance Cardiography, hemodynamic variables, cardiac output, stroke volume, non-invasive
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