Reliability of Pulse Waveform Separation Analysis Responses to an Orthostatic Challenge

Abstract

PURPOSE: Cardiovascular autonomic nervous system function can be assessed by recording arterial wave reflection responses to an orthostatic challenge. Using pulse wave analysis, arterial wave reflection can be estimated using pulse wave separation analysis, whereby a triangular or a physiologic flow waveform is assumed and the aortic wave is separated into its forward and timing-independent reflected (Pb) components. This study sought to determine the measurement precision (between-day reliability) of Pb responses to an modified tilt-table test. METHODS: Twenty healthy adults (26.4 y (SD 5.2), 55% F, 24.7 kg/m2 (SD 3.8)) were tested on three different mornings in the fasted state, separated by a maximum of seven days. Oscillometric pressure waveforms were recorded on the left upper arm, and aortic waveforms were generated using a generalized transfer function. The criterion for acceptable reliability was an intra-class correlation coefficient (ICC) of 0.75. To express the percentage change that must occur at a group and individual level, the standard error of measurement (%SEM) and smallest detectable change (%SDC) were calculated. RESULTS: The criterion ICC (0.75) was exceeded at baseline (0.79), following 5 min tilt (0.75), and following 5 min recovery from tilt (0.75). The %SEM and %SDC for the 5 min tilt response were 7% and 19%, respectively. CONCLUSION: Arterial wave reflection responses to an orthostatic challenge can be assessed with acceptable between-day reliability using oscillometric pulse wave analysis.