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Technical Brief

Time Course Response of the Heart and Circulatory System to Active Postural Changes

[+] Author and Article Information
Jo P Pauls

School of Medicine, The University of Queensland, Australia; Innovative Cardiovascular Engineering and Technology Laboratory, Critical Care Research Group, The Prince Charles Hospital, Australia; School of Engineering, Griffith University, Australia
j.pauls@uq.edu.au

Llion Roberts

School of Allied Health Sciences, Griffith University, Australia; Menzies Health Institute Queensland, Griffith University, Australia
l.roberts2@uq.edu.au

Tom Burgess

Innovative Cardiovascular Engineering and Technology Laboratory, Critical Care Research Group, The Prince Charles Hospital, Australia
tomburgess07@gmail.com

John / F. Fraser

School of Medicine, The University of Queensland, Australia; Innovative Cardiovascular Engineering and Technology Laboratory, Critical Care Research Group, The Prince Charles Hospital, Australia
john.fraser@health.qld.gov.au

Shaun / D. Gregory

School of Medicine, The University of Queensland, Australia; Innovative Cardiovascular Engineering and Technology Laboratory, Critical Care Research Group, The Prince Charles Hospital, Australia; School of Engineering, Griffith University, Australia
shaun.gregory1@gmail.com

Geoff Tansley

Innovative Cardiovascular Engineering and Technology Laboratory, Critical Care Research Group, The Prince Charles Hospital, Australia; School of Engineering, Griffith University, Australia
g.tansley@griffith.edu.au

1Corresponding author.

ASME doi:10.1115/1.4038429 History: Received April 03, 2017; Revised October 26, 2017

Abstract

Rotary blood pumps (RBPs) used for mechanical circulatory support of heart failure patients cannot passively change pump flow sufficiently in response to frequent variations in preload induced by active postural changes. A physiological control system that mimics the response of the healthy heart is needed to adjust pump flow according to patient demand. Thus, baseline data is required on how the healthy heart (i.e. heart rate (HR) and cardiac output (CO)) and circulatory system (i.e. systemic vascular resistance (SVR)) respond. This study investigated the response times of the healthy heart during active postural changes (supine-standing-supine) in 50 healthy subjects (27 male / 23 female). Early response times (te) and settling times (ts) were calculated for HR, CO and SVR from data continuously collected with impedance cardiography. The initial circulatory response of HR, CO and SVR resulted in te of 8.8 - 11.7 s when standing up and te of 4.7 - 5.8 s when lying back down. HR, CO and SVR settled in ts of 50.0 - 56.7 s and 46.3 - 66.5 s when standing up and lying down respectively. In conclusion, when compared to active stand up HR, CO and SVR responded significant faster initially when subjects were lying down (p<0.05); there were no significant differences in response times between male and female subjects. This data will be used during evaluation of physiological control systems for RBPs which may improve patient outcomes for end-stage heart failure patients.

Copyright (c) 2017 by ASME
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