System identification of dynamic closed-loop control of total peripheral resistance by arterial and cardiopulmonary baroreceptors

Prolonged exposure to microgravity it? space flight missions (days) impairs the mechanisms responsible for defense of arterial blood pressure (ABP) an d cardiac output (CO) against orthostatic stress in the post flight period. The mechanisms responsible for the observed orthostatic intolerance are no t yet completely understood. Additionally, effective counter measures to at tenuate this pathophysiological response are not available. The aim of this study was to investigate the ability of our proposed system identification method to predict closed-loop dynamic changes in TPR induced by changes in mean arterial pressure (MAP) and right atrial pressure (RAP). For this pur pose we designed and employed a novel experimental animal model for the exa mination of arterial and cardiopulmonary baroreceptors in the dynamic close d-loop control of total peripheral resistance (TPR), and applied system ide ntification to the analysis of beat-to-beat fluctuations in the measured si gnals. (C) 2001 Elsevier Science Ltd. All rights reserved.