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System identification of closed-loop cardiovascular control: effects of posture and autonomic blockadeWe applied system identification to the analysis of fluctuations in heart rate (HR), arterial blood pressure (ABP), and instantaneous lung volume (ILV) to characterize quantitatively the physiological mechanisms responsible for the couplings between these variables. We characterized two autonomically mediated coupling mechanisms [the heart rate baroreflex (HR baroreflex) and respiratory sinus arrhythmia (ILV-HR)] and two mechanically mediated coupling mechanisms [the blood pressure wavelet generated with each cardiac contraction (circulatory mechanics) and the direct mechanical effects of respiration on blood pressure (ILV-->ABP)]. We evaluated the method in humans studied in the supine and standing postures under control conditions and under conditions of beta-sympathetic and parasympathetic pharmacological blockades. Combined beta-sympathetic and parasympathetic blockade abolished the autonomically mediated couplings while preserving the mechanically mediated coupling. Selective autonomic blockade and postural changes also altered the couplings in a manner consistent with known physiological mechanisms. System identification is an "inverse-modeling" technique that provides a means for creating a closed-loop model of cardiovascular regulation for an individual subject without altering the underlying physiological control mechanisms.
Document ID
20040173067
Acquisition Source
Legacy CDMS
Document Type
Reprint (Version printed in journal)
Authors
Mullen, T. J.
(Harvard-Massachusetts Institute of Technology, Massachusetts Institute of Technology Division of Health Sciences and Technology, Cambridge 02139, United States)
Appel, M. L.
Mukkamala, R.
Mathias, J. M.
Cohen, R. J.
Date Acquired
August 22, 2013
Publication Date
January 1, 1997
Publication Information
Publication: The American journal of physiology
Volume: 272
Issue: 1 Pt 2
ISSN: 0002-9513
Subject Category
Aerospace Medicine
Funding Number(s)
CONTRACT_GRANT: 5 RO1-HL-39291
Distribution Limits
Public
Copyright
Other
Keywords
NASA Discipline Number 18-10
NASA Program Space Physiology and Countermeasures
NASA Discipline Regulatory Physiology
Non-NASA Center

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