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Hemodynamic effects of cardiac cycle-specific increases in intrathoracic pressure

Pinsky, MR and Matuschak, GM and Bernardi, L and Klain, M (1985) Hemodynamic effects of cardiac cycle-specific increases in intrathoracic pressure. Journal of Applied Physiology, 60 (2). 604 - 612. ISSN 8750-7587

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Abstract

Changes in intrathoracic pressure (ITP) can influence cardiac performance by affecting ventricular loading conditions. Because both systemic venous return and factors determining left ventricular (LV) ejection may vary over the cardiac cycle, phasic increases in ITP may differentially affect preload or afterload if delivered at specific points within the cardiac cycle. We studied the hemodynamic effects of cardiac cycle-specific increases in ITP (pulses) delivered by a high-frequency jet ventilator in an acute closed-chested canine model (n = 11), using electromagnetic flow probes to measure biventricular stroke volume. Measurements were taken during a control condition and after the induction of acute ventricular failure (AVF) by propranolol hydrochloride and volume infusion. ITP was independently varied without changing lung volume by the inflation of thoracoabdominal binders. Although synchronous pulses had minimal hemodynamic effects in unbound controls, binding pulses timed to occur in early diastole resulted in decreases in LV filling pressure and left ventricular stroke volume (SV(lv)) (P < 0.05). In the AVF condition, pulses increased LV performance, evidenced by increases in SV(lv) (P < 0.01), despite decreases in LV filling pressure (P < 0.05). This effect is maximized by binding and by timing the pulses to occur in systole. We conclude that cardiac cycle-specific increases in ITP can significantly affect cardiac performance. These effects appear to be related to the ability of such timed pulses to selectively affect LV preload and afterload.


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Details

Item Type: Article
Status: Published
Creators/Authors:
CreatorsEmailPitt UsernameORCID
Pinsky, MRpinsky@pitt.eduPINSKY
Matuschak, GM
Bernardi, L
Klain, M
Date: 1 December 1985
Date Type: Publication
Journal or Publication Title: Journal of Applied Physiology
Volume: 60
Number: 2
Page Range: 604 - 612
Schools and Programs: School of Medicine > Critical Care Medicine
Refereed: Yes
ISSN: 8750-7587
Date Deposited: 24 Feb 2012 16:04
Last Modified: 04 Feb 2019 15:56
URI: http://d-scholarship.pitt.edu/id/eprint/11018

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