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Determinants of cardiac augmentation by elevations in intrathoracic pressure

Pinsky, MR and Matuschak, GM and Klain, M (1985) Determinants of cardiac augmentation by elevations in intrathoracic pressure. Journal of Applied Physiology, 58 (4). 1189 - 1198. ISSN 8750-7587

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We studied the cardiovascular effects of phasic increases in intrathoracic pressure (ITP) by high-frequency jet ventilation in an acute pentobarbital-anesthetized intact canine model both before and after the induction of acute ventricular failure by large doses of propranolol. Chest and abdominal pneumatic binders were used to further increase ITP. Respiratory frequency, percent inspiratory time, mean ITP, and swings in ITP throughout the respiratory cycle were independently varied at a constant-circulating blood volume. We found that perturbations in mean ITP induced by ventilator adjustments accounted for all observable steady-state hemodynamic changes independent of respiratory frequency, inspiratory time, or phasic respiratory swings in ITP. Changes in ITP were associated with reciprocal changes in both intrathoracic vascular pressures (P < 0.01) and blood volumes (P < 0.01). When cardiac function was normal, left ventricular (LV) stroke volume decreased, whereas in acute ventricular failure, LV stroke volume increased in response to increasing ITP when apneic LV filling pressure was high (≥17 Torr) and did not change if apneic LV filling pressure was low (≤12 Torr). However, in all animals in acute ventricular failure, LV stroke work increased with increasing ITP. Our study demonstrates that the improved cardiac function seen with increasing ITP in acute ventricular failure is dependent upon adequate LV filling and decreased LV afterload in a manner analogous to that seen with arterial vasodilator therapy in heart failure.


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Item Type: Article
Status: Published
CreatorsEmailPitt UsernameORCID
Pinsky, MRpinsky@pitt.eduPINSKY0000-0001-6166-700X
Matuschak, GM
Klain, M
Date: 1 January 1985
Date Type: Publication
Journal or Publication Title: Journal of Applied Physiology
Volume: 58
Number: 4
Page Range: 1189 - 1198
DOI or Unique Handle: 10.1152/jappl.1985.58.4.1189
Schools and Programs: School of Medicine > Critical Care Medicine
Refereed: Yes
ISSN: 8750-7587
Date Deposited: 24 Feb 2012 15:52
Last Modified: 03 Aug 2020 13:55


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