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Ventricular assist by cardiac cycle-specific increases in intrathoracic pressure

Pinsky, MR and Marquez, J and Martin, D and Klain, M (1987) Ventricular assist by cardiac cycle-specific increases in intrathoracic pressure. Chest, 91 (5). 709 - 715. ISSN 0012-3692

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Abstract

Changes in intrathoracic pressure can influence cardiac performance by altering ventricular loading conditions. Since ventricular loading, both from systemic venous return (preload) and from left ventricular wall stress (afterload), varies during the cardiac cycle, we reasoned that appropriately placed, phasic, cardiac cycle-specific (synchronous) increases in intrathoracic pressure might augment ventricular ejection in acute ventricular failure. Recent studies in animals suggest that synchronous increases in intrathoracic pressure during systole increase ejection. We compared the hemodynamic effect of synchronous increases in intrathoracic pressure with similar increases delivered at random in the cardiac cycle in patients with congestive cardiomyopathy (n = 9). Intrathoracic pressure was estimated by measuring esophageal pressure. High-frequency jet ventilation (HFJV) synchronized with the electrocardiogram (synchronous HFJV) was compared with HFJV at a fixed frequency within 15 percent of the heart rate (asynchronous HFJV) and with intermittent positive-pressure breathing (IPPB) (tidal volume = 10 ml/kg; f = 15). All forms of ventilation resulted in the same mean airway pressure and esophageal pressure. Mean pulmonary arterial occlusion pressure and arterial pressure were constant in all conditions. Cardiac output was greater with synchronous HFJV than with either IPPB or asynchronous HFJV (4.5 ± 0.7 L/min compared with 3.5 ± 0.7 and 3.4 ± 0.6 L/min [mean ± SE], respectively; p < 0.05). Mixed venous oxygen saturation covaried with cardiac output (p < 0.05), such that calculated oxygen consumption remained constant for all conditions. We conclude that synchronous HFJV augments cardiac output more efficiently than do similar increases in intrathoracic pressure delivered randomly in the cardiac cycle.


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Details

Item Type: Article
Status: Published
Creators/Authors:
CreatorsEmailPitt UsernameORCID
Pinsky, MRpinsky@pitt.eduPINSKY
Marquez, J
Martin, D
Klain, M
Date: 1 January 1987
Date Type: Publication
Journal or Publication Title: Chest
Volume: 91
Number: 5
Page Range: 709 - 715
DOI or Unique Handle: 10.1378/chest.91.5.709
Schools and Programs: School of Medicine > Critical Care Medicine
Refereed: Yes
ISSN: 0012-3692
Date Deposited: 24 Feb 2012 16:09
Last Modified: 04 Feb 2019 15:56
URI: http://d-scholarship.pitt.edu/id/eprint/11023

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