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Effects of positive end-expiratory pressure on hepatic blood flow and performance

Matuschak, GM and Pinsky, MR and Rogers, RM (1987) Effects of positive end-expiratory pressure on hepatic blood flow and performance. Journal of Applied Physiology, 62 (4). 1377 - 1383. ISSN 8750-7587

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Abstract

Positive end-expiratory pressure (PEEP) may impair extrapulmonary organ function. However, the effects of PEEP on the liver are unclear. We tested the hypothesis that at a constant cardiac output (CO), PEEP does not induce changes in hepatic blood flow (Q̇L) and parenchymal performance. In splenectomized, close-chested canine preparations (group I, n = 6), Q̇L was derived as hepatic outflow using electromagnetic flow probes (Q̇Lemf), and hepatic performance was defined by extraction and clearance of indocyanine green (ICG). In a noninvasive model (group II, n = 7), the effects of PEEP on hepatic performance alone were similarly analyzed. Measurements were taken 1) during intermittent positive-pressure ventilation (IPPV1), 2) after addition of 10 cmH2O PEEP to IPPV (PEEP1), 3) during continued PEEP but after return of CO to IPPV1 levels by intravascular volume infusions (PEEP2), and 4) after removal of both PEEP and excess blood volume (IPPV2). Phasic inspiratory decreases in Q̇Lemf present during positive-pressure ventilation were not increased during either PEEP1 or PEEP2. Mean Q̇Lemf decreased proportionately with CO during PEEP1 (P < 0.05), but was restored to IPPV1 levels in a parallel fashion with CO during PEEP2. The ICG pharmacokinetic responses to PEEP were complex, with differential effects on extraction and clearance. Despite this, hepatic performance was not impaired in either group. We conclude that global Q̇L reductions during PEEP are proportional to PEEP-induced decreases in CO and are preventable by returning CO to pre-PEEP levels by intravascular volume infusions. However, covarying changes in blood volume and hepatic outflow resistance may independently modulate hepatic function.


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Details

Item Type: Article
Status: Published
Creators/Authors:
CreatorsEmailPitt UsernameORCID
Matuschak, GM
Pinsky, MRpinsky@pitt.eduPINSKY
Rogers, RM
Date: 1 January 1987
Date Type: Publication
Journal or Publication Title: Journal of Applied Physiology
Volume: 62
Number: 4
Page Range: 1377 - 1383
Schools and Programs: School of Medicine > Critical Care Medicine
Refereed: Yes
ISSN: 8750-7587
MeSH Headings: Animals; Dogs; Electromagnetic Phenomena; Liver--physiology; Liver Circulation; Models, Biological; Positive-Pressure Respiration; Rheology
PubMed ID: 2954939
Date Deposited: 25 Aug 2012 17:21
Last Modified: 04 Feb 2019 15:56
URI: http://d-scholarship.pitt.edu/id/eprint/13646

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