AJP - Regulatory, Integrative and Comparative Physiology, Vol 248, Issue 2 208-R213, Copyright © 1985 by American Physiological Society
Cardiovascular responses to elevation of intra-abdominal hydrostatic pressure
G. E. Barnes, G. A. Laine, P. Y. Giam, E. E. Smith and H. J. Granger
Intra-abdominal fluid volume and hydrostatic pressure were elevated by
positive pressure infusion of Tyrode solution into the peritoneal cavity of
anesthetized dogs. The compliance of the peritoneal cavity fell from 10.8
to 0.56 ml X mmHg-1 X kg-1 of body wt as intra-abdominal pressure increased
from 0 to 40 mmHg. Intrathoracic pressure also increased as elevated
peritoneal pressure caused diaphragmatic bulging. Cardiac output and stroke
volume were reduced by 36% after an intra-abdominal pressure rise of 40
mmHg; in contrast, heart rate did not change. Flow in the celiac, superior
mesenteric, and renal arteries was reduced by 42, 61, and 70%,
respectively. Pressure in the femoral vein increased to 46 mmHg, while flow
in the femoral artery decreased by 65%. Whole-body O2 consumption, pH, and
arterial PO2 decreased as intra-abdominal pressure rose. The peritoneal
cavity, with its high initial compliance, affords the body an ideal
location for the temporary accumulation of small to moderate volumes of
fluid during episodes of increased vascular pressure or permeability. The
marked alterations in the hemodynamic properties of the cardiovascular
system are indicative of the physiological changes that occur when
intra-abdominal fluid accumulation becomes excessive and peritoneal
pressure rises to high levels.
