Circulatory sequelae of administering cpap in hyperdynamic sepsis
are time-dependent.
Fox, George A., Calvin J. Lam, William B. Darragh, Andrea M. Neal,
Kevin J. Inman, Frank S. Rutledge, William J. Sibbald.
The A.C. Burton Vascular Biology Laboratory, Victoria Hospital
Research Institute and The Program in Critical Care, Departments of
Medicine and Surgery, The University of Western Ontario, London,
Canada
APStracts 3:0137A, 1996.
Evidence questions the circulation's ability to acutely compensate for
abrupt changes in O2 delivery (QO2). As both sepsis and continuous
positive airway pressure (CPAP) may alter the metabolic regulation of
tissue oxygenation, we designed an experiment to determine the
interaction, if any, between sepsis and time on circulatory
homeostasis following the application of CPAP. Twenty-four sheep were
randomized to cecal ligation and perforation (CLP) or SHAM procedure
(SHAM), and then re-randomized to receive either CPAP (10 mmHg) or NO
CPAP (CLP/CPAP, n=8; CLP/NO CPAP, n=8; SHAM/CPAP, n=4; SHAM/NO CPAP,
n=4). Forty-eight hours later, CLP animals demonstrated an elevated
cardiac index (+63%), systemic O2 delivery (+49%) and systemic O2
uptake (+28%). Organ blood flow (Q), measured with radiolabelled
microspheres, was augmented to the heart and depressed in organs
comprising the splanchnic circulation. Compared to the CLP/NO CPAP
group and both SHAM groups, myocardial QO2 in the CLP/CPAP group was
significantly elevated when measured both 2 and 8 hours following
CPAP. These changes were unrelated to differences in mean heart work
between the study groups. Simultaneously, QO2 to all of the small
gut, large gut, pancreas, and kidney in the CLP/CPAP group was
elevated during the 2 hour study, yet reverted to levels not
different from baseline by the 8 hour study. These data demonstrate
(i) a unique sepsis x time interaction with the use of 10 mmHg of
CPAP, particularly in the "non-vital" circulations, and (ii)
CPAP effects on the septic coronary circulation which were
unexplained by changes in external determinants of myocardial O2
need.
Received 2 December 1994; accepted in final form 9 February 1996.
APS Manuscript Number A1226-4.
Article publication pending Journal of Applied Physiology.
ISSN 1080-4757 Copyright 1996 The American Physiological Society.
Published in APStracts on 20 March 96