Myocardial oxygen extraction ratio is decreased during endotoxemia
in pigs.
Herbertson, Michael J., Heinrich A. Werner, James A. Russell, Karsten
Iversen, Keith R. Walley.
Pulmonary Research Laboratory, St. Paul's Hospital, University of
British Columbia, Vancouver, B.C., Canada
APStracts 2:0194A, 1995.
During human sepsis the whole body oxygen extraction ratio is often
decreased, reflected by an increase in mixed venous oxygen saturation
(1). This has been interpreted as reflecting a defect in tissue
oxygen extraction (12) and has been demonstrated at the whole body
level in models of sepsis (29), and in specific organs (23).
Defective tissue oxygen extraction capacity has been suggested to
lead to tissue hypoxia and organ dysfunction in sepsis (10). The
heart, like the whole body, has a decreased oxygen extraction ratio
(ERm) during human sepsis (9,11). This is of importance since a
decreased ERm may lead to myocardial tissue hypoxia and a consequent
decline in cardiac function (25). However, the time course, severity,
and consequences of any decline in ERm during sepsis and the
potential causes of this decline have not been investigated to our
knowledge. Therefore we asked the following questions. Does a decline
in ERm (ERm = myocardial oxygen consumption divided by myocardial
oxygen delivery) occur in an endotoxemic model of hyperdynamic sepsis
in pigs? If so, is myocardial oxygen consumption decreased, and
associated with myocardial tissue hypoxia? Alternatively, is
myocardial oxygen delivery increased by an increase in global
myocardial blood flow? Finally, could mismatch between myocardial
oxygen delivery and myocardial oxygen consumption account for
decreased ERm? We investigated these questions in a porcine
endotoxemic model of sepsis measuring the change in ERm over time
after the onset of endotoxemia.
Received 28 October 1994; accepted in final form 22 March 1995.
APS Manuscript Number A1098-4.
Article publication pending Journal of Applied Physiology.
ISSN 1080-4757 Copyright 1995 The American Physiological Society.
Published in APStracts on 9 May 1995.