Heterogeneity of oxygen delivery impairs oxygen extraction by
peripheral tissues : theory.
Walley, Keith R.
Pulmonary Research Laboratory, St. Paul's Hospital, University of
British Columbia, Vancouver, B.C., CANADA, V6Z 1Y6
APStracts 3:0153A, 1996.
The hypothesis that the distribution oxygen demand in relation to
oxygen supply (dO2/qO2) effects oxygen extraction in peripheral
tissues was tested. Using a simple theoretical model, realistic
biphasic oxygen consumption-delivery relationships were predicted
from dO2/qO2 distributions. Increasing width (relative dispersion) of
the dO2/qO2 distribution, indicating mismatch between oxygen demand
and supply, non-linearly decreased the critical oxygen extraction
ratio (calculated using dual-line regression). Skewed dO2/qO2
distributions had a lesser effect. Incomplete oxygen uptake, due to
diffusion limitation or other causes of physiologic arterio-venous
shunt, linearly decreased the critical oxygen extraction ratio.
Approximate dO2/qO2 distributions were then estimated from previously
reported capillary transit time distributions. Critical oxygen
extraction ratios predicted from these estimated dO2/qO2
distributions match reported values. This theoretical approach also
predicts the decrease in critical oxygen extraction ratio by porcine
gut following endotoxin infusion in the accompanying article (J.
Appl. Physiol. submitted). Much as pulmonary V/Q relationships
account for pulmonary gas exchange, dO2/qO2 distributions
quantitatively account for measured tissue oxygen extraction and
predict novel features of the relationship between heterogeneity and
oxygen extraction.
Received 6 October 1995; accepted in final form 4 March 1996.
APS Manuscript Number A1085-5.
Article publication pending Journal of Applied Physiology.
ISSN 1080-4757 Copyright 1996 The American Physiological Society.
Published in APStracts on 27 March 96