Heterogeneity of gut capillary transit times and impaired gut
oxygen extraction in endotoxemic pigs.
Humer, Michael F., P. Terry Phang, Byron P. Friesen, Michael F.
Allard, Christopher M. Goddard, Keith R. Walley.
Department of Surgery, Program of Critical Care Medicine, and the
Pulmonary Research Laboratory, St. Paul's Hospital, University of
British Columbia, Vancouver, B.C., CANADA V6Z 1Y6
APStracts 3:0148A, 1996.
We tested the hypothesis that endotoxin increases heterogeneity of gut
capillary transit times and impairs oxygen extraction. The gut
critical oxygen extraction ratio was determined by measuring multiple
oxygen delivery-consumption points during progressive phlebotomy in 8
control and 8 endotoxin-infused anesthetized pigs. In multiple 1-2 g
samples of small bowel we measured blood volume (radiolabelled
erythrocytes) and flow (radiolabelled 15 [mu]m microspheres) before
and after critical oxygen extraction. Erythrocyte transit time (=
volume/flow) multiplied by morphologically determined capillary/total
blood volume gave capillary transit time. During hemorrhage,
capillary/total blood volume did not change in the endotoxin group
(0.5 +/- 4.5%) but increased in controls (17.6 +/- 2.5%, p<0.05)
due to a decrease in total gut blood volume. Flow decreased
significantly in the endotoxin group (36 +/- 10%, p<0.05) but
not in controls (12 +/- 10%). Capillary transit time heterogeneity
increased in the endotoxin group (12.3 +/- 4.9%) compared to controls
(-5.8 +/- 7.4%, p<0.05) predicting a critical oxygen extraction
ratio 0.14 lower in the endotoxin group than in controls (J. Appl.
Physiol., submitted). This matches the measured difference (endotoxin
group 0.60 +/- 0.04; control group 0.74 +/- 0.03, p<0.05).
Increased heterogeneity of capillary transit times may be an
important cause of impaired oxygen extraction.
Received 6 October 1995; accepted in final form 4 March 1996.
APS Manuscript Number A1086-5.
Article publication pending Journal of Applied Physiology.
ISSN 1080-4757 Copyright 1996 The American Physiological Society.
Published in APStracts on 27 March 96