Effects of adenosine on the pressure-flow relationships in an in
vitro model of compartment syndrome.
Shrier, ian, Ari Baratz, and sheldon Magder.
Herzl Family Practice Centre, Centre for Clinical Epidemiology and
Community Studies, and Lady Davis Institute, Sir Mortimer B. Davis
Jewish General Hospital, Montreal, Qc.; Critical Care Division, Royal
Victoria Hospital, Montreal, Qc.; and the Meakins-Christie
Laboratories, McGill University, Montreal, Qc.
APStracts 3:0545A, 1996.
Blood flow through skeletal muscle is best modeled with a vascular
waterfall at the arteriolar level. Under these conditions, flow is
determined by the difference between perfusion pressure (Pper) and
the waterfall pressure (Pcrit), divided by the arterial resistance
(Ra). We observed an interaction between the pressure surrounding a
muscle (as occurs in compartment syndrome) and baseline vascular tone
by pump-perfusing an isolated canine gastrocnemius muscle (n=6) after
it was placed within an airtight box, with and without adenosine
infusion. We titrated adenosine concentration to double baseline
flow. We measured Pcrit and Ra at box pressures (Pbox) which resulted
in 100% (Pbox=0), 90%, 75%, and 50% flow without adenosine, and 200%,
180%, 150%, 100%, and 50% flow with adenosine. Without adenosine,
each 10% decline in flow was associated with a 5.7 mmHg increase in
Pcrit (p<0.01). With adenosine, the same decrease in flow was
associated with a 2.6 mmHg increase in Pcrit (p<0.01). Values of
Pcrit at 50% of flow were almost identical. Each 10% decrease in flow
was also associated with 2.2% increase in Ra with or without
adenosine (p<0.001). Ra decreased with adenosine infusion (p<0.05),
and there was no interaction between adenosine and flow (p>0.9). We
conclude that increases in pressure surrounding a muscle limit flow
primarily through changes in Pcrit with and without adenosine-induced
vasodilation. The interaction between Pbox and adenosine with respect
to Pcrit, but not Ra, suggests that Pbox affects the tone of the
vessels responsible for Pcrit but not Ra.
Received 16 January 1996; accepted in final form 2 October 1996.
APS Manuscript Number A37-6.
Article publication pending Journal of Applied Physiology.
ISSN 1080-4757 Copyright 1996 The American Physiological Society.
Published in APStracts on 31 December 1996