AJP - Heart and Circulatory Physiology, Vol 257, Issue 1 238-H243, Copyright © 1989 by American Physiological Society
O2 uptake in bled dogs after resuscitation with hypertonic saline or hydroxyethylstarch
K. Reinhart, T. Rudolph, D. L. Bredle and S. M. Cain
Department of Physiology and Biophysics, University of Alabama, Birmingham 35294.
Hemodynamic and metabolic variables were measured for the whole body and
isolated hindlimb of anesthetized dogs during resuscitation from
hemorrhagic shock, using a small volume of hypertonic saline or a larger
volume of hydroxyethylstarch. Twelve dogs were bled and maintained at a
mean arterial pressure (MAP) of 40 mmHg for 30 min. Six dogs were then
infused with 7.5% NaCl in 5 ml/kg hydroxyethylstarch (HTS group), and six
received 6% hydroxyethylstarch alone (HES group) in an amount to
approximate the maximum MAP achieved with hypertonic saline. Hypertonic
saline replacement was approximately 16% of shed blood volume compared with
66% for hydroxyethylstarch. With hypertonic saline, cardiac output returned
to base line, but O2 delivery did not. Hydroxyethylstarch increased cardiac
output above base line, and O2 delivery was near base line. O2 uptake with
hydroxyethylstarch peaked at 40% above control at 10 min of resuscitation.
Excess O2 uptake in recovery was higher than O2 deficit in hemorrhage with
the HES group but not with the HTS group. In the isolated hindlimb,
vascular resistance decreased rapidly on hypertonic saline infusion but
reached similar levels at 10 min of resuscitation with both fluids. With
progressive lowering of blood flow to the pump-perfused hindlimb, ability
of limb muscle to extract O2 was the same for the HTS and HES groups. With
hemodilution by volume replacement with acellular fluid after hemorrhage, a
seemingly adequate cardiac output and arterial pressure may be
underresuscitation if O2 delivery does not meet the increased O2 demand.
