AJP - Heart and Circulatory Physiology, Vol 249, Issue 1 188-H192, Copyright © 1985 by American Physiological Society
A simple method for reducing cardiac output in the conscious lamb
J. T. Fahey and G. Lister
We have developed a method for reducing cardiac output in a controlled
stepwise fashion using awake, intact, unsedated lambs. The method involves
placing a balloon-tipped (Foley) catheter into the right atrium from a
jugular vein isolated by a small neck incision. Systemic venous return and
cardiac output are limited by balloon inflation. With each balloon
inflation the animal reaches a new and stable cardiac output, which allows
the measure of steady-state hemodynamic and metabolic variables. We have
been able to decrease cardiac output to as low as 20% of the resting
cardiac output and maintain a stable preparation. The reductions in cardiac
output are quickly reversible by balloon deflation. Animal survival allows
repeated study. We present data from five lambs studied between 26 and 36
days of age. Alterations in O2 consumption, O2 transport, O2 extraction,
blood pressure, and arterial lactate concentration are examined in response
to decrements in systemic blood flow and are consistent with changes seen
in response to a reduction of cardiac output by other methods.
