The Journal of Thoracic and Cardiovascular Surgery, Vol 81, 155-162, Copyright © 1981 by The American Association for Thoracic Surgery and The Western Thoracic Surgical Association
Extending the limits of hemodilution on cardiopulmonary bypass using stroma-free hemoglobin solution
WY Moores, F De Venuto, WH Heydorn, RB Weiskopf, M Baysinger, AG Greenburg and JR Utley
Ten swine were subjected to exchange transfusion to a hematocrit level of
5% with either stroma-free hemoglobin solution (SFHS) or 7% albumin
solution. Myocardial performance, oxygen kinetics, and myocardial
metabolism were subsequently examined using a perfused, in situ, right
heart bypass, swine heart model with control of preload, afterload, and
heart rate. Animals were tested during a control period (hematocrit = 30%)
and following exchange transfusion with either solution to a hematocrit
level of 5%. We found that myocardial performance following albumin
solution exchange could not be sustained on right heart bypass, and these
animals had a stroke volume of zero at a left ventricular end- diastolic
pressure of 14 torr. SFHS animals had a significant drop in stroke volume
at 14 torr following exchange (20 +/- 3 versus 10 +/- 4, p < 0.025), but
this 50% performance level could be sustained. Coronary blood flow rose and
myocardial oxygen consumption fell in both groups, although the
statistically nonsignificant mean differences were less with SFHS.
Arterial-coronary sinus oxygen difference fell significantly (p < 0.05)
with albumin solution (7.3 +/- 0.8 versus 2.2 +/- 0.2) and nonsignificantly
with SFHS (5.6 +/- 0.4 versus 4.1 +/- 0.7). Lactate production occurred in
both groups, but was greater with albumin (34% +/- 6%) than with SFHS (3%
+/- 16%). No changes in myocardial tissue gasses were noted in either
group. Although myocardial performance decreased and some lactate
production occurred with SFHS, we believe these comparative results provide
promise in the eventual utilization of an oxygen-carrying agent such as
SFHS to extend the limits of hemodilution to a hematocrit value of 5% or
less.