Limitations of the efficacy of hemoglobin-based oxygen carrying
solutions.
Lee, Raymond, Kazuo Neya, Tracy A. Svizzero, and Gus J. Vlahakes.
Department of Surgery (Cardiac Surgical Unit), Massachusetts
General Hospital and Harvard Medical School, Boston, MA
APStracts 2:0118A, 1995.
Improvements in hemoglobin-based oxygen carrying solutions (HBOCs)
have overcome the toxicities which plagued earlier efforts. However,
limitations of the efficacy of HBOCs are emerging. The potential
limitations of an HBOC were studied in an ovine model (n=6) of
exchange transfusion. Hemodynamic, oxygen transport, and hemoglobin
kinetic parameters were examined during isovolumic blood exchange to
a final hematocrit of 3.2 +/- 0.7% and a plasma hemoglobin
concentration of 8.1 +/- 0.4 g/dl while awake and breathing room air.
However, the infusion of HBOC was associated with immediate increases
in systemic and pulmonary artery pressures. Despite hemodilution with
HBOC, systemic and pulmonary vascular resistance increased 43.9%
(p<0.001) and 204.2% (p<0.001), respectively, following HBOC
infusion. Following blood exchange, the plasma hemoglobin level
exhibited a circulatory half-life of 52.7 +/- 18.0 hours. The
formation of methemoglobin was significant, accounting for 33.0 +/-
7.1% of the total circulating plasma hemoglobin at 24 hours; the
half-life of HBOC capable of carrying oxygen was 30.1 +/- 5.4 hours.
This relatively short period of oxygen-carrying efficacy and the
observed vasoconstriction properties may constrain the potential
applications of HBOC solutions.
Received 28 March 1994; accepted in final form 10 March 1995.
APS Manuscript Number A289-4.
Article publication pending Journal of Applied Physiology.
ISSN 1080-4757 Copyright 1995 The American Physiological Society.
Published in APStracts on 28 March 1995.