Effect of oxygen affinity on systemic perfusion and brain tissue oxygen tension after extreme hemodilution with hemoglobin-starch conjugates in rats.

Abstract

To determine the oxygen affinity for optimal tissue oxygen delivery with a hemoglobin-hydroxyethyl starch conjugate (HRC 101). Anesthetized rats were hemodiluted (180 ml kg(-1)) with low (P(50) approximately 70 mmHg) or high affinity (P(50) approximately 14 mmHg) HRC 101 at hemoglobin (Hb) concentrations near 100 or 70 g l(-1) (n = 6-8). Hippocampal tissue oxygen tension (P(Br)O(2)), blood flow, arterial blood gases, Hb, hematocrit (Hct) and lactate were measured. Data (mean +/- SD) were analyzed by two-way ANOVA. Hemodilution reduced the hematocrit to 1 +/- 1% in all groups. P(Br)O(2) was best maintained after hemodilution with low affinity HRC 101 at Hb 100 and 70 g l(-1) (25.2 +/- 7.6 and 16.6 +/- 8.3 torr, respectively). P(Br)O(2) decreased (9.5 +/- 9.3 torr, P < 0.05) and serum lactate levels increased (5.0 +/- 1.7 mmol l(-1), P < 0.05) following hemodilution with the high affinity HRC 101 (Hb 100 g l(-1)). HRC 101 with a lower oxygen affinity favored tissue perfusion and maintained P(Br)O(2) after near complete blood volume exchange in rats.