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.