Coagulation dynamics after hemodilution with polyhemoglobin.

The effect of polyhemoglobin solution (PHS), a candidate erythrocyte cell substitute, on blood coagulation, was investigated. Whole blood samples from six male Sprague-Dawley rats were diluted in vitro 3:1, 1:1 and 1:3 with normal saline solution, stroma-free hemoglobin (SFH) (7 grams of hemoglobin per deciliter), PHS (14 grams of hemoglobin per deciliter) or 5 percent bovine albumin (ALB) and tested with a thrombelastograph (TEG) for effects of hemodilution on coagulation. For in vivo tests, 24 rats were randomly divided into four groups of six each and 50 percent of the estimated blood volume was replaced with SFH, PHS, ALB or 6 percent hydroxyethyl starch. Blood samples collected before and after the hemodilution were tested with a TEG. The TEG parameters (r, k, Ma, and fi) were determined and analyzed statistically. At 50 percent in vitro or in vivo hemodilution, PHS did not cause significant alteration (p greater than 0.05) in initial coagulation mechanism, while SFH slightly, but significantly (p less than 0.05), accelerated coagulation. Tensile strength of formed clot (Ma) did decrease after hemodilution with PHS (p less than 0.05), but the effect was attributable to dilutional effect. At moderate hemodilution (50 percent), PHS does not seem to cause undue coagulopathy in this rat model.