Effect of liposome-encapsulated hemoglobin on the development of endotoxin-induced shock in the rat.

Liposome-encapsulated hemoglobin (LEH) is an experimental oxygen-carrying resuscitation fluid. Because LEH is cleared from the circulation primarily by the reticuloendothelial system, its effect on the development of sepsis remains a major concern. Thus, the present study aimed to evaluate whether LEH modifies consequences of endotoxemia in the conscious normovolemic rat. LEH infusion at 10% of estimated blood volume (n = 10) did not affect mortality (30%, p < .05) and serum tumor necrosis factor-alpha levels (6204 +/- 414, p < .05) induced by 3.6 mg/kg Escherichia coli endotoxin administered (intravenous bolus) 22 h later. In contrast, when a shorter LEH-endotoxin time interval (<12 h, n = 10) or a higher dose of endotoxin (14.4 mg/kg, n = 20) was tested, LEH enhanced endotoxin-induced mortality (90% and 100%, respectively, p < .05) and broadened serum tumor necrosis factor-alpha response without modifying its peak levels. LEH (n = 20) did not exacerbate the endotoxin-induced tachycardia, leukopenia, and thrombocytopenia. Therefore, in this model, the effect of LEH on endotoxin-induced responses was dependent on the time interval between LEH and endotoxin administration as well as the endotoxin dose. The clinical relevance of these results should be further investigated.