Liver function and morphology after resuscitation from severe hemorrhagic shock with hemoglobin solutions or autologous blood

Abstract

To test the effects of three hemoglobin solutions on liver function and hepatic morphology after resuscitation from severe hemorrhagic shock. Prospective study. Laboratory. Thirty-three beagle dogs. Hemorrhagic shock was induced in anesthetized dogs by removal of blood at a rate of 2 mL/kg/min until systolic blood pressure (BP) reached 50 mm Hg. BP was maintained at this level 2 hrs by further withdrawing 5 to 10 mL aliquots whenever BP increased > 50 mm Hg. Resuscitation was then initiated with autologous whole blood (n = 7), 4% pyridoxalated-hemoglobin-polyoxyethylene conjugate (4% PHP [n = 6]), 8% pyridoxalated-hemoglobin-polyoxyethylene conjugate (8% PHP [n = 9], or 8% stroma-free hemoglobin (n = 7). Four dogs were managed identically but were not resuscitated. Gross necropsy and histologic examination of the liver were performed on all dogs after 7 days, or earlier if death occurred. In vitro interferences of PHP and stroma-free hemoglobin with liver function tests were determined and recommendations for interpretation of results from blood samples containing PHP and stroma-free hemoglobin were made. Blood was collected before, during, and after resuscitation from hemorrhagic shock. The dogs were then awakened and survivors were monitored daily with blood sampling until they were killed and necropsy was performed. After 7 days, the survival rate following hemorrhagic shock was 100% for whole blood and 4% PHP, 86% for stroma-free hemoglobin, and 33% for 8% PHP. Of the resuscitated dogs not surviving 7 days, all but one died within 27 hrs from coagulopathy. All dogs not resuscitated died within 1.75 hrs after 2 hrs of shock. Bilirubin, alkaline phosphatase, and lactic dehydrogenase concentrations could not be measured due to interferences of stroma-free hemoglobin and PHP. Aspartate (AST) and alanine (ALT) aminotransferase concentrations could be measured after dilution to overcome the interferences. Significant increases in AST and ALT values in all groups 24 hrs after resuscitation were attributed to hypoxic hepatocellular damage associated with the severity of the shock model rather than to the resuscitation fluid. Liver histology showed no changes attributed to toxic damage of hepatocytes in dogs resuscitated with stroma-free hemoglobin or PHP. However, changes, were less severe in dogs resuscitated with 4% PHP than in other groups. Morphologic studies at necropsy and liver function tests in dogs receiving hemoglobin solutions, compared with autologous blood, support the conclusion that the PHP and stroma-free hemoglobin solutions tested did not produce hepatic toxicity when used as resuscitation fluids in this model of severe shock.