Relationship between hepatic blood flow and tissue lipid peroxidation in the early postburn period.

Objectives: To determine the effect of a body burn on effective or nutrient liver blood flow and the relationship between blood flow and oxidant-induced lipid peroxidation.
Design: Anesthetized sheep were given a 40% of total body surface, third-degree burn, after which animals were fluid resuscitated to return ventricular filling pressures and cardiac output to baseline values. Animals, for the 6-hr study period, were resuscitated with lactated Ringer's solution alone or lactated Ringer's solution plus 1500 mL of 5% hydroxyethyl starch or lactated Ringer's solution plus hydroxyethyl starch on which was complexed the iron chelator deferoxamine to prevent oxidant release. Effective liver blood flow was measured using the galactose infusion technique. Liver tissue lipid peroxidation was monitored using malondialdehyde content.
Results: We found that effective liver blood flow was decreased by 50% in the 4- to 5-hr postburn period, even when animals were resuscitated to baseline cardiac output values with lactated Ringer's solution. Tissue malondialdehyde content increased in the group treated with lactated Ringer's solution from a control value of 110 +/- 7 to 202 +/- 59 nmol/g of tissue. Resuscitation with hydroxyethyl starch restored postburn effective liver blood flow to control values, but malondialdehyde content was still increased two-fold. Resuscitation with hydroxyethyl starch and deferoxamine resulted in an increase in effective liver blood flow postburn to a value 80% above controls. In addition, lipid peroxidation was prevented.
Conclusions: Effective liver blood flow is markedly decreased after burn injury, even with apparently adequate volume resuscitation, when using lactated Ringer's solution. Liver lipid peroxidation persists even when effective liver blood flow is maintained, indicating that the oxidant process is not solely related to blood flow. Infusion of the antioxidant deferoxamine during resuscitation not only prevents the lipid peroxidation, most likely by a nonblood-flow-related process, but also results in an increase in blood flow above normal rates, suggesting that postburn liver oxygen needs exceed normal values.