Systemic lipid peroxidation and inflammation induced by thermal injury persists into the post-resuscitation period

We determined the time course of the oxidant-induced systemic lipid peroxidation seen after burn injury. Twelve sheep were given a 15% of total body surface third-degree burn and monitored for 3 or 5 days. Circulating lipid peroxides were monitored by both malondialdehyde (MDA) and conjugated dienes (CD). Lung and liver tissue MDA was also measured and compared to controls. A significant but transient increase in circulating MDA and CD was noted several hours after burn. Venous plasma levels increased again 3-5 days postburn with onset of wound inflammation. Oxygen consumption, VO2, also increased by 35 +/- 12% at this time. Lung MDA, which increased to 64 +/- 5 from a control of 45 +/- 4 nMol/gm, at 12 hours after burn was still increased 3 days after injury. Marked lung inflammation was present early after injury and persisted for the 5-day study period. Liver MDA also increased from control value of 110 +/- 20 to 252 +/- 25 at 12 hours and remained increased over the 5-day period. Serum alkaline phosphatase was also increased. Burn biopsies revealed no infection to explain the ongoing lipid peroxidation process, i.e., bacterial content was less than 10(5) organisms/gram burn tissue. We conclude that an initial system lipid peroxidation occurs immediately after burn injury, and that this process continues well into the post-resuscitation period, corresponding in time with increased VO2, lung inflammation, and evidence of liver dysfunction. The ongoing oxidant changes with the presence of a burn may explain the accentuated organ dysfunction seen with an additional septic insult in burned patients.