Effect of partial burn excision and closure on postburn oxygen consumption.

We studied the effect of partial excision and wound closure on the postburn hypermetabolic state. A 25% of total body surface burn was produced in seven sheep. Oxygen consumption (VO2) was significantly increased to 215 +/- 44 ml/min/M2 by day 3 compared with baseline of 125 +/- 21 ml/min/M2. The calculated increase was the result of the increased cardiac index as the average oxygen (AvO2) difference remained relatively constant. Body temperature was not significantly increased. Plasma and burn lymph thromboxane B2 were significantly increased. On day 7, 60% of the burn was completely excised to fascia and covered with a full-thickness graft from a donor animal. The VO2 decreased to below preburn levels during the period of anesthesia but returned completely to the preexcision hypermetabolic state by 2 hours after anesthesia and remained at this level for the remaining 2-day postexcision period. Quantitative cultures of burn hide at day 7 postburn and of the remaining 10% of total body surface burn at 2 days after excision revealed values less than 10(5) bacteria/gram eschar. No positive blood cultures were evident. We conclude that postburn hypermetabolism, once developed, may be perpetuated by a burn of lesser size. Partial excision, therefore, does not appear to significantly decrease the hypermetabolic state if a substantial inflammatory wound remains. Infection is not necessary to perpetuate the increased VO2.