Lack of immediate effects of wound excision on the hyperdynamic circulation of burned patients.

The high cardiac output (CO) observed during the chronic phase in burned patients has been ascribed, among other factors, to the elevated blood flow in the burn wound. The hemodynamic effects of wound excision to fascia have been studied in eight patients with second- and third-degree burns ranging from 42% to 70% total body surface area (TBSA) undergoing debridement and skin-grafting procedures. The study was performed on the 4th to the 51st postburn day when all patients were in a hyperdynamic state. Serial hemodynamic measurements, including arterial and mixed-venous blood O2 saturation and content, were made before induction of anesthesia, during surgery both before and after wound excision, and in the recovery room a few hours after surgery. During anesthesia, the elevated CO decreased probably as a consequence of decreased metabolic requirements, but no further hemodynamic change was observed following wound excision. The size of burn wound excised to fascia averaged 24% TBSA and ranged from one-third to more than one-half of the initial burn. With discontinuation of anesthesia, CO rose rapidly above preoperative values, apparently to meet a similar increase in oxygen consumption. The excision of large areas of burned tissue did not attenuate the hyperdynamic circulation in burned patients, at least during and immediately after surgery. The data suggest that the elevated blood flow in the burn wound does not play a significant role in the pathogenesis of the hyperdynamic state.