Body fluid compartment changes during burn shock in the guinea pig.

The alterations in body fluid compartments 1, 4, and 8 hours after a 70% full-skin thickness burn were studied in conscious guinea pigs. Concurrently, we measured hemodynamic changes associated with the burn. Cardiac output and heart rate were depressed one hour postburn, and mean arterial blood pressure was depressed eight hours postburn. A hemoconcentration one-hour postburn, as evidence by an increase in hematocrit, was due exclusively to a loss of plasma volume. Red blood cell (RBC) volume remained constant after the burn. As a consequence of decreased plasma volume, total blood volume was also depressed. Extracellular fluid was decreased on hour after the burn; how ever, four and eight hours postburn, extracellular fluid space was comparable to that in the control group. Total body water and body weights of burned animals did not differ from control values. This study has demonstrated the very rapid redistribution of fluids in burn shock without a loss of fluids from the body.