Effect of thermal injury on energy metabolism, substrate kinetics, and hormonal concentrations

We have used a chronic dog model to study the kinetic aspects of the metabolic response to thermal injury. In order to interpret the kinetic data in the context of the overall response to injury, we also determined certain cardiovascular parameters as well as selected hormonal concentrations. We used a paired study design: each animal was studied twice before injury and then at 5 and 7 days following injury. The burn was induced while the animals were deeply anesthetized with sodium pentobarbital (30-35 mg/kg) but all studies were done in awake, unrestrained dogs using tracer methodology and both radiolabeled and stable isotopes. The burn induced a hyperdynamic state, with significant elevations in cardiac output, heart rate, and metabolic rate. The free fatty acid (FFA), glycerol and glucose flux rates were all elevated, as was the rate of production of urea. The increase in resting metabolic rate was due to comparable increases in the rates of oxidation of carbohydrate, fat, and protein. We found the responses of this canine burn model to closely resemble the human response to injury, and thus this model will be useful as a tool to elucidate some of the mechanisms responsible for the response to injury.