ARMY INST OF SURGICAL RESEARCH FORT SAM HOUSTON TX
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The stress of large thermal injuries initiates alterations of body homeostasis which are primarily catabolic in nature and which manifest as increased metabolic rate, erosion, of body mass, loss of nitrogen in the urine, and abnormalities of carbohydrate metabolism. Following severe injury, the initial metabolic and cardiovascular response presents as an ebb phase, in which blood flow is reduced and metabolic processes are decreased. With successful resuscitation, the ebb phase gives way to a flow phase, in which blood flow rises to supranormal levels and the patient becomes hypermetabolic. Wilmore and colleagues demonstrated that metabolic expenditure, as measured by indirect calorimetry, was proportional to size of injury until burn size covered approximately 50 of the total body surface, after which metabolic rate plateaued at levels of 100 or more above preinjury levels. The time of peak response occurred approximately 10-14 days following injury and then decreased in a gradual manner as the burn wound was covered and healing was completed. In a group of patients whose average burn size was 50 of the body surface, further studies indicated that their metabolic rates had approximately doubled and this increase was paralleled by a similar elevation in cardiac output and total body oxygen consumption.