The effect of age on severity of murine burns.

There is a higher mortality in elderly subjects with burns. Whether the same amount of heat will cause a greater degree of thermal injury in elderly subjects and thus account, in part at least, for this increased mortality has not been determined and was, therefore, the purpose of this study. Swiss white mice, 1-year-old (elderly) and 3-months-old (young) were anesthetized with pentobarbital sodium and burned uniformly on a depilated area of the back with a steel disc at 100 F for 10 seconds (10% body burn). Burn severity was evaluated in a blinded manner by gross and microscopic criteria at 1, 2, and 4 days postburn. The mean burn severity 1 day postburn was significantly less in the elderly mice compared with the young mice (1.72 versus 3.22, (P less than 0.001). On the 2nd and 4th days postburn, no differences were noted in the degree of burn severity between the two groups. The early apparent diminished burn severity in the elderly mice was unexpected. Possible mechanisms to account for this difference in the old animals may relate to decreased cutaneous microcirculation, alteration in chemical composition of the skin, and the effects of thromboxane A2 and prostaglandin I2. The clinical relevance of these findings concerns the need for more careful clinical management with intentional overassessment of the initial degree of the thermal damage.