Studies on the mechanism of shock. The impariment of thermoregulation by trauma.

The effect of changes in environmental temperature (10-33°) on the rate of O consumption of rats injured by hind-limb ischaemia or scalding has been investigated during the first few hours after injury. In the thermoneutral zone O consumption was not inhibited by trauma unless the injury proved fatal and even then O consumption was maintained at the normal rate until just before death. The critical temperature was lowered by trauma. The depression of this point increased with the severity of the injury. Within this new extended thermoneutral range the O consumption by the injured rats fell to the basal rate of the controls and remained there, only declining further in the terminal stages. At environmental temperatures below the new critical temperature trauma inhibited O consumption but a direct correlation with the environmental temperature was retained. The regression line for O consumption on environmental temperature was moved to the left without altering the slope, the separation from the controls depending on the severity of the injury. Trauma impaired thermoregulation in the rat but it was not possible to identify the site of interference with the mechanism.