Effects of induced hypothermia after soft-tissue injury

Hypothermia is occasionally employed to reduce the metabolic rate and to protect the brain in patients undergoing surgery, but it is controversial whether hypothermia (HT) is beneficial or harmful in trauma victims with soft-tissue injuries. For this purpose, we studied the acute effects of hypothermia induced after infliction of a standardized soft-tissue injury.

After a standardized high-energy gunshot wound to the right hind leg of 14 anesthetized piglets, the animals were randomized to normothermia or HT (30 degrees C) induced with a HT bed. The cardiovascular and hematological status was monitored for 6 h after the injury.

The heart rate, mean arterial pressure, neutrophil count, and plasma adrenaline level were significantly lower in the HT pigs than in the controls (p<0.05). The arterial oxygen tension was significantly elevated in the HT group. Cardiac index and oxygen delivery decreased slightly in both groups, but no difference developed between the groups in these parameters. Serum potassium increased significantly in the controls (p<0.001).

HT down to 30 degrees C following high-energy penetrating soft-tissue injury had a modest effect on the hemodynamics and oxygen delivery. However, evidence of 'stress' was reduced, and the pigs developed a progressive increase in their serum potassium concentration.