Traumatic hypothermia is related to hypotension, not resuscitation

Study objective: To determine whether posttraumatic hypothermia is associated with hemorrhage or with resuscitation. Methods: We used a sequential hemorrhage-resuscitation rat model. Rats were subjected to hemorrhage (30 mL/kg), then 1 hour of shock, followed by 2:1 crystalloid/blood resuscitation (60 mL/kg) at ambient temperature. A control group underwent neither hemorrhage nor resuscitation. Results: We recorded core temperature and blood pressure every 10 minutes. Temperature drop averaged 3.4 degrees C and was fastest during hypotensive shock. Rate of temperature change correlated with blood pressure (beta=.0102, P<.001), shock phase (beta=.4504, P=.041), and blood pressure during shock phase (beta=.0116, P<.001), but not with resuscitation phase or with duration of shock or resuscitation. Three of 14 rats died during shock, none during resuscitation. An increase in temperature was noted in 1 of 14 rats during shock and in 7 of 11 rats during resuscitation. Conclusion: Hemorrhage-associated hypothermia occurs during hypotensive shock, not during fluid resuscitation.