Rapid body cooling by cold fluid infusion prolongs survival time during uncontrolled hemorrhagic shock in pigs

Objective: The purpose of this study was to examine whether cold fluid infusion could rapidly decrease the core temperature and prolong survival during uncontrolled hemorrhagic shock in pigs. Methods: Fourteen pigs under light halothane anesthesia and spontaneous breathing underwent initial blood withdrawal of 25 mL/kg over 15 minutes, followed by uncontrolled hemorrhage (5-mm aortotomy). Immediately after the aortotomy, the pigs were randomized to receive 500 mL lactated Ringer's solution at either 4degreesC (group I, n = 7) or 37degreesC (group 2, n = 7) over 20 minutes through the internal jugular vein and observed until their death or for a maximum of 240 minutes. Results: The pulmonary artery temperature of group I decreased to 35.5degrees +/- 0.3degreesC after the infusion, then remained at 35.5degreesC during the observation period. Pulmonary artery temperature values of group 2 remained at around 37.5degreesC throughout the experiment. The mean survival time was 220 +/- 45 minutes in group I versus 136 +/- 64 minutes in group 2 (p < 0.05, life table analysis). The additional intraperitoneal blood loss of group I was similar to that of group 2 (9 +/- 4 g/kg vs. 10 +/- 5 g/kg). Conclusion: In lightly anesthetized pigs during uncontrolled hemorrhagic shock, infusion with 4degreesC lactated Ringer's solution (which seems to be feasible in the clinical setting) decreases the core temperature rapidly and prolongs survival.