Hypothermia From Realistic Flui d Resuscitation in a Mo del of Hemorrhagic Shock

Abstract

Study objective: To correlate changes in core body temperature with changes in mean arterial pressure (MAP) and cardiac output (CO) and with the administration of room-temperature intravenous fluids in a clinically relevant large-animal model of uncontrolled hemorrhage. Methods: Ten swine were subjected to uncontrolled hemorrhage through a flow-monitored shunt placed between the femoral artery and the peritoneal cavity. Animals were randomly assigned to a treatment or a control group. The control group (n=5) received no intravenous fluids. The treatment group (n=5) received 80 mL/kg (3:1 crystalloid/blood loss) ambient-temperature lactated Ringer's solution over a 10-minute resuscitation phase initiated 10 minutes after injury. CO and core body temperature, measured with the use of a pulmonary artery catheter, and MAP were the primary outcomes. We analyzed differences between groups with the use of repeated-measures ANOVA. Change of temperature was analyzed against the change in CO, and against fluid infusion for each interval, by means of regression analysis. Results: The unresuscitated control animals had no change in core temperature despite profound hemorrhagic shock and hypo-tension. The animals treated with fluids had a mean 2.6° C decrease in core temperature during fluid resuscitation (95% confidence interval [CI], 1.8 to 3.5). A 1.5° C decrease in core temperature (95% CI, .1 to 2.0) persisted at the end of 60 minutes (40 minutes after fluid resuscitation was discontinued). Core temperatures in control animals were 2.8° C lower than those in treated animals after fluid resuscitation (95% CI, .8 to 4.8). Decreases in core temperature correlated with fluid infusion (β= –35.2 mL/kg·° C, R 2=.75) and increases in CO (β= –1.46 L/min·° C, R 2=.69). Conclusion: Ambient-temperature crystalloid resuscitation in a clinically relevant large-animal model of hemorrhagic shock causes small decreases in core body temperature. Resuscitation rather than shock is the main cause of decreased body temperature in this model. [Silbergleit R, Satz W, Lee DC, McNamara RM: Hypothermia from realistic fluid resuscitation in a model of hemorrhagic shock. Ann Emerg Med March 1998;31:339-343.]