Hypothermia-Induced Coagulopathy during Hemorrhagic Shock

Abstract

A porcine model of hemorrhagic shock was used to study the effect of hypothermia on hemodynamic, metabolic, and coagulation parameters. The model was designed to simulate the events of severe blunt injury with hemorrhage occurring initially, to a systolic blood pressure of 30 mm Hg, followed by simultaneous hemorrhage and crystalloid volume replacement, followed by cessation of hemorrhage and blood replacement. Half of the animals were rendered hypothermic by external application of ice, and half remained normothermic. There was seven pigs in each group. Two deaths occurred in each during the hemorrhage phase. The hypothermic pigs demonstrated larger reduction in cardiac output than normothermic pigs. Volume replacement in the normothermic group restored cardiac output to baseline values. In the hypothermic group, cardiac output remained depressed despite volume replacement. Prothrombin times and partial thromboplastin times showed significantly more prolongation in the hypothermic group. Furthermore, this was not corrected by replacement of shed blood in the hypothermic group, as was seen in the normothermic group. We conclude that when shock and hypothermia occur together, their deleterious effect on hemodynamic and coagulation parameters are additive. The effects of hypothermia persist despite the arrest of hemorrhage and volume replacement. Thus, it is necessary to aggressively address both shock and hypothermia when they occur simultaneously.

Induced hypothermia does not impair coagulation system in a swine multiple trauma model

“…33 Nevertheless, pigs are commonly used for coagulation studies in experimental polytrauma models. 26,34,35 The results of the present study suggest that mild hypothermia can be safely performed after stabilization following major trauma. Mild hypothermia affects the coagulation system but does not aggravate trauma-induced coagulopathy in our model.…”

“…The authors conclude that hypothermia and shock have additive effects on hemodynamics and coagulation and that both need to be addressed. 26 However, it remains questionable if shed blood replacement is an appropriate treatment for coagulation disorders under hypothermic conditions.…”