Induced Moderate Hypothermia in Aortic Rupture With Retroperitoneal Bleeding: A Randomized Porcine Study

Abstract

Objective: Induced hypothermia improves outcome in aortic arch surgery, neonatal neurointensive care, and transplant surgery for example. In contrast, spontaneous hypothermia has been associated with worse outcomes in patients suffering from hemorrhagic shock, mostly explained by its adverse effects on the coagulation system. We investigated if induced hypothermia would impair short-term survival in experimental aortic rupture with retroperitoneal bleeding. Methods: Anesthetized pigs were randomized into 2 groups: hypothermia by peritoneal lavage of ice-cold Ringer’s acetate and external cooling ( n = 10) and normothermia ( n = 10). Aortic rupture with retroperitoneal bleeding was induced by endovascular means creating a 6 mm hole in the retroperitoneal portion of abdominal aorta. Survival (primary outcome), hemodynamics, and arterial blood gases including lactate were collected and analyzed up to 180 min after aortic rupture. Results: The body temperature (mean ± standard deviation) in the hypothermic group was 31.5 ± 1.0 °C and 38.7 ± 0.4 °C in the normothermic group at the time for aortic rupture. Survival up to 180 min after the retroperitoneal bleeding was significantly higher in the hypothermic compared with the normothermic group ( P = 0.023). Conclusions: Induced hypothermia did not impair survival in this experimental retroperitoneal aortic bleeding model in anesthetized pigs. This finding may indicate a minor role for the coagulation system in this type of bleeding.