The long-awaited Eurotherm trial was published in NEJM in autumn 2015. The premise of the study was to examine the impact of induced hypothermia on outcomes after traumatic brain injury. In a multi center randomized controlled trial patients were allocated to either therapeutic hypothermia (32-35 degrees) or the control group (standard care, normothermia). The study group planned to enroll 600 patients but patient recruitment was stopped at 387 patients due to an interim analysis that suggested significant harm from TH.
“The adjusted common odds ratio for the GOS-E score was 1.53 (95% confidence interval, 1.02 to 2.30; P=0.04), indicating a worse outcome in the hypothermia group than in the control group. A favorable outcome (GOS-E score of 5 to 8, indicating moderate disability or good recovery) occurred in 26% of the patients in the hypothermia group and in 37% of the patients in the control group (P=0.03)”
Although a well designed trial, it did meet with some criticism that should make us a bit cautious about throwing TH out of the mix altogether. One issue was the time factor. Patients were included up to 10 days post-injury. That may be viewed as somewhat pathophysiologically irrational given the usual natural history of cerebral oedema development. Furthermore, the mode of hypothermia induction was through administering 2000 ml of cold fluids. It may be argued that in the frailest patients with a severely damaged blood-brain barrier infusion of a fairly large volume over a relatively short time-period may be deleterious.
The POLAR-RCT (The Prophylactic Hypothermia Trial to Lessen Traumatic Brain Injury), an ANZICS sponsored trial ongoing since 2009, has yet to publish results. The intervention group is cooled to a target of 33C using surface temperature control equipment vs. normothermia (37C) in the control arm. Rewarming is done gradually, titrated to response in ICP, which seems more physiologically sound. The jury is thus still out…