Thromboelastography to Assess Coagulopathy in Traumatic Brain Injury Patients Undergoing Therapeutic Hypothermia.

Abstract

Therapeutic hypothermia has been a treatment option for patients with severe traumatic brain injury (TBI) for many years. There has, however, been uncertainty whether hypothermia in this context also increased clinical bleeding risk, perhaps due to platelet dysfunction. Standard coagulation tests do not allow accurate assessment of in vivo coagulation. We studied specific coagulation abnormalities in patients undergoing therapeutic hypothermia for severe TBI using bedside thromboelastography (TEG).We studied 20 patients with severe blunt TBI from a single tertiary ICU who were enrolled in the prophylactic hypothermia to lessen traumatic brain injury (POLAR) trial. Ten patients had been randomized to hypothermia, and 10 were controls receiving normothermic standard care. TEG was undertaken during and after therapeutic hypothermia, and at the same time points in controls. Coagulation profiles were then compared between the hypothermic and control patients, and also between hypothermia and later normothermia in the study patients. Patients were primarily young (mean age 34 years) and male (85%). Measures of injury severity, including Glasgow coma score and injury severity scale, were not different between groups. Using TEG, the median alpha angle was reduced in hypothermic patients compared with controls (69.2° vs. 72.0°, p = 0.02), although both were within the normal range. LY30 was also reduced (0.0% vs. 0.5%, p < 0.01). Both differences persisted when hypothermic patients were compared with themselves during later normothermia. Therapeutic hypothermia during severe TBI causes a small decrease in the rate of clot formation. However, this decrease is within the normal range, and is unlikely to be clinically significant.