Therapeutic hypothermia for severe traumatic brain injury: a critically appraised topic

Traumatic brain injury (TBI) is common and confers a high rate of disability and mortality. Current treatments are primarily supportive. Therapeutic hypothermia has been proposed for severe TBI because of its ability to reduce intracranial pressure and putative neuroprotective effects.

To critically appraise the current evidence concerning the efficacy of therapeutic hypothermia in the treatment of severe TBI.

The objective was addressed through the development of a structured, critically appraised topic. This incorporated a clinical scenario, background information, a structured question, literature search strategy, critical appraisal, results, evidence summary, commentary, and bottom line conclusions. Participants included consultant and resident neurologists, a medical librarian, clinical epidemiologists, and critical care and neurocritical care content experts.

A recent multicenter randomized controlled trial was selected for critical assessment; meta-analyses were also reviewed. Subjects with severe TBI were randomized to either rapid cooling to 33°C for 48 hours (treatment, n=52) or normothermia (control, n=45). Outcome assessments included mortality and disability at 6 months as measured by the Glasgow Outcome Scale. Initiation of hypothermia began within 2.5 hours of injury and patients were rewarmed over a mean of 17.2 hours. The study was terminated for futility; no difference in outcome or mortality was detected between treatment groups. Post hoc subgroup analysis showed that among subjects who required hematoma evacuation, hypothermia was associated with a lower rate of poor clinical outcome (number needed to treat=2.8; 95% confidence interval, 1.4-78.3, P=0.02) and a trend toward a decrease in mortality (P=0.16).

Current cumulative evidence does not support general use of therapeutic hypothermia for acute severe TBI. However, further investigation of the role of therapeutic hypothermia may be warranted for specific TBI subgroups.