Therapeutic hypothermia in patients following traumatic brain injury: a systematic review

Background The efficacy of therapeutic hypothermia in adult patients with traumatic brain injury is not fully understood. The historical use of therapeutic hypothermia at extreme temperatures was associated with severe complications and led to it being discredited. Positive results from animal studies using milder temperatures led to renewed interest. However, recent studies have not convincingly demonstrated the beneficial effects of therapeutic hypothermia in practice. Aim This review aims to answer the question: in adults with a severe traumatic brain injury (TBI), does the use of therapeutic hypothermia compared with normothermia affect neurological outcome? Design Systematic review. Method Four major electronic databases were searched, and a hand search was undertaken using selected key search terms. Inclusion and exclusion criteria were applied. The studies were appraised using a systematic approach, and four themes addressing the research question were identified and critically evaluated. Results A total of eight peer-reviewed studies were found, and the results show there is some evidence that therapeutic hypothermia may be effective in improving neurological outcome in adult patients with traumatic brain injury. However, the majority of the trials report conflicting results. Therapeutic hypothermia is reported to be effective at lowering intracranial pressure; however, its efficacy in improving neurological outcome is not fully demonstrated. This review suggests that therapeutic hypothermia had increased benefits in patients with haematoma-type injuries as opposed to those with diffuse injury and contusions. It also suggests that cooling should recommence if rebound intracranial hypertension is observed. Conclusion Although the data indicates a trend towards better neurological outcome and reduced mortality rates, higher quality multi-centred randomized controlled trials are required before therapeutic hypothermia is implemented as a standard adjuvant therapy for treating traumatic brain injury. Relevance to clinical practice Therapeutic hypothermia can have a positive impact on patient outcome, but more research is required

Covariate adjustment increased power in randomized controlled trials: an example in traumatic brain injury.

OBJECTIVE: We aimed to determine to what extent covariate adjustment could affect power in a randomized controlled trial (RCT) of a heterogeneous population with traumatic brain injury (TBI). STUDY DESIGN AND SETTING: We analyzed 14-day mortality in 9,497 participants in the Corticosteroid Randomization After Significant Head Injury (CRASH) RCT of corticosteroid vs. placebo. Adjustment was made using logistic regression for baseline covariates of two validated risk models derived from external data (International Mission on Prognosis and Analysis of Clinical Trials in Traumatic Brain Injury [IMPACT]) and from the CRASH data. The relative sample size (RESS) measure, defined as the ratio of the sample size required by an adjusted analysis to attain the same power as the unadjusted reference analysis, was used to assess the impact of adjustment. RESULTS: Corticosteroid was associated with higher mortality compared with placebo (odds ratio=1.25, 95% confidence interval=1.13-1.39). RESS of 0.79 and 0.73 were obtained by adjustment using the IMPACT and CRASH models, respectively, which, for example, implies an increase from 80% to 88% and 91% power, respectively. CONCLUSION: Moderate gains in power may be obtained using covariate adjustment from logistic regression in heterogeneous conditions such as TBI. Although analyses of RCTs might consider covariate adjustment to improve power, we caution against this approach in the planning of RCTs

Absence of electroencephalographic seizure activity in patients treated for head injury with an ICP targeted therapy

OBJECT: The authors prospectively studied the occurrence of clinical and nonclinical electroencephalographically verified seizures during treatment with an intracranial pressure (ICP)-targeted protocol in patients with traumatic brain injury (TBI). METHODS: All patients treated for TBI at the Department of Neurosurgery, University Hospital Umea, Sweden, were eligible for the study. The inclusion was consecutive and based on the availability of the electroencephalographic (EEG) monitoring equipment. Patients were included irrespective of pupil size, pupil reaction, or level of consciousness as long as their first measured cerebral perfusion pressure was > 10 mm Hg. The patients were treated in a protocol-guided manner with an ICP-targeted treatment based on the Lund concept. The patients were continuously sedated with midazolam, fentanyl, propofol, or thiopental, or combinations thereof. Five-lead continuous EEG monitoring was performed with the electrodes at F3, F4, P3, P4, and a midline reference. Sensitivity was set at 100 muV per cm and filter settings 0.5-70 Hz. Amplitude-integrated EEG recording and relative band power trends were displayed. The trends were analyzed offline by trained clinical neurophysiologists. RESULTS: Forty-seven patients (mean age 40 years) were studied. Their median Glasgow Coma Scale score at the time of sedation and intubation was 6 (range 3-15). In 8.5% of the patients clinical seizures were observed before sedation and intubation. Continuous EEG monitoring was performed for a total of 7334 hours. During this time neither EEG nor clinical seizures were observed. CONCLUSIONS: Our protocol-guided ICP targeted treatment seems to protect patients with severe TBI from clinical and subclinical seizures and thus reduces the risk of secondary brain injury