The effectiveness of early prophylactic hypothermia in adult patients with traumatic brain injury: A systematic review and meta-analysis

Abstract

Objectives: Previously published systematic reviews have explored the effects of therapeutic hypothermia on adult patients with traumatic brain injury (TBI). However, none explored the effect of early prophylactic hypothermia (within 6 h from injury to hypothermia induction). Animal studies indicated that early prophylactic hypothermia may reduce secondary injury and improve neurological outcomes. This systematic review aimed to investigate the effects of early prophylactic hypothermia on adult TBI regarding mortality, favourable outcomes, and complications.

Data source: We searched electronic databases including Cochrane CENTRAL, PubMed, MEDLINE, CINAHL, EMBASE, Web of Science, OpenGrey, and ClinicalTrials.gov from inception to June 12, 2019. Manual search was conducted for additional information.

Review methods: Only randomised controlled trials were included. The Cochrane Collaboration Risk of Bias Tool was used to assess the quality of included studies. We extracted general demographic characteristics, the initiation timing, methods of cooling, duration, target temperature, rewarming rate, mortality, neurological outcomes, and complications.

Results: Six studies with a total of 1207 participants were included. Meta-analyses showed no significant difference in mortality and favourable outcomes (risk ratio = 1.11, 95% confidence interval = 0.90-1.37, P = 0.32; risk ratio = 1.03, 95% confidence interval = 0.91-1.16, P = 0.65, respectively). Similar results were found regarding different durations of hypothermia and different rewarming rates. Various complications were reported in the included studies. No statistical difference was found in three studies, while complications were reported to be significantly higher in the hypothermia group in the other three studies.

Conclusions: This review does not support the use of early prophylactic hypothermia (within 6 h after injury) as a neurological protection strategy in adult patients with TBI, irrespective of the short term or long term. No significant benefits were found regarding hypothermia with different rewarming rates. Owing to the limited number of studies, more randomised controlled trials with higher quality are required to establish true effects of early hypothermia in adult TBI.

Keywords: Adult; Brain; Hypothermia; Injury; Mortality; Traumatic.