Therapeutic hypothermia in patients with traumatic brain injury: an umbrella review

Therapeutic hypothermia (TH) is an intervention conducted to reduce brain damage in neonatal asphyxia and postcardiac arrest patients. Traumatic brain injury (TBI) dysregulates cerebral blood flow and causes ischemic brain damage. TH could lower brain damage by reducing the metabolism rate and need for oxygen. In this umbrella review, we aim to investigate different aspects of TH intervention in TBI patients.

We searched MEDLINE, Scopus, Embase, Cinahl, Epistemonikos, Cochrane Library, Web of Science, and Google Scholar for relevant systematic reviews until August 03, 2025. Then, studies entered the screening process, and systematic reviews of TH`s effect on TBI patients were included. We excluded studies without any quality assessments. Data for mortality, favorable and unfavorable neurologic outcomes, and possible complications of TH were extracted from the included studies. We avoided meta-analysis due to the vast heterogeneity between the studies' methodologies.

Of the 1466 studies identified from the primary search, 30 met our inclusion criteria. According to the JBI critical appraisal tool for systematic reviews, 29 studies were of high quality, and 1 was of medium quality. Studies had different methodologies, such as different induction methods and durations, different age groups, target temperatures, and rewarming rates. Mortality was the most common outcome assessed by the studies. Morbidity was assessed as either favorable or unfavorable neurological outcomes at a follow-up of 1,3,6,12,24 months. Pneumonia was the most investigated side-effect of TH, and most studies reported a greater chance of pneumonia in the TH group. Other investigated complications of TH were electrolyte abnormalities, coagulopathy, and arrhythmia.

Studies have shown controversial results regarding the effect of TH on mortality and morbidity. Differences in the target population, hypothermia protocol, and quality of included studies may be responsible for part of this controversy. Some of the important parameters that may affect the results are the age of TBI patients, the use of barbiturates, target TH temperature, rewarming rates, and method of cooling. Additionally, the subgroup analysis of high-quality studies differed from the pooled analysis provided by each study. More high-quality studies with specific protocols are needed to better understand TH's role in TBI patients.