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Hypothermia for traumatic head injury

  1. Emma Sydenham1,*,
  2. Ian Roberts1,
  3. Phil Alderson2

Editorial Group: Cochrane Injuries Group

Published Online: 21 JAN 2009

Assessed as up-to-date: 22 MAY 2008

DOI: 10.1002/14651858.CD001048.pub3


How to Cite

Sydenham E, Roberts I, Alderson P. Hypothermia for traumatic head injury. Cochrane Database of Systematic Reviews 2009, Issue 1. Art. No.: CD001048. DOI: 10.1002/14651858.CD001048.pub3.

Author Information

  1. 1

    London School of Hygiene & Tropical Medicine, Cochrane Injuries Group, London, UK

  2. 2

    National Institute for Health and Clinical Excellence, Manchester, UK

*Emma Sydenham, Cochrane Injuries Group, London School of Hygiene & Tropical Medicine, Room 280, Keppel Street, London, WC1E 7HT, UK. emma.sydenham@lshtm.ac.uk.

Publication History

  1. Publication Status: Edited, conclusions changed
  2. Published Online: 21 JAN 2009

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This is not the most recent version of the article. View current version (15 APR 2009)

 

Abstract

  1. Top of page
  2. Abstract
  3. Plain language summary

Background

Hypothermia has been used in the treatment of head injury for many years. Encouraging results from small trials and laboratory studies led to renewed interest in the area and some larger trials.

Objectives

To estimate the effect of mild hypothermia for traumatic head injury on mortality and long-term functional outcome complications.

Search strategy

We searched the Injuries Group Specialised Register, Current Controlled Trials MetaRegister of trials, Zetoc, Web of Knowledge; Science Citation Index [expanded], CENTRAL, MEDLINE and EMBASE. We handsearched conference proceedings and checked reference lists of relevant articles. The search was updated on 23 May 2008.

Selection criteria

Randomised controlled trials of hypothermia to a maximum of 35ºC for at least 12 hours versus control in patients with any closed traumatic head injury requiring hospitalisation. Two authors independently assessed all trials.

Data collection and analysis

Data on death, Glasgow Outcome Scale and pneumonia were sought and extracted, either from published material or by contacting the investigators. Odds ratios (ORs) and 95% confidence intervals (CIs) were calculated for each trial on an intention-to-treat basis.

Main results

We found 22 trials with a total of 1409 randomised patients. Twenty trials involving 1382 patients reported deaths. There were fewer deaths in patients treated with hypothermia than in the control group (OR 0.76, 95% CI 0.60 to 0.97). Eight trials with good allocation concealment showed a non-significant reduction in the likelihood of death for patients treated with hypothermia (OR 0.96, 95% CI 0.68 to 1.35). Twenty trials involving 1382 patients reported data on unfavourable outcomes (death, vegetative state or severe disability). Patients treated with hypothermia were less likely to have an unfavourable outcome than those in the control group (OR 0.69, 95% CI 0.55 to 0.86). Eight trials with good allocation concealment showed a non-significant reduction in the likelihood of unfavourable outcome for patients treated with hypothermia (OR 0.79, 95% CI 0.57 to 1.08). Hypothermia treatment was associated with an increase in odds of pneumonia but this increase was not statistically significant for trials with good allocation concealment (3 trials, 69 patients, OR 1.06, 95% CI 0.38 to 2.97).

Authors' conclusions

Hypothermia may be effective in reducing death and unfavourable outcomes for traumatic head injured patients, but significant benefit was only found in low quality trials. Low quality trials have a tendency to overestimate the treatment effect. The high quality trials found some statistically non-significant benefit of hypothermia which could be due to the play of chance. Hypothermia may increase the risk of pneumonia. Due to uncertainties in its effects, hypothermia should only be given to patients taking part in a randomised controlled trial with good allocation concealment.

 

Plain language summary

  1. Top of page
  2. Abstract
  3. Plain language summary

Hypothermia (body temperature cooling) for traumatic head injury

Twenty-two randomised controlled trials involving 1409 patients with traumatic head injury were included in this review. In each trial, the patients were randomly divided into two groups: one group remained at normal body temperature, and the other group was cooled to a maximum of 35 degrees Celsius for at least 12 hours. Cooling could be of the whole body (e.g. with a blanket with circulating cold water), or just the head (e.g. with a helmet with circulating cold water). Information on death, disability, and pneumonia was evaluated for each trial.

The review authors found that fewer people died or became severely disabled if they were treated with hypothermia, but this finding may be due to the play of chance. It was also found that patients given hypothermia were more likely to develop pneumonia, and some patients died from pneumonia, but the increased risk of pneumonia could also be due to the play of chance.

Some of the trials included in the review were of low methodological quality. Low quality trials have a tendency to overestimate the effect of a treatment. In this review, the lower quality trials showed hypothermia treatment to be effective in reducing death and disability among head injured patients. However, the good quality trials showed less benefit for hypothermia treatment and a lower chance of pneumonia.

The review authors conclude that hypothermia might reduce death and disability in traumatic head injured patients, but it may also increase the risk of pneumonia. These effects may be due to the play of chance. Due to uncertainties in its effects, hypothermia should only be given to patients taking part in good quality randomised controlled trials.