Elsevier

Resuscitation

Volume 82, Issue 5, May 2011, Pages 508-516
Resuscitation

Review
The role of hypothermia in post-cardiac arrest patients with return of spontaneous circulation: A systematic review

https://doi.org/10.1016/j.resuscitation.2011.01.021Get rights and content

Abstract

Objectives

To update a comprehensive systematic review of the use of therapeutic hypothermia after cardiac arrest that was undertaken initially as part of the 2010 International Consensus on Cardiopulmonary Resuscitation and Emergency Cardiovascular Care Science. The specific question addressed was: ‘in post-cardiac arrest patients with a return of spontaneous circulation, does the induction of mild hypothermia improve morbidity or mortality when compared with usual care?’

Methods

Pubmed was searched using (“heart arrest” or “cardiopulmonary resuscitation”) AND “hypothermia, induced” using ‘Clinical Queries’ search strategy; EmBASE was searched using (heart arrest) OR (cardiopulmonary resuscitation) AND hypothermia; The Cochrane database of systematic reviews; ECC EndNote Library for “hypothermia” in abstract OR title. Excluded were animal studies, reviews and editorials, surveys of implementation, analytical models, reports of single cases, pre-arrest or during arrest cooling and group where the intervention was not hypothermia alone.

Results

77 studies met the criteria for further review. Of these, four were meta-analyses (LOE 1); seven were randomised controlled trials (LOE 1), although six of these were from the same set of patients; nine were non-randomised, concurrent controls (LOE 2); 15 were trials with retrospective controls (LOE 3); 40 had no controls (LOE 4); and one was extrapolated from a non-cardiac arrest group (LOE 5).

Conclusion

There is evidence supporting the use of mild therapeutic hypothermia to improve neurological outcome in patients who remain comatose following the return of spontaneous circulation after a cardiac arrest; however, much of the evidence is from low-level, observational studies. Of seven randomised controlled trials, six use data from the same patients.

Section snippets

Background

Out-of-hospital cardiac arrest (OHCA) occurs in about 1 in 1500 adults in the developed world each year1; this means that about 375,000 people in Europe have a sudden cardiac arrest each year.2 The number of patients surviving to hospital discharge remains low: in a recent meta-analysis the aggregate survival rate was recorded between 6.7 and 8.4%.3 Among survivors, anoxic neurological injury is an important cause of morbidity.4 Over the last few years, mild hypothermia (32–34 °C for 12–24 h) has

Methods

The review was conducted in accordance with the International Liaison Committee on Resuscitation (ILCOR) 2010 evidence evaluation process, which has been well described.11 Expert review of the search strategy and findings were conducted by the worksheet evaluation experts who had been appointed specifically for this task. In keeping with all the ILCOR systematic reviews undertaken for 2010 CoSTR, a formal meta-analysis was not undertaken.

Results

The search identified 2991 papers. Seventy-seven studies met with the criteria for further review. Of these, four were LOE 1 (meta-analyses)14, 15, 16, 17; seven were LOE 1 (Randomized Controlled Trials),18, 19, 20, 21, 22, 23, 24 but six of these were from the same group of patients18; nine LOE 2 (non-randomized, concurrent controls)16, 25, 26, 27, 28, 29, 30, 31, 32; 15 LOE 3 (retrospective controls)7, 8, 33, 34, 35, 36, 37, 38, 39, 40, 41, 42, 43, 44, 45; 40 LOE 4 (no controls); and one LOE

Discussion

This review has identified some evidence that therapeutic hypothermia following cardiac arrest in comatose patients with ROSC improves mortality and neurological outcome. The strongest data remain those provided by the HACA Study Group,18 which showed both a reduction in mortality and improved neurological outcome at 6 months following out-of-hospital cardiac arrest where the initial rhythm was VF. These findings are supported by other, lower level, studies.25, 33, 35, 41 The extrapolation of

Authors conclusion and recommendation

This review has identified data on the use of therapeutic hypothermia to improve neurological outcome in comatose patients with ROSC after cardiac arrest. There is reasonable evidence that this therapy is effective for comatose survivors of VF/VT out-of-hospital cardiac arrest but there are only observational data to support its use after cardiac arrest from non-shockable rhythms or after in-hospital cardiac arrest. Cooling can be achieved in both the pre- and in-hospital setting and it can be

Disclaimer

This review includes information on resuscitation questions developed through the C2010 Consensus on CPR and ECC Science with Treatment Recommendations (CoSTR) process managed by the International Liaison Committee on Resuscitation.11 The questions were developed by ILCOR Task Forces, using strict conflict of interest guidelines.83 In general, each question was assigned to two experts to complete a detailed structured review of the literature, and complete a detailed worksheet. Worksheets were

Conflict of interest

JW – none; PM is a reimbursed consultant for Evidence Evaluation Expert position with ILCOR/AHA; and JN is Co-chair ILCOR and Editor-in-Chief of Resuscitation.

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    A Spanish translated version of the abstract of this article appears as Appendix in the final online version at doi:10.1016/j.resuscitation.2011.01.021.

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