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Abstract
A short cut review was carried out to establish whether therapeutic hypothermia improves outcome in comatose post cardiac arrest patients. Altogether 176 papers were found using the reported search, of which four presented the best evidence to answer the clinical question. The author, date and country of publication, patient group studied, study type, relevant outcomes, results and study weaknesses of these best papers are tabulated. A clinical bottom line is stated.
- hypothermia
- cardiac arrest
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Report by Bernard A Foëx,Consultant Checked by John Butler, Consultant
Clinical scenario
A 46 year old father of three collapses in the street with a cardiorespiratory arrest. He receives five minutes of bystander CPR. When the ambulance crew arrives he is in ventricular fibrillation. Return of spontaneous circulation is achieved after defibrillation. On arrival in the emergency department he is still in coma. You wonder if his chances of survival or of a good neurological outcome would be improved by therapeutic hypothermia?
Three part question
In [adults who have sustained an out of hospital cardiac arrest] does [therapeutic hypothermia] [improve outcome]?
Search strategy
Medline 1966-05/04 using the Ovid interface, The Cochrane Library, Issue 2, 2004 and Bandolier to 05/04. Medline: [exp Hypothermia, Induced/OR hypothermia, therapeutic.mp.] AND [exp Heart Arrest/OR cardiac arrest.mp.] LIMIT to human AND English language. Cochrane Library: “hypothermia”.
Search outcome
Altogether 176 papers were found in Medline, only four described any sort of comparative study. Four papers were found in Cochrane, none of which were relevant to the three part question (see table 5).
Comment(s)
There are only four trials of mild hypothermia after cardiac arrest, and only two are randomised controlled trials. Treatment could not be blinded. All show a neurological benefit from mild hypothermia. Only two showed a survival benefit. The main inclusion criterion for these two trials was that patients had been in ventricular fibrillation. In study number 3 patients with a non-perfusing ventricular tachycardia were also included. There is no uniform protocol for how long hypothermia should be maintained, or the rate of rewarming.
CLINICAL BOTTOM LINE
Patients remaining unconscious after out of hospital cardiac arrest, from ventricular fibrillation or non-perfusing ventricular tachycardia, should be cooled to 32–34°C for at least 12 hours as part of their post-arrest intensive care to optimise neurological recovery. This therapeutic strategy has been endorsed by the International Liaison Committee on Resuscitation.
Report by Bernard A Foëx,Consultant Checked by John Butler, Consultant