Clinical paperMild therapeutic hypothermia is associated with favourable outcome in patients after cardiac arrest with non-shockable rhythms☆
Introduction
The incidence of out-of-hospital cardiac arrest ranges from 37 to 46 per 100,000 events per year.1 Approximately 25% of all cardiac arrest patients are younger than 65 years of age.2 The favourable outcomes of patients who are admitted to the hospital range from 11% to 48%, indicating that a large number of patients die after successful resuscitation during their hospital stay or develop severe permanent neurological impairment.3, 4 The only therapy that has been shown to improve survival and neurological outcome after successful resuscitation from sudden cardiac arrest is the induction of mild therapeutic hypothermia for 12–24 h.5, 6Two large randomised clinical trials investigating the effect of mild hypothermia in cardiac arrest survivors only included patients with primary shockable cardiac rhythms.5, 6 There is a lack of data concerning the effect of mild therapeutic hypothermia in survivors after cardiac arrest with asystole or pulseless electrical activity as the first documented rhythms. Approximately 60–80% of patients who have suffered from an out-of-hospital cardiac arrest present with an initial non-shockable rhythm.4, 7, 8, 9 Some preliminary analyses have reported a non-significant reduction in unfavourable outcomes in patients who present with pulseless electrical activity or asystole and who were treated with mild hypothermia.10, 11, 12
The aim of this retrospective cohort study was to investigate the effect of mild therapeutic hypothermia on neurological outcome and mortality in patients who had been successfully resuscitated from non-ventricular fibrillation cardiac arrest.
Section snippets
Methods
This cohort study is based on a cardiac arrest registry that consists of all adult patients who were admitted to the department of emergency medicine of a tertiary-care hospital with cardiac arrest between January 1992 and October 2009. The institutional ethical review board has approved this registry. The data of all patients were prospectively documented according to the ‘Utstein Style Criteria’, which are the recommended guidelines for cardiac arrest and cardiopulmonary resuscitation outcome
Results
During an observational period from 1992 to 2009, 3391 patients with cardiac arrest were seen at the emergency department and documented in the registry. Out of these, 374 patients were analysed. The flow chart of case selection is shown in Fig. 1. Mild therapeutic hypothermia was induced in 135 patients. At baseline (Table 1), there were no statistically significant differences between the two groups except that there were less female patients in the group that was treated with hypothermia.
Discussion
Treatment with mild therapeutic hypothermia at temperatures between 32 °C and 34 °C for 24 h is associated with an improved neurological outcome and a reduced risk of death during a six-month observational period in patients who were successfully resuscitated from out-of-hospital cardiac arrests of non-traumatic origin with asystole or pulseless electrical activity as the first documented rhythm. This association remains unchanged after adjustment for confounders. The fact that patients with
Conclusion
Treatment with mild therapeutic hypothermia at a temperature of 32–34 °C for 24 h is associated with an improved neurological outcome and a reduced risk of death in patients following out-of-hospital cardiac arrest with an initial non-shockable rhythm. Nevertheless, the need for a prospective randomised clinical trial in this patient population to recommend the use of mild hypothermia after cardiac arrest is evident.
Conflict of interest statement
The authors declare that they have no financial and personal relationships with other people or organisations that could inappropriately influence (bias) their work.
Role of the funding source
There have been no study sponsors, who could have had a role in the study design, in the collection, analysis and interpretation of data; in the writing of the manuscript; and in the decision to submit the manuscript for publication.
Acknowledgements
We are indebted to the nurses and staff for their enthusiastic cooperation and to the patients who participated in this study for their trust and support.
References (26)
- et al.
Incidence of EMS-treated out-of-hospital cardiac arrest in Europe
Resuscitation
(2005) - et al.
Current burden of sudden cardiac death: multiple source surveillance versus retrospective death certificate-based review in a large U.S. community
J Am Coll Cardiol
(2004) - et al.
Out-of-hospital cardiac arrest in the 1990's: a population-based study in the Maastricht area on incidence, characteristics and survival
J Am Coll Cardiol
(1997) - et al.
Epidemiology, trends, and outcome of out-of-hospital cardiac arrest of non-cardiac origin
Resuscitation
(2007) - et al.
Decrease in the occurrence of ventricular fibrillation as the initially observed arrhythmia after out-of-hospital cardiac arrest during 11 years in Sweden
Resuscitation
(2004) - et al.
Incidence of EMS-treated out-of-hospital cardiac arrest in the United States
Resuscitation
(2004) - et al.
Mild hypothermia induced by a helmet device: a clinical feasibility study
Resuscitation
(2001) - et al.
Cardiac arrest and cardiopulmonary resuscitation outcome reports: update and simplification of the Utstein templates for resuscitation registries. A statement for healthcare professionals from a task force of the international liaison committee on resuscitation (American Heart Association, European Resuscitation Council, Australian Resuscitation Council, New Zealand Resuscitation Council, Heart and Stroke Foundation of Canada, InterAmerican Heart Foundation, Resuscitation Council of Southern Africa)
Resuscitation
(2004) - et al.
Assessment of outcome after severe brain damage
Lancet
(1975) - et al.
Effects of mild and moderate hypothermia on apoptosis in neuronal PC12 cells
Br J Anaesth
(2002)
Changing incidence of out-of-hospital ventricular fibrillation, 1980–2000
JAMA
Mild therapeutic hypothermia to improve the neurologic outcome after cardiac arrest
N Engl J Med
Treatment of comatose survivors of out-of-hospital cardiac arrest with induced hypothermia
N Engl J Med
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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.2011.05.022.