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Three Part Question

Is [induced hypothermia following out-of-hospital cardiac arrest] [effective] in [patients presenting with pulseless electric activity or asystole]?

Clinical Scenario

69 year old male presents to the Emergency Department after having an asystolic arrest with spontaneous return of circulation following CPR. You wonder if therapeutic hypothermia would offer any benefit to this patient.

Search Strategy

Medline 1946-06/13 using OVID interface, Cochrane Library (2013), PubMed clinical queries

[(exp hypothermia,induced) AND (exp out-of-hospital cardiac arrest)]. Limit to English language

Search Outcome

96 papers were identified; of which 4 answered the clinical question.

Relevant Paper(s)

Author, date and country	Patient group	Study type (level of evidence)	Outcomes	Key results	Study Weaknesses
January 2005 - December 2009 Japan	Comatose adults treated with therapeutic hypothermia after return of spontaneous circulation (ROSC) subsequent to an out-of-hospital cardiac arrest of cardiac etiology.	Cohort	30 day favorable neurological outcome	75 of 452 cases were non-shockable rythms. If time of arrest to ROSC was greater than 16 min then there was a lower frequency of a favorable outcome compared to shockable rythms (32% vs. 66%, P<0.001). If time of arrest to ROSC was less than or equal to 16 min then there was a similar frequency of a favorable outcome compared to shockable rythms (90% non-shockable group vs. 92% shockable group, odds ratio 0.80, 95% confidence interval 0.09–7.24, P=0.84).	No control group. Cooling strategies differed between the 14 centers. Only patients with documented arrest to ROSC times were included.
January 1992 and October 2009 Austria	Patients 18 years of age or older, with a witnessed out of hospital cardiac arrest of non-traumatic origin, with a non-shockable initial cardiac rhythm (asystole or pulseless electric activity) and a restoration of spontaneous circulation	Cohort	6 month favorable neurological outcome, and six month mortality	Of the 374 patients, hypothermia was induced in 135. Patients treated with hypothermia were more likely to have better neurological outcomes (odds ratio of 1.84, 95% confidence interval: 1.08–3.13). 6 month mortality also lower in hypothermia group (odds ratio: 0.56; 95% confidence interval: 0.34–0.93).	Not a randomized prospective trial.
January 2000 to June 2009 France	Non-traumatic out of hospital cardiac arrest patients with ROSC.	Prospective observational cohort	cerebral performance categories scale at hospital discharge	Hypothermia induced in 261/437 patients in PEA/asystole. Hypothermia not significantly associated with good neurological outcome (adjusted odds ratio, 0.71; 95% confidence interval, 0.37 to 1.36)	Outcome only measured at hospital discharge. There was a progressive implementation of hypothermia over the study period.
December 2004 to October 2006	Adult comatose patients <80 years of age with an out of hospital cardiac arrest and ROSC.	Prospective cohort	Survival and neurologic recovery was assessed using Glasgow-Pittsburgh Cerebral Performance Categories at hospital discharge	3.1% of patients survived with time of ROSC greater than 25 mins compared to 65.7% of patients that had ROSC less than or equal to 25 mins. Initial rythm had no prediction on survival. However in comparison to a previous study hypothermia improved neurological outcome from 21.2% of patients to 57.9%.	Small sample size. No control group.

Comment(s)

Although there is conflicting evidence on the utility of therapeutic hypothermia in out of hospital cardiac arrest patients with non-shockable rhythms, the majority of evidence supports its use in this population.Many studies identified that outcomes were significantly better if time of arrest to ROSC was short (16-25 minutes)

Editor Comment

KMJ

Clinical Bottom Line

Therapeutic hypothermia should be considered in patients who present with ROSC after an out of hospital cardiac arrest with an initial non-shockable rhythm (PEA/asystole). This is especially relevant if time of arrest to ROSC is short.

References

1. Soga T. Nagao K. Sawano H. Yokoyama H. Tahara Y. Hase M. Otani T. Shirai S. Hazui H. Arimoto H. Kashiwase K. Kasaoka S. Motomura T. Kuroda Y. Yasuga Y. Yonemoto N. Nonogi H Neurological benefit of therapeutic hypothermia following return of spontaneous circulation for out-of-hospital non-shockable cardiac arrest Circulation Journal 2012; 76(11):2579-85,
2. Testori C. Sterz F. Behringer W. Haugk M. Uray T. Zeiner A. Janata A. Arrich J. Holzer M. Losert H Mild therapeutic hypothermia is associated with favourable outcome in patients after cardiac arrest with non-shockable rhythms Resuscitation Sept. 2011; 82(9):1162-7
3. Dumas F. Grimaldi D. Zuber B. Fichet J. Charpentier J. Pene F. Vivien B. Varenne O. Carli P. Jouven X. Empana JP. Cariou A Is hypothermia after cardiac arrest effective in both shockable and nonshockable patients?: Insights from a large registry Circulation Mar 1 2011; 123:877
4. Oddo M. Ribordy V. Feihl F. Rossetti AO. Schaller MD. Chiolero R. Liaudet L Early predictors of outcome in comatose survivors of ventricular fibrillation and non-ventricular fibrillation cardiac arrest treated with hypothermia: A prospective study Critical Care Medicine Aug. 2008; 36(8):2296-301