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The beneficial effect of mild therapeutic hypothermia depends on the time of complete circulatory standstill in patients with cardiac arrest

Christoph Testori, Fritz Sterz, Michael Holzer, Heidrun Losert, Jasmin Arrich, Harald Herkner, Danica Krizanac, Christian Wallmüller, Peter Stratil, Andreas Schober, David Hörburger, Mathias Stöckl, Christoph Weiser & Thomas Uray

abstract

AIM
Mild therapeutic hypothermia has shown to improve long-time survival as well as favorable functional outcome after cardiac arrest. Animal models suggest that ischemic durations beyond 8 min results in progressively worse neurologic deficits. Based on these considerations, it would be obvious that cardiac arrest survivors would benefit most from mild therapeutic hypothermia if they have reached a complete circulatory standstill of more than 8 min.

METHODS
In this retrospective cohort study we included cardiac arrest survivors of 18 years of age or older suffering a witnessed out-of-hospital cardiac arrest, which remain comatose after restoration of spontaneous circulation. Data were collected from 1992 to 2010. We investigated the interaction of 'no-flow' time on the association between post arrest mild therapeutic hypothermia and good neurological outcome. 'No-flow' time was categorized into time quartiles (0, 1-2, 3-8, >8 min).

RESULTS
One thousand-two-hundred patients were analyzed. Hypothermia was induced in 598 patients. In spite of showing a statistically significant improvement in favorable neurologic outcome in all patients treated with mild therapeutic hypothermia (odds ratio [OR]: 1.49; 95% confidence interval [CI]: 1.14-1.93) this effect varies with 'no-flow' time. The effect is significant in patients with 'no-flow' times of more than 2 min (OR: 2.72; CI: 1.35-5.48) with the maximum benefit in those with 'no-flow' times beyond 8 min (OR: 6.15; CI: 2.23-16.99).

CONCLUSION
The beneficial effect of mild therapeutic hypothermia increases with cumulative time of complete circulatory standstill in patients with witnessed out-of-hospital cardiac arrest.
   
citation Testori C, Sterz F, Holzer M, Losert H, Arrich J, Herkner H, Krizanac D, Wallmüller C, Stratil P, Schober A, Hörburger D, Stöckl M, Weiser C, Uray T. The beneficial effect of mild therapeutic hypothermia depends on the time of complete circulatory standstill in patients with cardiac arrest. Resuscitation 2011; 83:596-601.
   
type journal paper/review (English)
date of publishing 29-11-2011
journal title Resuscitation (83/5)
ISSN electronic 1873-1570
pages 596-601
PubMed 22138057
DOI 10.1016/j.resuscitation.2011.11.019