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06-10-2016 | Cardiology | News | Article

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Hypothermia effectiveness for in-hospital cardiac arrest challenged

medwireNews: Analysis of the Get With The Guidelines–Resuscitation registry suggests that therapeutic hypothermia does not benefit and may even harm patients with in-hospital cardiac arrest.

Researcher Paul Chan (Saint Luke’s Mid America Heart Institute, Kansas City, Missouri, USA) and colleagues call for a randomised trial to test their observational findings.

The team reports in JAMA that 27.4% of 1524 in-hospital cardiac arrest patients who were treated with hypothermia and achieved return of spontaneous circulation survived to hospital discharge. However, so did 29.2% of 3714 patients not treated with hypothermia but matched for their propensity to receive the intervention. This equated to a significant 12% reduced likelihood of survival among patients treated with hypothermia.

Worse survival in patients given hypothermia versus those not was evident for those with shockable cardiac arrest rhythms (41.3 vs 44.1%) and for those with nonshockable rhythms (22.2 vs 24.5%). And the association persisted after excluding patients who died within 24 hours after return of spontaneous circulation.

Among patients who survived to discharge, hypothermia was associated with a reduced rate of favourable neurological outcome (17.0 vs 20.5%). It had no measurable effect on 1-year survival, with 14.2% of hypothermia-treated patients and 14.1% of those not treated still alive at this point.

“Collectively, these findings do not support current use of therapeutic hypothermia for patients with in-hospital cardiac arrest”, say the researchers.

They note: “The finding that therapeutic hypothermia was not associated with better survival outcomes may raise questions about plausibility. However, clinical trials have found that therapeutic hypothermia leads to worse survival outcomes for other conditions, such as traumatic brain injury and bacterial meningitis.”

Although hypothermia is demonstrably effective, this is only proven for out-of-hospital cardiac arrest due to ventricular fibrillation. Chan et al stress that in-hospital cardiac arrest is a very different situation, with the much faster response times “potentially limiting the theorized benefit of therapeutic hypothermia to reduce free radical–mediated reperfusion injury from anoxic brain injury”.

In addition, only 16.8% of the in-hospital cardiac arrest patients in the study had ventricular fibrillation, with initial rhythms being pulseless electrical activity in 46.9%, asystole in 26.0% and pulseless ventricular tachycardia in 10.4%. The effects of hypothermia have not been assessed in patients with these rhythms, says the team.

By Eleanor McDermid

medwireNews is an independent medical news service provided by Springer Healthcare Limited. © Springer Healthcare Ltd; 2016

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