Induced Hypothermia After VF Cardiac Arrest Improves Outcomes
Hypothermia led to significantly better survival rates and neurological outcomes in patients with ventricular fibrillation but not in those with other initial rhythms.
Despite evidence that induced hypothermia therapy after cardiac arrest improves neurological outcomes and survival, cooling protocols have not been widely implemented. In a retrospective observational study, researchers compared outcomes in consecutive patients with out-of-hospital cardiac arrest who were resuscitated in the 2 years before (204 patients) and the 2 years after (287) implementation of a therapeutic hypothermia protocol at a teaching hospital in Seattle. Patients with severe infection, active bleeding, or nonintact skin from recent burns or who were in a persistent vegetative state prior to cardiac arrest were excluded.
Patients in the hypothermia group were cooled with ice packs, cooling blankets, or cooling pads and received intravenous vecuronium and diazepam. Temperature was measured with an esophageal probe; the goal of 32°C–34°C was achieved in 65% of patients. Passive rewarming commenced after 24 hours of cooling.
Rates of survival to hospital discharge were significantly higher in the hypothermia group than in the control group among patients with an initial rhythm of ventricular fibrillation (VF) (54% vs. 39%) but did not differ among patients with other rhythms. Similarly, the rate of favorable neurological outcomes was significantly higher in the hypothermia group than in the control group among patients with VF (35% vs. 15%).
Comment: Although a greater incidence of witnessed arrests in the hypothermia group (66%) than in the control group (57%) might have skewed the results, the findings suggest that cardiac arrest patients with an initial rhythm of VF might benefit from therapeutic cooling. Based on this and previous outcome studies (JW Emerg Med Oct 27 2006) and on other studies showing that induced hypothermia in the emergency department is feasible (JW Emerg Med Jul 11 2008), it is time for EDs (and some emergency medical services systems) to implement hypothermia protocols for comatose survivors of cardiac arrest.
Kristi L. Koenig, MD, FACEP
Published in Journal Watch Emergency Medicine November 6, 2009
Citation(s): Don CW et al. Active surface cooling protocol to induce mild therapeutic hypothermia after out-of-hospital cardiac arrest: A retrospective before-and-after comparison in a single hospital. Crit Care Med 2009 Sep 16; [e-pub ahead of print]. (http://tinyurl.com/yht8qs7)