MedWire News: Patients with out-of-hospital cardiac arrest who receive minimally interrupted cardiac resuscitation (MICR) are more likely to survive than those receiving the standard emergency medical services (EMS) protocol, US study findings indicate.

Bentley Bobrow (Mayo Clinic, Scottsdale, Arizona) and colleagues carried out a prospective study to investigate whether the survival of patients with out-of-hospital cardiac arrest would improve with MICR.

MICR consists of an initial series of 200 uninterrupted chest compressions, rhythm analysis with a single shock, 200 immediate post-shock chest compressions before pulse check or rhythm reanalysis, early administration of epinephrine, and delayed endotracheal intubation.

The emergency medical personnel were trained on MICR between 2005 and 2007. During this period, 886 patients from two metropolitan cities in Arizona who suffered out-of-hospital cardiac arrests were included in the before versus after training analysis.

In these patients, survival to hospital discharge increased from 1.8% before MICR training to 5.4% after MICR training (odds ratio[OR]=3.0). In the subgroup of 174 patients with witnessed cardiac arrest and ventricular fibrillation, survival increased from 4.7% before MICR training to 17.6% after MICR training (OR=8.6).

A second analysis of MICR protocol compliance involving 2460 patients with out-of-hospital cardiac arrest showed significant survival benefits with the MICR protocol.

Patients who received MICR were significantly more likely to survive hospital discharge than those who did not receive MICR (9.1% vs 3.8%, OR=2.7). Among patients with witnessed ventricular fibrillation, those who received the MICR protocol were significantly more likely to survive compared with patients who did not (28.4% vs 11.9%, OR= 3.4).

Bobrow et al conclude in the Journal of the American Medical Association: "Survival-to-hospital discharge of patients with out-of-hospital cardiac arrest increased after implementation of MICR as an alternate EMS protocol."

They note that "these findings require confirmation in randomized trials."

Mary Ann Peberdy and Joseph Ornato, from the Virginia Commonwealth University in Richmond, wrote in an accompanying editorial: "This study represents confirmation that the quality of CPR, particularly the need for minimally interrupted chest compression and the lesser importance of positive pressure ventilation, is a meaningful development in the evolution of resuscitation science."

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