Prophylactic Lidocaine for Out-of-Hospital Cardiac Arrest Seen Helpful

June 13, 2013

NEW YORK (Reuters Health) Jun 13 - Giving lidocaine prophylactically upon return of spontaneous circulation (ROSC) after out-of-hospital cardiac arrest has some benefits, a new study hints.

Antiarrhythmic drugs like lidocaine are typically given to promote ROSC during ongoing out-of-hospital cardiac arrest from ventricular fibrillation or pulseless ventricular tachycardia.

Accordingly, in the new retrospective study, lidocaine was the first-line antiarrhythmic therapy for shock-refractory ventricular fibrillation/tachycardia (VF/VT).

But Dr. Peter J. Kudenchuk from University of Washington, Seattle and colleagues found that when first responders also gave lidocaine prophylactically upon ROSC, the treatment was consistently associated with fewer re-arrests.

They conducted a retrospective study of witnessed out-of-hospital cardiac arrests from VF/VT treated by EMS in King County, Washington between 1992 and 2008. Patients were excluded if paramedics thought resuscitation attempts would be futile.

Among a total of 1,721 patients, 1,296 received prophylactic lidocaine at first ROSC and 425 did not, according to a paper online June 5 in Resuscitation.

The researchers say both groups were well matched, except for shorter time to first ROSC and higher systolic blood pressure at ROSC in those who got lidocaine.

In univariate analysis, recipients of prophylactic lidocaine had fewer re-arrests due to shockable and non-shockable arrhythmias than nonrecipients (16.7% vs 37.4% and 3.2% vs 7.8%, respectively, p<0.0001).

Prophylactic lidocaine recipients were also more likely to be admitted to the hospital (93.5% vs 84.9%, p<0.0001) and to survive to discharge (62.4% vs 44.5%, p<0.0001) in univariate analysis. (The likelihood of surviving an out-of-hospital cardiac arrest is greater for VF/VT than for other presenting arrhythmias, the authors say.)

In multivariate analyses, prophylactic lidocaine reduced the risk of re-arrest from recurrent VF/VT by roughly two-thirds (OR 0.34) and the risk of recurrent cardiac arrest from nonshockable arrhythmias by roughly half (OR 0.47).

It was also linked to a higher likelihood of admission to the hospital (OR 1.88) and survival to discharge (OR 1.49).

However, in a smaller propensity score-matched sensitivity analysis, lidocaine's only beneficial association with outcome was in a lower incidence of recurrent VF/VT arrest (22.8% vs 38.5%, p<0.0001).

"Notably, there was no evidence of harm" associated with prophylactic lidocaine in this patient population, the researchers say.

They note in their paper that recurrent ventricular arrhythmias are common following defibrillation for VF/VT cardiac arrest. "The prospect of a promising association between lidocaine prophylaxis and outcome, without evidence of harm, warrants further investigation," they conclude.

The study did not have commercial funding and the authors have no conflicts of interest. They did not respond to request for comment by press time.

SOURCE: http://bit.ly/1bA2Izk

Resuscitation 2013.

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