Quicker transition from cardiopulmonary resuscitation to automated external defibrillation may improve survival after cardiac arrest


A quicker "hands-off" transition from chest compressions to automated external defibrillation may result in improved survival after cardiac arrest, according to a report in the April 23rd rapid access issue of Circulation. The hands-off interval is the time necessary for an automated external defibrillator to analyze a cardiac arrest victim's electrocardiogram, charge, and deliver a shock--- so called because cardiopulmonary resuscitation chest compressions must stop during this period and hands are off the patient.

Researchers found indications that the shorter the interval between discontinuation of chest compressions and delivery of electrical shock, the better the chance of surviving ventricular fibrillation.

According to the American Heart Association, about 250,000 Americans annually die of coronary heart disease without being hospitalized. That accounts for roughly half of all deaths from coronary heart disease -- more than 680 Americans each day. Most of these are sudden deaths caused by cardiac arrest.

"Our study suggests that not only do you need to act quickly to get an automated external defibrillator on the scene of a cardiac arrest, but you also should move as quickly as possible from cardiopulmonary resuscitation to defibrillation," says study author Dr. Trygve Eftestol of Norway.

To determine the link between the hands-off interval and survival, researchers studied 634 hands-off intervals in 156 patients with ventricular fibrillation in which external defibrillators were used. The durations of hands-off intervals varied by a median of 20 seconds.

Researchers grouped cardiac arrest victims according to their initial probability (high, medium or low) of return of spontaneous circulation, which was estimated from the starting point of electrocardiographic readings of their hands-off intervals.

The probability of successful defibrillation with return to spontaneous circulation was also estimated at 5, 10, 15, and 20 seconds into each of the hands-off intervals.

Researchers compared the calculated probabilities with the actual rates of return of spontaneous circulation for the medium-level and high-level groups. From this comparison they found that the shorter the hands-off interval, the greater the chance of regaining spontaneous circulation.

People with the highest initial likelihood of circulation return would have received the most benefit from a shorter hands-off interval -- if they had received a shock immediately, they might have had a rate of return of spontaneous circulation as high as 50 percent, says Eftestol. Within 5 seconds, their estimated ROSC rate dropped to 25 percent; after 15 seconds to15 percent; and after 20 seconds, 8 percent.

For those with a medium initial probability of return of spontaneous circulation, shock delivery after a 5-second hands-off period resulted in return of circulation in 24 percent; after 15 seconds, 17 percent; and at 20 seconds, 11 percent. The group with the lowest probability of return of spontaneous circulation had only about a 5 percent estimated chance of return of spontaneous circulation throughout the intervals.

"This study is extremely important for several reasons," says Mary-Fran Hazinski, R.N., M.S.N., former chair of the American Heart Association's emergency cardiovascular care committee. "First, it reaffirms the importance of cardiopulmonary resuscitation training and the important role of cardiopulmonary resuscitation with the use of automated external defibrillators. Second, it provides very solid data that supports the need to shorten the time required for defibrillator rhythm analysis and charging."

 


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