Abstract 7: Professionals Decrease Survival After Takeover from Lay Rescuers by Interrupting the Automated External Defibrillator Protocol
Introduction - There are no guidelines for transition of care with ongoing cardiopulmonary resuscitation (CPR) from rescuers with automated external defibrillator (AED) to paramedics. The objective of this study was to determine whether takeover of the AED a) needles delays shocks, b) interrupts CPR and c) influences survival.
Methods - This was a prospective observational study. Between July 2005 and April 2007, we collected continuous ECG recordings with impedance signal of AEDs and associated manual defibrillators of all non-traumatic out-of-hospital cardiac arrests. Continuous ECG recordings were analyzed for shock delay after takeover (defined as the interval between expected moment of shock by the AED and observed moment of shock by professionals) and interruption of CPR. Time available for CPR given during that time interval was set at 100%. Survival to discharge was determined from hospital records.
Results - Full recordings of 216 of the 353 patients (pts) with initially connected AEDs were available for analysis. During takeover, 144 pts had a non-shockable, and 72 had a shockable rhythm. Shocks were delayed in 35/72 (49%) of the pts, with a median (range) delay of 162 (12– 862) seconds. The delayed shock was the first in 28% of the cases. Shocks were given prematurely in 25/72 (35%) of the pts and CPR was given 27% (0%–72%) of the available time. Shocks were given in time in 8/72 cases (11%), and 4/72 (6%) pts were not defibrillated at all. When shocks were delayed over 10 seconds, survival was 17% (6/35) vs 45% (15/33) when the shock was given premature or in time (RR 0.53 [95%CI, 0.34 – 0.84] P=0.01). CPR continuation during less than 75% of the available time did not influence survival rates in either shockable or non-shockable rhythms.
Conclusion - Disconnection of the AED by paramedics interrupts the treatment protocol, delaying time of defibrillation by almost three minutes. Shock delay of more than 10 seconds significantly lowered survival. Premature defibrillation leads to decrease in CPR time. The AED should only be disconnected immediately after rhythm analysis or shock delivery.