Recurrent ventricular fibrillation during advanced life support care of patients with prehospital cardiac arrest.
OBJECTIVE
The response of recurrent episodes of ventricular fibrillation (VF) to defibrillation shocks has not been systematically studied. We analyzed outcomes from countershocks delivered for VF during advanced life support (ALS) care of patients with out-of-hospital cardiac arrest.


METHODS
Cohort of patients with prehospital cardiac arrest presenting with VF, treated by ALS ambulance staff following ERC Guidelines 2000. Biphasic defibrillators provided shocks increasing from 200 to 360J. Recorded signals were analyzed to determine, for each shock, if VF was terminated and if a sustained organized rhythm was restored within 60s.


RESULTS
In 465 of the 467 patients enrolled, the initial VF episode was terminated within three shocks: 92%, 61%, and 83% responded to 200J first, 200J second and 360J third shocks, respectively. VF recurred in 48% of patients within 2min of the first episode, and in 74% sometime during prehospital care. In the 175 patients experiencing five or more VF episodes, single shock VF termination dropped from the first to the fifth episode (90-80%, p<0.001) without change in transthoracic impedance, yet the proportion returning to organized rhythms increased (11-42%, p<0.0001).


CONCLUSIONS
Repeated refibrillation is common in patients with VF cardiac arrest. The likelihood of countershocks to terminate VF declines for repeated episodes of VF, yet shocks that terminate these episodes result increasingly in a sustained organized rhythm.
Academic Medical Center, University of Amsterdam, Amsterdam, The Netherlands. R.W.Koster@amc.nl
Rudolph W
RW
Koster
Robert G
RG
Walker
Fred W
FW
Chapman
D022561:Advanced Cardiac Life Support; D000368:Aged; D004554:Electric Countershock; D004632:Emergency Medical Services; D005260:Female; D005500:Follow-Up Studies; D006323:Heart Arrest / Q000209:etiology / Q000503:physiopathology / Q000628:therapy*; D006801:Humans; D008297:Male; D008875:Middle Aged; D020380:Needs Assessment; D009426:Netherlands; D011446:Prospective Studies; D012008:Recurrence; D016896:Treatment Outcome; D014693:Ventricular Fibrillation / Q000175:diagnosis / Q000503:physiopathology / Q000628:therapy*