Literature Review: Defibrillation and Recurrent VF

     Koster RW, Walker RG, Chapman FW. Recurrent ventricular fibrillation during advanced life support care of patients with prehospital cardiac arrest. Resusc 78(3):252–7, Sept 2008.

Abstract
     The response of recurrent episodes of ventricular fibrillation (VF) to defibrillation shocks has not been systematically studied. The authors analyzed outcomes from countershocks delivered for VF during ALS care of patients with out-of-hospital cardiac arrest. Methods—[Authors examined a] cohort of patients with prehospital cardiac arrest presenting with VF treated by ALS ambulance staff following the 2000 AHA guidelines. Biphasic defibrillators provided shocks increasing from 200J to 360J. Recorded signals were analyzed to determine, for each shock, if VF was terminated and if a sustained organized rhythm was restored within 60 seconds.

     Results—In 465 of the 467 patients enrolled, the initial VF episode was terminated within three shocks: Respectively, 92%, 61% and 83% responded to 200J first, 200J second and 360J third shocks. VF recurred in 48% of patients within two minutes 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 &llt; 0.001) without change in transthoracic impedance, yet the proportion returning to organized rhythms increased (11%–42%, p &llt; 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.

Comment
     Most of us know this occurs, but may not be aware of how common it is. Three of four patients who go into ventricular fibrillation have it recur before reaching the hospital. After successful defibrillation it is easy to be distracted by other tasks—starting the IV, giving antiarrhythmic medication, moving the patient—which many times results in a delay in recognizing the patient is again in VF. Since time to shock directly relates to the likelihood of survival, it is critically important to be continuously monitoring these patients and immediately defibrillating VF. EMS QI programs may want to look at times to defibrillation for recurring VF.

EMS BLOGSPOT: Psychic Computing by Tom Reynolds
     A couple of months ago we had a quiet start to the day—three crews all sitting on station waiting for someone to be sick. We talked about some of the jobs we'd been on, did some informal teaching and generally renewed the sense of teamwork between those crews. It was unusual, but very, very valuable. But that's not going to happen anymore because, from yesterday, we have the brilliant new idea of 'Active Area Cover.'

     Active Area Cover means we will no longer spend more than 30 minutes on station. Between the hours of 8 a.m. and 10 p.m., if we are not out on a job, we will be expected to go to an area to either sit in the cab of the ambulance waiting for a call, or roam around in a half mile radius. Outside those hours we may be sent to different stations, or sent to sit outside a hospital. We are to remain at these locations for up to an hour before being allowed to return to station. Or if we keep getting sent jobs, then we are to be given three chances to go to the cover point before being allowed back to station. The idea behind this is that it will reduce our activation time by a whole 60 seconds, while also putting us closer to the next job that is about to come in.

     But how, I hear you ask, do our management know where the next call is coming from? Well, we have a brand new piece of software that can see into the future. Connected to a crystal ball, it uses past trends to tell us where the next person to fall off a ladder will be. Now, while there is evidence that the psychic computer can be of some use in rural settings, according to my crewmate who studied the system for her degree, in urban settings its effectiveness is unproved. Essentially the population density is such that a computer system like this is almost certainly worthless.

     And the purpose behind this? Well, obviously it's to meet targets. Getting to a patient one minute quicker won't matter in 99% of the jobs that we do. The psychic computer will be useless, as useless as the automated dispatch we have been using for the last few months. Patient care won't change, it may even get worse—especially if the computer is wrong. I suspect that our targets will continue to plummet. What is needed is either fewer patients or more ambulances, and these ways of 'working more efficiently' are all trying to disguise this truth.

     Tom Reynolds is an EMT for the London Ambulance Service. He is the author of Blood, Sweat and Tea: Real Life Adventures in an Inner-city Ambulance and has kept an online diary of his daily working life since 2003. See https://randomreality.blogware.com/blog.

Angelo Salvucci, Jr., MD, FACEP, is an emergency physician and medical director for the Santa Barbara County and Ventura County (CA) EMS Agencies.