Date: February 13th, 2015
Guest Skeptic: Dr. Manrique Umaña. Manrique (@umanamd) is an Emergency Physician from San Jose, Costa Rica and the Residency Program Director. He is the co-author of a Spanish-based blog called www.ViaMedEM.com and an active person in #FOAMed world.
Case: You receive in your emergency department a 55-year-old male who goes into cardiac arrest minutes after he arrives. He´s rushed into the shock room and CPR is started.
Chest compressions are ongoing and as soon as the monitor pads are attached, you notice the patient to be in ventricular fibrillation. A resident next to you says that he has read that the patient can be shocked without stopping chest compressions.
Everyone in the room immediately turns their eyes on you to make the call and the intern doing CPR asks if it´s really safe to do so.
Background: Defibrillation is the treatment of choice for rhythm disturbances like ventricular fibrillation and ventricular tachycardia without a pulse. Rapid and early defibrillation has been shown to increase survival after cardiac arrest.
There was some suggestion that a short period of CPR should be done prior to defibrillation in out of hospital cardiac arrest. However, a systematic review by Simpson et al in Resuscitation 2010 on this topic demonstrated no superiority of delayed vs. immediate shocking.
High quality chest compressions have also been shown to improve outcomes in cardiac arrest, to the extent that delays in starting them and even brief interruptions are associated with worse survival rates.
- AHA Guidelines stress no interruptions. Travers et al. American Heart Association guidelines for cardiopulmonary resuscitation and emergency cardiovascular care. Circulation 2010
- Cheskes el al. Perishock pause: an independent predictor of survival from out-of-hospital shockable cardiac arrest. Circulation 2011
Having this in mind, the use of hands-on defibrillation to reduce interruption of chest compressions after cardiac arrest has been suggested as a means of improving resuscitation outcomes.
Lloyd et al 2008 looking at the electrical current flow through the rescuers who had their hands on patients being defibrillated.
- 43 hands-on shocks with most at 200j but a few at 360j
- None of the rescuers felt the shocks who wore polyethylene gloves
- About 10% of the shocks were above the allowable 0.5mA
- The authors concluded shocking while doing CPR was feasible
The potential dangers of this strategy in regard to exposing rescuers to electrical energy are still being debated. There is a study on how much protection different glove types might provide. Sullivan and Chapman in 2012 study called Will medical examination gloves protect rescuers from defibrillation voltages during hands-on defibrillation?
- Four types of gloves (latex, chloroprene, nitrile, and vinyl)
- Tested single glove and double glove both tested in two parts
- Part 1 looked at 8 gloves and increased the voltage until breakdown occurred
- Part 2 looked at two current levels (0.1mA and 10mA)
- 45% of single gloves and 77% of double gloves allowed at least 0.1 mA of current flow with external defibrillation
- 5% of single gloves and 6.2% of gloves allowed at least 10 mA of current flow with external defibrillation
- Concluded of the tested gloves only a few limited the current to levels proven to be safe
Question: Is it safe to shock a patient during ongoing chest compressions (so-called hands-on defibrillation)?
Reference: Lemkin et al Electrical exposure risk associated with hands-on defibrillation. Resuscitation 2014
- Population: Eight cadavers, neither frozen nor embalmed, with BMI between 12-29.
- Intervention: Resistance measurements taken from eight cadavers and two investigators using a calibrated multi-meter connected to monitoring electrodes placed 40cm apart on the chest. A variety of preparations to measure resistance differences (intact skin, abraded skin, water, saline, ultrasound gel and needle probes). After this, six of the cadavers were placed on tables, not grounded. Defibrillation pads were placed in the anterior and posterior chest walls. Measurement electrodes were placed, one at the back and the rest at diverse anterior anatomic landmarks. Voltages were measured with respect to the posterior electrode. The anterior and posterior defibrillation pads were attached to a defibrillator and 360J biphasic discharges were given, with the subsequent voltages measured.
- Control: There was no control group.
- Outcome: With the variables measured (resistance and voltage), they estimated the rescuer-received dose to estimate energy received during the defibrillation.
Authors’ Conclusions: Hands-on defibrillation using currently available personal protective equipment and resuscitative procedures poses a risk to rescuers. The process should be considered potentially dangerous until equipment and techniques that will protect rescuers are developed.
- Was this study based on a random or pseudo-random sample? No
- Were the criteria for inclusion in the sample clearly defined? Yes
- Were confounding factors identified and strategies to deal with them stated? No
- Were outcomes assessed using objective criteria? Yes
- If comparisons are being made, was there sufficient descriptions of the groups? NA
- Was follow up carried out over a sufficient time period? NA
- Were the outcomes of people who withdrew described and included in the analyses? NA
- Were outcomes measured in a reliable way? Yes
- Was appropriate statistical analysis used? Yes
Key Results: Defibrillation resulted in rescuer exposure voltages ranging from 827V to ~200V, depending on cadaver and anatomic location. The rescuer received dose under the test scenarios ranged from 1 to 8 J, which is in excess of accepted energy exposure levels.
This study adds to the literature on the topic of hands on defibrillation. However, it is not patient oriented or provider oriented literature. The key message is to perform high quality chest compression and defibrillate early.
Our Conclusions Compared to Authors’: We agree with the authors conclusion in that even thought the amount of energy transferred during hands-on defibrillation might not be that much, it’s sufficient to post a threat to the medical personnel and therefore it shouldn’t be done for now.
SGEM Bottom Line: Performing hands on defibrillation poses a risk and it’s a practice that should NOT be performed.
Case Resolution: You quickly state to the team that a recent study in resuscitation demonstrates that hands-on defibrillation is potentially dangerous and should not be done. You keep the compressions going while you charge the defibrillator to avoid longer pauses but do stop compressions for the electrical discharge and immediately resume CPR.
Clinical Application: Although you can find many case reports of people doing hands on defibrillation, this study shows that there’s a risk involved and that this practice should be avoided. Instead, you can charge the defibrillator during the compressions and just stop for a brief period to give the discharge and resume compressions immediately.
What Do I Tell Patients (Providers)? The evidence available to this day shows that hands-on defibrillation is potentially dangerous and should not be done.
Keener Kontest: Last weeks winner was Dr. Glen Armstrong from Beaverlodge Alberta. Glen knew that Ian Stiell’s group has just published a new clinical decision tool paper on COPD. Clinical characteristics associated with adverse events in patients with exacerbation of chronic obstructive pulmonary disease: a prospective cohort study. CMAJ. 2014
Listen to this weeks episode of the SGEM. If you know the answer to the keener question then send me your answer to ThesSGEM@gmail.com with keener in the subject line. The first person with the correct answer will receive a cool skeptical prize.
Thank you to Manrique and the other Costa Rican doctors who showed me such a wonderful time and taught me about Pura Vida (pure life).
Remember to be skeptical of anything you learn, even if you heard it on the Skeptics’ Guide to Emergency Medicine