Simulation and educationWill medical examination gloves protect rescuers from defibrillation voltages during hands-on defibrillation?☆
Introduction
Pauses in chest compressions during CPR are known to be detrimental to survival.1 The 2005 American Heart Association Guidelines eliminated some reasons for pauses,2 but interruptions still occur to allow intubation,3 ventilations,4 AED analyses, charging, and defibrillation shocks.5 While shock delivery accounts for a relatively minor fraction of the total hands-off time in most cases, elimination of the shock pause is consistent with the overall goal of minimizing hands-off time. In addition, pausing CPR for shock delivery complicates the resuscitation protocol, requiring close coordination between multiple members of the resuscitation team to avoid inadvertent rescuer shocks while minimizing hands-off time.
Recently, Lloyd et al. suggested that it may be possible for rescuers to continue chest compressions during a defibrillation shock.6 They studied the safety of “hands-on defibrillation” by simulating chest compressions while delivering external cardioversion shocks to patients with atrial fibrillation. No harm came to the “rescuers,” and although the authors cautioned against extrapolation beyond the limits of their model, they concluded that, “Uninterrupted manual chest compressions during shock delivery are feasible.”
Although defibrillator shock intensity is commonly expressed in terms of joules, it is the voltage that determines the risk of an unintended operator shock. For common biphasic external defibrillators, the voltage applied to the patient for the first shock ranges from about 1300 to 1800 V.13 Maximum energy biphasic shocks can be as high as 2700 V.7 Due to the large magnitude of these voltages caution is wise. The best approach for providing optimal patient care while minimizing the rescuer hazards is unclear.
A number of factors contribute to the risk of hands-on defibrillation. Two key factors are, (1) the fraction of the shock voltage presented across the rescuer and (2) the voltage standoff capability of the gloves. Neither of these factors is known.
The fraction of the shock voltage presented across the rescuer is dependent on the electrical circuit formed by the patient and the rescuer. This is illustrated in Fig. 1.
The possible current paths through a rescuer have not been well studied but one model has been proposed that includes current flow through the rescuer's chest.17 In this model the gloves can serve as a barrier to current flow through the rescuer and may provide an important safety mechanism.
In general, medical examination gloves are designed as a barrier to bodily fluids, not electricity, and manufacturers typically do not provide electrical specifications for their gloves. One study using the AC (alternating current) voltage from an electrocautery device found latex and neoprene glove breakdown voltages as low as 2000 V,8 but it is unclear how these results relate to hands-on defibrillation. Little other information is available that would allow the safety of hands-on defibrillation to be assessed. A recent review paper by Petley et al. suggested, “Further work needs to be carried out to determine the necessary electrical and mechanical properties required of an insulator suitable to be used to protect rescuers.”9
The purpose of this study was to compare the DC (direct current) electrical characteristics of common medical examination gloves with the output voltages of biphasic defibrillators.
Section snippets
Part 1
Part one of this study examined the shape of the voltage–current curve for several types of gloves by applying a range of DC voltages to each glove and recording the current flow at each level. The goal of this part of the study was to determine if the current flow in these gloves typically exhibits a “breakdown” characteristic and, if so, to determine the voltage level at which it occurs.
A dielectric analyzer (Vitrek 944i, San Diego, CA) was used to apply the voltage to the gloves and monitor
Part 1
All gloves exhibited a highly nonlinear “hockey-stick” shaped voltage–current relationship that is characteristic of an electrical breakdown (Fig. 2). The current flow for every glove stayed below about 1 mA until breakdown, at which point current flow abruptly jumped up and the dielectric analyzer removed the voltage. The breakdown voltage varied greatly among gloves, ranging from 2500 V to 4000 V.
Part 2
Some single gloves (32/80 = 40% chloroprene, 2/60 = 3% latex, 42/60 = 70% nitrile, and 42/60 = 70% vinyl) of
Discussion
The main findings of this study are that current flow through medical examination gloves is highly non-linear with respect to voltage, and that the current flow is very inconsistent among glove types and between samples of a single glove type. This makes the risks of hands-on defibrillation difficult to predict (Fig. 4).
This study was the first to measure voltage–current curves for medical examination gloves. These data are relevant because they illustrate the difficulty of assessing the safety
Limitations
This study was limited primarily because it characterized only one factor relating to the safety of hands-on defibrillation: the electrical characteristics of medical examination gloves. The other factor – the fraction of the shock voltage presented to the rescuer – is equally important. Currently, there are no data available on that factor.
In order for current to flow through a rescuer there must be a current path. This study is not predicated on a particular current path but merely postulates
Conclusions
Few of the gloves tested limited the current to levels proven to be safe. A lack of sensation during hands-on defibrillation does not guarantee that a safety margin exists. As such, we encourage rescuers to minimize rather than eliminate the pause in compressions for defibrillation.
Conflict of interest statement
The authors are both employees of Physio-Control, Inc., a manufacturer of external defibrillators.
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Cited by (21)
Ex vivo evaluation of personal protective equipment in hands-on defibrillation
2022, Resuscitation PlusThe safety and efficacy of hands-on defibrillation in the management of adult cardiac arrest: A systematic review
2020, American Journal of Emergency MedicineTeam-focused Cardiopulmonary Resuscitation: Prehospital Principles Adapted for Emergency Department Cardiac Arrest Resuscitation
2018, Journal of Emergency MedicineHands-on defibrillation during active chest compressions: eliminating another interruption
2016, American Journal of Emergency MedicineCitation Excerpt :Only latex gloves consistently performed well as a single glove, requiring voltage well above biphasic defibrillator voltage range before current leakage beyond IEC standards occurred. Although electrical leakage occurred for all other single glove types, breakdown voltages were above the highest biphasic defibrillator voltage for all gloves [22]. Similarly, Petley et al [29] exposed 3 varieties of nitrile gloves and 1 type of vinyl glove to 10 successive “worst-case” shocks (contact with both defibrillation electrodes), both monophasic and biphasic.
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A Spanish translated version of the summary of this article appears as Appendix in the final online version at http://dx.doi.org/10.1016/j.resuscitation.2012.07.031.