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Do clinical examination gloves provide adequate electrical insulation for safe hands-on defibrillation? II: Material integrity following exposure to defibrillation waveforms
Resuscitation 84 (2013) 900–903
Contents lists available at ScienceDirect
Resuscitation journal homepage: www.elsevier.com/locate/resuscitation
Clinical paper
Do clinical examination gloves provide adequate electrical insulation for safe hands-on defibrillation? II: Material integrity following exposure to defibrillation waveforms夽 Graham W. Petley a , Charles D. Deakin b,∗ a b
Department of Medical Physics, University Hospital Southampton, United Kingdom Department of Anaesthetics, University Hospital Southampton, United Kingdom
a r t i c l e
i n f o
Article history: Received 22 December 2012 Received in revised form 7 March 2013 Accepted 8 March 2013 Keywords: Defibrillation Safety External chest compression Current Voltage
a b s t r a c t Introduction: Maintaining contact with the patient during defibrillator discharge has been proposed as a method for reducing no flow time but carries an associated risk of electrocution of the rescuer. This study describes an investigation to determine if typical clinical examination gloves possess the dielectric strength needed to prevent breakdown at defibrillation voltages; a factor essential to protect the rescuer. Methods: Four types of examination glove typically used in a clinical environment were tested with two types of defibrillation waveform commonly used. For each type of glove, 10 samples were tested initially using a monophasic defibrillation waveform and then, using a fresh sample of gloves, with a Biphasic waveform. For each glove the number of shocks required before electrical breakdown occurred was recorded. Results: Kimberly Clark KC300 (nitrile), Kimberly Clark KC500 purple (nitrile), PH Medisavers GN90 (nitrile) and Bodyguards GL6622 (Vinyl) were tested using a monophasic defibrillation waveform and broke down after a median of 1, 4.5, 1 and 1 shocks respectively. The equivalent values for Biphasic defibrillator were 2, >10, 2.5 and 1 shocks. Discussion: Typical clinical examination gloves do not possess the dielectric strength required to protect a rescuer from defibrillation voltages during hands-on chest compressions. © 2013 Elsevier Ireland Ltd. All rights reserved.
1. Introduction Although the quality of external chest compression is a key determinant of survival, chest compressions may be absent for 24–63%1–4 of the total resuscitation time. A large component of this no flow time is associated with ensuring rescuer safety and specifically by them being required to stand clear during shock delivery. ‘Hands-on defibrillation’ has been proposed as a solution to this; an approach enabling the rescuer to continue chest compressions during shock delivery, thereby significantly reducing no-flow time.5 Any change to the established and proven safety protocol for the rescuer should not be undertaken lightly, and testing is essential to ensure that rescuer safety is not compromised as a result.
夽 A Spanish translated version of the abstract of this article appears as Appendix in the final online version at http://dx.doi.org/10.1016/j.resuscitation.2013.03.012. ∗ Corresponding author at: University Hospital Southampton, Tremona Road, Southampton SO16 6YD, United Kingdom. E-mail address: [email protected] (C.D. Deakin). 0300-9572/$ – see front matter © 2013 Elsevier Ireland Ltd. All rights reserved. http://dx.doi.org/10.1016/j.resuscitation.2013.03.012
Defibrillators produce voltages as high as 3000 V for a biphasic defibrillator and 5000 V for older monophasic defibrillators6 which have the potential to cause significant harm to the rescuer.7 It has been suggested that gloves may allow hands-on defibrillation by providing a safe electrical barrier for the rescuer.8 In the European Union, medical devices such as medical examination gloves must comply with the requirements of the Medical Devices Directive.9 A key component of this directive is to ensure adequate performance when the device is used for the purpose specified by the manufacturer. Medical examination gloves are intended as a barrier to bodily fluids and are not designed to provide electrical protection of the rescuer. Consequently, electrical performance is variable and may also change over time as manufacturer’s modify their production processes. Gloves should not therefore be relied upon for rescuer protection, unless this is their intended purpose.10 For gloves to provide effective electrical protection, they must provide adequate electrical impedance to limit current, remain intact during exposure to the physical shear stresses typically encountered when performing chest compressions and have a dielectric strength capable of withstanding defibrillation voltages. Our previous paper has documented that the first two of these
G.W. Petley, C.D. Deakin / Resuscitation 84 (2013) 900–903
901
Fig. 1. Apparatus used to deliver defibrillation shock and measure electrical resistance across the gloves.
requirements are not met by commonly used clinical examination gloves.11 In this paper we focus on the third of these requirements and examine whether commonly used clinical examination gloves remain intact following exposure to the high voltages delivered by specific defibrillator waveforms. 2. Methods Four types of clinical examination glove commonly used in the UK healthcare system and specifically in the acute teaching hospital in which this study was undertaken were included in the study. These were: o o o o
Kimberly Clark KC300 Sterling nitrile examination gloves Kimberly Clark KC500 purple nitrile examination gloves PH Medisavers GN90 nitrile examination gloves Bodyguards GL6622 Easy Fit vinyl gloves
Gloves were tested using two waveforms; Monophasic (HP Codemaster) and Biphasic (Philips Heartstart XL). The first shock energy levels recommended in the current resuscitation guidelines for the particular defibrillator were selected and used throughout, simulating a fixed protocol (monophasic waveform @ 360J, biphasic waveform @ 150J).12 Prior to testing gloves, the accuracy and repeatability of the defibrillator output was checked using a Metron QA 45 Mk II defibrillation analyzer. For each defibrillator, up to ten successive shocks were delivered and the energy and peak voltage measured. Using previously described methodology, new, unused gloves were filled with saline and mounted in a saline bath.11 A copper electrode was placed in each of the saline baths so as to make good electrical contact with both the inner and outer glove surfaces. To simulate a patient, the defibrillator was attached to a 50 load. Leads were then extended from the load and connected to the
copper electrodes in the saline water baths (Fig. 1). This circuit represents the worst case scenario of the rescuer making contact with one electrode via a gloved hand, and a return current path to the second electrode via a low impedance pathway. Having mounted the new glove in the test rig, confirmation that it was intact was made by measuring the resistance between the electrodes, comparing it with the range previously established for intact gloves.11 Once charging was complete, the defibrillator was discharged manually and the glove monitored for audible or visual evidence of arching. If none were present, then the defibrillator was discharged a second time (at the same energy level) and so on up to a maximum of ten discharges. Confirmation that glove integrity had been breached was achieved by measuring resistance following a suspected arching event. Four glove types were tested. Ten gloves of each type were exposed to a maximum of 10 shocks of a monophasic waveform following which the study was repeated using a fresh sample of gloves with a biphasic waveform. For each glove test, the peak voltage associated with a breach of insulation (or the tenth test if no breach) was recorded using the defibrillation analyzer.
3. Results For the monophasic defibrillator, discharging 10 successive shocks into a test load gave a mean (SD) energy of 356.5 (1.1) J compared with a selected energy of 360 J. Peak voltage was 2817.5 (2) V. This equates to a coefficient of variation of 0.3% for energy and 0.1% for voltage. The equivalent values for the biphasic defibrillator were 146.0 (3.3) J for a selected energy of 150 J with a peak voltage of 1604.3 (12.4) V giving coefficient of variation of 2.3% for energy and 0.8% for voltage. Results are summarized in Table 1, showing the percentage of gloves remaining intact after 10 sequential shocks and, of those that
Table 1 Median number of shocks (monophasic @ 360 J, biphasic @ 150 J) resulting in glove breakdown. Results are shown as median and range. Monophasic waveform
Kimberley Clark KC300 (Nitrile) Kimberley Clark purple (Nitrile) Medisave examination gloves (Nitrile) Bodyguards Easy Fit gloves (Vinyl)
Biphasic waveform
% Intact gloves (n) after 10 shocks
Median (range) number of shocks for breakdown
% Intact gloves (n) after 10 shocks
Median (range) number of shocks for breakdown
0% (0) 80% (8) 0% (0) 0% (0)
1 (1) 4.5 (4–5) 1 (1) 1 (1)
70% (7) 100% (10) 0% (0) 0% (0)
2 (1–8) 2.5 (1–7) 1 (1)
902
G.W. Petley, C.D. Deakin / Resuscitation 84 (2013) 900–903
Table 2 Mean (SD) peak voltage applied to each sample group.
Kimberley Clark KC300 Kimberley Clark purple KC500 PH Medisavers GN90 Bodyguards GL6622
Monophasic waveform
Biphasic waveform
2622 (152) V 2781 (86) V 2216 (208) V 1822 (204) V
1596 (29) V 1548 (54) V 1588 (33) V 1603 (21) V
broke down, the median number of shocks with each waveform resulting in glove breakdown. In all cases the resistance following visual and audible indication of arcing fell to below 5% of the initial value thereby confirming a breach of glove integrity. Following failure, glove resistance fell to a mean of 0.6% (monophasic) and 2.7% (biphasic) of baseline value. Conversely, the resistance of gloves displaying no qualitative evidence of failure remained above 90% of the initial value. The peak voltage to which the gloves were exposed is summarized in Table 2. As expected, the peak voltage applied by the higher energy monophasic shock was greater than for the biphasic shock (2360 V vs 1584 V – mean of all gloves tested). 4. Discussion No clinical examination glove type was 100% effective at preventing dielectric breakdown for monophasic shocks at 360 J and only one glove type was effective for the biphasic defibrillator waveform. Dielectric breakdown of gloves has previously been shown to be associated with a rapid rise in current suggesting a significant risk to the rescuer10 . Even if gloves remain intact following exposure to defibrillation waveforms, we have previously demonstrated that the integral resistance of gloves is inadequate to limit leakage current in the rescuer to below the safe threshold of 1 mA, demonstrating that clinical examination gloves fail to provide the necessary protection to a rescuer required during hands-on chest compressions. This finding is perhaps not unsurprising since none of the clinical examination glove manufacturers list electrical protection as an intended use. Consequently, even if the sample tested had been successful in withstanding defibrillation voltages, the conclusion would remain unaltered as manufacturers are unlikely to design or test products with this application in mind, leaving the possibility of a large variation in dielectric property and lack of compliance with the European Medical Devices Directive.9 It has previously been shown that electrical breakdown occurs at voltages typically encountered during defibrillation, but the study was performed using a stepwise increase in voltage and therefore used a waveform that bears little resemblance to a defibrillation waveform used clinically.10,13 Our study, performed with defibrillator waveforms, tested gloves using a more realistic scenario but has resulted in similar findings. As is expected, the higher energy delivered by the monophasic defibrillator was associated with a higher voltage and produced more glove failures. Defibrillation waveforms are alternating current (AC) for which it is important to consider impedance. Impedance takes account not only of the effect of resistance but also of inductance and capacitance. In this scenario, the capacitance across the glove is likely to be particularly important and although not assessed, can be assumed to further reduce the total impedance and therefore increase current flow compared with consideration of resistance alone. The glove area tested in this study was larger than the likely contact area with the patient during a clinical scenario. This will have the effect of reducing measured resistance and increasing the likelihood that the gloves weakest point is coincident with the area tested. However, since material properties do not alter to any great
extent over the surface of the glove, this is unlikely to alter the conclusion. In this study, the gloves that were tested were new and had not been worn prior to testing. Evidence from our previous study suggests that wearing gloves degrades their electrical properties, probably through a number of mechanisms including stretching, shear stresses and ingress of conductive moisture.11 It might be expected therefore that the results presented in this study are a best case as far as the gloves’ resistance to electrical breakdown is concerned and that gloves may fail at an earlier defibrillation attempt in a clinical scenario. The use of double gloves has been suggested as a method of improving safety for rescuers, but two glove layers are still likely to provide inadequate resistance. Tears to gloves are relatively common and would then leave the rescuer exposed to a single layer which we have demonstrated is likely to breakdown. Two glove layers will provide double the resistance of a single layer and will therefore still provide inadequate electrical resistance, enabling defibrillator current to exceed the safe threshold of 1 mA.6 Examination gloves are not intended for use as an electrical insulator and therefore have neither been designed nor tested for this purpose.14 Gloves used by other industries (e.g. power industry) are available that are specifically design as personal protective equipment through providing an insulating barrier to high voltages. Further work is required to develop a glove that combines the material properties of the examination glove designed for the clinical environment, with those of insulating gloves designed as personal protective equipment (PPE). In conclusion, in order to provide electrical protection to the rescuer during hands on defibrillation, it is necessary for a glove to have adequate electrical impedance to limit current to a safe level, remain intact during exposure to the physical shear stresses typically encountered when performing chest compressions and have a dielectric strength capable of withstanding defibrillation voltages. This study again confirms that the material properties of typical examination gloves do not prevent dielectric breakdown using standard defibrillation waveforms and energy levels and are therefore unsuitable as PPE for the rescuer during hands-on defibrillation.13 Unless gloves are manufactured and sold as protective devices, then they should not be used as such, irrespective of their response to defibrillation voltages. Conflict of interest statement No conflicts of interest to declare. Acknowledgements The authors are grateful to David Johnson, Steve Clitheroe and Brad Olden for their assistance with developing the measurement apparatus. Appendix A. Supplementary data Supplementary data associated with this article can be found, in the online version, at http://dx.doi.org/10.1016/ j.resuscitation.2013.03.012. References 1. Abella BS, Alvarado JP, Myklebust H, et al. Quality of cardiopulmonary resuscitation during in-hospital cardiac arrest. JAMA 2005;293:305–10. 2. Wik L, Kramer-Johansen J, Myklebust H, et al. Quality of cardiopulmonary resuscitation during out-of-hospital cardiac arrest. JAMA 2005;293:299–304. 3. Valenzuela TD, Kern KB, Clark LL, et al. Interruptions of chest compressions during emergency medical systems resuscitation. Circulation 2005;112:1259–65. 4. van Alem AP, Sanou BT, Koster RW. Interruption of cardiopulmonary resuscitation with the use of the automated external defibrillator in out-of-hospital cardiac arrest. Ann Emerg Med 2003;42:449–57.
G.W. Petley, C.D. Deakin / Resuscitation 84 (2013) 900–903 5. Lloyd MS, Heeke B, Walter PF, Langberg JJ. Hands-on defibrillation: an analysis of electrical current flow through rescuers in direct contact with patients during biphasic external defibrillation. Circulation 2008;117:2510–4. 6. Petley GW, Cotton AM, Deakin CD. Hands-on defibrillation: theoretical and practical aspects of patient and rescuer safety. Resuscitation 2012;83:551–6. 7. Hoke RS, Heinroth K, Trappe H-J, Werdan K. Is external defibrillation an electric threat for bystanders? Resuscitation 2009;80:395–401. 8. Kerber RE. “I’m clear, you’re clear, everybody’s clear”: a tradition no longer necessary for defibrillation? Circulation 2008;117:2435–6. 9. Medical Devices Directive 93/42/EEC. In. 10. Sullivan JL. Hands-on defibrillation: an analysis of electrical current flow through rescuers in direct contact with patients during biphasic external defibrillation. Circulation 2008;118:e712.
903
11. Deakin CD, Lee-Shrewsbury V, Hogg K, Petley G. Do clinical examination gloves provide adequate electrical insulation for safe handson defibrillation? I: Resistive properties of nitrile gloves. Resuscitation, http://dx.doi.org/10.1016/j.resuscitation.2013.03.011, in press. 12. Deakin CD, Nolan JP, Sunde K, Koster RW. European Resuscitation Council Guidelines for Resuscitation 2010 Section 3. Electrical therapies: automated external defibrillators, defibrillation, cardioversion and pacing. Resuscitation 2010;81:1293–304. 13. Sullivan JL, Chapman FW. Will medical examination gloves protect rescuers from defibrillation voltages during hands-on defibrillation? Resuscitation 2012;83:1467–72. 14. Deakin CD. Clinical examination gloves – fit only for their intended purpose. Resuscitation 2012;83:1421–2.
Contents lists available at ScienceDirect
Resuscitation journal homepage: www.elsevier.com/locate/resuscitation
Clinical paper
Do clinical examination gloves provide adequate electrical insulation for safe hands-on defibrillation? II: Material integrity following exposure to defibrillation waveforms夽 Graham W. Petley a , Charles D. Deakin b,∗ a b
Department of Medical Physics, University Hospital Southampton, United Kingdom Department of Anaesthetics, University Hospital Southampton, United Kingdom
a r t i c l e
i n f o
Article history: Received 22 December 2012 Received in revised form 7 March 2013 Accepted 8 March 2013 Keywords: Defibrillation Safety External chest compression Current Voltage
a b s t r a c t Introduction: Maintaining contact with the patient during defibrillator discharge has been proposed as a method for reducing no flow time but carries an associated risk of electrocution of the rescuer. This study describes an investigation to determine if typical clinical examination gloves possess the dielectric strength needed to prevent breakdown at defibrillation voltages; a factor essential to protect the rescuer. Methods: Four types of examination glove typically used in a clinical environment were tested with two types of defibrillation waveform commonly used. For each type of glove, 10 samples were tested initially using a monophasic defibrillation waveform and then, using a fresh sample of gloves, with a Biphasic waveform. For each glove the number of shocks required before electrical breakdown occurred was recorded. Results: Kimberly Clark KC300 (nitrile), Kimberly Clark KC500 purple (nitrile), PH Medisavers GN90 (nitrile) and Bodyguards GL6622 (Vinyl) were tested using a monophasic defibrillation waveform and broke down after a median of 1, 4.5, 1 and 1 shocks respectively. The equivalent values for Biphasic defibrillator were 2, >10, 2.5 and 1 shocks. Discussion: Typical clinical examination gloves do not possess the dielectric strength required to protect a rescuer from defibrillation voltages during hands-on chest compressions. © 2013 Elsevier Ireland Ltd. All rights reserved.
1. Introduction Although the quality of external chest compression is a key determinant of survival, chest compressions may be absent for 24–63%1–4 of the total resuscitation time. A large component of this no flow time is associated with ensuring rescuer safety and specifically by them being required to stand clear during shock delivery. ‘Hands-on defibrillation’ has been proposed as a solution to this; an approach enabling the rescuer to continue chest compressions during shock delivery, thereby significantly reducing no-flow time.5 Any change to the established and proven safety protocol for the rescuer should not be undertaken lightly, and testing is essential to ensure that rescuer safety is not compromised as a result.
夽 A Spanish translated version of the abstract of this article appears as Appendix in the final online version at http://dx.doi.org/10.1016/j.resuscitation.2013.03.012. ∗ Corresponding author at: University Hospital Southampton, Tremona Road, Southampton SO16 6YD, United Kingdom. E-mail address: [email protected] (C.D. Deakin). 0300-9572/$ – see front matter © 2013 Elsevier Ireland Ltd. All rights reserved. http://dx.doi.org/10.1016/j.resuscitation.2013.03.012
Defibrillators produce voltages as high as 3000 V for a biphasic defibrillator and 5000 V for older monophasic defibrillators6 which have the potential to cause significant harm to the rescuer.7 It has been suggested that gloves may allow hands-on defibrillation by providing a safe electrical barrier for the rescuer.8 In the European Union, medical devices such as medical examination gloves must comply with the requirements of the Medical Devices Directive.9 A key component of this directive is to ensure adequate performance when the device is used for the purpose specified by the manufacturer. Medical examination gloves are intended as a barrier to bodily fluids and are not designed to provide electrical protection of the rescuer. Consequently, electrical performance is variable and may also change over time as manufacturer’s modify their production processes. Gloves should not therefore be relied upon for rescuer protection, unless this is their intended purpose.10 For gloves to provide effective electrical protection, they must provide adequate electrical impedance to limit current, remain intact during exposure to the physical shear stresses typically encountered when performing chest compressions and have a dielectric strength capable of withstanding defibrillation voltages. Our previous paper has documented that the first two of these
G.W. Petley, C.D. Deakin / Resuscitation 84 (2013) 900–903
901
Fig. 1. Apparatus used to deliver defibrillation shock and measure electrical resistance across the gloves.
requirements are not met by commonly used clinical examination gloves.11 In this paper we focus on the third of these requirements and examine whether commonly used clinical examination gloves remain intact following exposure to the high voltages delivered by specific defibrillator waveforms. 2. Methods Four types of clinical examination glove commonly used in the UK healthcare system and specifically in the acute teaching hospital in which this study was undertaken were included in the study. These were: o o o o
Kimberly Clark KC300 Sterling nitrile examination gloves Kimberly Clark KC500 purple nitrile examination gloves PH Medisavers GN90 nitrile examination gloves Bodyguards GL6622 Easy Fit vinyl gloves
Gloves were tested using two waveforms; Monophasic (HP Codemaster) and Biphasic (Philips Heartstart XL). The first shock energy levels recommended in the current resuscitation guidelines for the particular defibrillator were selected and used throughout, simulating a fixed protocol (monophasic waveform @ 360J, biphasic waveform @ 150J).12 Prior to testing gloves, the accuracy and repeatability of the defibrillator output was checked using a Metron QA 45 Mk II defibrillation analyzer. For each defibrillator, up to ten successive shocks were delivered and the energy and peak voltage measured. Using previously described methodology, new, unused gloves were filled with saline and mounted in a saline bath.11 A copper electrode was placed in each of the saline baths so as to make good electrical contact with both the inner and outer glove surfaces. To simulate a patient, the defibrillator was attached to a 50 load. Leads were then extended from the load and connected to the
copper electrodes in the saline water baths (Fig. 1). This circuit represents the worst case scenario of the rescuer making contact with one electrode via a gloved hand, and a return current path to the second electrode via a low impedance pathway. Having mounted the new glove in the test rig, confirmation that it was intact was made by measuring the resistance between the electrodes, comparing it with the range previously established for intact gloves.11 Once charging was complete, the defibrillator was discharged manually and the glove monitored for audible or visual evidence of arching. If none were present, then the defibrillator was discharged a second time (at the same energy level) and so on up to a maximum of ten discharges. Confirmation that glove integrity had been breached was achieved by measuring resistance following a suspected arching event. Four glove types were tested. Ten gloves of each type were exposed to a maximum of 10 shocks of a monophasic waveform following which the study was repeated using a fresh sample of gloves with a biphasic waveform. For each glove test, the peak voltage associated with a breach of insulation (or the tenth test if no breach) was recorded using the defibrillation analyzer.
3. Results For the monophasic defibrillator, discharging 10 successive shocks into a test load gave a mean (SD) energy of 356.5 (1.1) J compared with a selected energy of 360 J. Peak voltage was 2817.5 (2) V. This equates to a coefficient of variation of 0.3% for energy and 0.1% for voltage. The equivalent values for the biphasic defibrillator were 146.0 (3.3) J for a selected energy of 150 J with a peak voltage of 1604.3 (12.4) V giving coefficient of variation of 2.3% for energy and 0.8% for voltage. Results are summarized in Table 1, showing the percentage of gloves remaining intact after 10 sequential shocks and, of those that
Table 1 Median number of shocks (monophasic @ 360 J, biphasic @ 150 J) resulting in glove breakdown. Results are shown as median and range. Monophasic waveform
Kimberley Clark KC300 (Nitrile) Kimberley Clark purple (Nitrile) Medisave examination gloves (Nitrile) Bodyguards Easy Fit gloves (Vinyl)
Biphasic waveform
% Intact gloves (n) after 10 shocks
Median (range) number of shocks for breakdown
% Intact gloves (n) after 10 shocks
Median (range) number of shocks for breakdown
0% (0) 80% (8) 0% (0) 0% (0)
1 (1) 4.5 (4–5) 1 (1) 1 (1)
70% (7) 100% (10) 0% (0) 0% (0)
2 (1–8) 2.5 (1–7) 1 (1)
902
G.W. Petley, C.D. Deakin / Resuscitation 84 (2013) 900–903
Table 2 Mean (SD) peak voltage applied to each sample group.
Kimberley Clark KC300 Kimberley Clark purple KC500 PH Medisavers GN90 Bodyguards GL6622
Monophasic waveform
Biphasic waveform
2622 (152) V 2781 (86) V 2216 (208) V 1822 (204) V
1596 (29) V 1548 (54) V 1588 (33) V 1603 (21) V
broke down, the median number of shocks with each waveform resulting in glove breakdown. In all cases the resistance following visual and audible indication of arcing fell to below 5% of the initial value thereby confirming a breach of glove integrity. Following failure, glove resistance fell to a mean of 0.6% (monophasic) and 2.7% (biphasic) of baseline value. Conversely, the resistance of gloves displaying no qualitative evidence of failure remained above 90% of the initial value. The peak voltage to which the gloves were exposed is summarized in Table 2. As expected, the peak voltage applied by the higher energy monophasic shock was greater than for the biphasic shock (2360 V vs 1584 V – mean of all gloves tested). 4. Discussion No clinical examination glove type was 100% effective at preventing dielectric breakdown for monophasic shocks at 360 J and only one glove type was effective for the biphasic defibrillator waveform. Dielectric breakdown of gloves has previously been shown to be associated with a rapid rise in current suggesting a significant risk to the rescuer10 . Even if gloves remain intact following exposure to defibrillation waveforms, we have previously demonstrated that the integral resistance of gloves is inadequate to limit leakage current in the rescuer to below the safe threshold of 1 mA, demonstrating that clinical examination gloves fail to provide the necessary protection to a rescuer required during hands-on chest compressions. This finding is perhaps not unsurprising since none of the clinical examination glove manufacturers list electrical protection as an intended use. Consequently, even if the sample tested had been successful in withstanding defibrillation voltages, the conclusion would remain unaltered as manufacturers are unlikely to design or test products with this application in mind, leaving the possibility of a large variation in dielectric property and lack of compliance with the European Medical Devices Directive.9 It has previously been shown that electrical breakdown occurs at voltages typically encountered during defibrillation, but the study was performed using a stepwise increase in voltage and therefore used a waveform that bears little resemblance to a defibrillation waveform used clinically.10,13 Our study, performed with defibrillator waveforms, tested gloves using a more realistic scenario but has resulted in similar findings. As is expected, the higher energy delivered by the monophasic defibrillator was associated with a higher voltage and produced more glove failures. Defibrillation waveforms are alternating current (AC) for which it is important to consider impedance. Impedance takes account not only of the effect of resistance but also of inductance and capacitance. In this scenario, the capacitance across the glove is likely to be particularly important and although not assessed, can be assumed to further reduce the total impedance and therefore increase current flow compared with consideration of resistance alone. The glove area tested in this study was larger than the likely contact area with the patient during a clinical scenario. This will have the effect of reducing measured resistance and increasing the likelihood that the gloves weakest point is coincident with the area tested. However, since material properties do not alter to any great
extent over the surface of the glove, this is unlikely to alter the conclusion. In this study, the gloves that were tested were new and had not been worn prior to testing. Evidence from our previous study suggests that wearing gloves degrades their electrical properties, probably through a number of mechanisms including stretching, shear stresses and ingress of conductive moisture.11 It might be expected therefore that the results presented in this study are a best case as far as the gloves’ resistance to electrical breakdown is concerned and that gloves may fail at an earlier defibrillation attempt in a clinical scenario. The use of double gloves has been suggested as a method of improving safety for rescuers, but two glove layers are still likely to provide inadequate resistance. Tears to gloves are relatively common and would then leave the rescuer exposed to a single layer which we have demonstrated is likely to breakdown. Two glove layers will provide double the resistance of a single layer and will therefore still provide inadequate electrical resistance, enabling defibrillator current to exceed the safe threshold of 1 mA.6 Examination gloves are not intended for use as an electrical insulator and therefore have neither been designed nor tested for this purpose.14 Gloves used by other industries (e.g. power industry) are available that are specifically design as personal protective equipment through providing an insulating barrier to high voltages. Further work is required to develop a glove that combines the material properties of the examination glove designed for the clinical environment, with those of insulating gloves designed as personal protective equipment (PPE). In conclusion, in order to provide electrical protection to the rescuer during hands on defibrillation, it is necessary for a glove to have adequate electrical impedance to limit current to a safe level, remain intact during exposure to the physical shear stresses typically encountered when performing chest compressions and have a dielectric strength capable of withstanding defibrillation voltages. This study again confirms that the material properties of typical examination gloves do not prevent dielectric breakdown using standard defibrillation waveforms and energy levels and are therefore unsuitable as PPE for the rescuer during hands-on defibrillation.13 Unless gloves are manufactured and sold as protective devices, then they should not be used as such, irrespective of their response to defibrillation voltages. Conflict of interest statement No conflicts of interest to declare. Acknowledgements The authors are grateful to David Johnson, Steve Clitheroe and Brad Olden for their assistance with developing the measurement apparatus. Appendix A. Supplementary data Supplementary data associated with this article can be found, in the online version, at http://dx.doi.org/10.1016/ j.resuscitation.2013.03.012. References 1. Abella BS, Alvarado JP, Myklebust H, et al. Quality of cardiopulmonary resuscitation during in-hospital cardiac arrest. JAMA 2005;293:305–10. 2. Wik L, Kramer-Johansen J, Myklebust H, et al. Quality of cardiopulmonary resuscitation during out-of-hospital cardiac arrest. JAMA 2005;293:299–304. 3. Valenzuela TD, Kern KB, Clark LL, et al. Interruptions of chest compressions during emergency medical systems resuscitation. Circulation 2005;112:1259–65. 4. van Alem AP, Sanou BT, Koster RW. Interruption of cardiopulmonary resuscitation with the use of the automated external defibrillator in out-of-hospital cardiac arrest. Ann Emerg Med 2003;42:449–57.
G.W. Petley, C.D. Deakin / Resuscitation 84 (2013) 900–903 5. Lloyd MS, Heeke B, Walter PF, Langberg JJ. Hands-on defibrillation: an analysis of electrical current flow through rescuers in direct contact with patients during biphasic external defibrillation. Circulation 2008;117:2510–4. 6. Petley GW, Cotton AM, Deakin CD. Hands-on defibrillation: theoretical and practical aspects of patient and rescuer safety. Resuscitation 2012;83:551–6. 7. Hoke RS, Heinroth K, Trappe H-J, Werdan K. Is external defibrillation an electric threat for bystanders? Resuscitation 2009;80:395–401. 8. Kerber RE. “I’m clear, you’re clear, everybody’s clear”: a tradition no longer necessary for defibrillation? Circulation 2008;117:2435–6. 9. Medical Devices Directive 93/42/EEC. In. 10. Sullivan JL. Hands-on defibrillation: an analysis of electrical current flow through rescuers in direct contact with patients during biphasic external defibrillation. Circulation 2008;118:e712.
903
11. Deakin CD, Lee-Shrewsbury V, Hogg K, Petley G. Do clinical examination gloves provide adequate electrical insulation for safe handson defibrillation? I: Resistive properties of nitrile gloves. Resuscitation, http://dx.doi.org/10.1016/j.resuscitation.2013.03.011, in press. 12. Deakin CD, Nolan JP, Sunde K, Koster RW. European Resuscitation Council Guidelines for Resuscitation 2010 Section 3. Electrical therapies: automated external defibrillators, defibrillation, cardioversion and pacing. Resuscitation 2010;81:1293–304. 13. Sullivan JL, Chapman FW. Will medical examination gloves protect rescuers from defibrillation voltages during hands-on defibrillation? Resuscitation 2012;83:1467–72. 14. Deakin CD. Clinical examination gloves – fit only for their intended purpose. Resuscitation 2012;83:1421–2.