Dangers of defibrillation: injuries to emergency personnel during patient resuscitation

Analysis of Emergency Medical Response Team Performance during the International Winter Championships in Emergency Medicine

Background and Objectives: Conducting advanced life support (ALS) according to the guidelines of the European Resuscitation Council (ERC) requires medical personnel to implement the appropriate emergency actions. In particular, these actions include chest compressions, airway management, artificial ventilation, defibrillation and the administering of medicines. An appropriate training system enables members of medical response teams (MRT) to acquire the essential knowledge and skills necessary to correctly conduct cardiopulmonary resuscitation (CPR). One way to improve the quality of interventions by MRT personnel is participation in emergency medicine championships. Materials and Methods: The research analysed assessment cards for tasks carried out during the International Winter Championships in Emergency Medicine in the years 2013–2020. The assessed tasks were prepared and led by European Resuscitation Council instructors of advanced life support. During ten-minute scenarios of simulated sudden cardiac arrest (SCA) in adults, the judges assessed the compliance of procedures with current ERC guidelines. This research analysed the performance of 309 teams from Poland made up of paramedics from medical response units from all over the country. Results: In most cases, the study showed significant differences in the percentage of correctly performed procedures between years. Most often, the highest percentage of correctly performed procedures was recorded in 2019 and 2020. The lowest percentage of correctly performed procedures was most often recorded in 2013. In subsequent years, the percentage of use of tracheal intubation decreased (from 54.76% to 31.25%) in favour of an increase in the use of supraglottic airway device SAD (from 35.71% to 59.38%). Conclusions: The research has shown that in subsequent years of the Championships, the quality of the majority of assessed procedures carried out by members of MRT gradually improved. The research authors also observed that in subsequent years, the percentage of intubations decreased in favour of SAD.

Cardiopulmonary resuscitation (CPR) during spaceflight - a guideline for CPR in microgravity from the German Society of Aerospace Medicine (DGLRM) and the European Society of Aerospace Medicine Space Medicine Group (ESAM-SMG)

BACKGROUND

With the "Artemis"-mission mankind will return to the Moon by 2024. Prolonged periods in space will not only present physical and psychological challenges to the astronauts, but also pose risks concerning the medical treatment capabilities of the crew. So far, no guideline exists for the treatment of severe medical emergencies in microgravity. We, as a international group of researchers related to the field of aerospace medicine and critical care, took on the challenge and developed a an evidence-based guideline for the arguably most severe medical emergency - cardiac arrest.

METHODS

After the creation of said international group, PICO questions regarding the topic cardiopulmonary resuscitation in microgravity were developed to guide the systematic literature research. Afterwards a precise search strategy was compiled which was then applied to "MEDLINE". Four thousand one hundred sixty-five findings were retrieved and consecutively screened by at least 2 reviewers. This led to 88 original publications that were acquired in full-text version and then critically appraised using the GRADE methodology. Those studies formed to basis for the guideline recommendations that were designed by at least 2 experts on the given field. Afterwards those recommendations were subject to a consensus finding process according to the DELPHI-methodology.

RESULTS

We recommend a differentiated approach to CPR in microgravity with a division into basic life support (BLS) and advanced life support (ALS) similar to the Earth-based guidelines. In immediate BLS, the chest compression method of choice is the Evetts-Russomano method (ER), whereas in an ALS scenario, with the patient being restrained on the Crew Medical Restraint System, the handstand method (HS) should be applied. Airway management should only be performed if at least two rescuers are present and the patient has been restrained. A supraglottic airway device should be used for airway management where crew members untrained in tracheal intubation (TI) are involved.

DISCUSSION

CPR in microgravity is feasible and should be applied according to the Earth-based guidelines of the AHA/ERC in relation to fundamental statements, like urgent recognition and action, focus on high-quality chest compressions, compression depth and compression-ventilation ratio. However, the special circumstances presented by microgravity and spaceflight must be considered concerning central points such as rescuer position and methods for the performance of chest compressions, airway management and defibrillation.

The automated external defibrillator, an underused simple life-saving device: a review of the literature. A joint document from the Italian Resuscitation Council (IRC) and Associazione Italiana di Aritmologia e Cardiostimolazione (AIAC)

: The role of early defibrillation has been well established as a pivotal ring of the chain of survival since the nineties. In the following years, the scientific evidences about the beneficial role of early defibrillation have grown, and most of all, it has been demonstrated that the main determinant of survival is the time of defibrillation more than the type of rescuer. Early lay defibrillation was shown to be more effective than delayed defibrillation by healthcare providers. Moreover, because of the ease of use of automated external defibrillators (AEDs), it has been shown that also untrained lay rescuers can safely use an AED leading the guidelines to encourage early defibrillation by untrained lay bystanders. Although strong evidence has demonstrated that an increase in AED use leads to an increase in out-of-hospital cardiac arrest (OHCA) survival, the rate of defibrillation by laypeople is quite variable worldwide and very low in some realities. Our review of the literature about lay defibrillation highlights that the AED is a life-saving device as simple and well tolerated as underused.

Hospital resuscitation teams: a review of the risks to the healthcare worker

Background

“Code blue” events and related resuscitation efforts involve multidisciplinary bedside teams that implement specialized interventions aimed at patient revival. Activities include performing effective chest compressions, assessing and restoring a perfusing cardiac rhythm, stabilizing the airway, and treating the underlying cause of the arrest. While the existing critical care literature has appropriately focused on the patient, there has been a dearth of information discussing the various stresses to the healthcare team. This review summarizes the available literature regarding occupational risks to medical emergency teams, characterizes these risks, offers preventive strategies to healthcare workers, and highlights further research needs.

Methods

We performed a literature search of PubMed for English articles of all types (randomized controlled trials, case-control and cohort studies, case reports and series, editorials and commentaries) through September 22, 2016, discussing potential occupational hazards during resuscitation scenarios. Of the 6266 articles reviewed, 73 relevant articles were included.

Results

The literature search identified six potential occupational risk categories to members of the resuscitation team—infectious, electrical, musculoskeletal, chemical, irradiative, and psychological. Retrieved articles were reviewed in detail by the authors.

Conclusion

Overall, we found there is limited evidence detailing the risks to healthcare workers performing resuscitation. We identify these risks and offer potential solutions. There are clearly numerous opportunities for further study in this field.

Hands-on defibrillation during active chest compressions: eliminating another interruption

After decades of research, effective chest compressions have emerged as a key component of high-quality cardiopulmonary resuscitation (CPR) for cardiac arrest patients. Minimizing interruptions in chest compressions is garnering increasing attention as a method to improve CPR quality and outcomes. Hands-on defibrillation has been suggested as both a safe and effective means of reducing interruptions in chest compressions. This article discusses the safety and efficacy of a novel and controversial method to reduce interruptions: hands-on defibrillation.

Assessing student paramedic visual and verbal checks for defibrillation safety-an observational study

One of the cornerstones in resuscitation training is defibrillation safety, inadvertent “shocking” of the patient when another person has contact with the patient may have a range of safety consequences. The objective of the study was to assess visual and verbal safety checks by paramedic students prior to defibrillation. This was a prospective observational mannequin study of defibrillation safety during a simulated cardiac arrest by paramedic students. The study was conducted in the lounge room of the Department of Community Emergency Health & Paramedic Practice simulation flat, a replica of a complete flat where prehospital simulations are conducted. Each student completed two 10-min cardiac arrest simulations with multiple defibrillation attempts. Each student and an independent Faculty member rated the simulation safety performance using a defibrillation safety self-assessment (DSSA) form. Twenty-four (20 %) students participated in the study with 14 (58 %) being female. For scenario one agreement between student and assessor proved significant for “scanning the incident scene” for all three defibrillation attempts, with agreement ranging from 29 % (p = 0.044) to 47 % (p = 0.007), and stating “stand clear” for defibrillation attempt one and three with the agreement ranging from 47 % (p = 0.007) to 100 % (p < 0.001). For scenario two agreement between student and assessor proved significant for “charging eye contact” for all three defibrillation attempts, with agreement ranging from 40 % (p = 0.043) to 53 % (p = 0.003), and “scanning the scene to ensure all persons are clear of the patient” before defibrillation attempt one and two with agreement ranging from 29 % (p = 0.044) to 46 % (p < 0.007). The results of this study suggest student perception of their performance and what they actually do is vastly different. Further studies using video recording glasses are required so students can gain an accurate and realistic sense of their defibrillation safety performance.

Defibrillation safety: an examination of paramedic perceptions using eye-tracking technology

Objective

The importance of access to early defibrillation for patients in cardiac arrest has been emphasised as a critical part of the chain of survival by resuscitation bodies internationally; as such defibrillation has become a key procedure for many out-of-hospital emergency healthcare providers. However, little research has been undertaken specifically addressing students’ safety during defibrillation procedures. The objective of this study was to examine visual and verbal safety checks prior to defibrillation utilising eye-tracking technology.

Methods

This was an observational study of student safety during cardiac rhythm analysis, defibrillator charging and immediately prior to defibrillation during a resuscitation attempt using a medium fidelity mannequin. The participants completed two 10 min simulations each requiring three defibrillation attempts. The κ statistic was used to determine the agreement by the student of their perceived safety performance and that viewed in the video.

Results

In both scenarios the student's level of agreement for their perceived defibrillation safety performance and what was observed in the video decreased from defibrillation one to three in both scenarios. However, there was agreement in their overall defibrillation safety performance for both scenarios.

Conclusions

Student perceptions of their actions during defibrillation are not always an accurate representation of their actual actions.

Electrical exposure risk associated with hands-on defibrillation

BACKGROUND

The use of hands-on defibrillation (HOD) to reduce interruption of chest compression after cardiac arrest has been suggested as a means of improving resuscitation outcomes. The potential dangers of this strategy in regard to exposing rescuers to electrical energy are still being debated. This study seeks to determine the plausible worst-case energy-transfer scenario that rescuers might encounter while performing routine resuscitative measures.

METHODS

Six cadavers were acquired and prepared for defibrillation. A custom instrumentation-amplifier circuit was built to measure differential voltages at various points on the bodies. Several skin preparations were used to determine the effects of contact resistance on our voltage measurements. Resistance and exposure voltage data were acquired for a representative number of anatomic landmarks and were used to map rescuers' voltage exposure. A formula for rescuer-received dose (RRD) was derived to represent the proportion of energy the rescuer could receive from a shock delivered to a patient. We used cadaver measurements to estimate a range of RRD.

RESULTS

Defibrillation resulted in rescuer exposure voltages ranging from 827V to ∼200V, depending on cadaver and anatomic location. The RRD under the test scenarios ranged from 1 to 8J, which is in excess of accepted energy exposure levels.

CONCLUSIONS

HOD 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.

Defibrillation and external pacing in flight: incidence and implications

INTRODUCTION

Emergency electrical intervention for patients in the form of defibrillation, cardioversion and external cardiac pacing can be life saving. Advances in medical technology have enabled electrical intervention to be delivered from small, portable devices. With the rising use of air transport for patients, electrical intervention during aeromedical transfer has an increasing incidence. Our aim was to describe the incidence of electrical intervention in a cohort of critically ill patients undergoing aeromedical transfer and review the risks associated with electrical intervention.

METHODS

All secondary retrievals undertaken by a national aeromedical critical care retrieval service were reviewed over a 48-month period.

RESULTS

In a mixed medical and trauma critical care population, 11 of 967 (1.1%) secondary retrievals required electrical intervention during aeromedical critical care retrieval. The median age of these patients was 77 years (range 32-86) and the median transport time was 70 min (range 40-100 min). All of these patients had an underlying primary cardiac condition and had been identified as high risk for developing an arrhythmia.

CONCLUSIONS

Electrical intervention in a transport environment brings unique challenges, particularly during aeromedical transport. Our study in a European model shows that there is a small but significant incidence of electrical intervention required during aeromedical flight for critically ill patients. There are potential safety issues with electrical intervention in aeromedical flight; therefore, any service involved in the transport of critically ill patients needs to have a robust procedure in place to deliver this safely.

Will medical examination gloves protect rescuers from defibrillation voltages during hands-on defibrillation?

BACKGROUND

Continuing compressions during a defibrillation shock has been proposed as a method of reducing pauses in cardiopulmonary resuscitation (CPR) but the safety of this procedure is unproven. The medical examination gloves worn by rescuers play an important role in protecting the rescuer yet the electrical characteristics of these gloves are unknown. This study examined the response of medical examination gloves to defibrillation voltages.

METHODS

Part 1 of this study measured voltage-current curves for a small sample (8) of gloves. Part 2 tested more gloves (460) to determine the voltage required to produce a specific amount of current flow. Gloves were tested at two current levels: 0.1 mA and 10 mA. Testing included four glove materials (chloroprene, latex, nitrile, and vinyl) in a single layer and double-gloved.

RESULTS

All gloves tested in part 1 allowed little current to flow (<1 mA) as the voltage was increased until breakdown occurred, at which point current flow increased precipitously. In part 2, 118 of 260 (45%) single gloves and 93 of 120 (77%) double gloves allowed at least 0.1 mA of current flow at voltages within the external defibrillation voltage range. Also, 6 of 80 (7.5%) single gloves and 5 of 80 (6.2%) double gloves allowed over 10 mA.

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.

Hands-on defibrillation: theoretical and practical aspects of patient and rescuer safety

Defibrillators are used to treat many thousands of people each year using very high voltages, but, despite this, reported injuries to rescuers are rare. Although even a small number of reported injuries is not ideal, the safety record of the defibrillator using the current protocol is widely regarded as being acceptable. There is increasing evidence that clinical outcome is significantly improved with continuous chest compressions, but defibrillation is a common cause of interruptions; even short interruptions, such as those associated with defibrillation, may detrimentally affect the outcome. This has led to discussions regarding the possibility of continuing chest compressions during defibrillation; a process involving a rescuer working in close proximity to voltages of up to 5000 V. Not only do voltages of this magnitude have significant implications for the rescuer performing chest compressions, but there are also risks to other rescuers in the proximity, the patient and other bystanders. Clearly any deviation from accepted practice should only be undertaken following careful consideration of the risks and benefits to the patient, rescuers and others. This review summarises the physical principles of electrical risk and identifies ways in which these could be managed. In doing so, it is hoped that in future it may be possible to deliver continuous and safe manual chest compressions during defibrillator discharge in order to improve patient outcome.

Defibrillation delivered during the upstroke phase of manual chest compression improves shock success

OBJECTIVE

The current standard of manual chest compression during cardiopulmonary resuscitation requires pauses for rhythm analysis and shock delivery. However, interruptions of chest compression greatly decrease the likelihood of successful defibrillations, and significantly better outcomes are reported if this interruption is avoided. We therefore undertook a prospective randomized controlled animal study in an electrically induced ventricular fibrillation pig model to assess the effects of timing of defibrillation on the manual chest compression cycle on the defibrillation threshold.

DESIGN

Prospective, randomized, controlled animal study.

SETTING

University-affiliated research laboratory.

SUBJECTS

Yorkshire-X domestic pigs (Sus scrofa).

INTERVENTIONS

In eight domestic male pigs weighing between 24 and 31 kg, ventricular fibrillation was electrically induced and untreated for 10 secs. Manual chest compression was then performed and continued for 25 secs with the protection of an isolation blanket. The depth and frequency of chest compressions were guided by a cardiopulmonary resuscitation prompter. Animals were randomized to receive a biphasic electrical shock in five different compression phases with a predetermined energy setting. A control phase was chosen at a constant 2 secs after discontinued chest compression. A grouped up-down defibrillation threshold testing protocol was used to compare the success rate at different coupling phases. After a recovery interval of 4 mins, the sequence was repeated for a total of 60 test shocks for each animal.

MEASUREMENTS AND MAIN RESULTS

No difference in coronary perfusion pressure before delivering of the shock was observed among the six study phases. The defibrillation success rate, however, was significantly higher when shocks were delivered in the upstroke phase of manual chest compression.

CONCLUSION

Defibrillation efficacy is maximal when electrical shock is delivered during the upstroke phase of manual chest compression.

The resuscitation blanket: a useful tool for "hands-on" defibrillation

AIM OF STUDY

We investigated the safety, feasibility and efficacy of a resuscitation blanket designed with the intent to protecting the rescuer from the risk of receiving electrical current during defibrillation which, would allow for uninterrupted chest compressions.

METHODS

Fifteen pigs weighing between 22 and 40 kg were investigated with an established model of cardiac arrest and CPR. CPR was performed with the interposition of the blanket between the rescuer's hands and the chest of the animal. Defibrillation voltage and current over the blanket were measured. Hemodynamics, including coronary perfusion pressure (CPP), end-tidal CO(2) (EtCO(2)) and 50% successful defibrillation threshold (DFT50) were measured and compared during CPR with and without the blanket.

RESULTS

Leakage through the blanket was nominal. Voltages of 42.0, 56.6 and 105 V and mean leakage currents of 1.1, 1.4 and 3.3 microA were measured above the blanket for 150, 200 and 360 J defibrillation shocks. CPP and EtCO(2) in the animals during chest compression with the resuscitation blanket were not significantly different compared to those measured without the blanket. However, when the blanket was not utilized, CPP decreased (P<0.05) during the 15-s hands-off interruption prior to defibrillation. Defibrillation threshold was significantly lower when the blanket was used.

CONCLUSION

The resuscitation blanket is a safe and useful tool which protects the rescuer from hands-on defibrillation shocks, allowing for uninterrupted chest compressions, and therefore improving defibrillation success.

Is external defibrillation an electric threat for bystanders?

BACKGROUND

Safety precautions during defibrillation and cardioversion are generally taken very seriously. The actual hazard for bystanders and rescuers, however, has rarely been investigated. Recently, continuing chest compressions during defibrillation has been suggested to improve outcome from cardiac arrest. This article is to review reports on electric shocks to persons other than patients and to discuss the pertinent biomedical principles.

METHODS

Systematic search in medical literature databases and consecutive hand-search of reference lists.

RESULTS

A total of 29 adverse events are reported in the medical literature; seven due to accidental or intentional defibrillator misuse, three due to device malfunction, four during training/maintenance procedures, and 15 during regular resuscitation efforts. Tingling sensations and minor burns are frequently reported consequences of inadvertent shocks. There are no accounts on immediate life-threatening conditions or long-term disability in rescuers/bystanders inflicted by defibrillation/cardioversion of a patient. Discharging a defibrillator directly to a healthy person's chest can be lethal.

CONCLUSIONS

External electric therapy is likely to be safer than traditionally assumed, especially with self-adhesive thoracic electrodes. Sound clinical experiments are urgently needed before safety measures are revised.

Defibrillation during renal dialysis: A survey of UK practice and procedural recommendations

INTRODUCTION

Defibrillation of patients connected to medical equipment that is not defibrillation proof risks ineffective defibrillation and harm to the operator as a result of aberrant electrical pathways taken by the defibrillation current. Many renal dialysis systems are not currently defibrillation proof. Although national and international safety standards caution against defibrillating under this circumstance, it appears to be an area of confusion that we have investigated in more detail.

METHODS

Thirty renal dialysis units across the UK were invited to participate in a telephone survey of current practice from 1 October 2004 to 1 October 2005. The Medical Healthcare Regulatory Agency and renal dialysis machine manufacturers were contacted for advice, and current safety standards were reviewed.

RESULTS

Twenty-eight renal dialysis units completed the survey. Seven (25%) units would not disconnect patients from dialysis equipment during defibrillation, collectively reporting 14 patients who had required defibrillation during dialysis. Eighteen (64.3%) units would disconnect patients from dialysis equipment during defibrillation, collectively reporting 29 patients who had required defibrillation during dialysis. No complications were identified by this survey, through the MHRA or through a literature search.

CONCLUSION

Defibrillation of patients while undergoing renal dialysis is common practice in the UK. Although no adverse events have been reported, this practice risks injury to the patient and clinical staff, and equipment damage if the dialysis equipment is not defibrillation proof. It is in breach of national and international safety standards and should not be practiced.

Electrical injuries

Electrical injury is a relatively infrequent but potentially devastating form of multisystem injury with high morbidity and mortality. Most electrical injuries in adults occur in the work-place, whereas children are exposed primarily at home. In nature, electrical injury occurs due to lightning, which also carries the highest mortality. The severity of the injury depends on the intensity of the electrical current (determined by the voltage of the source and the resistance of the victim), the pathway it follows through the victim's body, and the duration of the contact with the source of the current. Immediate death may occur either from current-induced ventricular fibrillation or asystole or from respiratory arrest secondary to paralysis of the central respiratory control system or due to paralysis of the respiratory muscles. Presence of severe burns (common in high-voltage electrical injury), myocardial necrosis, the level of central nervous system injury, and the secondary multiple system organ failure determine the subsequent morbidity and long-term prognosis. There is no specific therapy for electrical injury, and the management is symptomatic. Although advances in the intensive care unit, and especially in burn care, have improved the outcome, prevention remains the best way to minimize the prevalence and severity of electrical injury.

THERAPEUTIC PROCEDURES IN THE EMERGENCY DEPARTMENT PATIENT WITH ACUTE MYOCARDIAL INFARCTION

Life-threatening cardiac arrhythmias and other peri-infarct complications are often unexpected and commonly present with little warning. The therapeutic procedures reviewed often require immediate implementation and should be second nature to any physician involved in the management of patients with an AMI.

The use of diltiazem for treating rapid atrial fibrillation in the out-of-hospital setting

STUDY OBJECTIVE

We sought to evaluate the use of intravenous diltiazem for treatment of rapid atrial fibrillation or flutter (RAF) in the out-of-hospital setting.

METHODS

This study is a retrospective review of data with historical control subjects. Data were drawn from out-of-hospital patients reported to a statewide paramedic system who presented with atrial fibrillation or flutter and a ventricular response rate (VRR) of 150 beats/min or greater. The intervention (diltiazem) group included patients who received diltiazem during a 9-month period in 1999. The control group included patients from 1998 who did not receive diltiazem. Patients who were intubated or underwent cardioversion were omitted. Therapeutic response was defined as the occurrence of change to sinus rhythm, reduction of VRR to 100 beats/min or less, or reduction of baseline VRR by 20% or greater. Data were analyzed by using the chi(2) test, the Student's t test, and odds ratios (ORs). A Bonferroni adjusted P value of.005 was used to define statistical significance.

RESULTS

Forty-three patients receiving diltiazem and 27 control subjects were included in the study. The mean total diltiazem dose was 19.8 mg (95% confidence interval 17.8 to 21.8). The diltiazem and control groups did not significantly differ with respect to age; sex; history of atrial fibrillation; prior use of digitalis, beta-blockers, or calcium channel blockers; concurrent out-of-hospital therapies; or baseline VRR or systolic blood pressure (P =.09 to 1.00). The difference in VRR reduction between the diltiazem and control groups was 38 beats/min (95% confidence interval 24 to 52); this difference was statistically significant (P <.001). The mean percentage reduction of VRR in the diltiazem group was -33.1%. The difference in systolic blood pressure change between the diltiazem and control groups was not statistically significant (P =.17). The diltiazem group had a higher prevalence of achieving VRR reduction to 100 beats/min or less than did the control group (OR 22.6; P <.001), of achieving a VRR reduction of 20% or greater (OR 19.3; P <.001), and of achieving overall therapeutic response (OR 19.3; P <.001). Few changed to sinus rhythm in either group (estimated OR 6.3; P =.15). No patients in the diltiazem group required treatment for hypotension, endotracheal intubation, resuscitation from cardiac arrest, or emergency treatment of unstable dysrhythmias.

CONCLUSION

The effects of diltiazem on RAF can be appreciated within the constraints of the out-of-hospital environment. Diltiazem should be considered as a viable field therapy for rate control of RAF.

The occupational hazards of emergency physicians

Emergency physicians are exposed to a variety of occupational hazards. Among these are infectious diseases, such the human immunodeficiency virus, hepatitis B and C viruses, and tuberculosis. Hepatitis G virus is transmissible but may not be a cause of illness. The likelihood of being exposed to these agents appears to be higher in the ED than other medical settings but estimates of the prevalence of these diseases in the ED vary, depending on the patient population served. Estimates of risk for contracting these infections are reviewed. Measures to prevent these exposures can reduce risk, but compliance is low, particularly for those involving changes in the behavior of emergency physicians (such as not recapping needles). Latex allergy is a hazard of health care workers. Its prevalence is reported to be quite high, but these findings are difficult to interpret in the absence of a universally accepted definition of the condition. Its prevalence in emergency physicians is not known. Other noninfectious hazards include workplace violence and exposure to nitrous oxide. The health effects of rotating shift work may put emergency physicians at increased risk of coronary artery disease and impaired reproductive health. Emotional stress is another hazard of emergency physicians, and may lead to burnout.

Ambient oxygen concentrations during simulated cardiopulmonary resuscitation

Oxygen concentrations were measured at 12 points around a cardiopulmonary resuscitation practice mannequin following simulated ventilation with a self-inflating bag, a 'Waters' bag and a ventilator to determine whether increased oxygen concentrations may contribute to the risk of combustion from arcing defibrillator paddles. Ventilation was simulated using either a mask or via a tracheal tube fitted to the airway. The head of the mannequin rested upon a 10-cm-high pillow. Gas sampling took place after 5 min of ventilation with subsequent removal of the ventilatory device and placement on the pillow to the left of the mouth, with the tubing of the device removed to a point 1 m behind the mouth and with the device left connected to the tracheal tube. Gas was sampled after using all devices at oxygen flows of 10l.min-1 and 15l.min-1. Slightly increased oxygen concentrations were noted over the anterior chest after placement of all devices on the pillow at the higher flow. Concentrations of greater than 30% were measured in the left axilla after placement of all devices on the pillow at both flows. No increase in oxygen concentration was seen when the devices were either left connected to the tracheal tube or removed to a distance of 1 m. It would appear that leaving a patient connected to a ventilator poses no increase in risk of fire from ignition of combustible material in an oxygen-enriched atmosphere during defibrillation. Disconnecting any device which continues to discharge oxygen and leaving it on the pillow before defibrillation is dangerous.

Current concepts in electrical defibrillation

The electrical defibrillator has been proven to be a life-saving device in the treatment of cardiac arrest due to ventricular tachycardia or ventricular fibrillation. An understanding of the physiology and technology behind this device is useful for providers of emergency care. In this article, we review the current concepts in electrical defibrillation and briefly discuss the developmental history. The physiology and the technical considerations will make up the bulk of the discussion. The latest developments in electrical defibrillation also will be reviewed.

Defibrillation--a burning issue in coronary care units!

Skin burns are accepted to be a complication of defibrillation, however there is no published data on their frequency, cause and treatment. A postal questionnaire survey was designed to assess the relative frequency of defibrillation burns in coronary care units and identify the possible factors contributing to their occurrence. Treatments prescribed in coronary care units were also noted. The questionnaire was sent to the Senior Sister/Charge Nurse in all 263 coronary care units in the United Kingdom. 232 Replies were received (88.2%). Defibrillation burns were seen in 98.7% of CCU's. Ten contributory factors were proposed. The commonest implicated cause was recurrent defibrillation. The most frequently prescribed topical treatment was 1% silver sulphadiazine cream (Flamazine). Defibrillation burns are relatively common in coronary care units. Many result from recurrent defibrillation and may be unavoidable in the patient undergoing prolonged resuscitation. However there are other identifiable factors which, if avoided, may lead to a reduction in the number of burns seen.

Electric shock, Part I: Physics and pathophysiology

Electric shock causes injury and death through a variety of mechanisms. The proper treatment of a patient with electric shock depends upon the nature of the injuries sustained. The primary electric injuries to be expected depend in large part on the type of electric energy source, the amount and duration of current flow, and the parts of the body affected. Secondary injury can be caused by trauma associated with the electric accident such as falls and explosions.

Report of nitropatch explosions complicating defibrillation

Reports of complications associated with the use of electrical defibrillators have been relatively rare. In two patients, defibrillation performed over a nitroglycerin skin patch resulted in electrical arcing with a resultant flash of light and thermal injuries. Skin burns as a complication of defibrillation over nitropatches has not been previously reported. Such burn injuries respond to standard therapeutic measures. Healthcare professionals who may perform defibrillation should be aware of this potential complication.