Automatic external defibrillators

The use of automated external defibrillators by non-medical first responders in Finland

OBJECTIVE

To assess the spread of automated external defibrillators and their use by non-medical first responders in Finland.

METHODS

A structured survey was mailed to all voluntary and ordinary fire brigades in Finland. The questions were related to the purchase, experience of use and anticipated benefits from the devices.

RESULTS

Approximately 90% of all users (133 providers) in the target group of non-medical first responders answered. The number of automated external defibrillators in use by these operators has increased progressively since 1992. Most respondents possessed only one automated external defibrillator, and a median of 12 users were trained to use each device. A total of 85% of the respondents retrained at least once a year, and 94% checked the device on a daily basis. Half of the users had written authorization to use the automated external defibrillator, and two thirds had written instructions on how to operate it. Each automated external defibrillator was used on average five to 10 times annually. Although none of the respondents could provide data on how many cardiac arrests they had attended or the success of resuscitation during the preceding year, 94% reported that they considered the automated external defibrillator useful, and 80% thought that the cost-benefit of the device was either very good or good.

CONCLUSION

Although there are many automated external defibrillators in use by non-medical first responders in Finland, the results of this study show that there are large variations between individual fire brigades regarding the use of these devices as part of the first response system. This is considered to be caused by the lack of national standards and regulations, which should define a full integration of first-responder programmes into the emergency medical service system.

The effect of seeing the rhythm display on performance of cardiopulmonary resuscitation

Semiautomated external defibrillators are widely used by prehospital emergency personnel. Some of the devices have a rhythm display and some show only text commands on the screen. To evaluate the effects on cardiopulmonary resuscitation (CPR) performance of seeing the rhythm during resuscitation, 60 fire-fighter students were randomly divided in two groups and trained to use either a defibrillator with a rhythm display or one without a display. The students in both groups formed teams of two rescuers, and their performance of CPR on a manikin was tested using a predefined rhythm sequence in a simulated cardiac arrest situation. The teams using a defibrillator with a rhythm display more often interrupted CPR for pulse checks than those who did not see the rhythm (P=0.003). The duration of CPR between rhythm analyses was shorter in the group who saw the rhythm on the screen (P=0.002). Our data suggest that seeing an organised rhythm on a monitor during CPR interferes with adherence to CPR algorithms which may have a negative influence on the performance of CPR.

Automatic external defibrillators: lessons from the past, present and future

Coronary artery disease remains the leading cause of death in the United States and most developed countries. Many of the victims die from sudden cardiac arrests, resulting from dysrhythmias-most commonly ventricular fibrillation. Since most cardiac arrests occur outside the hospital, implementing emergency services in the field will have a great impact on survival. With the development of the modern automatic external defibrillator (AED), early recognition and correction of these dysrhythmias by lay rescuers can significantly improve outcome from sudden death. This paper reviews the past, present and future development and applications of AEDs.

Sudden death of a young hockey player: case report of commotio cordis

Despite the use of protective gear, a 15-year-old hockey player died when he was struck in the chest by a puck. This is the fifth recorded hockey death related to so-called commotio cordis, that is, blunt chest injury without myocardial structural damage. In light of inadequacies of commercial chest protectors currently in use for hockey, the authors hope to educate players and coaches about the danger of blocking shots with the chest. Physicians should be aware that commotio cordis represents a distinctive pathological condition, in the event of which immediate recognition, precordial thump, CPR, and defibrillation are potentially lifesaving. Appropriate medical supervision at amateur hockey games, 911 telephone access, and on-site automated external defibrillators are issues that deserve careful consideration.

Comparative assessment of shockable ECG rhythm detection algorithms in automated external defibrillators

The sensitivity and specificity to ventricular fibrillation (VF) and ventricular tachycardia (VT), classified as requiring immediate DC shock, of four automated external defibrillators (AEDs) and three advisory defibrillators were assessed using the Department of Health Arrhythmia library. This library collected mostly from patients in hospital, includes a wide variety of ECG rhythms including many with additional noise and interference artefact. The library comprised 278 16-s rhythms, 59 of which were VF, 36 were VT requiring cardioversion and 183 were deemed non-shockable. Non-shockable rhythms included asystole, pacing, slow VT, idioventricular rhythms, sinus and atrial based rhythms, some of which contained ventricular ectopic activity of differing grades. For the AEDs, a positive result (indicating detection of a shockable rhythm) was recorded if charging started or was able to be started at any time during the 16 s of rhythm output and energy subsequently available for discharge. For the advisory defibrillators, a positive result was recorded if a 'shock advised' alert was issued at any time during output of the rhythm. The AEDs exhibited sensitivities to VF in the range 81-94%, and to VF plus shockable VT 64-73%, or 72-83% depending whether VT > 150 beats/min or > 180 beats/min is considered to be shockable. The specificities recorded were in the range 90-94% and 86-92%, respectively. All but one of the advisory defibrillators performed similarly. Excluding the artefact rhythms, specificities in the range 79-91% were obtained. All figures stated are at the lower limit of the 95% confidence interval.

Automatic external defibrillators in the hospital as well?

When a cardiac arrest occurs in a non-intensive area of the hospital, the emergency response is not always adequate from the point of view of timeliness and technical quality. The aims of this study were evaluate an experimental programme to improve the CPR skills of staff operating in non-intensive areas of our general hospital and to test the usefulness of placing automatic external defibrillators (AEDs) within these areas. In the experimental phase, two AEDs were placed in 2 non-intensive wards of our hospital for 8 months. The staff of these wards received specific training in CPR and early defibrillation (CPR-D). The devices were used in 19 cases; for defibrillation in four cases of ventricular fibrillation (VF) (three patients were discharged alive from hospital), and for monitoring three supraventricular arrhythmias, one bradyarrhythmia and 11 cardiac rhythms during critical situations. In the implementation phase, four AEDs were indefinitely assigned to as many non-intensive awards. Periodical CPR-D courses and refresher exercises were run; the cardiology staff co-operated in the maintenance of the AEDs and in the registration of technical and clinical data. In the first period of this phase (9 months), AEDs were utilized in 24 cases by the ward-staff: in nine cases for VF (three patients were discharged alive from hospital) and in 15 cases for other rhythm detection in critical conditions. The number and the quality of these uses seem to confirm the favourable impact of the adoption of a more user-friendly defibrillator, such as an AED. The active co-operation between intensive and non-intensive staff was important to facilitate a quick activation of the chain of survival outside the intensive care units. We conclude that AEDs, which were developed for out-of-hospital use by non-physician operators, are suitable for use inside the hospital as well.

Ventricular fibrillation, automatic external defibrillators, and the United States Food and Drug Administration: confrontation without comprehension

More people die in the United States each day of potentially reversible VF than of any other cause of death, reversible or not. Early defibrillation is the definitive treatment. Automated external defibrillation is a proven technology now confirmed to have saved thousands of lives. As with all medical devices and technology, perfection is not possible. Some problems, such as those represented by the two cases discussed in this article, are inevitable and acceptable and give little cause for alarm. One would not stop penicillin from being manufactured and distributed because of a sudden, unexpected allergic reaction in one patient (error of commission) or an unexpected resistant organism in another (error of omission). The FDA must understand that AEDs, even if they are imperfect, are not anywhere near as dangerous as no defibrillator at all. AEDs have finally allowed many EMS systems to achieve early defibrillation. Discontinuing use of AEDs or closing AED manufacturers could mean a significant number of lives lost unnecessarily. Therefore EMS agencies planning to implement early-defibrillation programs should continue with such plans. Why the agents of an important federal regulatory agency have singled out this technology for an intense review puzzles many observers in the medical-device field. Two meetings have been hosted by officials of the FDA to discuss the continuing concern the FDA officials have expressed over automated defibrillation technology. These meetings included representatives from the AHA, the American College of Cardiology, ACEP, defibrillator manufacturers, and other interested organizations. The FDA leadership has repeatedly focused on data acquired through the FDA Medical Device Reporting systems. Congress requires the FDA to investigate reports of problems with "critical medical devices." Because the indication for the use of a defibrillator is cardiac arrest, there will inevitably be a high association between defibrillator use and patient deaths. FDA personnel may view such reports of device problems in association with patient deaths as evidence that an intrinsically flawed technology has reached the marketplace without rigorous testing and evaluation. From the clinician's perspective, however, these reports represent a small numerator over a huge denominator of daily, lifesaving clinical use. The non-FDA participants at the two meetings have stated that the FDA complaints appear to be random and reveal a lack of understanding of AED technology.(ABSTRACT TRUNCATED AT 400 WORDS)

Assessment of the ventricular fibrillation detection algorithm in the semi-automatic Cardio-Aid defibrillator

The sensitivity and specificity of ventricular fibrillation (VF) detection in the semi-automatic Cardio-Aid defibrillator was assessed with 25 ECG recordings, each of length 40 s. Of the 25 ECG recordings, 12 contained VF requiring defibrillation, 3 contained a tachyarrhythmia with a waveform similar to VF but which self-terminated, and 10 were selected from abnormal rhythms and artefacts which contained some features similar to VF. Sensitivity was assessed from the VF data. Specificity was assessed from both the rhythm preceding VF or the tachyarrhythmias, and from the VF-like data. The response to a changing rhythm was assessed from the self-terminating tachyarrhythmias. Each recording was replayed to the defibrillators at 3 signal amplitudes (normal, half and double). Request to analyse the ECG because of possible VF and advice to shock were noted separately. The sensitivity for recommending a shock when a shock was required was 92%. The sensitivity for drawing attention to VF, through requesting analysis was 97%. There were no false detections in the rhythms preceding VF or the tachyarrhythmias (specificity with good quality signals 100%). The specificity with the VF-like data ws 90%. There was significant difference between this defibrillator and other semi-automated defibrillators previously assessed.

Strengthening the in-hospital chain of survival with rapid defibrillation by first responders using automated external defibrillators: training and retention issues

STUDY OBJECTIVE

To determine whether staff outside critical care areas who were proficient in basic life support (BLS) could be easily trained to use automated external defibrillators (AEDs) and whether they would retain these skills.

DESIGN

Prospective, longitudinal cohort series.

SETTING

Two university teaching hospitals.

PARTICIPANTS

One hundred forty nurses who had previously learned BLS and constituted the staff from three medical/surgical nursing units from each study hospital.

INTERVENTIONS

The nurses were taught how to use the Heartstart 1000s, a lightweight portable shock-advisory AED, in a 2-hour class with an instructor and manikin-to-student ratio of 1:5. The course emphasized hands-on practice of the BLS-AED algorithm on a computerized manikin.

RESULTS

Using a similar scenario, each nurse was evaluated on the computerized manikin immediately after training (posttest). At 1 to 3, 4 to 6, and 7 to 9 months after the initial training, convenience samples of the cohort in three different groups were evaluated for retention. Satisfactory performance was defined as delivery of the first AED shock within 2 minutes of recognition of the arrest. At the posttest after training, 139 of 140 nurses (99%) demonstrated satisfactory performance. Of 77 nurses evaluated, 31 of 32 at 1 to 3 months, 18 of 18 at 4 to 6 months, and 24 of 27 at 7 to 9 months after initial training (95% overall) performed satisfactorily.

CONCLUSION

As has been demonstrated with prehospital emergency personnel, nurses outside critical care areas who are proficient in BLS can easily learn and retain the knowledge and skills to use AEDs. Automated external defibrillation, a BLS skill, should be incorporated into BLS programs (BLS-AED) for all hospital personnel expected to respond to a patient in cardiac arrest, with rapid defibrillation taking priority over CPR.

Comparative assessment of the ventricular fibrillation detection algorithms in five semi-automatic or advisory defibrillators

The sensitivity and specificity of ventricular fibrillation (VF) detection in three semi-automatic defibrillators (Laerdal Heartstart 3000, Spacelabs First Medic 610, Physio-Control Lifepak 300) and two advisory defibrillators (S&W DMS940, Marquette Responder 1500) were assessed with 25 ECG recordings, each of length 40 s. Of the 25 ECG recordings, 12 contained VF requiring defibrillation, three contained a tachyarrhythmia with a waveform similar to VF but which self-terminated, and 10 were selected from abnormal rhythms and artefacts which contained some features similar to VF. Sensitivity was assessed from the VF data. Specificity was assessed from both the rhythm preceding VF or the tachyarrhythmias, and from the VF-like data. The response to a changing rhythm was assessed from the self-terminating tachyarrhythmias. Each recording was replayed to the defibrillators at three signal amplitudes (normal, half and double). For each defibrillator, requests to check the patient and advice to shock were noted separately. The sensitivity for recommending a shock when a shock was required varied from 81 to 97%. The sensitivity for drawing attention to VF, either through requesting the patient to be checked or advising a shock, varied from 92% to 100%. There were no false detections in the rhythms preceding VF or the tachyarrhythmias (specificity with good quality signals 100%). The specificity with the VF-like data ranged from 63 to 90% for recommending a shock, and from 63% to 70% for requesting the patient be checked or shocked. There was no difference between the defibrillators for VF detection, but there was a significant difference between the semi-automatic and advisory defibrillators (P < 0.05) for the specificity of the final recommendation.

Preventing Sudden Death

In brief To address the leading cause of brief sudden death in high school and college athletes, the sports medicine team can consider using automated external defibrillators. When incorporated into an emergency response plan, these devices have dramatically improved cardiac arrest survival rates. Issues to review carefully include safety, efficacy, personnel training, medical control, pertinent regulations, and cost.