Advances for treating in-hospital cardiac arrest: safety and effectiveness of a new automatic external cardioverter-defibrillator

The fully automatic external cardioverter defibrillator: reality of a new meaningful scenario for in-hospital cardiac arrests

Sudden cardiac death is an unresolved problem which causes significant mortality and morbidity in both the community and in-hospital setting. Cardiac arrest is often caused by ventricular tachyarrhythmias which may be mostly interrupted by cardioversion or defibrillation. The single most critical factor for survival is the response time. Over the last 30 years, there have been virtually no procedural changes in the way hospitals address in-hospital resuscitation. A unique device has been developed that eliminates human intervention and assures defibrillation therapy is administered in seconds. This is accomplished with a fully automatic, external bedside monitor defibrillator designed to be prophylactically attached to hospitalized patients at risk of ventricular tachyarrhythmia. The safety and efficacy of the device has been demonstrated in multicenter US and European trials. Thus, this device allows a new scenario which may increase survival and enables meaningful redistribution of health resources.

Automated external cardioversion defibrillation monitoring in cardiac arrest: a randomized trial

Background

In-hospital cardiac arrest has a poor prognosis despite active electrocardiography monitoring. The initial rhythm of approximately 25% of in-hospital cardiopulmonary resuscitation (CPR) events is pulseless ventricular tachycardia/ventricular fibrillation (VT/VF). Early defibrillation is an independent predictor of survival in CPR events caused by VT/VF. The automated external cardioverter defibrillator (AECD) is a device attached by pads to the chest wall that monitors, detects, and within seconds, automatically delivers electric countershock to an appropriate tachyarrhythmia.

Study Objectives

• To evaluate safety of AECD monitoring in hospitalized patients.

• To evaluate whether AECDs provide earlier defibrillation than hospital code teams.

Methods

The study is a prospective trial randomizing patients admitted to the telemetry ward to standard CPR (code team) or standard CPR plus AECD monitoring (PowerHeart CRM). The AECD is programmed to deliver one 150 J biphasic shock to patients in sustained VT/VF. Data is collected using the Utstein criteria for cardiac arrest. The primary endpoint is time-to-defibrillation; secondary outcomes include neurological status and survival to discharge, with 3-year follow-up.

Results

To date, 192 patients have been recruited in the time period between 10/10/2006 to 7/20/2007. A total of 3,655 hours of telemetry data have been analyzed in the AECD arm. The AECD has monitored ambulatory telemetry patients in sinus rhythm, sinus tachycardia, supraventricular tachycardia, atrial flutter or fibrillation, with premature ventricular complexes and non-sustained VT without delivery of inappropriate shocks. One patient experienced sustained VT during AECD monitoring, who was successfully defibrillated (17 seconds after meeting programmed criteria). There are no events to report in the control arm. The patient survived the event without neurological complications. During the same time period, mean time to shock for VT/VF cardiac arrest occurring outside the telemetry ward was 230 ± 50 seconds.

Conclusion

AECD monitoring is safe and likely results in earlier defibrillation than standard telemetry monitoring.

Trial Registration

National Institutes of Health registration ID: NCT00382928

Recent advances and controversies in adult cardiopulmonary resuscitation

Since its introduction more than four and half decades ago, the science of cardiopulmonary resuscitation has been enriched with a significant amount of scientific evidence. This in turn has led to the birth of new evidence based guidelines for resuscitation published by the European Resuscitation Council and the American Heart Association in late 2005. This article aims to review the recent advances and controversies in the science of resuscitation.

Future shock: automatic external defibrillators

PURPOSE OF REVIEW

This review provides a practical overview of the performance capabilities of automatic external defibrillators (AEDs), and of advances in technology and dissemination programmes for these devices.

RECENT FINDINGS

Arrhythmia analysis by AEDs is extremely reliable in most settings (sensitivity 81-100%, specificity 99.9-97.6%). Accurate detection of arrhythmias has also been demonstrated in children, leading the US Food and Drug Administration to approve the use of several AEDs in children aged 8 years or younger. Factors that potentially may reduce the quality of arrhythmia detection are the presence of wide complex supraventricular tachycardia and location of an arrythmic event near to high-power lines. AED use by professional basic life support providers resulted in increased survival in the prehospital setting. However, provision of AEDs to nonmedical rescue services did not result in universal improvement in patient outcome. Public access defibrillation programmes have led to higher rates of survival from cardiac arrest. The role of AEDs in hospitals has yet to be elucidated, although in-hospital mortality from ventricular arrhythmias has been shown to decrease following AED deployment.

SUMMARY

Given the correct setting, AEDs can ensure that defibrillation is not limited by lack of medical knowledge or difficulties in decision making. However, event-related variables and operator-related factors, that are yet to be determined, can significantly affect the efficacy of automatic external defibrillation.

Fully automatic external defibrillators in acute care: Clinicians' experiences and perceptions

BACKGROUND

Fully automatic external defibrillators (FAEDs) reduce the time to defibrillation [Martinez-Rubio A, Kanaan N, Borggrefe M, Block M, Makijarvi M, Fedele F, et al. Advances in treating in-hospital cardiac arrest: safety and effectiveness of a new automatic external cardioverter-defibrillator. J Am Coll Cardiol 2003;41(4):627-32; Mattioni T, Kanaan N, Riggio D, Bahu M, Lin D, Welch S, et al. Performance of an automatic external-cardioverter-defibrillator algorithm in the discrimination of supraventricular from ventricular tachycardia. Am J Cardiol 2003;91:1323-6] and improve outcomes [Martinez-Rubio A, Kanaan N, Borggrefe M, Block M, Makijarvi M, Fedele F, et al. Advances in treating in-hospital cardiac arrest: safety and effectiveness of a new automatic external cardioverter-defibrillator. J Am Coll Cardiol 2003;41(4):627-32]. There is, however, no guidance or standard about their use in the UK. This paper presents the results of a study, which explored clinicians' experiences and perceptions of using FAEDs in acute care in the UK.

AIMS

This study sought to understand clinicians' experiences and perceptions of the use of FAEDs in acute care and their impact on decision making.

METHODS

Using a qualitative approach, 43 nurses and four physicians were included in a trial of FAEDs in a Coronary Care Unit (CCU) and cardiology ward during 2004. Semi-structured interviews were conducted with nurses and physicians prior to and following the trial. Data were analysed using thematic analysis [Attride-Stirling J, Thematic networks: an analytic to research. Qual Res 2001;1(3):385-405].

RESULTS

Decision control, safety, a lack of confidence in the technology, previous experience and concerns about the psychological affect on patients affected clinicians' decision making and limited the use of the FAED.

CONCLUSION

Despite reported benefits of the FAED [Martinez-Rubio A, Kanaan N, Borggrefe M, Block M, Makijarvi M, Fedele F, et al. Advances in treating in-hospital cardiac arrest: safety and effectiveness of a new automatic external cardioverter-defibrillator. J Am Coll Cardiol 2003;41(4):627-32; Mattioni T, Kanaan N, Riggio D, Bahu M, Lin D, Welch S, et al. Performance of an automatic external-cardioverter-defibrillator algorithm in the discrimination of supraventricular from ventricular tachycardia. Am J Cardiol 2003;91:1323-26], personal and contextual issues affected the clinicians' decision making. More and better understanding about how FAEDs and their context of use may challenge established practice is required in order that it is utilised in the most effective way.

Preliminary in-hospital experience with a fully automatic external cardioverter-defibrillator

BACKGROUND

Ventricular fibrillation (VF) and ventricular tachycardia (VT) are frequently present as initial rhythms during in-hospital cardiac arrest. Although ample evidence exists to support the need for rapid defibrillation, the response to in-hospital cardiac arrest remains without major advances in recent years. The delay between the arrhythmic event and intervention is still a challenge for clinical practice.

OBJECTIVE

To analyze the performance and safety of in-hospital use of a programmable, fully automatic external cardioverter-defibrillator (AECD).

METHODS

We conducted a prospective study at the Emergency Department of a university hospital. A total of 55 patients considered to be at risk of sustained VT/VF were included. Patients underwent monitoring of their cardiac rhythm by the AECD. Upon detection of a ventricular tachyarrhythmia, the AECD was programmed to automatically deliver shock therapy.

RESULTS

We recorded 19 episodes of VT/VF in 3 patients. The median time between the beginning of the arrhythmia and the first defibrillation was 33.4 s (21-65 s). One episode of spontaneous reversion of VT was documented 20 s after its origin and shock therapy was aborted. The defibrillation success was 94.4% (17/18) for the first shock and 100% (1/1) for the second shock. No case of inappropriate shock discharge was registered during the study period.

CONCLUSION

The AECD has the feasibility to combine long-term monitoring with automatic defibrillation safely and effectively. It presents the possibility of providing rapid identification of, and response to, in-hospital ventricular tachyarrhythmias.

The benefits and use of shock advisory defibrillators in hospitals

Survival to discharge following a cardiac arrest is dependent on rapid and effective basic and advanced life support. Paramount to a rapid response is access to sufficiently trained health care providers, who have a duty to perform basic life support and initiate early defibrillation. In hospitals, defibrillation remains the domain of specially prepared staff and the type of defibrillator used might be crucial to rapid and effective defibrillation. The advent of automatic external defibrillators has increased the range of people who can use a defibrillator successfully. For nurses, arguably a lack of familiarity about the benefits of and the use of automatic external defibrillators are the greatest barriers to nurse-initiated defibrillation programmes. This paper explores the use of automatic external defibrillators, their relationship to the associated defibrillator waveforms and the benefits of their use by registered nurses within the hospital setting.

Performance of an automatic external cardioverter-defibrillator algorithm in the discrimination of supraventricular from ventricular tachycardia

An automatic external cardioverter-defibrillator (AECD) with a programmable supraventricular-ventricular tachycardia (VT) zone underwent evaluation of arrhythmia discrimination performance in the electrophysiologic laboratory during induced supraventricular tachycardia (SVT) and unipolar and bipolar atrial pacing. The AECD SVT zone was programmed so that the induced SVT rate would fall within this zone. Atrial pacing was also performed at a rate within this zone. The ability of the AECD to accurately discriminate between VT and SVT and to recommend shock delivery was assessed. A total of 98 patients underwent conventional diagnostic electrophysiologic studies (49 men, age 59 +/- 19 years) with a total of 55 inducible sustained SVTs. High right atrial pacing was performed in 56 patients in unipolar and in 82 patients in bipolar fashion. In response to induced sustained SVT, the AECD correctly classified 47 episodes as nonshockable, 4 incorrectly as shockable, and 4 episodes correctly as shockable with a resultant sensitivity of 100% and specificity of 92%. Bipolar high right atrial pacing was correctly identified as nonshockable in 75 episodes, incorrectly identified as shockable in 5 episodes, and correctly identified as shockable in 2 episodes with a resultant sensitivity of 100% and specificity of 94%. The Powerheart AECD accurately discriminates SVT from VT and is expected to correctly deliver automatic external shocks rapidly in the presence of spontaneous life-threatening tachycardia and appropriately withhold therapy during SVT.