A more effective approach to in-hospital defibrillation

Hospital-wide first-responder automated external defibrillator programme: 1 year experience

The first year experience with a hospital-wide first-responder automated external defibrillator (AED) programme implemented in a 683-bed University Hospital is reported. Throughout the hospital, 14 "AED access spots" were identified which could be easily reached from all wards and diagnostic rooms within 30s. AEDs were installed (Lifepak 500; Medtronik PhysioControl Corp., Redmond, USA, equipped with a Biolog 3000i portable ECG monitor; Micromedical Industries Ltd., Labrador, Australia). Within 3 months, 120 medical officers, 750 nurses, and 50 administrative or technical staff underwent a 2h training programme. An AED was applied and activated by nurses/medical staff before the cardiac arrest team arrived in 27 of 33 cases (81.8%) of witnessed cardiac arrest. The median time from onset of the emergency call to the activation of the AED (record of ECG) was on average 2.1 min (range 1.0--4.5 min). In 18 of 27 cases in which the AED was installed promptly, the primary arrest rhythm was either VT or VF, and the AED delivered a shock. For this subgroup, the rate of return of spontaneous circulation and the rate of discharge at home were 88.9 and 55.6%, respectively. This encourages us to extend the concept of first-responder AED-defibrillation throughout our hospital.

Should ward nurses be using automatic external defibrillators as first responders to improve the outcome from cardiac arrest? A systematic review of the primary research

INTRODUCTION

The outcome from in-hospital cardiac arrest has improved little since the implementation of cardiopulmonary resuscitation 40 years ago. Early defibrillation improves survival following ventricular fibrillation and pulseless ventricular tachycardia. The emergence of automatic external defibrillators and advisory defibrillators has been heralded as the answer to defibrillation delays in-hospital.

AIM

To locate and evaluate the evidence supporting automatic external defibrillator use in-hospital on general wards.

METHOD

A systematic review of indexed and grey literature to identify primary research.

RESULTS

Fifteen in-hospital automatic external defibrillator studies were located, five met the inclusion criteria.

CONCLUSIONS

There is limited primary research evaluating automatic external defibrillators in-hospital. Manual defibrillators remain the most commonly used device for in-hospital defibrillation. Automated external defibrillators offer an alternative to manual defibrillation providing they have a screen and manual override capability, and the technology for pacing is close to hand. For in-hospital automatic external defibrillator programmes to be effective a change in nursing philosophy must occur, and defibrillation must become an expected rather than an extended nursing role.

Initial clinical experience with a fully automatic in-hospital external cardioverter defibrillator

Sudden cardiac death due to ventricular tachyarrhythmia remains a significant problem in the in-hospital setting. Although the probability of survival is closely correlated with the rapidity of a response by qualified personnel, response times can be prolonged, even in specialized care units. In an effort to decrease response time, a fully automatic external cardioverter defibrillator was recently devised. This device was evaluated in the in-hospital setting to assess safety and efficacy. A total of 79 patients were studied in a multicenter trial. Patients were monitored with fully functional devices in the electrophysiology laboratory (51 patients) and in the cardiac care unit (28 patients). Performance of the device was assessed by comparing automatic responses to any sustained change in cardiac rhythm, either spontaneous or induced, to a retrospective review of stored ECG data and programmed parameters. During a total duration of 964 hours of monitoring, there were 99 episodes of sustained tachycardia. Therapy was appropriately delivered or advised in all episodes. Therapy was advised in one episode of supraventricular tachycardia. There were no episodes of inappropriate therapy delivery. There were no complications or adverse events. The device performed with a sensitivity of 100% and specificity of 98.8% with an average response time of 22 seconds. In conclusion, this automatic external defibrillator was safe, effective, and functioned as designed. Significant improvement in response time to life-threatening ventricular tachyarrhythmia in the in-hospital setting would be expected if this technology was widely adopted.

Detecting ventricular tachycardia and fibrillation by complexity measure

Sinus rhythm (SR), ventricular tachycardia (VT) and ventricular fibrillation (VF) belong to different nonlinear physiological processes with different complexity. In this study, we present a novel, and computationally fast method to detect VT and VF, which utilizes a complexity measure suggested by Lempel and Ziv [1]. For a specific window length (i.e., the length of data segment to be analyzed), the method first generates a 0-1 string by comparing the raw electrocardiogram (ECG) data to a selected suitable threshold. The complexity measure can be obtained from the 0-1 string only using two simple operations, comparison and accumulation. When the window length is 7 s, the detection accuracy for each of SR, VT, and VF is 100% for a test set of 204 body surface records (34 SR, 85 monomorphic VT, and 85 VF). Compared with other conventional time- and frequency-domain methods, such as rate and irregularity, VF-filter leakage, and sequential hypothesis testing, the new algorithm is simple, computationally efficient, and well suited for real-time implementation in automatic external defibrillators (AED's).