Safety and effectiveness of a portable external automatic defibrillator‐pacemaker

Abstract

Sudden cardiac death in the community can be reduced by early resuscitation. The commonest arrhythmia encountered in this setting is ventricular fibrillation. A portable external automatic defibrillator‐pacing machine for use by emergency services and laymen after basic training, has recently been introduced. This device has a tongue‐abdominal pathway for sensing the electrocardiogram and respiration, as well as delivery of current. In its automatic mode, the machine cannot defibrillate unless the patient's breathing and gag reflex are virtually absent. The decision‐making characteristics of the machine were defined in isolation from the patient using simulated ECG signals and recordings of arrhythmias obtained during cardiac surgery and during electrophysiological studies. The pathway was evaluated separately by attaching it to a conventional defibrillator and using it in the elective cardioversion of 15 patients. Electrode sites were examined and creatine phosphokinase (CPK) and creatinine phosphokinase isoenzyme (CPKMB) release determined following conversion. Repeated playback of the same 34 minutes of selected recordings showed that decisions were consistent 95% of the time. Automatic pacing always occurred with asystole. ECG signals less than 0.35 mV in amplitude were not recognized, but a manual override switch could be operated in those circumstances where there was failure to act upon fine ventricular fibrillation. Defibrillation of 50% of the recordings of supraventricular and ventricular tachycardia did occur, but this could not have happened in practice unless the patient was unconscious, and in addition, the operator failed to countermand this decision. The tongue‐abdominal pathway yielded good recordings of the ECG. There was no significant damage to the tongue and the defibrillator charges employed were comparable to those that would be used with conventional chest paddles. In conclusion, the tongue‐abdominal pathway was safe and the machine, although its ECG logic made some inappropriate decisions, had sufficient safeguards to recommend its use in the emergency setting of the victim collapsing out of hospital. Copyright © 1983 Wiley Periodicals, Inc.