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.