Refibrillation and automated external defibrillators

There is a number of patients that after being rehabilitated from ventricular fibrillation to normal cardiac rhythms by defibrillation-trained ambulance technicians (EMT-Ds) will refibrillate on the way to hospital. Concerning this matter, Stults and Brown carried out a research on refibrillation . 271 cases in ventricular fibrillation were studied. These 271 patients were assisted by EMT-Ds without being supported by paramedics. The EMTs succeeded to render the heart rhythm to normal for 111 patients. 19 (17%) of the 271 patients refibrillated before the arrival at the hospital, and 11 out of the 19 were brought back to having normal cardiac rhythm. For the 111 patients that were rehabilitated, the admission rates were 53%. This is a low number compared to the 73% admission rate for the patients who did not refibrillate. The discharge rates were almost similar 37% for those who refibrillated and 35% for those who did not.

The research has also shown the fact that the times of transportation from the scene of the incident to the hospital did not influence the frequency of the refibrillation or the survival rate. However, this research has proven that the defibrillation-trained EMTs can successfully deal with refibrillation even if there are no paramedics assisting their work.

Another study has observed the incidence and time course of refibrillation and the survival rate. This study has been done on 49 adults that were administrated the Basic Life Support treatment (BLS). 44% of the patients received cardiopulmonary resuscitation. On average, the first shock was administrated after 6.1 minutes after the occurrence of the cardiac arrest. 61% of the patients refibrillated under BLS treatment, 35% of which more than once. The BLS treatment was associated with survival at discharge and neurological outcome the percentage being 41%. This study proves that refibrillation does not always mean survival to hospital discharge - however, it might indicate higher chances of survival for patients.

Time to defibrillation - the benefit of automated external defibrillators

Studies in AED and EMT using manual defibrillation were conducted to determine whether there are differences in time to defibrillation. For AEDs usage 1 minute was needed, while for the manual defibrillation done by EMTs, 2 minutes were required.

Bocka has proven in a study that people using automatic external defibrillators were 30 seconds quicker than people using semiautomatic device. Early Seattle studies found a significant difference in time to defibrillation: 1.1 minutes for AEDs versus 2 minutes for EMTs with manual defibrillators. Bocka found that EMTs using fully automatic defibrillators in the field were on average 30 seconds faster than counterparts using semiautomatic devices. These studies show that having an AED at hand at all times is clearly an advantage and therefore, must be prioritized.

Detailed information on automated external defibrillators is available through our other resources.