Out-of-Hospital Cardiac Arrest

Using a defibrillator for a cardiac arrest victim improves 30-day survival even with ambulance response times as low as two minutes, according to research presented at the 2023 ESC Congress.

You can save the life of a cardiac arrest victim even if an ambulance arrives within two minutes

Most sudden cardiac arrests occur in the community. A cardiac arrhythmia, called ventricular fibrillation , causes the heart to stop pumping and blood flow to stop. If blood flow is not restored quickly, the individual passes out and dies within 10 to 20 minutes. The public can help by calling an ambulance and performing chest compressions (cardiopulmonary resuscitation; CPR) while asking someone else to find a defibrillator. The defibrillator is then used to deliver a high-energy electrical shock that restarts the heart.

Study author Dr Mathias Hindborg from Nordsjaellands Hospital, Hilleroed, Denmark, said: “When a person collapses due to sudden cardiac arrest, the most effective way a bystander can help is to perform CPR and use an external defibrillator . automatic (DEA). Previous studies have investigated the best location for AEDs, but there is little information on how ambulance response times might affect their location. Therefore, we examined the effect of AED use on survival based on ambulance response times.”

The study used data from the Danish Cardiac Arrest Registry on out-of-hospital cardiac arrests that occurred between 2016 and 2020. Information was collected on age, sex, location, bystander defibrillation and CPR, ambulance response time, and 30-day survival after of cardiac arrest. The study only included adults with a witnessed cardiac arrest, who received bystander CPR, and who had an ambulance arrive in 25 minutes or less.

The researchers compared the probability of survival between patients who had been defibrillated by a bystander before the ambulance arrived and those who had not. The difference was measured at eight different ambulance response time intervals. Analyzes were adjusted for factors that could influence the relationship, including age, sex, location of arrest (public/private), and other medical conditions, such as a previous heart attack or stroke.

The study included 7,471 adults with a bystander who witnessed a cardiac arrest outside the hospital and who received CPR before an ambulance arrived. Of these, 14.7% (1,098/7,471) received defibrillation by a bystander before the arrival of an ambulance and 85.3% (6,373/7,471) did not. About 44.5% (489/1,098) of patients survived up to 30 days when bystander defibrillation was performed, compared to 18.8% (1,200/6,373) when no bystander defibrillation was performed. of a witness.

Patients who received bystander defibrillation were more likely to survive up to 30 days compared to those who did not receive bystander defibrillation during all ambulance arrival time intervals except 0 to 2 minutes, where the increase did not reach statistical significance. Compared with no defibrillation, the chance of survival with bystander defibrillation was 37% higher when the ambulance arrived within 2 to 4 minutes, 55% higher if the ambulance arrived within 4 to 6 minutes, and approximately two times higher if the ambulance arrived within 4 to 6 minutes. remaining intervals studied, with relative risks of 2.23 for 6 to 8 minutes, 1.99 for 8 to 10 minutes, 1.89 for 10 to 12 minutes, 1.86 for 12 to 15 minutes, and 1.98 for 15 to 15 minutes. 25 minutes.

Dr Hindborg said: “All patients in the study received CPR and the results show the additional benefit of bystander defibrillation on survival. The greatest positive impact of bystander defibrillation on the probability of survival was achieved when it took six to eight minutes for the ambulance to arrive at the scene. “The findings indicate that when resources are limited, defibrillators should be located in areas where ambulance response time is likely to be greater than six minutes.”

He concluded: “Anyone can help revive a person in cardiac arrest, whether by performing CPR, recovering or using an AED, or even purchasing an AED for your workplace, community or home. “Defibrillation saves lives and we can’t have too many AEDs in the community, but if we need to prioritize locations, this study can help in that process.”