Bystander defibrillation after cardiac arrest improves survival with quick EMS response
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Key takeaways:
- Bystander use of an automated external defibrillator after cardiac arrest improves survival odds at 30 days.
- Relative risk for improved survival was significant even with quick EMS response.
Adults are more likely to survive an out-of-hospital cardiac arrest if they receive bystander defibrillation, even when an ambulance arrives within as little as 2 minutes, researchers reported.
Danish researchers have focused on improving the rates of bystander defibrillation after an out-of-hospital cardiac arrest and have studied the placement of public available automated external defibrillators but have not yet investigated whether ambulance response time should be considered in the placement of AEDs, Mathias Hindborg, MD, a doctoral student at Nordsjaellands Hospital in Hillerød, Denmark, told Healio.
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“Bystander defibrillation helps save lives when out-of-hospital cardiac arrests occur,” Hindborg told Healio. “If you need to prioritize where to place defibrillators, our data show that they have the greatest impact on survival if placed in areas with ambulance response times of greater than 6 minutes.”
Hindborg and colleagues analyzed data from the Danish Cardiac Arrest Registry of 7,471 adult out-of-hospital cardiac arrests from 2016 to 2020. Included cases had bystander witnesses with the patient receiving CPR, with an emergency medical service (EMS) response time of 25 minutes or less. Cardiac arrest cases witnessed by EMS were excluded. Researchers calculated crude survival proportions for each minute of EMS response time and estimated relative risk for 30-day survival for eight different intervals of EMS response time, adjusted for age, place of arrest (public vs. private), initial cardiac rhythm (shockable vs. not shockable) and comorbidities (prior CVD, chronic obstructive pulmonary disease or cancer).
The findings were presented at the European Society of Cardiology Congress.
Of the 7,471 cases, 14.7% received bystander defibrillation before EMS arrived.
Overall, 44.5% of those who received bystander defibrillation were alive at 30 days compared with 18.8% of those who did not receive bystander defibrillation. Researchers found that 30-day survival was consistently higher in the group who received bystander defibrillation for the first 20 minutes, after which survival was the same for the two groups.
Compared with no defibrillation, the likelihood of survival with bystander defibrillation was 37% higher when the ambulance arrived in 2 to 4 minutes (RR = 1.37; 95% CI, 1.1-1.7), 55% higher for arrival in 4 to 6 minutes (RR = 1.55; 95% CI, 1.33-1.8), and approximately twofold higher for the remaining intervals studied, with RRs 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 25 minutes. There was no significant difference between the groups when the ambulance arrived in less than 2 minutes.
“There is a need to examine and understand the relationship between how early the bystanders perform defibrillation and how fast the ambulance personnel reach the scene and how this time difference affects survival chances,” Hindborg told Healio. “A better understanding of this would help in organizing emergency medical services better in order to reach their goals in terms of cardiac arrest survival.”
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Hindborg M, et al. Abstract 82936. Presented at: European Society of Cardiology Congress; Aug. 25-28, 2023; Amsterdam (hybrid meeting).
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