Patients with a public out-of-hospital cardiac arrest treated with an automated external defibrillator by a bystander had an increased chance of survival and improved functional outcomes, according to a study published in Circulation.
“We estimate that about 1,700 lives are saved in the United States per year by bystanders using an AED,” Myron Weisfeldt, MD, university distinguished service professor at Johns Hopkins School of Medicine, said in a press release. “Unfortunately, not enough Americans know to look for AEDs in public locations, nor are they trained on how to use them despite great and effective efforts of the American Heart Association.”
Ross A. Pollack, BS, medical student at Johns Hopkins University School of Medicine, and colleagues analyzed data from 49,555 patients from the Resuscitation Outcomes Consortium Epistry dataset who had a shockable observed public out-of-hospital cardiac arrest from 2011 to 2015. Patients were from six regions in the United States and three regions from Canada. To confirm the findings, data from patients with private and unobserved out-of-hospital cardiac arrests were also reviewed.
The primary outcome measure was discharge with favorable or normal functional status, which was defined as a modified Rankin Scale score of 2 or less. The secondary outcome measure was survival to hospital discharge.
From 2011 to 2015, 8.3% of patients had public out-of-hospital cardiac arrests (median age, 62 years; 80% men). Of those, 60.8% of patients had cardiac arrests that were shockable (median age, 61 years; 85% men). Bystanders used an AED to deliver a shock before emergency medical services (EMS) arrived in 18.8% of shockable observed public out-of-hospital cardiac arrests.
Patients who were shocked by a bystander were more likely to survive to discharge (66.5% vs. 43%; P < .001) and have a favorable functional outcome at discharge (57.1% vs. 32.7%; P < .001) compared with patients who received a shock by EMS. After adjustment, the OR for survival to discharge was 2.62 (95% CI, 2.07-3.31) and the OR for favorable functional outcome at discharge was 2.73 (95% CI, 2.17-3.44) in patients who received shocks from bystanders.
Compared with EMS initial shock, the adjusted OR for favorable functional outcome in patients who received a shock from a bystander increased with the EMS response interval at 4 minutes (OR = 1.86; 95% CI, 1.03-3.37), 8 minutes (OR = 3.49; 95% CI, 1.59-7.67) and 12 minutes (OR = 6.54; 95% CI, 2.15-19.91).
“We contend that the results presented here, therefore, are readily generalizable and serve as an example of the benefit provided by rigorously optimizing the pre- and posthospital systems as many [Resuscitation Outcomes Consortium] sites have done,” Pollack and colleagues wrote. – by Darlene Dobkowski
Weisfeldt and Pollack report no relevant financial disclosures. Please see the study for all other authors’ relevant financial disclosures.