Choosing cardiac-arrest volunteers by estimated travel time improved their chances of arriving before an ambulance compared with a small geographic alert radius, according to results released November 7 by the American Heart Association.
The ALARM randomized trial compared three smartphone dispatch strategies in Freiburg, Germany: alerts within about 600 meters, alerts within about 2,500 meters, and a calculation comparing volunteer travel time with expected ambulance arrival.
At least one volunteer arrived before emergency medical services in 31% of incidents with the small radius, 57% with the larger radius and 58% with travel-time calculations. Smart dispatch also withheld assignments from 31% of volunteers who accepted alerts because they were expected to arrive after the ambulance.
The system was activated more than 820 times during January–July 2024, with strategies randomly switched each day. Results were released at the association’s resuscitation symposium, with simultaneous journal publication reported.
The study measured dispatch performance rather than patient survival. Its findings come from one German region with a particular responder network and defibrillator availability; researchers said survival benefits require further study.