Out-of-hospital cardiac arrest (OHCA) is a significant cause of sudden cardiac death, with survival rates highly dependent on immediate recognition and intervention. Approximately 50–75% of OHCA cases are unwitnessed, reducing the likelihood of immediate medical response and resuscitation. Researchers evaluated whether a smartwatch could autonomously detect pulseless events and contact emergency services while minimizing false alarms.

In the study, “Automated Loss of Pulse Detection on a Consumer Smartwatch,” published in Nature, researchers trained an algorithm using photoplethysmography (PPG) and motion data. The team then validated the system across six distinct cohorts, including controlled clinical settings and free-living real-world environments.