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The latest guidelines for cardiopulmonary resuscitation recommend that in case of suspected cardiac arrest first responders, who are close to the emergency location, should be notified by a smartphone app or text message. Smartphone Alerting Systems (SAS) aim to reduce the resuscitation-free interval. Thus, there is a need for uniform reporting of process times. Objective: To compare the response times in a SAS either by using global positioning system (GPS) data or by manual confirmation of first responders arriving at the scene. Methods: In the region of Freiburg (Southern Germany, 1,531 km2, 493,000 inhabitants), a SAS is activated when the emergency dispatch center receives a call regarding suspected cardiac arrest. First responders who accept a mission are tracked using GPS. GPS-based times are logged for each responder when their position is within a radius of 100, 50, or 10 meters around the geographical position of the reported emergency. When arriving at the patient location, the first responders manually confirm "arrived" via their app. GPS-based and manually confirmed response arrival times were compared for all cases between 1 October and 31 March. Results: 192 missions with correct manual logging of the arrival time were included. GPS-based times were available in 175 (91%), 100 (52%), and 30 (16%) cases within radii of 100, 50, and 10 meters, respectively. GPS arrival times were approximately 1.5 minutes shorter when using a 100-meter radius and significantly longer when using a 10-meter radius. No difference was found for a 50-meter radius, but this would result in a lack of data in nearly half of the cases. Conclusion: GPS-based logging of arrival times leads to missing data. A 100-meter circle is associated with a low number of missing values, but 1.5 minutes must be added for the last 100 meters the first responder has to move. A wide range of the difference in response times (GPS vs. manual confirmation) must be regarded as a disadvantage. Manual confirmation reveals precise response times, but first responders may forget to confirm when they arrive. Trial registration: DRKS00016625 (14 April 2019). [ABSTRACT FROM AUTHOR]

Aim: Smartphone alerting systems (SAS) alert volunteers in close vicinity of suspected out-of-hospital cardiac arrest. Some systems use sophisticated algorithms to select those who will probably arrive first. Precise estimation of departing times and travel times may help to further improve algorithms. We developed a global positioning system (GPS) based method for automatic measurements of departing times. The aim of this pilot study was to evaluate feasibility and precision of the method., Methods: Region of Lifesavers alerting app (iOS/ Android, version 3.0, FirstAED ApS, Denmark) was used in this study. 27 experiments were performed with 9 students, who were instructed to stay in their flats during the study days. A geofence was set for each alarm in the alerting system with a radius of 10 m (8 cases), 15 m (10 cases), and 20 m (9 cases) around the GPS position at which the alarm was accepted in the app. The system logged responders as being departed when the smartphone position was registered outside the geofence. The students were instructed to manually start a stopwatch at the time of the alert and to stop the stopwatch once they had entered the street in front of their flat., Results: The median difference between automatically and manually retrieved times were -16 seconds [interquartile range IQR 50 seconds] (geofence 10 m), 30 seconds [IQR 25 seconds] (15 m), and 20 seconds [IQR 13 seconds] (20 m), respectively. The 20 m geofence was associated with the smallest interquartile range., Conclusion: Departing times of volunteer responders in SAS can be retrieved automatically using GPS and a geofence., Competing Interests: The authors declare the following financial interests/personal relationships which may be considered as potential competing interests: MPM is chair of Region of Lifesavers (non-profit organisation), received speaker honoraria from Stryker, and holds shares (SmartResQ ApS, Denmark). JG is member of the board of Region of Lifesavers (non-profit organisation). HJB is member of the executive committee of the German Resuscitation Council and vice chair of Region of Lifesavers (non-profit organisation). TB received honoraria from FirstAED ApS, Denmark, for technical support regarding FirstAED alerting software. AR, JO, and JF have no conflicts of interest., (© 2023 The Author(s).)