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Comment on “Mobile phone-based alerting of CPR-trained volunteers simultaneously with the ambulance can reduce the resuscitation-free interval and improve outcome after out-of-hospital cardiac arrest: A German, population-based cohort study”

  • Michael Patrick Müller
    Correspondence
    Corresponding author at: Dept. of Anaesthesiology, Intensive Care, and Emergency Medicine, Artemed St. Josef's Hospital, Sautierstr. 1, 79104 Freiburg, Germany.
    Affiliations
    Department of Anaesthesiology, Intensive Care, and Emergency Medicine, Artemed St. Josef's Hospital, Germany

    German Resuscitation Council (GRC), Germany
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  • Domagoj Damjanovic
    Affiliations
    Department of Cardiovascular Surgery, University Heart Center Freiburg, Faculty of Medicine, University of Freiburg, Freiburg, Germany
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  • Julian Ganter
    Affiliations
    Department of Cardiovascular Surgery, University Heart Center Freiburg, Faculty of Medicine, University of Freiburg, Freiburg, Germany
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  • Georg Trummer
    Affiliations
    German Resuscitation Council (GRC), Germany

    Department of Cardiovascular Surgery, University Heart Center Freiburg, Faculty of Medicine, University of Freiburg, Freiburg, Germany
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      To the editor
      We congratulate Stroop and coworkers to their successful implementation of a smartphone alerting system (SAS) in the city of Gütersloh,
      • Stroop R.
      • Kerner T.
      • Strickmann B.
      • Hensel M.
      Mobile phone-based alerting of CPR-trained volunteers simultaneously with the ambulance can reduce the resuscitation-free interval and improve outcome after out-of-hospital cardiac arrest: a German, population-based cohort study.
      aiming to improve survival following cardiac arrest via shortening no-flow times. An important way to demonstrate the benefit of SAS is assessing first responders’ response times (RTs). Stroop et al. report a RT of 4 min following smartphone alert. However, we are concerned about the validity of the presented data. The authors do not describe the method of how they measure response times. Very recently, Stroop published another study,
      • Stroop R.
      • Hensel M.
      • Kerner T.
      Smartphone-basierte Ersthelferalarmierung – Auswertung der Alarmierungsdaten aus 7 Mobile-Retter-Regionen.
      in which estimated RTs were used for benchmarking between different regions, participating in the Mobile Rescuer (MR) program. Timeframe, setting and mean RT of the study (10/2013-08/2018, city of Gütersloh, 4:33 min) suggest an overlap with the cases in the Resuscitation article.
      • Stroop R.
      • Kerner T.
      • Strickmann B.
      • Hensel M.
      Mobile phone-based alerting of CPR-trained volunteers simultaneously with the ambulance can reduce the resuscitation-free interval and improve outcome after out-of-hospital cardiac arrest: a German, population-based cohort study.
      In the German paper, Stroop explains that the response times have been calculated based on Google Maps plus a generalized set-up time of 1 min.
      • Stroop R.
      • Hensel M.
      • Kerner T.
      Smartphone-basierte Ersthelferalarmierung – Auswertung der Alarmierungsdaten aus 7 Mobile-Retter-Regionen.
      The authors state that “Since a digital, smartphone-based recording of […] arrival times, which would be of interest for direct comparison with rescue service arrival times, is not reliably available, the comparison of the MR regions is based on indirect key figures. These are expected arrival times based on the route calculation at the time of the alarm…
      The estimated RTs of MR were compared to the measured ambulance RTs, and the results tested for statistical significance. The data presented in the manuscript do not support the statement in the title: “Mobile phone-based alerting … can reduce the resuscitation-free interval…”. The real response times will be by far longer as the given values. Many of the mobile rescuers are not working in emergency services and, at least when being alerted at night, they will need more than 1 min until travelling. Mobile rescuers being alerted at daytime will commonly need more than 1 min to leave their work. Furthermore, a calculation based on Google Maps cannot precisely anticipate the travelling time. Some first responders are running, while some others are travelling by bicycle, and If the rescuer is driving by car, one single red traffic light may double real travel time compared to calculated.
      Since the last guidelines were published in 2015, SAS have been emerging quickly in several regions but there is not yet a standard. However, the first systematic review regarding these systems was published recently.
      • Scquizzato T.
      • Pallanch O.
      • Belletti A.
      • et al.
      Enhancing citizens response to out-of-hospital cardiac arrest: a systematic review of mobile-phone systems to alert citizens as first responders.
      Within this manuscript, the results of Stroop are cited in table 3 (page 22) with a 4 min “time to arrival of first responders”. Thus, response times of the city of Gütersloh system are among the best times within the papers included, but we are concerned about the quality of the data, the derived conclusions and therefore the overall scientific quality published by Stroop and colleagues in their paper.
      • Stroop R.
      • Kerner T.
      • Strickmann B.
      • Hensel M.
      Mobile phone-based alerting of CPR-trained volunteers simultaneously with the ambulance can reduce the resuscitation-free interval and improve outcome after out-of-hospital cardiac arrest: a German, population-based cohort study.
      It is very important that readers know, how accurate and valid published data are, as reference to estimated instead of measured data without further clarification will reduce significance of this important new area of research.

      Conflict of interest statement

      All authors declare the following conflicts of interest:
      Scientific conflict of interest as we are researchers in the same field of interest (smartphone based alerting systems).
      GT is board member (secretary) in the German Resuscitation Council (GRC) and board member in the non-profit organization Region der Lebensretter e.V. (Region of Lifesavers).
      GT is shareholder of Resuscitec GmbH.
      MPM is member of the executive committee of the GRC and chair of the non-profit organization Region der Lebensretter e.V. (Region of Lifesavers). MPM is shareholder of SmartResQ ApS, Denmark.
      All authors have no further conflict of interest.

      References

        • Stroop R.
        • Kerner T.
        • Strickmann B.
        • Hensel M.
        Mobile phone-based alerting of CPR-trained volunteers simultaneously with the ambulance can reduce the resuscitation-free interval and improve outcome after out-of-hospital cardiac arrest: a German, population-based cohort study.
        Resuscitation. 2020; 147: 57-64https://doi.org/10.1016/j.resuscitation.2019.12.012
        • Stroop R.
        • Hensel M.
        • Kerner T.
        Smartphone-basierte Ersthelferalarmierung – Auswertung der Alarmierungsdaten aus 7 Mobile-Retter-Regionen.
        Notarzt. 2020; 31 (239–9)https://doi.org/10.1055/a-1224-4103
        • Scquizzato T.
        • Pallanch O.
        • Belletti A.
        • et al.
        Enhancing citizens response to out-of-hospital cardiac arrest: a systematic review of mobile-phone systems to alert citizens as first responders.
        Resuscitation. 2020; 152: 16-25https://doi.org/10.1016/j.resuscitation.2020.05.006

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