{
  "abstract": "Introduction Public Access Defibrillators (PADs) are widely promoted as a life-saving intervention in out-of-hospital cardiac arrest (OHCA). PAD effectiveness is often inferred from shock delivery alone, which does not necessarily reflect sustained return of spontaneous circulation (ROSC). This study aims to determine the incidence of failure of PAD shock to achieve ROSC.Methods This is an analysis of consecutive OHCA patients within the prospectively collected BCIS OHCA registry [REC (22/NW/0146)/CAG (22/CAG/0106)] receiving an initial PAD shock in the East of England, UK, between November 2024 and November 2025. PAD failure was defined as PAD shock delivery not resulting in ROSC and requiring subsequent ambulance service defibrillation (ASD). PAD success for the purpose of this study, was defined as PAD shock resulting in ROSC and requiring no further ASD. Outcomes included the incidence of PAD failure, ROSC at scene and final outcomes including mortality on scene and 30-day survival.Results A total of 3,630 OHCA patients were screened. After excluding those younger than 18 years, initial non-shockable rhythms, traumatic OHCA, or without PAD use, a final cohort of 92 patients was identified (mean age 64.0 ± 14.0 years; 83.7% male).Of these 92 patients, 83 (90.2%) required subsequent ASD, meeting criteria for PAD failure. Nine patients (9.8%) did not require further defibrillation following PAD use; within this subgroup, sustained ROSC was achieved in five patients (5.4%), while four patients experienced rhythm change to non-shockable without ROSC or died prior to further intervention.Mortality at scene was higher in the PAD failure group compared with the PAD success group (73.5% vs 55.6%, p=0.25), with lower 30-day survival (25.5% vs 44.4%, p=0.27), though these differences did not reach statistical significance, likely due to small sample size. The PAD failure group required a higher number of defibrillation attempts (median 5 shocks) compared with the PAD success group (median 1 shock).Conclusion In this real-world study, PAD shocks alone rarely resulted in sustained recovery, with PAD success, defined as ROSC without subsequent ASD, occurring in only 5.4% of cases. Most patients required escalation to ASD, highlighting a substantial gap between PAD deployment and clinical effectiveness. These findings suggest that shock delivery alone is an insufficient metric for PAD performance. Factors such as time to first shock, pad integrity and placement, chest preparation, PAD model/joule use and bystander CPR performance may contribute to PAD failure. System-level interventions, including real-time remote bystander support such as the ongoing OHCA desk video-CPR pilot in the East of England, may help optimise on-scene performance and improve the likelihood of sustained ROSC prior to professional arrival. These findings should be considered hypothesis-generating and warrant further confirmation in larger, adequately powered cohorts.",
  "authors": [
    {
      "affiliations": [
        "Essex Cardiothoracic Centre, Mid and South Essex NHS Trust, Basildon, United Kingdom",
        "MTRC, Anglia Ruskin School of Medicine, Chelmsford, United Kingdom"
      ],
      "name": "Soyun Choi"
    },
    {
      "affiliations": [
        "Essex Cardiothoracic Centre, Mid and South Essex NHS Trust, Basildon, United Kingdom",
        "MTRC, Anglia Ruskin School of Medicine, Chelmsford, United Kingdom"
      ],
      "name": "Uzma Sajjad"
    },
    {
      "affiliations": [
        "Essex Cardiothoracic Centre, Mid and South Essex NHS Trust, Basildon, United Kingdom",
        "MTRC, Anglia Ruskin School of Medicine, Chelmsford, United Kingdom"
      ],
      "name": "Guilherme Movio"
    },
    {
      "affiliations": [
        "Essex Cardiothoracic Centre, Mid and South Essex NHS Trust, Basildon, United Kingdom",
        "MTRC, Anglia Ruskin School of Medicine, Chelmsford, United Kingdom"
      ],
      "name": "Abdalla Ibrahim"
    },
    {
      "affiliations": [
        "East of England Ambulance Service, Welwyn Garden City, United Kingdom"
      ],
      "name": "Luke Robert-Andreou"
    },
    {
      "affiliations": [
        "East of England Ambulance Service, Welwyn Garden City, United Kingdom",
        "Association of Ambulance Chief Executives, London, United Kingdom"
      ],
      "name": "Liam Sagi"
    },
    {
      "affiliations": [
        "East of England Ambulance Service, Welwyn Garden City, United Kingdom",
        "East and Herts Air Ambulance, Epping, United Kingdom"
      ],
      "name": "Adam Pitcairn"
    },
    {
      "affiliations": [
        "Essex Cardiothoracic Centre, Mid and South Essex NHS Trust, Basildon, United Kingdom",
        "MTRC, Anglia Ruskin School of Medicine, Chelmsford, United Kingdom"
      ],
      "name": "Gerald Clesham"
    },
    {
      "affiliations": [
        "Essex Cardiothoracic Centre, Mid and South Essex NHS Trust, Basildon, United Kingdom",
        "MTRC, Anglia Ruskin School of Medicine, Chelmsford, United Kingdom"
      ],
      "name": "Maria Maccaroni"
    },
    {
      "affiliations": [
        "King’s College Hospital NHS Foundation Trust, London, United Kingdom",
        "School of Cardiovascular and Metabolic Medicine & Sciences, British Heart Foundation Centre of Excellence, King’s College, London, United Kingdom"
      ],
      "name": "Nilesh Pareek"
    },
    {
      "affiliations": [
        "Essex Cardiothoracic Centre, Mid and South Essex NHS Trust, Basildon, United Kingdom",
        "MTRC, Anglia Ruskin School of Medicine, Chelmsford, United Kingdom"
      ],
      "name": "John R Davies"
    },
    {
      "affiliations": [
        "Essex Cardiothoracic Centre, Mid and South Essex NHS Trust, Basildon, United Kingdom",
        "MTRC, Anglia Ruskin School of Medicine, Chelmsford, United Kingdom"
      ],
      "name": "Thomas R Keeble"
    }
  ],
  "title": "478 Clinical effectiveness of public access defibrillators (PAD) to cardiovert patients and obtain ROSC following shockable out-of-hospital cardiac arrest (OHCA)",
  "uid": "d3a146a3-6840-569a-baf6-29e2d50115c4"
}