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Time to first shock: Out of hospital cardiac arrest in Qatar

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conference contribution
submitted on 2024-05-16, 11:04 and posted on 2024-05-26, 06:00 authored by Padarath Gangaram, Ian Howard, Ian Howland, Bernard Pillay, Hassan Farhat, Guillaume Alinier


Early defibrillation to a cardiac arrest (CA) patient in a shockable rhythm (ventricular fibrillation/pulseless ventricular tachycardia) is key to improving the return of spontaneous circulation (ROSC) and a successful patient outcome. Time to first shock is the time from when the patient in CA starts presenting with a shockable rhythm to when the first defibrillation is delivered. This study aimed to audit Hamad Medical Corporation Ambulance Service (HMCAS) data with respect to time to defibrillation to out-of-hospital CA patients.


This retrospective chart review resulted in 193 medical and trauma cases being found during the period 01/01/2022 to 31/12/2022. Time to first shock included initial rhythm assessment with a patient in CA or witnessed CA with a shockable rhythm. Initial rhythm assessment was identified when HMCAS paramedics placed the defibrillation pads on a patient in CA for the first time and the presenting rhythm was shockable. Witnessed CA with a shockable rhythm was identified when the patient went into CA with a shockable rhythm during care.


The fastest time to first defibrillation was 11 seconds (sec) and the slowest time was 336 sec. The mean time was 21.91 sec with a standard deviation of 30.41 sec. 187 (97%) patients who presented with CA and shockable rhythms for first defibrillation were medical patients (Figure 1). All patients presented with ventricular fibrillation. Patients with medical CA and shockable rhythms for first defibrillation presented with chest pains or cardiac related illnesses (bradycardia, dizziness, hypotension, STEMI, etc.). 177 (91.71%) of the patients presenting with CA and shockable rhythms underwent first defibrillation within the 90 sec benchmark time and 16 (8.29%) were outside of the benchmark time (Figure 2).


Reviewing time to first shock is essential in improving quality patient care. ROSC to hospital discharge is an area of future focus.



  • English


Hamad Medical Corporation

Publication Year

  • 2024

License statement

This Item is licensed under the Creative Commons Attribution 4.0 International License.

Institution affiliated with

  • Hamad Medical Corporation
  • Ambulance Service - HMC
  • Weill Cornell Medicine - Qatar
  • Ministry of Public Health - State of Qatar

Geographic coverage