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Key information


POSED - Prehospital Optimal Shock Energy for Defibrillation

Chief Investigator: Prof. Gavin Perkins, Co-Chief Investigator: Helen Pocock

Sponsor: University of Warwick

Funder: NIHR Clinical Doctoral Research Fellowship (ICA-CDRF-2018-04-ST2-005)

Registration Number: tbc


Each year, the UK ambulance services attempt to restart the hearts of 30,000 people who have suffered cardiac arrest (when the heart stops beating). Performance of good chest compressions (CPR) and, where appropriate, delivery of an electric shock to the heart (defibrillation) are the only proven methods of reviving these patients. Defibrillators (electric shock machines) can deliver a range of shock strengths (low, medium or high). Because we don’t currently know the best shock strength to deliver, there is variation between UK ambulance services.

POSED is a feasibility study, necessary to help ensure time and money would be well spent on a full-scale trial. This involves:

  • Programming defibrillators to deliver different shock strategies. All of these shock strengths are currently used in UK ambulance services.
  • Finding the ‘recruitment rate’ by comparing the number of patients included with the number who could have been included (from 999 call records).
  • Tracking patients’ condition in hospital for the following 30 days.

Sample size:

I aim to include 90 patients in this study. I will speak to ambulance staff to explore how to improve processes so that a full clinical trial would work.

Primary outcome:

The primary objective of this study is to establish whether it is feasible to conduct a large-scale definitive trial by establishing the number of eligible patients and the number recruited.


Study recruitment will take place over two years.


Study Co-ordinator: Jeskaran Rai


Address: POSED study

Warwick Clinical Trials Unit
Warwick Medical School
University of Warwick
Gibbet Hill Road

Resuscitation Council UK - Statement in support of POSED

RCUK_Statement in support of POSED

  View statement by clicking here.Link opens in a new window

Click here to go to the South Central Ambulance Service - Research pageLink opens in a new window