Introduction

Electrical defibrillation is well established as the only effective therapy for cardiac arrest due to ventricular fibrillation (VF) or pulseless ventricular tachycardia (VT). The scientific evidence to support early defibrillation is overwhelming, the single most important determinant of survival being the delay from collapse to delivery of the first shock. The chances of successful defibrillation decline at a rate of 7 - 10% with each minute; basic life support will help to sustain a shockable rhythm but is not a definitive treatment.

The 'chain of survival' concept

The chances of survival following cardiac arrest are considerably improved if appropriate steps are taken to deal with the emergency. These steps are:

• Recognition of cardiac arrest

• Early activation of appropriate emergency services

• Early basic life support

• Early defibrillation

• Early advanced life support

The Resuscitation Council (UK) strongly recommends the implementation of early defibrillation.

Manual defibrillation has been widely available for many years, but the requirement for training in arrhythmia recognition limits the application of this technique to medical practitioners, nurses working in critical care areas and ambulance paramedics.

Recent developments in automated external defibrillators (AEDs) have enabled increasing numbers of individuals to perform defibrillation safely and effectively. Such individuals (designated first responders) include ambulance technicians, general ward nurses, members of first aid and rescue organisations, police officers, fire-fighters, airline cabin crew, security personnel and specially trained members of the public.

Increased provision of early defibrillation through the widespread deployment of AEDs is now considered a realistic strategy for reducing mortality from cardiac arrest due to ischaemic heart disease. The following recommendations are intended to provide guidance to those responsible for the provision of cardiopulmonary resuscitation in various settings.

Automated external defibrillators must be totally reliable, simple to operate, of low weight, require little routine maintenance and be competitively priced. Recording facilities are considered essential to facilitate evaluation and audit. Standardisation of consumables (electrode pads etc.), connecting cables, control switches and testing procedures is strongly recommended. There is no consensus on standards for battery capacity at present. Equipment should be configurable to facilitate upgrading as new guidelines and treatment algorithms are developed.

Monophasic defibrillators should deliver energy in accordance with current advanced life support algorithms (200, 200, 360 joules). Some newer devices deliver lower energy shocks using biphasic waveforms. These are currently undergoing evaluation, and the results to date would support their use.

Because it is occasionally necessary to cut through clothing and/or shave a victim's chest to facilitate electrode placement, it is recommended that AEDs are provided with a sturdy carrying pouch, which should contain spare electrodes, strong scissors and a disposable safety razor, as well as spare electrodes.

AEDs have been used successfully in the community by lay first responders, including police officers, fire-fighters, security staff, airline cabin crew and members of first aid and rescue organisations. The Resuscitation Council (UK) recommends that AEDs be made available wherever large crowds gather, for example at sports stadiums, pop concerts, theatres, cinemas and shopping complexes. The Council strongly recommends that organisations contemplating deployment of AEDs should seek the advice of a recognised training organisation, for example a statutory ambulance service, a voluntary aid society or equivalent body.

Sequence of actions for automated external defibrillation

• If two rescuers are present, assign tasks - defibrillation has priority

• Fetch AED and activate emergency system.

• Check response: Gently shake his shoulders and shout

• Open airway; check for breathing: Tilt head and lift chin

• Give two effective breaths

• Check for signs of a circulation
  For lay rescuers this means look, listen and feel for normal breathing, coughing, or movement by the victim. Take no more than 10 seconds to do this.
  For health care providers this will also include checking the carotid pulse.

• If breathing is present put victim into recovery position

• If not breathing start rescue breathing and re-check for a circulation every minute.

• Switch on defibrillator and attach the electrode pads

• Follow spoken/visual directions

Ensure that nobody touches the victim whilst the AED is analysing the rhythm.

• Ensure that everybody is clear of the victim

• Push shock button as directed

• Repeat "analyse" or "shock" as directed

Do not perform pulse checks between the first three shocks

• After three shocks check for signs of a circulation:
  (1) If NO circulation present:

  • Perform CPR for 1 minute
    There should be no voice prompts during this time. CPR will be timed by the AED timer - this will usually be four cycles of one-rescuer CPR

  • After 1 minute stop CPR and "analyse" rhythm (most AEDs will automatically initiate this analysis)

  • Continue the AED algorithm as directed by voice and visual prompts.

   
  (2) If signs of a circulation ARE present:

  • Check for breathing

  • If breathing is present, put victim into recovery position

  • If no breathing, start rescue breathing and re-check circulation every minute.

• Look for signs of a circulation

• If no circulation present, perform CPR for 1 minute

There should be no voice prompts during this time. CPR will be timed by the AED timer - this will usually be four cycles of one-rescuer CPR

• After 1 minute stop CPR and "analyse" rhythm (most AEDs will automatically initiate this analysis)

• Continue the AED algorithm as directed by voice and visual prompts.