basic life support during advanced life support

Last reviewed 01/2018

Basic life support should be performed in all cases of cardiac arrest and only interrupted for such circumstances as defibrillation or intubation.

When ventilation is provided by mouth-to-mouth, a pocket mask, or a self-inflating bag-mask-valve circuit, then the ratio of ventilations to chest compressions should always be 2:30 irrespective of one or more rescuers.

Once the airway has been secured by an endotracheal tube or combitube, then continuous ventilations and chest compressions should be given; ventilations at a rate of 2:30. This continuous, asynchronous basic life support is uninterrupted except for pulse checks, defibrillation or other procedures.

When using a laryngeal mask airway, continuous, asynchronous basic life support may be possible. However, if it is difficult to adequately ventilate whilst chest compressions are given, then basic life support must revert back to cycles of 2:30.


  • the Resuscitation Council (UK) now recommends:
    • for adults:
      • CPR with a chest compression to ventilation ratio of 30:2
      • no initial ventilations before starting compressions
      • when professional help is delayed for more than 4-5 minutes, one option is to give compressions for up to three minutes before attempting defibrillation
      • compressions for two minutes after defibrillation
      • if coordinated rhythm is not restored by defibrillation, second and further shocks should be given only after additional cycles of chest compressions


  1. BMJ editorial. New international concensus on cardiopulmonary resuscitation. BMJ 2005;331:1281-2.