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choking / cardiac arrest / BLS / ALS / CPR


  • mortality from in-hospital VF arrest:
    • “30%” if VF occurs and immediate defibrillation is perfomed
    • >95% if defibrillation delayed by > 12 minutes
  • mortality from Out-of-Hospital cardiac arrest (OHCA):
    • VF arrest - 66-96%
      • depending on bystander CPR, availability of early defibrillator use
      • likelihood of survival largely determined by return of spontaneous output by the time patient arrives in ED.
    • asystole - >99%
  • thus prevention is far better than the cure!
    • in-hospital Medical Emergency Team (MET) to attend and manage critically ill ward patients ASAP
    • timely assessment and Mx of patients presenting to ED with early senior doctor input to detect at risk patients.
    • community awareness of chest pain and need for ambulance transfers ASAP

Mx of choking victim

  • call for help
  • if effective cough:
    • implied mild airway obstruction thus encourage coughing and get help, remain with victim
  • ineffectual coughing:
    • implies severe airway obstruction
    • conscious:
      • call for help
      • give up to 5 back blows
      • if not effective, give up to 5 chest thrusts
      • if no relief but remains conscious, repeat above
    • unconscious:
      • call for help
      • commence CPR as below

summary of Basic Life Support (BLS) for cardiac arrest

The Zombie CPR instructional video

7 components of BLS:

  • D: remove from danger
  • R: assess patient responsiveness
  • S: send for help
  • A: clear airway
    • head tilt-chin lift if non-trauma, or jaw thrust if trauma
    • remove vomitus using suction if possible
    • recognition and relief of foreign body airway obstruction
  • B: restore breathing although no longer the priority in adult out-of-hospital arrest
    • cardiac compressions alone (no ventilations) recommended for adult, out-of-hospital primary cardiac arrest (not respiratory) if witnessed, and with shockable rhythm or short period (<4 minutes) of untreated arrest
    • cardiac compressions alone also recommended if bystander not trained in CPR, or not confident in their ability
    • breaths (in hospital or those trained in CPR):
      • bag and mask if available (and oxygen at 15L/min to deliver 85% oxygen if available)
      • 2 effective breaths every 30 compressions with a 1 second inspiratory time (except neonates, give 40-60 breaths/min)
        • if unprotected airway, pause compressions during breaths
        • if protected airway (eg. ETT in situ), don't pause compressions, and rate should 1 breath every 15 compressions (2 breaths in children every 15 compressions)
      • bag size:
        • > 18kg or > 5yrs old, use a 1600ml adult bag
        • infant, use a 500ml bag
        • neonate, use a 240ml bag or neonatal circuit
  • C: establish circulation:
    • checking for pulses is unreliable, instead start compressions if no signs of life, for instance:
      • unresponsive or unconscious
      • not breathing or the occasional gasping breath
      • not moving
    • cardiac compressions over mid-sternum to a depth of 1/3rd chest (eg. 4-5cm in an adult) at a rate of 100 per minute for all ages, stopping to allow 2 breaths every 30 compressions if unprotected airway
    • early cardiac compressions may:
      • prevent VF deteriorating into asystole
      • increase the chance of successful defibrillation in VF
      • add to the preservation of brain and cardiac function
  • D: availability of semi-automatic external defibrillators:
    • defibrillation as soon as possible provides the best chance of survival in victims with VF or pulseless VT
    • C/I to SAED (await ALS team instead):
      • children < 8yrs age or < 25kg
      • unsafe environment
      • conscious and breathing normally
  • if cardiac arrest occurs in the obviously pregnant woman, place in a left lateral tilt by placing a pillow or wedge under the right buttock - this will reduce compression of IVC and aid venous return.

summary of Advanced Life Support (ALS) for cardiac arrest

  • consider and correct:
    • hypoxia
    • hypovolaemia
    • hyperkalaemia, hypokalaemia and other metabolic disorders
    • tension pneumothorax
    • tamponade
    • toxins
    • thrombosis (PE/AMI)

further airway management if still unconscious

  • intubation should not interrupt chest compressions for more than 20 seconds
  • avoid hyperventilation as risk of complications from increased intrathoracic pressure, and decreased coronary and cerebral perfusion.
  • ventilation rate once intubated should usually be 8-10 breaths/minute, without pausing for chest compressions (rate 15:1)
  • confirmation of correct endotracheal tubbe placement - eg. end-tital CO2

references and other resources

and for fun

Mr Bean - CPR at the bus stop

Clin. Toxicol. (Phila.) 2010; 48(1):1-27
c_asystole.txt · Last modified: 2019/01/05 18:19 (external edit)