The following is based on the 2021 Resus Council guidelines. Please see the link for more details, below is only a very brief summary of key points.

It should be remembered that the algorithm divides patients into those with:

• 'shockable' rhythms: ventricular fibrillation/pulseless ventricular tachycardia (VF/pulseless VT)
• 'non-shockable' rhythms: asystole/pulseless-electrical activity (asystole/PEA)

Major points include:

• chest compressions
  • the ratio of chest compressions to ventilation is 30:2
  • chest compressions are now continued while a defibrillator is charged
• defibrillation
  • a single shock for VF/pulseless VT followed by 2 minutes of CPR
  • if the cardiac arrested is witnessed in a monitored patient (e.g. in a coronary care unit) then the 2015 guidelines recommend 'up to three quick successive (stacked) shocks', rather than 1 shock followed by CPR
• drug delivery
  • IV access should be attempted and is first-line
  • if IV access cannot be achieved then drugs should be given via the intraosseous route (IO)
  • delivery of drugs via a tracheal tube is no longer recommended
• adrenaline
  • adrenaline 1 mg as soon as possible for non-shockable rhythms
  • during a VF/VT cardiac arrest, adrenaline 1 mg is given once chest compressions have restarted after the third shock
  • repeat adrenaline 1mg every 3-5 minutes whilst ALS continues
• amiodarone
  • amiodarone 300 mg should be given to patients who are in VF/pulseless VT after 3 shocks have been administered.
  • a further dose of amiodarone 150 mg should be given to patients who are in VF/pulseless VT after 5 shocks have been administered
  • lidocaine used as an alternative if amiodarone is not available or a local decision has been made to use lidocaine instead
• thrombolytic drugs
  • should be considered if a pulmonary embolus is suspected
  • if given, CPR should be continued for an extended period of 60-90 minutes

Other points

• atropine is no longer recommended for routine use in asystole or pulseless electrical activity (PEA)
• following successful resuscitation oxygen should be titrated to achieve saturations of 94-98%. This is to address the potential harm caused by hyperoxaemia

Reversible causes of cardiac arrest: