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Cardiac Arrest

Written 27th February 2020 - Last Update 7th August 2026

Cardiac Arrest

75% of cardiac arrests are due to VF; 75% of patients have severe coronary artery disease.

Causes

  • Arrhythmias — VF, VT, torsades, severe bradycardia, sick sinus syndrome.
  • Pump failure — AMI, cardiomyopathy.
  • Rupture — ventricular rupture, dissecting aneurysm, hypertrophic cardiomyopathy (ASH).
  • Obstruction — PE, aortic stenosis, pulmonary hypertension, mitral valve prolapse.
  • Electrolyte abnormalities (hyperkalaemia).
  • Other: glue sniffing (volatile substance misuse).

Reversible causes — 4 H’s and 4 T’s

Hypoxia; hypovolaemia; hyper/hypokalaemia (metabolic); hypo/hyperthermia; tension pneumothorax; tamponade; toxins; thrombosis (PE, ACS).

Advanced life support algorithm

Advanced Life Support for Adults — start CPR, attach defibrillator/monitor, assess rhythm; shockable vs non-shockable pathways to return of spontaneous circulation and post-resuscitation care

Shockable rhythm: adrenaline 1mg after the 2nd shock, then every 2nd loop; amiodarone 300mg IV after the 3rd shock.

Non-shockable rhythm: adrenaline 1mg immediately, then every 2nd loop.

During CPR: airway adjuncts (LMA/ETT), oxygen, waveform capnography, IV/IO access; plan actions before interrupting compressions (e.g. charging the manual defibrillator).

Post-resuscitation care: re-evaluate ABCDE; 12-lead ECG; treat precipitating causes; aim for SpO2 94–98%, normocapnia, and normoglycaemia; targeted temperature management.