Definition
Despite attempting to pump normally, there is not enough cardiac output to produce a pulse.
>95% mortality.

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Classification

Primary
Electrical rhythm persists, but insufficient contractility due to poor heart pumping.
- myocardial ischaemia for any reason incl secondary PEA
- ventricular / septal rupture.
- metabolic disturbance (acidosis / electrolyte abnormalities)
- drug toxicity
- hypothermia.
- stunned myocardium after defibrillation.

Secondary
Myocardium functional, but secondary interference with pumping.
- hypovolaemia
- tension pneumothorax
- cardiac tamponade
- vasodilatory shock
- pulmonary embolus.
Myocardial ischaemia results, leading to primary PEA or lethal rhythm.

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Treatment

The key is recognising and treating the cause preceeding the arrest.