What defines pulseless electrical activity?
Pulseless electrical activity (PEA) is a clinical diagnosis defined by the absence of a palpable pulse in patients presenting with an organized electrical rhythm on the monitor. It is not a specific electrocardiographic entity, but rather a dissociation between cardiac electrical activity and effective mechanical contraction.
The monitor displays a rhythm that would typically be perfusing under normal conditions. However, the lack of cardiac output renders this a non-shockable cardiac arrest, requiring immediate chest compressions and an active search for underlying causes.
How to identify PEA on the monitor and in the patient?
Recognition relies on the systematic verification of the absence of a central pulse in any organized rhythm. A common error is trusting ECG morphology, assuming that a narrow QRS complex or sinus rhythm implies peripheral perfusion.
Pulse oximetry loses immediate utility, as the absence of a plethysmographic waveform is an early sign of lost output. Invasive blood pressure, if available, will show a flat line or insufficient perfusion pressure, confirming myocardial mechanical failure.
| Finding | Status in PEA |
|---|---|
| Monitor rhythm | Organized (sinus, junctional, idioventricular) |
| Central pulse | Absent |
| Plethysmography | Absent |
| Initial action | Chest compressions and airway support |
What are the reversible causes (4Hs and 4Ts)?
PEA management depends on the rapid identification of reversible causes, typically categorized as 4Hs and 4Ts. Resuscitation must continue while investigating the etiology, according to current guidelines.
- Hypovolaemia: Frequently due to occult haemorrhage or severe dehydration.
- Hypoxia: Verify airway patency and oxygenation.
- Hypo/Hyperkalaemia and metabolic disorders: Evaluate clinical history and blood gas analysis.
- Hypothermia: Consider environmental context.
- Tension (Tension pneumothorax): Look for tracheal deviation or asymmetric breath sounds.
- Tamponade (Cardiac): Assess for jugular venous distension and muffled heart sounds.
- Toxins: Investigate drug ingestion or chemical exposure.
- Thrombosis (Coronary or Pulmonary): Consider the context of chest pain or sudden dyspnoea.
How to distinguish PEA from other rhythms?
The main pitfall is confusing PEA with slow perfusing rhythms or monitoring artefacts. A slow idioventricular rhythm may mimic PEA, but the rule is absolute: if there is no palpable pulse, the treatment is the cardiac arrest protocol, regardless of QRS morphology.
The presence of electrical activity does not guarantee myocardial viability. Continuous monitoring must focus on the quality of compressions and periodic rhythm re-evaluation, ensuring no transition to a shockable rhythm, such as ventricular fibrillation, occurs.
References
Frequently asked questions
Is PEA always a slow rhythm?
No. PEA can present with any organized rhythm, including sinus rhythms with normal rates or tachycardias. The determining factor is not the rate, but the absence of a palpable pulse.
What is the first step in PEA?
The first step is to initiate high-quality chest compressions and secure the airway. The search for reversible causes must occur in parallel with cardiopulmonary resuscitation, following local protocols.
Can PEA be confused with artefacts?
Yes. Patient movement or electrode failure can simulate organized rhythms on the monitor. Clinical pulse verification and patient observation are essential to rule out artefacts.
This article is training material, not clinical guidance. Management depends on the patient context and on your local protocol. It does not replace certified training or clinical judgement.