AKT · Acute care/Cardiac & respiratory

Cardiac tamponade

Pericardial fluid under pressure compressing the heart

Overview

Accumulation of pericardial fluid (or blood) under enough pressure to compress the heart and impair filling — obstructive shock. The classic Beck triad is hypotension, raised JVP and muffled heart sounds, with pulsus paradoxus. It needs urgent echo and pericardiocentesis; rapid bleeds (trauma, type A dissection) cause it with small volumes.

Recognise

Beck triad: HYPOTENSION + raised JVP (distended neck veins) + muffled heart sounds
Pulsus paradoxus (an exaggerated >10 mmHg fall in systolic BP on inspiration); tachycardia, dyspnoea
ECG: low-voltage QRS ± electrical alternans; causes — pericarditis/effusion, malignancy, uraemia, trauma, post-MI rupture, aortic dissection

Red flags

Haemodynamic compromise/obstructive shock, especially after trauma or in known dissection/post-MI → emergency echo + pericardiocentesis

Differentials & how to tell them apart

Tension pneumothoraxalso obstructive shock with raised JVP, but with a hyperresonant chest + tracheal deviation and absent breath sounds — needle decompression, not pericardiocentesis

Massive PEobstructive shock with hypoxia and right-heart strain — different management

Cardiogenic shock (pump failure)no large pericardial effusion on echo

Hypovolaemic shocklow JVP — tamponade raises the JVP

Investigations

Urgent ECHOCARDIOGRAM (the key test — effusion + diastolic chamber collapse); ECG (low voltage/electrical alternans), CXR (globular heart if chronic). Do not delay drainage in arrest/peri-arrest.

Management

Urgent echo-guided pericardiocentesis (+ IV fluids as a bridge)

1Recognise clinically (Beck triad + pulsus paradoxus), confirm with urgent echo, give IV fluids as a temporising measure, and perform urgent pericardiocentesis (or surgical drainage) to relieve the compression.Gate: Both tamponade and tension pneumothorax cause OBSTRUCTIVE shock with a raised JVP — the chest exam separates them (muffled heart sounds + pulsus paradoxus vs a hyperresonant chest with tracheal deviation); the wrong procedure (needle chest vs pericardiocentesis) wastes critical time
2Treat the underlying cause (drainage of a malignant/uraemic effusion, surgery for traumatic/dissection haemopericardium, reverse anticoagulation); recurrent effusion → pericardial window.

Pericardiocentesis (or surgical drainage) — the definitive treatment — drain the fluid to relieve compression

IV fluids — a temporising bridge to maintain filling while preparing to drain

Treat the cause — e.g. reverse anticoagulation, surgery for traumatic/dissection-related haemopericardium

Key points

Beck triad + pulsus paradoxus + low-voltage/electrical-alternans ECG = tamponade → echo + drain. A small rapid bleed can tamponade (trauma, dissection, post-MI). Distinguish from tension pneumothorax by the chest.

Monitor & prognosis

Haemodynamics, echo, re-accumulation; treat the cause.

Rapidly fatal untreated; excellent immediate response to drainage.

Source: Resuscitation Council UK / acute care