Pericardial effusion and tamponade

At a glance

• A pericardial effusion is fluid beyond the normal 10 to 50 mL. Tamponade is the point where that fluid impairs diastolic filling enough to drop cardiac output. It is a clinical diagnosis, confirmed by echo.
• Rate of accumulation matters more than volume. Tamponade is a "last drop" phenomenon, so removing a small amount gives large haemodynamic relief.
• In developed countries up to half of moderate to large effusions are idiopathic. Cancer, infection (including TB), iatrogenic causes and connective tissue disease make up most of the rest.