Cardiac Tamponade

Keep it fast, full, and tight - Maintain preload with fluids, keep the heart rate up (bradycardia is catastrophic with a fixed low stroke volume), and preserve contractility and systemic vascular resistance.

Decompress before inducing when you can - Induction of general anesthesia and positive-pressure ventilation reduce venous return and can precipitate arrest; drain the effusion under local anesthesia first in an unstable patient whenever feasible.

If general anesthesia is unavoidable - Use a hemodynamically stable, spontaneous-ventilation technique (ketamine maintains rate and afterload), keep the patient breathing spontaneously as long as possible, and avoid high airway pressures and PEEP. Have the surgeon prepped and draped before induction.

Prepare for collapse - Arterial line, resuscitation drugs (epinephrine, vasopressors) drawn up, and fluids running; treat hypotension with volume and pressors while decompression proceeds.

Accumulation of pericardial fluid or blood under pressure that compresses the heart and prevents diastolic filling, collapsing stroke volume and cardiac output. The classic findings are Beck's triad (hypotension, muffled heart sounds, and distended neck veins) and pulsus paradoxus. The heart compensates with tachycardia and high filling pressures, so the whole physiology depends on a fast rate, a full circulation, and maintained afterload - and anything that reduces preload, slows the heart, drops afterload, or adds positive intrathoracic pressure can cause abrupt arrest.