Review Question - QID 107358

The patient presents with a stab wound to the chest with hypotension, distension of neck veins, and muffled heart sounds. This patient has cardiac tamponade and should be treated urgently with pericardiocentesis.

Cardiac tamponade typically results from fluid accumulation in the pericardial sac. This restricts ventricular filling and leads to decreased preload, and consequently, decreased cardiac output. While trauma is a common cause, other causes include tuberculosis, malignancy, systemic lupus erythematous, and pericarditis (typically viral). In acute settings, as little as 100-200 mL fluid within the pericardial space can result in hemodynamic instability as the cardiovascular system has not had time to adapt. However, if the pericardial fluid is slow to accumulate, as many as a couple of liters of fluid can exist without hemodynamic instability.

Snyder et al. discuss acute pericarditis. They report that Beck's triad of hypotension, distant heart sounds, and distended neck veins should be looked for when trying to diagnose cardiac tamponade. They state that cardiac tamponade is present in 5% to 15% of patients with acute idiopathic pericarditis and in 60% of those with neoplastic, tuberculous, or purulent pericarditis. They also state that aside from acute hemodynamic instability, pericardiocentesis may also be indicated for large (greater than 20 mm) effusions or symptomatic effusions refractory to medical treatment (such as diuretics).

Tsant et al. discuss the diagnosis and management of cardiac tamponade. They state that the current tool of choice diagnosis is the transthoracic or transesophageal echocardiogram (echo) due to it's high sensitivity and specificity. They report that though echo guided pericardiocentesis is the treatment of choice for tamponade. Many times, effusions recur within 48 hours if left alone. For this reason, placing a pericardiac catheter for continuous drainage along with diuretics has been shown to treat up to 95% of the cases of pericardial effusions with low complication rates (around 4%).

Incorrect Answers:
Answers 1 and 2: Though the patient's condition may be helped by intravenous solutions of fluids and colloids, the patient emergently needs pericardiocentesis to stabilize his hemodynamic status.
Answers 3 and 4: Both aspirin and heparin will anticoagulate the patient. This would be contraindicated as it can lead to increased bleeding into the pericardial sac.