A 63-year-old man is brought to the emergency department because of progressive shortness of breath and lightheadedness. Three weeks ago, he underwent surgical aortic valve replacement for severe aortic stenosis. His postoperative course was initially uncomplicated. Over the past several days, he has developed increasing fatigue and dyspnea. This morning he became dizzy while standing and nearly lost consciousness. Temperature is 37.1°C (98.8°F), blood pressure is 84/60 mm Hg, pulse is 118/min, respiratory rate is 24/min, and oxygen saturation is 95% on room air. Physical examination reveals an anxious-appearing man in mild respiratory distress. The jugular veins are markedly distended. Heart sounds are distant. Lung examination is clear bilaterally. The extremities are cool. During inspiration, systolic blood pressure decreases from 84 mm Hg to 70 mm Hg.
Laboratory studies show the following:
ECG demonstrates sinus tachycardia with low-voltage QRS complexes. Chest radiography demonstrates a mildly enlarged cardiac silhouette without pulmonary edema.
A pulmonary artery catheter is placed. Hemodynamic measurements are:
Right atrial pressure: 18 mm Hg
Right ventricular diastolic pressure: 18 mm Hg
Pulmonary capillary wedge pressure: 19 mm Hg
Cardiac index: 1.7 L/min/m²
Which of the following is the most appropriate next step in management?
The correct answer is:
A) Emergent pericardiocentesis
This patient has cardiac tamponade causing obstructive shock.
Several findings point toward tamponade:
The pulmonary artery catheter data provide the most important clue. Cardiac tamponade causes equalization of diastolic pressures because rising intrapericardial pressure compresses all cardiac chambers during diastole.
Notice that:
These nearly identical diastolic pressures are classic for tamponade. As intrapericardial pressure rises, ventricular filling becomes impaired, resulting in reduced stroke volume and cardiac output. The definitive treatment is urgent removal of pericardial fluid.
A common Step 2 pitfall is confusing tamponade with cardiogenic shock. Both can present with hypotension, elevated filling pressures, and low cardiac output. However, tamponade demonstrates equalization of diastolic pressures and typically has clear lungs because the primary problem is impaired filling rather than left ventricular pump failure.
Answer choice B: Intravenous dobutamine infusion, is incorrect.
Dobutamine may transiently increase cardiac output but does not relieve the mechanical compression of the heart. Definitive treatment requires drainage of the pericardial effusion. This is an attractive distractor because low cardiac output is present. However, the underlying problem is obstructive physiology rather than impaired contractility.
Answer choice C: Intravenous furosemide administration, is incorrect.
Diuresis would reduce preload and further impair ventricular filling. Patients with tamponade are preload dependent and may deteriorate rapidly with aggressive diuresis.
Answer choice D: Intravenous nitroprusside infusion, is incorrect.
Nitroprusside decreases systemic vascular resistance and may worsen hypotension. It does not address the obstructive process preventing cardiac filling.
Answer choice E: Urgent coronary angiography, is incorrect.
There is no evidence of acute coronary occlusion. The hemodynamic findings strongly support tamponade as the cause of shock.
Key Learning Point
Cardiac tamponade is a form of obstructive shock characterized by hypotension, elevated jugular venous pressure, pulsus paradoxus, and equalization of diastolic cardiac pressures. Definitive treatment is emergent pericardiocentesis.
