A 65-year-old man is evaluated in the cardiovascular intensive care unit due to a sudden o… — USMLE Step 2 CK

A 65-year-old man is evaluated in the cardiovascular intensive care unit due to a sudden onset of shortness of breath and confusion. He underwent a four-vessel coronary artery bypass grafting procedure three days ago. His medical history includes hypertension, hyperlipidemia, and chronic obstructive pulmonary disease. Vital signs are temperature $37.0^\circ\text{C}$ ( $98.6^\circ\text{F}$ ), blood pressure $82/50\text{ mmHg}$ , pulse $122\text{ /min}$ , and respirations $24\text{ /min}$ . Physical examination demonstrates distended jugular veins, muffled heart sounds, and clear lung fields bilaterally. His systolic blood pressure decreases by $18\text{ mmHg}$ during inspiration. Which of the following is the most appropriate next step in management?

Bedside echocardiographyAnswer
B
Administration of nebulized ipratropium and intravenous corticosteroids
C
Computed tomography angiography of the chest
D
Intravenous administration of furosemide
E
Obtaining blood cultures and starting broad-spectrum antibiotics

Answer

Bedside echocardiography

The correct action is to perform a bedside echocardiography. This patient exhibits the classic features of acute cardiac tamponade: Beck's triad (hypotension, jugular venous distention, and muffled heart sounds) and pulsus paradoxus (an inspiratory drop in systolic blood pressure of

>10\text{ mmHg}

). Cardiac tamponade is a classic, life-threatening complication in the early postoperative period following cardiothoracic surgery due to localized bleeding or fluid accumulation in the pericardial sac. Bedside echocardiography is the most rapid, definitive, and safe diagnostic modality to confirm the diagnosis by demonstrating pericardial fluid and right ventricular diastolic collapse. Once confirmed, emergent surgical re-exploration or pericardiocentesis is indicated.

Step-by-Step Solution

Analyze the patient's vital signs and physical examination findings.

The patient has hypotension (

82/50\text{ mmHg}

), tachycardia (

122\text{ /min}

), jugular venous distention, muffled heart sounds, and a systolic blood pressure drop of

18\text{ mmHg}

during inspiration (pulsus paradoxus).

Identifying these specific clinical signs is necessary to formulate a differential diagnosis for postoperative shock.

Correlate the findings with the clinical context (post-CABG day 3).

The combination of Beck's triad and pulsus paradoxus in a recent cardiothoracic surgery patient points directly to acute cardiac tamponade (likely from bleeding into the pericardial space).

Cardiac tamponade is a known, life-threatening complication of cardiothoracic surgery that causes obstructive shock.

Determine the most appropriate immediate diagnostic step.

Bedside echocardiography is selected to confirm the presence of a pericardial effusion and right-sided chamber collapse before proceeding to definitive treatment (e.g., surgical re-exploration or pericardiocentesis).

Echocardiography is non-invasive, rapid, can be performed at the bedside in an unstable patient, and is the gold standard for diagnosing tamponade.

Key Concept

Diagnosis of Postoperative Cardiac Tamponade

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