A 64-year-old man comes to the emergency department due to 2 days of fevers, chills, and positional chest pain. Medical history is significant for type 2 diabetes mellitus, hypertension, and end-stage kidney disease. The patient undergoes hemodialysis 3 times a week but missed his last session because he did not feel well. Temperature is 39.2 C (102.6 F), blood pressure is 100/60 mm Hg, pulse is 130/min and irregular, and respirations are 20/min. The patient appears unwell and uncomfortable. Examination shows clear lungs, distant heart sounds, no heart murmurs, and minimal lower extremity edema. The dialysis catheter site appears clean without erythema or purulence. The remainder of the examination shows no abnormalities. Blood leukocytes are 25,000/mm³ with 80% neutrophils. ECG shows atrial fibrillation with rapid ventricular response and low-amplitude QRS complexes. Chest x-ray reveals normal lung fields. Bedside echocardiography reveals normal left and right ventricular function, no significant valvular disease, and a moderate pericardial effusion with no evidence of tamponade. Blood cultures are obtained, and broad-spectrum antibiotics are administered. Which of the following is the most appropriate next step in management?

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11ec25c8_d8ae_6f84_bc81_6f47be422a97_MD0003_00 This patient has fever, chills, leukocytosis with left shift, new arrhythmia, and a pericardial effusion on echocardiography. This presentation is most concerning for purulent pericarditis. Purulent pericarditis is an acute febrile illness resulting from bacterial infection (or fungal infection) of the pericardium. The most common cause is Staphylococcus aureus secondary to hematogenous spread of bacteria to the pericardium (via the bloodstream). Chronic hemodialysis, which is associated with fluid shifts and bacteremia, places patients at increased risk. Other causes include direct spread from an intrathoracic infection (eg, pneumonia) and inoculation of bacteria into the pericardium during cardiothoracic surgery. Purulent pericarditis is rapidly progressive and highly fatal; hence, prompt diagnosis and treatment are necessary (Choice B). Affected patients typically have systemic symptoms (eg, fever, chills, fatigue) and chest pain and appear severely ill on examination. Tachycardia is typical, and sometimes, new arrhythmias (eg, atrial fibrillation) can occur due to epicardial inflammation and irritation. Pericardial effusion commonly develops due to exudative fluid buildup in the pericardial space and can lead to distant heart sounds and low-voltage QRS complexes on ECG. Chest x-ray may show an enlarged cardiac silhouette with clear lung fields. Cardiac tamponade can sometimes develop. Echocardiography confirms pericardial effusion but cannot distinguish whether it is purulent. Therefore, when purulent pericarditis is suspected, urgent pericardiocentesis is indicated for both confirmation of the diagnosis and treatment (removal of infectious fluid). Purulent fluid is usually turbid due to a high leukocyte count (neutrophil predominant), and Gram stain and culture often reveal the causative organism to guide antibiotic therapy. (Choice A) Ibuprofen and colchicine are used to treat idiopathic or viral pericarditis. These conditions can cause pleuritic chest pain, tachycardia, and, sometimes, fever; a small pericardial effusion may be seen. However, this patient's toxic appearance, marked leukocytosis, and relatively significant effusion (enlarged cardiac silhouette, low-voltage QRS complexes) make purulent pericarditis more likely. (Choice D) Transesophageal echocardiography is more sensitive than transthoracic echocardiography for detecting infective endocarditis. Acute endocarditis may present similarly to purulent pericarditis (eg, high fever, leukocytosis), but purulent pericarditis is more likely in this patient with distant heart sounds and an absent cardiac murmur. Educational objective: Purulent pericarditis is an acute, rapidly fatal infection most commonly caused by hematogenous spread of Staphylococcus aureus. Urgent echocardiography-guided pericardiocentesis is essential for confirmation of the diagnosis and treatment. References: Pericardial effusion and pericardiocentesis: role of echocardiography. (http://www.ncbi.nlm.nih.gov/pubmed/23236323) Diagnosis and management of pericardial effusion. (http://www.ncbi.nlm.nih.gov/pubmed/21666814)

A 64-Year-Old Man Comes to the Emergency Department Due to 2