An 83-year-old man comes to the emergency department due to a 1-week history of fever, malaise, cough, right-sided chest pain, and worsening dyspnea. Temperature is 38.4 C (101.1 F), blood pressure is 116/70 mm Hg, and pulse is 98/min. On physical examination, the patient is frail appearing. Breath sounds are decreased on the right side. Heart sounds are normal. The abdomen is soft and nontender. Chest x-ray shows a moderate-sized right pleural effusion. Thoracentesis yields purulent fluid. Pleural fluid analysis reveals a large number of leukocytes with 80% neutrophils. Which of the following is the most likely underlying mechanism for this patient's pleural effusion?
Parapneumonic effusions | ||
Uncomplicated | Complicated* | |
Etiology | Sterile exudate in | Bacterial invasion of |
Radiologic | Small to moderate & | Moderate to large, |
Pleural fluid |
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Treatment | Antibiotics | Antibiotics + drainage |
*Empyema represents advanced progression of a complicated effusion. | ||
Thoracentesis yielding purulent fluid is diagnostic of empyema, a pleural effusion that has been contaminated by bacteria (or, rarely, fungi or parasites) with subsequent inflammatory progression and fibrotic organization within the pleural space (often with loculated fluid collections). Empyema most commonly results from bacterial translocation from the alveoli into the pleural space and represents advanced progression of a complicated parapneumonic effusion. Affected patients have a symptomatic presentation similar to that of pneumonia (eg, fever, cough, shortness of breath, pleuritic chest pain), but the presentation can be more insidious than uncomplicated pneumonia, taking place over 1-2 weeks or more.
Treatment of empyema requires prompt drainage (eg, chest tube, surgery in some cases) in addition to antibiotics. Following drainage, some patients have persistent pleural fibrosis that prevents full lung reexpansion, a complication known as trapped lung.
(Choices B, C, D, and E) Contiguous spread from a mediastinal focus (eg, Staphylococcal mediastinitis), direct inoculation (eg, surgery, penetrating trauma), hematogenous dissemination of a distant infection, and reactivation of a dormant infection (eg, tuberculosis) are all possible but less common etiologies of bacterial contamination of the pleural space leading to empyema. In the absence of evidence that suggests one of these sources (eg, recent surgery or trauma, lymphocyte-predominant effusion consistent with tuberculosis), empyema in this patient is most likely due to bacterial translocation from the alveoli (a complication of pneumonia).
Educational objective:
Empyema is an accumulation of pus within the pleural space that can result from multiple sources of bacterial contamination. It usually represents advanced progression of a complicated parapneumonic effusion resulting from bacterial translocation from the alveoli.