1. Malignant pleural effusion (1,2,3,4)

a. Tumor invasion into the pleural space may lead to lymphatic obstruction resulting in pleural fluid accumulation.

b. Indications for treatment

(1) Patients with dyspnea, cough, and/or chest pain

(2) Large effusions prior to chemotherapy to prevent accumulation of therapeutic agents in the pleural space

(3) Symptomatic refractory/recurrent effusions

(4) Predictors of need for definitive therapy (indwelling catheter and/or pleurodesis) at diagnosis are low pH (< 7.2), large size, and increasing patient age.

c. Staging

(1) Cytologic evaluation of pleural fluid may provide important clinical staging information. The presence of a malignant effusion indicates stage IV disease for most cancers.

(2) The cellular yield for genetic diagnostic and prognostic tumor markers from pleural fluid is often insufficient for analysis; however, small studies have reported potential applications for lung cancer and malignant pleural mesothelioma (5,6). Further investigation is required for validation.

2. Parapneumonic effusion/empyema (3,7,8,9,10)

a. Sequential stages in the evolution of a parapneumonic effusion and development of an empyema with associated treatment recommendations

(1) Exudative —Interstitial parenchymal fluid accumulates adjacent to a site of infection and flows across the visceral pleura into the pleural space (high protein, sterile fluid, normal pH, and glucose). Antibiotic therapy is generally effective in treating both the underlying pneumonia and effusion.

(2) Fibropurulent—Bacteria, polymorphonuclear leukocytes, and cellular debris within the pleural space. In addition, fibrin barriers can create loculated pockets. Percutaneous drainage is recommended when the fluid analysis shows a pleural glucose <60 mg per dL or a pH <7.2.

(3) Organizing—Fibroblasts produce an extensive fibrotic response (pleural peel), creating significant resistance to respiratory motion and rendering percutaneous drainage of limited value.

b. Parapneumonic effusions occur in 20% to 57% of patients with pneumonia and 10% require drainage. Categorization of the effusion determines management. The American College of Chest Physicians classifies effusions on the basis of size, chemistry, and bacteriology.

(1) Category 1: Free-flowing pleural effusion <1 cm in thickness on decubitus radiograph does not require treatment.

(2) Category 2: Small to moderate (>1 cm, <50% of hemithorax) free-flowing effusions with pleural pH >7.2, glucose >60 mg per dL, lactate dehydrogenase (LDH) less than three times the upper limit of serum, and Gram stain and culture negative do not usually require drainage as most patients respond to antibiotic therapy.

(3) Category 3: Large (>50% of hemithorax) free-flowing effusions, loculated effusions, or effusions with thickened parietal pleura and/or pleural pH
<7.2, and/or pleural glucose <60 mg/dL, and/or Gram stain and culture positive require drainage.

(4) Category 4: Frank pus in the pleural space requires drainage.

3. Lung abscess (8)

a. A total of 10% to 20% of patients with a pyogenic abscess will fail to respond to medical therapy (systemic antibiotics, postural drainage), and drainage is recommended when

(1) There is persistent sepsis 5 to 7 days after initiation of antibiotic therapy.

(2) The abscess is >4 cm with an air fluid level.

(3) The abscess increases in size while the patient is on medical therapy.

(4) In children <7 years of age as these abscesses often do not drain spontaneously and are less likely to respond to medical management