Medico

C LINIC A L PR AC TIC E

Clinical Practice

This Journal feature begins with a case vignette highlighting a common clinical problem. Evidence supporting various strategies is then presented, followed by a review of formal guidelines, when they exist. The article ends with the author’s clinical recommendations.
CAUSE

TABLE 1. LEADING CAUSES OF PLEURAL EFFUSION IN THE UNITED STATES,ACCORDING TO ANALYSIS OF PATIENTS SUBJECTED TO THORACENTESIS.*
ANNUAL INCIDENCE

TRANSUDATE

EXUDATE

P LEURAL E FFUSION
RICHARD W. LIGHT, M.D.

A 70-year-old man with an 80-pack-year history of smoking and a history of congestive heart failure presents with increasing shortness of breath. He also has aching chest pain on the right side that worsens with deep inspiration. He is afebrile. Thechest radiograph reveals bilateral pleural effusions, with more pleural fluid on the right than on the left. How should this patient be evaluated?
THE CLINICAL PROBLEM

Congestive heart failure Pneumonia Cancer Pulmonary embolus Viral disease Coronary-artery bypass surgery Cirrhosis with ascites *Adapted from Light.1

500,000 300,000 200,000 150,000 100,000 60,000 50,000

Yes No No SometimesNo No Yes

No Yes Yes Sometimes Yes Yes No

Although many different diseases may cause a pleural effusion (Table 1), the most common causes in the United States are congestive heart failure, pneumonia, and cancer. The diagnostic workup of a patient with a pleural effusion will depend on the probable causes of the condition in that patient.
STRATEGIES AND EVIDENCE
Initial Evaluation

Sinceconditions other than pleural effusions may produce similar radiologic findings, alternative imaging studies are frequently necessary to verify that a pleural effusion is present. Ultrasonographic studies or lateral decubitus radiographs are used most commonly, but computed tomographic (CT) scans of the chest allow imaging of the underlying lung parenchyma or mediastinum.
Indications forThoracentesis

The history and the physical examination are critical in guiding the evaluation of pleural effusion. Several aspects of the physical examination should receive special attention. Chest examination typically reveals dullness to percussion, the absence of fremitus, and diminished breath sounds or their absence. Distended neck veins, an S3 gallop, or peripheral edema suggests congestiveheart failure, and a right ventricular heave or thrombophlebitis suggests pulmonary embolus. The presence of lymphadenopathy or hepatosplenomegaly suggests neoplastic disease, and ascites may suggest a hepatic cause.

From the Pulmonary Disease Program, St. Thomas Hospital, and the Department of Medicine, Vanderbilt University School of Medicine — both in Nashville. Address reprint requests to Dr.Light at the Pulmonary Disease Program, St. Thomas Hospital, 4220 Harding Rd., Nashville, TN 37205, or at rlight98@yahoo.com.

The indication for diagnostic thoracentesis is the presence of a clinically significant pleural effusion (more than 10 mm thick on ultrasonography or lateral decubitus radiography) with no known cause (Fig. 1). If a patient presents with congestive heart failure andbilateral effusions of similar size, is afebrile, and has no chest pain, a trial of diuresis can be undertaken. Since more than 80 percent of patients with pleural effusions caused by congestive heart failure have bilateral pleural effusions,2 thoracentesis is indicated if the effusion is unilateral. Approximately 75 percent of effusions due to congestive heart failure resolve within 48 hours afterdiuresis is begun.2 If the effusions persist for more than three days, thoracentesis is indicated. The initial thoracentesis is usually performed for purposes of diagnosis, unless the patient has shortness of breath when at rest, in which case therapeutic thoracentesis to remove up to 1500 ml of fluid is indicated. Thoracentesis can be performed at the bedside with the aid of diagnostic imaging....