• CT angiography should be ordered if pulmonary embolism is strongly suggested.
• Pleural biopsy should be considered, especially if TB or malignancy is suggested. Medical thoracoscopy with the patient under conscious sedation and local anesthesia has emerged as a diagnostic tool to directly visualize and take a biopsy specimen from the parietal pleura in cases of undiagnosed exudative effusions. Closed-needle pleural biopsy is a blind technique but can be performed at the patient's bedside. Medical thoracoscopy has a higher diagnostic yield for malignancy; closed-needle pleural biopsy findings aid in diagnosis of only 7-12% of malignant effusions when cytology findings alone are negative. However, the yield of closed-needle pleural biopsy (histology plus culture) is as high as thoracoscopy for TB and is a useful alternative procedure for this diagnosis when available.
• Among patients with undiagnosed pleural effusions after the primary evaluation, predict a benign course for those who meet all 6 of the following clinical parameters. No further evaluation is necessary. 
• Patients are clinically stable.
• Patients do not have weight loss.
• The results of the PPD test are negative and the pleural ADA value is less than 43 U/mL.
• The patient does not have a fever.
• The pleural fluid differential blood cell count has less than 95% lymphocytes.
• The effusion occupies less than 50% of the hemithorax.

For other patients with undiagnosed exudative effusions, approximately 20% have a specific etiology determined, including malignancy. For such patients, weigh the benefits and risks of pursuing a diagnosis using progressively more invasive procedures, given the low likelihood of finding a curable etiology.  

• Consider bronchoscopy only if a patient has parenchymal abnormalities or hemoptysis.
• Surgical approaches to the diagnosis of pleural effusions include thoracoscopy (pleuroscopy) and open thoracotomy, which reveal an etiology in 92% of effusions that remain undiagnosed after a medical evaluation.
• Where available, medical thoracoscopy may be both diagnostic and therapeutic; talc sclerosis can be performed at the time of the procedure.
• Note that in most medical centers, surgical exploration using thoracoscopy or thoracotomy entails the risks of general anesthesia and is probably warranted only in patients who are symptomatic and anxious for a diagnosis.

Imaging Studies

Chest radiograph   

Effusions of more than 175 mL are usually apparent as blunting of the costophrenic angle on upright posteroanterior chest radiographs. On supine chest radiographs, which are commonly used in the intensive care setting, moderate-to-large pleural effusions may appear as a homogenous increase in density over the lower lung fields on a supine chest radiograph. Apparent elevation of the hemidiaphragm, lateral displacement of the dome of the diaphragm, or increased distance between the apparent left hemidiaphragm and the gastric air bubble suggests subpulmonic effusions.

Lateral decubitus films more reliably detect smaller pleural effusions. Layering of an effusion on lateral decubitus films defines a freely flowing effusion and, if the layering fluid is 1 cm thick, indicates an effusion of greater than 200 mL that is amenable to thoracentesis. Failure of an effusion to layer on lateral decubitus films indicates loculated pleural fluid or some other etiology causing the increased pleural density.

Chest radiograph showing left-sided pleural effusion.

Left lateral decubitus film showing freely layering pleural effusion.

Procedures

Diagnostic thoracentesis

Perform diagnostic thoracentesis if the etiology of the effusion is unclear or if the presumed cause of the effusion does not respond to therapy as expected. Pleural effusions do not require thoracentesis if they are too small to safely aspirate or, in clinically stable patients, if their presence can be explained by underlying congestive heart failure (especially bilateral effusions) or by recent thoracic or abdominal surgery.

Relative contraindications to diagnostic thoracentesis include a small volume of fluid (<1 cm thickness on a lateral decubitus film), bleeding diathesis or systemic anticoagulation, mechanical ventilation, and cutaneous disease over the proposed puncture site. Mechanical ventilation with positive end-expiratory pressure does not increase the risk of pneumothorax after thoracentesis, but it increases the likelihood of a tension pneumothorax or persistent bronchopleural fistula if the lung is punctured.

Complications of diagnostic thoracentesis include pain at the puncture site, cutaneous or internal bleeding, pneumothorax, empyema, and spleen/liver puncture. Pneumothorax complicates approximately 12-30% of thoracenteses but requires treatment with a chest tube in less than 5% of cases. Use of needles larger than 20 gauge increases the risk of a pneumothorax complicating the thoracentesis. In addition, significant chronic obstructive or fibrotic lung disease increases the risk of a symptomatic pneumothorax complicating the thoracentesis.

In patients with large, freely flowing effusions and no relative contraindications to thoracentesis, diagnostic thoracentesis can usually be performed safely, with the puncture site initially chosen based on the chest radiograph and located at 1-2 rib interspaces below the level of dullness to percussion determined during the physical examination.

Once the site is disinfected with chlorhexidine and/or povidone/iodine solution and sterile drapes are placed, anesthetize the skin, periosteum, and parietal pleura with 1% lidocaine through a 25-gauge needle. If pleural fluid is not obtained with the shorter 25-gauge needle, continue anesthetizing with a 1.5-inch, 22-gauge needle; for patients with larger amounts of subcutaneous tissue, a 3.5-inch, 22-gauge spinal needle with inner stylet removed can be used to find the effusion. Confirm the correct location for thoracentesis by aspirating pleural fluid through the 25- or 22-gauge needle before introducing larger-bore thoracentesis needles or catheters.

When possible, patients should sit upright for thoracentesis. Patients should not lean forward because this causes pleural fluid to move to the anterior costophrenic space and increases the risk of puncture of the liver or spleen. For debilitated and ventilated patients who cannot sit upright, obtain pleural fluid by puncturing over the eighth rib at the mid-to-posterior axillary line.

Supplemental oxygen is often administered during thoracentesis, both to offset hypoxemia produced by changes in ventilation-perfusion relationships as fluid is removed and to facilitate reabsorption of pleural air if pneumothorax complicates the procedure.

The frequency of complications from thoracentesis is lower when a more experienced clinician performs the procedure. Consequently, a skilled and experienced clinician should perform thoracentesis in patients who have a higher risk of complications or relative contraindications for thoracentesis or those who cannot sit upright. Postprocedure chest radiographs to exclude pneumothorax are not needed in asymptomatic patients after uncomplicated procedures (single needle pass without aspiration of air).

Therapeutic thoracentesis

Therapeutic thoracentesis to remove larger amounts of pleural fluid is used to alleviate dyspnea and to prevent ongoing inflammation and fibrosis in parapneumonic effusions. In addition to the precautions listed for diagnostic thoracentesis at the beginning of Procedures, note 3 additional considerations when performing therapeutic thoracentesis.  

• To avoid producing a pneumothorax during the removal of large quantities of fluid, perform therapeutic thoracentesis with a catheter rather than a sharp needle. Various specially designed thoracentesis trays are available for introducing small catheters into the pleural space. Alternatively, newer systems using spring-loaded, blunt-tip needles that avoid lung puncture are also available.
• Monitor oxygenation closely during and after thoracentesis because arterial oxygen tension paradoxically might worsen after pleural fluid drainage. Patients should receive supplemental oxygen during the procedure.
• Only remove moderate amounts of pleural fluid to avoid reexpansion pulmonary edema and to avoid causing a pneumothorax.
• • A mediastinal position on the chest radiograph may predict whether a patient is likely to benefit from the procedure. A mediastinal shift away from the pleural effusion indicates a positive pleural pressure and compression of the underlying lung that can be relieved by thoracentesis. In contrast, a mediastinal shift towards the side of the effusion indicates lung entrapment by extensive pleural involvement or endobronchial obstruction that prevents reexpansion of the lung when the pleural fluid is removed.
  • Removal of 400-500 mL of pleural fluid might be enough to alleviate symptoms. The recommended limit is 1000-1500 mL in a single thoracentesis procedure.
  • Larger amounts of pleural fluid can be removed if pleural pressure is monitored by pleural manometry and maintained above -20 cm water.
  • The onset of chest pressure or pain during the removal of fluid indicates trapped lung physiology, and the procedure should be stopped.

Tube thoracostomy   

Although small, freely flowing parapneumonic effusions can be drained by therapeutic thoracentesis, most larger effusions and complicated parapneumonic effusions or empyemas require drainage by tube thoracostomy (see Treatment).

Traditionally, large-bore chest tubes (20-36F) have been used to drain thick pleural fluid and to break up loculations in empyemas. However, such tubes are not always well tolerated by patients and are difficult to direct correctly into the pleural space. More recently, small-bore tubes (8-14F) inserted at the bedside or under radiographic guidance have been shown to provide adequate drainage, even when empyema is present. These tubes cause less discomfort and are more likely to be placed successfully within a pocket of pleural fluid. Using 20-cm water suction and flushing the tube with normal saline every 6-8 hours may prevent occlusion of small-bore catheters.

Insertion of additional pleural catheters, usually under radiographic guidance, or instilling fibrinolytics (eg, streptokinase, urokinase, or alteplase) through the pleural catheter can help drain multiloculated pleural effusions.

Pleurodesis or pleural sclerosis   

Pleurodesis or pleural sclerosis is most often used for recurrent malignant effusions, such as in patients with lung cancer or metastatic breast or ovarian cancer. Given the limited life expectancy of these patients, the goal of therapy is to palliate symptoms while minimizing patient discomfort, hospital length of stay, and overall costs.

Patients with poor performance status (Karnofsky score <70) and life expectancy of less than 3 months can be treated with repeated outpatient thoracentesis as needed to palliate symptoms. Unfortunately, pleural effusions can reaccumulate rapidly, and the risk of complications increases with repeated drainage. Alternatively, the best treatment for effusions in such patients may be insertion of an indwelling tunneled catheter, which allows patients to remove pleural fluid as needed at home.⁴

Various agents, including talc, doxycycline, bleomycin sulfate (Blenoxane), zinc sulfate, and quinacrine hydrochloride can sclerose the pleural space and effectively prevent recurrence of the malignant pleural effusion.  

• Talc is the most effective sclerosing agent and can be administered as slurry through chest tubes or pleural catheters. Although a systematic review suggested that direct insufflation of talc via thoracoscopy was more effective than talc slurry, both were equally effective in a 2005 prospective trial of malignant effusions.⁵
• Doxycycline and bleomycin are also effective in most patients and can be administered more easily through small-bore catheters, although they are somewhat less effective and substantially more expensive than talc.
• All sclerosing agents can produce fever, chest pain, and nausea.
• Talc rarely causes more serious adverse effects such as empyema and acute lung injury. The latter appears to be related to the particle size and amount of talc injected for pleurodesis.
• Injection of 50 mL of 1% lidocaine hydrochloride prior to instillation of the sclerosing agent might help alleviate pain. Additional analgesia might be required in some cases.
• Clamp chest tubes for approximately 2 hours after instillation of the sclerosing agent.
• A 2006 systematic review confirms that rotating the patient through different positions does not appear necessary to ensure distribution of soluble sclerosing agents throughout the pleural space. In addition, neither protracted drainage after instillation of sclerotics nor use of larger bore chest tubes increased the effectiveness of pleurodesis.⁶
• Pleural sclerosis is likely to be successful only if the pleural space is drained completely before pleurodesis and if the lung is fully reexpanded to appose the visceral and parietal pleura after sclerosis. Animal studies suggest that systemic corticosteroids can reduce inflammation during sclerosis and can cause pleurodesis failures.

TREATMENT

Section 6 of 10  

• Authors and Editors
• Introduction
• Clinical
• Differentials
• Workup
• Treatment
• Follow-up
• Miscellaneous
• Multimedia
• References

Medical Care

Transudative effusions are usually managed by treating the underlying medical disorder. However, whether transudates or exudates, drain large pleural effusions if they are causing severe respiratory symptoms, even if the cause is understood and disease-specific treatment is available. The management of exudative effusions depends on the underlying etiology of the effusion. Pneumonia, malignancy, or TB causes most exudative pleural effusions, or effusions are deemed idiopathic. Drain complicated parapneumonic effusions and empyemas to avoid fibrosing pleuritis. Malignant effusions are usually drained to palliate symptoms and may require pleurodesis to prevent recurrence.

Although medications cause only a small proportion of all pleural effusions, they are associated with exudative pleural effusions.  

• Implicated drugs include medications that cause drug-induced lupus syndrome (eg, procainamide, hydralazine, quinidine), nitrofurantoin, dantrolene, methysergide, procarbazine, and methotrexate.
• Recognition of these iatrogenic causes of pleural effusion avoids unnecessary additional diagnostic procedures and leads to definitive therapy, which is discontinuation of the medication.

Of the common causes for exudative pleural effusions, parapneumonic effusions have the highest diagnostic priority. Even in the face of antibiotic therapy, infected pleural effusions can rapidly coagulate and organize to form fibrous peels that might require surgical decortication. Therefore, quickly assess pleural fluid characteristics predictive of a complicated course to identify parapneumonic effusions that require urgent tube drainage, which are observed more commonly in indolent anaerobic pneumonias than in typical community-acquired pneumonia.  

• Indications for urgent drainage of parapneumonic effusions include (1) frankly purulent fluid, (2) pleural fluid pH less than 7.2, (3) loculated effusions, and (4) bacteria on Gram stain or culture.
• Patients with parapneumonic effusions who do not meet criteria for immediate tube drainage should improve clinically within 1 week with appropriate antibiotic treatment.
• Radiographically reassess patients with parapneumonic effusions who do not improve or who deteriorate clinically.

Malignant pleural effusions usually signify incurable disease with considerable morbidity and a dismal mean survival of less than 1 year. Drainage of large malignant effusions might relieve dyspnea caused by distortion of the diaphragm and chest wall produced by the effusion. Pleural sclerosis also might be necessary to prevent recurrence of symptomatic effusions. 

TB pleuritis typically is self-limited. However, because 65% of patients with primary TB pleuritis reactivate their disease within 5 years, empiric anti-TB treatment is usually begun pending culture results when sufficient clinical suspicion is present, such as an unexplained exudative or lymphocytic effusion in a patient with a positive PPD finding.

Chylous effusions are usually managed by dietary and surgical modalities discussed below. However, studies suggest that somatostatin analogues also may help in reducing efflux of chyle into the pleural space.

Surgical Care

Surgical intervention is most often required for parapneumonic effusions that cannot be drained adequately by needle or small-bore catheters, and surgery might be required for diagnosis and sclerosis of exudative effusions.

• Video-assisted thoracoscopy with the patient under local or general anesthesia allows direct visualization and biopsy of the pleura for diagnosis of exudative effusions.
• Pleural sclerosis by insufflating talc directly onto the pleural surface using video-assisted thoracoscopy is an alternative to using talc slurries.
• Decortication is usually needed to remove a thick, inelastic pleural peel that restricts ventilation and produces progressive or refractory dyspnea. In patients with chronic, organizing parapneumonic pleural effusions, technically demanding operations might be required to drain loculated pleural fluid and to obliterate the pleural space.
• Surgically implanted pleuroperitoneal shunts are another treatment option for recurrent symptomatic effusions, most often in the setting of malignancy, but they are also used for management of chylous effusions. However, the shunts are prone to malfunction over time and can require surgical revision.
• In unusual cases, surgery might be required to close diaphragmatic defects (thereby preventing recurrent accumulation of pleural effusions in patients with ascites) and to ligate the thoracic duct to prevent reaccumulation of chylous effusions.

Consultations

A pulmonologist can be consulted for assistance with high-risk diagnostic thoracentesis, depending on the experience of the clinician. Drainage of complicated effusions usually requires consultation with a pulmonologist, interventional radiologist, or thoracic surgeon, depending on the location of the effusion and the clinical situation.

Diet

Restrictions of fat intake might help in the management of chylous effusions, although management remains controversial. Ongoing drainage of these effusions can rapidly deplete patients of fat and protein stores. Limiting oral fat intake might slow the accumulation of chylous effusions in some patients. Hyperalimentation or total parenteral nutrition can preserve nutritional stores and limit accumulation of the chylous effusion but probably should be restricted to patients in whom definitive therapy for the underlying cause of the chylous effusion is possible.

FOLLOW-UP

Section 7 of 10  

• Authors and Editors
• Introduction
• Clinical
• Differentials
• Workup
• Treatment
• Follow-up
• Miscellaneous
• Multimedia
• References

Further Inpatient Care

Monitoring pleural drainage   

• Record the amount and quality of fluid drained and monitor for an air leak (bubbling through the water seal) each shift.
• Repeat the chest radiographs when drainage decreases to less than 100 mL/d to evaluate whether the effusion has been fully drained. If a large effusion persists radiographically, reevaluate the position of the chest catheter. If the catheter is positioned appropriately, consider injecting lytics through the chest tube to break up clots that may be obstructing drainage.
• Large air leaks (steady streams of air throughout the respiratory cycle) may be indications of loose connectors or of a drainage port on the catheter that has migrated out to the skin. Alternatively, they may indicate large bronchopleural fistulae. Consequently, dressings should be taken down and the position of the catheter inspected at the puncture site. Clamping the catheter at the skin helps determine whether the air leak is emanating from within the pleural cavity (in which case it stops when the tube is clamped) or from outside the chest (in which case the leak persists).

Prognosis

Prognosis varies in accordance with the underlying etiology.  

• Malignant effusions convey a very poor prognosis, with survival typically measured in months.⁷
• Parapneumonic effusions, when recognized and treated promptly, typically resolve without significant sequelae. However, untreated or inappropriately treated parapneumonic effusions may lead to constrictive fibrosis.

Patient Education

For excellent patient education resources, visit eMedicine's Lung and Airway Center. Also, see eMedicine's patient education article Pleurisy.

MISCELLANEOUS

Section 8 of 10  

• Authors and Editors
• Introduction
• Clinical
• Differentials
• Workup
• Treatment
• Follow-up
• Miscellaneous
• Multimedia
• References

Medical/Legal Pitfalls

• Failure to recognize potentially lethal underlying conditions producing pleural effusions, including pulmonary embolus and esophageal rupture
• Discharge or transfer of a patient with an unrecognized pneumothorax following thoracentesis
• Failure to prevent constrictive pleuritis from untreated parapneumonic effusions or hemothorax
• Unnecessary attempts to perform thoracentesis

MULTIMEDIA

Section 9 of 10  

• Authors and Editors
• Introduction
• Clinical
• Differentials
• Workup
• Treatment
• Follow-up
• Miscellaneous
• Multimedia
• References

Media file 1:  Large, malignant, right-sided pleural effusion.
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Media type:  X-RAY

Media file 2a:  Chest radiograph showing left-sided pleural effusion.
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Media type:  Radiograph

Media file 2b:  Left lateral decubitus film showing freely layering pleural effusion.
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Media type:  Radiograph

REFERENCES

Section 10 of 10

• Authors and Editors
• Introduction
• Clinical
• Differentials
• Workup
• Treatment
• Follow-up
• Miscellaneous
• Multimedia
• References

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Article Last Updated: Jun 5, 2008