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Information ⬇

Author: Ioannis Psallidas

Pleural effusion is a feature of a wide range of diseases. Transudative and exudative effusions (Tables 12.1 and 12.2) are caused by distinctive pathogenic mechanisms, and Light's criteria should be used for their differentiation.

Evaluation requires clinical assessment, imaging (by chest X-ray and thoracic ultrasonography) and examination of pleural fluid. Assessment and management of pleural effusion is summarized in Figure 12.1.

Priorities ⬆ ⬇

Outline

Clinical Assessment and Imaging!!navigator!!

The clinical assessment is summarized in Table 12.3.

  • Review the history, with a focus on occupational exposures, drugs, risk factors for pulmonary embolism or tuberculosis, extrapleural sources (e.g. ascites) and comorbid conditions.
  • Review the chest X-ray. Pleural effusion results in basal shadowing obscuring the hemidiaphragm with a concave upper border. Massive effusion demonstrates a complete 'white-out' of the hemithorax with mediastinal displacement away from the effusion. If mediastinal shift is not present, consider the possibility of a co-existing bronchial obstruction with the effusion (e.g. lung cancer).
  • Thoracic ultrasonography is more sensitive than chest radiography in detecting pleural effusion and also provides additional diagnostic information as to the cause of the effusion (exudative, empyema, malignant pleural effusion).

Thoracentesis!!navigator!!

  • There is no need for thoracentesis if the patient has an obvious reason for pleural effusion (e.g. small bilateral pleural effusions and a history of heart failure).
  • It may be diagnostic (50–60 mL of fluid) and/or therapeutic (target: symptomatic relief).
  • Pleural fluid examination should be analysed carefully. Vital diagnostic clues may lie in simple inspection or smell. Tests needed are summarized in Table 12.4.
    • If pleural infection is suspected send fluid in blood culture bottles in addition to a plain tube.
    • Cytology (approximately 40–50 mL should be sent for malignant cell identification and for cell differential diagnosis). The sensitivity of the technique for detecting malignant pleural effusion is around 60% (i.e. false-negative rate 40%) and the additional yield from sending more than two specimens of pleural fluid taken on different occasions is low.
    • If pleural fluid pH is needed, use ABG analyser (but do not analyse a purulent sample, as this is unnecessary and may damage the machine).
    • Additional tests may be indicated, depending on clinical scenario (e.g. chylomicrons, cholesterol, triglycerides, adenosine deaminase, amylase).

Categorizing an Effusion As a Transudate or an Exudate!!navigator!!

To answer this important question, Light's criteria should be employed. The effusion is an exudate if it meets one of the following criteria:

  • Pleural fluid protein/serum protein ratio >0.5
  • Pleural fluid LDH/serum LDH ratio >0.6
  • Pleural fluid LDH greater than two-thirds of the upper limit of normal serum LDH

Light's criteria correctly identify almost all exudates, but mis-classifies about 20% of transudates as exudates. If a transudative effusion is suspected (e.g. due to heart failure or cirrhosis) and none of the biochemical measurements is >15% above the cutoff levels for Light's criteria, the difference between serum and the pleural fluid protein is measured. If the difference is >31g/L, the effusion is probably a transudate.

Further Management ⬆ ⬇

Outline

Treatment of Symptoms and Underlying Disorder!!navigator!!

  • The effusion itself generally does not require treatment if the patient is asymptomatic.
  • Many effusions resorb spontaneously when the underlying disorder is treated, especially effusions due to heart failure, pulmonary embolism or after CABG.
  • Pleuritic pain can usually be managed with NSAIDs or other oral analgesics.

Drainage of a Symptomatic Effusion!!navigator!!

  • Therapeutic aspiration is a sufficient treatment for many symptomatic effusions and can be repeated for effusions that re-accumulate. Seek advice from a chest physician.
  • In most cases, 1–1.5L of pleural fluid can be aspirated with careful attention to the development of chest symptoms; re-expansion pulmonary oedema is a recognized but rare consequence of large-volume aspiration. Pleural aspiration should be stopped if the patient develops chest tightness, chest pain or severe coughing
  • Effusions that are chronic, recurrent and causing symptoms, can be treated with pleurodesis or by intermittent drainage with an indwelling catheter.

Specific Management for Parapneumonic Effusions and Empyema!!navigator!!

  • Seek advice from a chest physician. For indications for chest drain insertion see Table 12.5.
  • All patient with pleural infection should be treated with antibiotics (refer to local hospital prescribing guidelines) and treatment options ought to be rationalized with culture and sensitivity results of the pleural fluid or blood cultures (note that anaerobes are frequently difficult to culture and may coexist with other organisms).
  • Refer to a thoracic surgeon if there is persistent sepsis after 5–7 days of maximum therapy with antibiotics and pleural fluid drainage.

Specific Management for Malignant Pleural Effusions!!navigator!!

  • Seek advice from a chest physician.
  • Asymptomatic effusions and those causing dyspnoea unrelieved by thoracentesis do not require additional procedures.
  • If dyspnoea caused by malignant pleural effusion is relieved by thoracentesis but fluid and dyspnea re-develop, definitive treatment is required (talc pleurodesis or placement of an indwelling pleural catheter).
  • Pleurodesis is performed by instilling a sclerosing agent into the pleural space in order to seal the visceral and parietal pleura and eliminate the space. The most effective and commonly used sclerosing agent is talc. Talc pleurodesis can be performed either by the insertion of a small chest tube (10–14 F) as a slurry or by medical thoracoscopy as a poudrage.
  • Indwelling pleural catheter (IPC) drainage is the preferred approach for ambulatory patients because hospitalization is not necessary for catheter insertion and the pleural fluid can be drained intermittently into vacuum bottles. IPC is the preferred option for patients with significant trapped lung (when tumour encases the visceral pleura and prevents lung re-expansion).
  • Chest CT scan with pleural phase contrast (late venous phase) is useful in distinguishing nodular, mediastinal or circumferential pleural thickening (features present in around 80% of cases of malignant pleural disease).
  • Pleural tissue biopsy for histological or microbiological examination may be indicated. Pleural biopsy can be performed using image-guided (CT or US guidance) techniques or via medical thoracoscopy. Both techniques have significantly better results compared to closed pleural biopsies. Thoracoscopy also offers diagnostic and therapeutic approaches to patients with pleural effusion (e.g. talc poudrage pleurodesis).
  • Bronchoscopy has no role in investigating pleural effusions, and is only used if the chest CT scan is suggestive of parenchymal abnormities that require further investigation, or if main bronchial obstruction is suspected.
  • Even after extensive investigations, 25% of pleural effusions remain undiagnosed. These are often due to occult pulmonary embolism, TB, viral infection or cancer.

Further Reading ⬆

Corcoran JP, Wrightson JM, Belcher E, DeCamp MM, Feller-Kopman D, Rahman NM (2015) Pleural infection: past, present, and future directions. Lancet Respir Med 3, 563–577.

Light RW (2013) The Light criteria: the beginning and why they are useful 40 years later. Clin Chest Med 34, 21–26. http://dx.doi.org/10.1016/j.ccm.2012.11.006.

Psallidas I, Kalomenidis I, Porcel JM, Robinson BW, Stathopoulos GT (2016) Malignant pleural effusion: from bench to bedside. European Respiratory Review 25, 189–198. DOI: 10.1183/16000617.0019-2016.