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Olli-PekkaSeppälä

Pleural Effusions and Thoracentesis

Essentials

  • Pleural effusion, either unilateral or bilateral, may be caused by many different diseases of the lung, pleura or other organs, or by systemic diseases.
  • Characterization of pleural fluid either as exudate or transsudate helps in diagnostic workout.
    • Exudate is usually caused by a disease of the lung or pleura or by a systemic disease.
    • Transsudate is usually caused by heart failure or by a hepatic or renal disease.

Aetiology

  • Causes of pleural effusion are presented in table T1.

Causes of pleural effusion (E = exudate, T = transsudate)

Common causesLess common causes
Pneumonia PneumoniaEHypoproteinaemia: nephrotic syndromeNephrotic Syndrome, hepatic failureT
Heart failure Acute Heart Failure and Pulmonary OedemaTTuberculosis Diagnosing TuberculosisE
Cancer Lung CancerEAbdominal diseases: pancreatitisAcute Pancreatitis, subphrenic abscessE
Pulmonary embolism Pulmonary EmbolismE/TSystemic connective tissue diseases: rheumatoid arthritis Disease-Specific Signs and Symptoms in Patients with Inflammatory Joint Diseases, SLE Systemic Lupus Erythematosus (Sle), vasculitis VasculitidesE
Postinfarction syndrome or sequela of thoracotomyE
AsbestosAsbestos-Related DiseasesE
Several drugs, most commonly methotrexate, amiodarone and nitrofurantoinE

Symptoms and signs

  • Dyspnoea and dry cough
  • In pleurisy, additionally flank pain and often fever
  • Dull percussion note
  • In pleurisy, friction rub on auscultation (not common). The friction rub will disappear when there is so much fluid in the pleural cavity that the layers of the pleura do not rub against each other anymore.

Investigations

  • In practice there are three stages in investigating the cause of pleural effusion.
    1. The first question to ask is whether the effusion is transudate or exudate by nature. This is defined by determination of the protein concentration of the fluid.
    2. In the case of exudate, the question is whether it is due to a malignant or inflammatory condition.
    3. In the case of an inflammatory condition, a search for indications of bacterial pneumonia, tuberculosis and connective tissue disorders will be made.
  • Detailed examination of the patient
    • Since a considerable share of pleural effusion cases is caused by other diseases than those of the pleura or lungs, extensive attention should be paid also to possible signs of disease in other organ groups.
  • Indices of inflammation
    • ESR, plasma CRP, basic blood count
  • Thoracentesis
    • Unless the reason is self-evident
  • Diagnosis of cancer and tuberculosis often require thoracentesis and pleural biopsy, sometimes also thoracoscopy.

Indications for thoracentesis

  • Diagnostic thoracentesis in connection with pleural effusions of uncertain aetiology
  • Therapeutic thoracentesis if a large amount of pleural fluid causes symptoms
  • Thoracentesis is usually unnecessary in cases of right-sided or bilateral pleural effusion in connection with evident heart failure. Such accumulation of pleural fluid is reversed by treatment (pleural effusion that is limited to the left side is not considered to be due to heart failure).
  • There are no actual contraindications for thoracentesis. Careful consideration and caution are required if the patient has bleeding diathesis or medication that affects blood coagulation. With the exception of aspirin, drugs that affect blood coagulation should be paused before the procedure. Platelet level should be over 50 × 109 /l and INR level below 1.5.

Performance of thoracentesis

  • Video Thoracentesis
  • Before the procedure, the presence of excess fluid in the pleural cavity should be established. This can be demonstrated by chest x-ray showing rounding of the lateral and posterior costodiaphragmatic recess (picture 1). Sometimes rounding of the recess is not seen with infrapulmonary pleural effusions. Ultrasound examination can be used to confirm the presence of pleural effusion and to locate a suitable puncture site (it is advisable to perform an ultrasound examination whenever the apparatus is easily available).
  • The patient should sit leaning slightly forward with forearms on the examination table and with his/her forehead resting on the forearms.
  • The area of dull percussion caused by pleural fluid is located by comparing the percussion sound with that obtained from the healthy lung. The diaphragmatic margin is marked on the side of the healthy lung. The upper border of dull percussion on the affected side should be at least two intercostal spaces higher than the diaphragmatic margin on the healthy side.
  • The site of puncture is one or two intercostal spaces below the upper border of percussion dullness along the posterior axillary line (or a site determined by echography).
  • The site is anaesthetized over the upper border of a rib by 1% lidocaine. At the end of administration of anaesthetic, some pleural fluid is withdrawn to confirm the presence of excess fluid.
  • In general, pleural aspiration is best performed using a disposable needle, syringe, three-way stopcock and tubing connected to a collection bag. It should be kept in mind that there is negative pressure in the pleural cavity, so the needle-syringe system should be airtight. If a small amount of sample is needed (e.g. for protein determination when suspecting transudate), the sample may be aspirated with a thin needle into a 20 ml syringe.
  • When performing therapeutic thoracentesis, no more than 1500 ml fluid (depending on the patient's weight) should be aspirated at a time to avoid pulmonary oedema.
  • With diagnostic thoracentesis, attention is paid to the smell and appearance of the pleural fluid. Empyema has a putrid smell. Blood-stained pleural fluid is probably caused by trauma, cancer or pulmonary infarction. Milky pleural effusion (chylothorax) is usually related to a trauma or a mediastinal malignancy.

Samples of pleural fluid

  • Protein: 1 ml in a test tube
  • Differential cell count: e.g. a 10 ml EDTA tube
  • Bacterial culture is necessary only if the fluid is turbid or purulent: about 5 ml in a blood culture bottle (aerobic and anaerobic) or 1 ml in a Transpocult® tube, e.g., with a tuberculin syringe.
  • Mycobacterial culture in a 5 ml test tube or preferably directly in a culture medium, e.g., a Bactec® bottle
  • A cytology sample is shipped to the laboratory for example in two 50 ml plastic bottles. If the sample cannot be analysed right away, 5 ml of pleural fluid and 5 ml of 96% alcohol may be placed in three clean test tubes.
  • If the accumulation of pleural fluid is associated with pneumonia it is advisable to determine the pH of the fluid which guides the decisions concerning further treatment (drainage tube, operation or continuation of antimicrobial treatment).
  • Other investigations are performed according to a consultation with a specialist.

Interpretation of the results

  • If the protein concentration is less than 30 g/l, the sample is a transudate.
  • A predominance of neutrophils (over 50%) suggests bacterial pneumonia.
  • A predominance of lymphocytes is typical for tuberculosis and malignancy but it is also encountered in other types of chronic pleurisy.
  • The sensitivity of a cytology sample is in the order of 30-50% in cancer.
  • The sensitivity of mycobacterial culture from pleural fluid is usually poor.

    References

    • Bintcliffe OJ, Lee GY, Rahman NM ym. The management of benign non-infective pleural effusions. Eur Respir Rev 2016;25(141):303-16. [PubMed]
    • Havelock T, Teoh R, Laws D ym. Pleural procedures and thoracic ultrasound: British Thoracic Society Pleural Disease Guideline 2010. Thorax 2010;65 Suppl 2():ii61-76. [PubMed]
    • Hooper C, Lee YC, Maskell N ym. Investigation of a unilateral pleural effusion in adults: British Thoracic Society Pleural Disease Guideline 2010. Thorax 2010;65 Suppl 2():ii4-17. [PubMed]

Related Keywords ⬆

ATC Code:

N01BB02

Primary/Secondary Keywords