thoracentesis

Thoracentesis, commonly known as a pleural tap or chest tap, is a procedure where excess pleural fluid is drained from the pleural space for diagnostic and/or therapeutic reasons. Ultrasound-guided thoracentesis performed by radiologists has been shown to have fewer complications than blind thoracentesis. A success rate of up to 90% has been demonstrated after failed blind thoracentesis.

Indications

  • symptomatic pleural effusions
  • investigation of cause of pleural fluid collection, e.g. malignancy, infection, etc

Contraindications

  • coagulopathy/thrombocytopenia, anticoagulation or other bleeding disorders
  • respiratory disease such as severe respiratory failure, intractable coughing, contralateral pneumonectomy, emphysema, suspected echinococcal disease or the inability to hold one's breath

Procedure

Thoracentesis can be performed blind, partially imaged-guided or image-guided (usually ultrasound but may be CT). Below the technique for an ultrasound-guided  therapeutic thoracentesis with a trocar technique is outlined as this is the most commonly performed in radiology . Seldinger technique is an alternative method.

Preprocedural evaluation
  • review history, pathology results and prior imaging
    • e.g. 75% of pleural effusions secondary to congestive cardiac failure will resolve with two days of diuresis and thoracentesis should be reserved for refractory cases
  • obtain informed written consent
  • completion of a "time-out" with nursing staff
Positioning/room set up
  • patient sitting on edge of bed, leaning forward with arms on a table
  • monitoring (BP, pulse rate, SpO2)
  • access from behind the patient
Equipment
  • ultrasound with CH-4 probe
  • sterile pack including wash, gown and gloves, drape, ultrasound cover and sterile gel
  • long hypodermic needle, syringe and lignocaine
  • scalpel
  • thoracentesis/paracentesis catheter-over-needle set
  • three-way tap and drainage bag
  • dressings
Technique
  • pre-procedure ultrasound to confirm presence of drainable pleural effusion
  • sterile glove and gown followed by sterile preparation and drape
  • subcutaneous and deep infiltration to pleura of local anesthetic under ultrasound guidance
  • small skin nick with scalpel
  • under ultrasound guidance, introduction of thoracentesis needle along the superior margin of the rib, aspirating while advancing until pleural fluid is aspirated; catheter is then slid off needle
  • connection of three-way tap and drainage bag and airtight dressing applied
  • for diagnostic thoracentesis 50 mL of fluid is usually required
Postprocedural care
  • volume to be drained varied depending on the number of prior taps
    • ~1500 mL or until symptoms such as vague chest pain commence is recommended to reduce the occurrence of re-expansion pulmonary edema
    • some authors believe it is safe to drain larger volumes
  • requirement for post-thoracentesis chest x-ray to assess for pneumothorax is debated; literature has demonstrated there is a very low risk of pneumothorax in asymptomatic patients
  • patient should be advised of the risk of pneumothorax and not to fly for one week

Complications

Common complications from thoracentesis include :

Serious, but less common, complications from thoracentesis include :

Outcomes