From the Guidelines
Pleural tap, also known as thoracentesis, is indicated for both diagnostic and therapeutic purposes in patients with pleural effusions, including suspected pleural infection, malignant pleural effusion, unexplained pleural effusion, symptomatic pleural effusion, and tuberculous pleurisy. The procedure involves inserting a needle into the pleural space under ultrasound guidance, typically in the mid-axillary line at the level of the effusion, after administering local anesthesia (1-2% lidocaine) 1.
Diagnostic Indications
Diagnostic indications for pleural tap include:
- Suspected pleural infection (empyema or parapneumonic effusion)
- Malignant pleural effusion
- Unexplained pleural effusion requiring diagnosis
- Symptomatic pleural effusion causing shortness of breath
- Tuberculous pleurisy
Therapeutic Indications
Therapeutic indications for pleural tap include relieving respiratory distress caused by large effusions that compress the lung and impair breathing.
Procedure and Complications
The procedure works by directly accessing the pleural space to remove fluid that has accumulated due to imbalances in hydrostatic and oncotic pressures or inflammatory processes affecting the pleural membranes. Contraindications include bleeding disorders, anticoagulation therapy, severe respiratory failure requiring mechanical ventilation, and skin infection at the insertion site. Complications may include pneumothorax, bleeding, infection, and re-expansion pulmonary edema, particularly when removing large volumes (>1.5 liters) of fluid rapidly 1.
Best Practice
Performing thoracentesis under ultrasound guidance improves the rate of successful pleural aspiration and reduces the incidence of iatrogenic pneumothorax, independent of the size of the effusion 1. The diagnostic yield for malignancy depends on sample preparation, the experience of the cytologist, and the tumor type, with the highest diagnostic yields retrieved in patients with adenocarcinoma 1.
From the Research
Indications of Pleural Tap
The indications of pleural tap, also known as thoracentesis, can be summarized as follows:
- To differentiate between a transudate and an exudate, which is essential for further diagnostic work-up 2
- To evaluate the presence of pleural effusion in patients with pneumonia, as it may indicate the development of an empyema 2
- To investigate the cause of pleural effusion, especially in cases where the underlying disease is not clear 3
- To guide treatment, as the treatment of pleural effusion depends on its cause 2
- To detect complications such as infection or malignancy in the pleural space 3
Specific Conditions
Pleural tap is indicated in the following specific conditions:
- Pulmonary embolism, as it can help diagnose the condition and guide treatment 4, 5
- Heart failure, to differentiate between transudative and exudative effusions 3
- Malignancy, to diagnose and manage malignant pleural effusions 2, 3
- Infection, to diagnose and manage parapneumonic effusions 3
Diagnostic Criteria
The decision to perform a pleural tap is based on the following diagnostic criteria:
- Presence of pleuritic chest pain in a patient with a pleural effusion, which is highly suggestive of pulmonary embolism 4
- Presence of bloody pleural fluid, which is not a contraindication for anticoagulant therapy 4
- Light's criteria, which can help differentiate exudates from transudates 3
- Point-of-care ultrasound, which can guide thoracentesis and reduce complications 3