From the Guidelines
Image-guided thoracentesis should be performed with ultrasound guidance to minimize complications and improve procedural safety, as evidenced by a significant reduction in pneumothorax risk (1.0% vs. 8.9%, relative risk [RR] = 0.10,95% confidence interval [CI] = 0.03–0.37) 1.
Pre-Procedure Evaluation
Pre-procedure imaging studies should include a chest X-ray and ultrasound to confirm pleural effusion and determine the optimal puncture site. Laboratory tests including complete blood count, coagulation profile (PT/INR, PTT), and platelet count should be obtained, with correction of any coagulopathy (INR <1.5, platelets >50,000/μL) prior to the procedure 1.
Procedure Technique
The patient should be positioned sitting upright with arms supported on a table or lying on the unaffected side. After sterile preparation, local anesthesia with 1-2% lidocaine is administered. Using ultrasound guidance, a 20-22 gauge needle is inserted into the pleural space above the rib to avoid neurovascular structures.
- Fluid is aspirated for diagnostic purposes (50-100 mL) or therapeutic drainage (up to 1.5 L to prevent re-expansion pulmonary edema) 1.
- Samples should be sent for cell count, biochemistry, cytology, and microbiology as indicated.
Post-Procedure Care
Post-procedure, a chest X-ray is recommended to rule out pneumothorax. Complications include pneumothorax, hemothorax, re-expansion pulmonary edema, and infection.
- Ultrasound guidance significantly reduces complication rates by allowing real-time visualization of the pleural space and surrounding structures, improving procedural safety and success rates compared to blind techniques 1.
- The use of ultrasound guidance also allows for the identification of intercostal vessels, which can help decrease the risk of hemorrhagic complications associated with pleural procedures 1.
From the Research
Image-Guided Thoracentesis Studies
- The use of ultrasound guidance for thoracentesis has been associated with a higher sensitivity for identifying pleural effusions and a lower pneumothorax rate 2.
- Pleural manometry can be used to distinguish patients with lung entrapment from those with trapped lung, and to predict the ability to pleurodesis patients with malignant effusions 3.
- The incidence of reexpansion pulmonary edema (RPE) after large-volume thoracentesis is rare and independent of the volume of fluid removed, pleural pressures, and pleural elastance 4.
- The use of ultrasound and pleural manometry enhances the understanding of pleural disease and is associated with clinical benefit that will lead to improved patient care 3.
Recommended Procedures
- Ultrasound-guided thoracocentesis can be done equally as safely by residents as by senior radiologists, and the safety and feasibility of the method are evident among mechanically ventilated intensive care patients 2.
- A unique experiential training paradigm in a zero-risk simulation environment can improve efficacy, timeliness, service orientation, and safety in thoracentesis procedures 5.
- CT-guided diagnostic thoracocentesis (CT-TC) can be used in patients with a small amount of pleural fluid, and can also be used therapeutically in debilitated patients who cannot maintain a sitting position or when the pleural fluid needs to be drained completely 6.
Complications and Risks
- The incidence of pneumothorax after ultrasound-guided thoracocentesis is low, and the use of ultrasound guidance can reduce the risk of pneumothorax 2, 5.
- The risk of reexpansion pulmonary edema (RPE) after large-volume thoracentesis is rare, but can be minimized by monitoring pleural pressures and symptoms during the procedure 4.
- Procedure-related pain, cough, and hypotension are potential complications of thoracentesis, but can be minimized with proper training and technique 5.