Mastering ultrasound guidance for thoracentesis

Learn how to use ultrasound to guide thoracentesis procedures.

Sara Damewood, MD
Sara Damewood, MD
24th Jan 2018 • 2m read

If you have a patient with pleural effusion and need to perform a thoracentesis, this video will help you get started. By the end of this lesson, you will be familar with the technique of using ultrasound to guide a thoracentesis and dramatically improve the safety of the procedure.

Want to perform your own thoracentesis procedures? Take our Procedural Ultrasound Masterclass course and start using ultrasound to improve the safety of your procedures. Your instructor, Dr Sara Damewood–the Emergency Ultrasound Section Chief and Clinical Ultrasound Fellowship Director at the University of Wisconsin–will guide you through the essentials of procedural ultrasound.

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Video Transcript

[00:00:00] There are two basic approaches for performing an ultrasound-guided thoracentesis. The most common is the posterior approach, with the patient sitting up and leaning forward. An alternative approach is the anterolateral approach, when the patient is at a semirecumbent position. This is helpful for patients that are unable to sit up, such as those who are sedated and receiving mechanical ventilation. Your goal is to slide the needle above the rib and

[00:00:30] to avoid the neurovascular bundle, that travels along the inferior rib. You will likely not be able to visualize this on ultrasound, given the extent of rib shadowing. You can use ultrasound to define your safety zone. You can measure the distance, here, from the entry of the skin into the pocket of fluid and know how far you can go, without hitting critical structures. On the right, you can see the measurement marks of the ultrasound machine screen. This is set to a depth of 21 cm.

[00:01:00] This tick, here, with the second blue arrow is showing 10 cm. This would be a good idea of how deep your needle can go in, before it hits crucial structures. Another way ultrasound can be useful is to get a sense of how deep your lidocaine needle has to travel. That's this distance, here. Again, this is the superficial tissue prior to entering the cavity of the effusion. It doesn't help the patient very much if you instill lidocaine into their pleural effusion, instead of their skin. Once the effusion is identified

[00:01:30] and the spot for thoracentesis is identified, as long as you don't allow the patient to reposition or move, you don't necessarily need ultrasound real-time, while inserting the needle for thoracentesis. You could have an assistant hold the probe, with a sterile cover, for you. If you prefer to have real-time guidance or if the patient is unable to lie still, it's good practice to have your probe sterile and available. Once you are finished with the fluid draining out, take another look with ultrasound to see if enough fluid has drained out. Sometimes, there can

[00:02:00] be loculations or clot that the needle can be obstructed by, useful information to have before pulling the needle out. If you need to get more fluid out, you can gently reposition the needle. Hurray! Now you know the basics for ultrasound guidance for thoracentesis.