Written by Peter Liu
Spoon Feed
Wall suction for thoracentesis appears to be faster than gravity drainage, as comfortable, and safe.
For thoracentesis, wall suction might not suck after all
There are roughly three ways to drain pleural fluid during a thoracentesis:
- Gravity drainage: Connect the tube to a bag lower to the ground, and let gravity do all of the work. (the slowest method)
- Manual drainage: Hand crank your syringe back and forth until you’ve done a good job. (the sweatiest method, particularly in an isolation gown)
- Vacuum drainage: Connect the catheter to a vacuum and let it rip! (the quickest, least sweaty method)
So why hasn’t everybody been vacuum draining? Well, in a previous small randomized control trial (RCT) comparing vacuum to manual drainage, patients had more pain and complications with vacuum drainage. All three of the feared complications occurred more in the vacuum-assisted procedures: re-expansion pulmonary edema, pneumothorax, and hemothorax.
Today’s featured study essentially contradicts the findings from the smaller previous study. This multicenter, single-blinded RCT randomized 221 participants to wall suction or gravity drainage and found no difference in symptoms of chest discomfort (p = 0.08; measured by a 100-mm visual analogue scale), nor in breathlessness, fluid volume drained, or complication rates. Gravity drainage required an additional 3 minutes on average (p = 0.0001). Combined with findings from the same group in the GRAVITAS trial, the results suggest that vacuum drainage is faster and more effortless without a clear downside.
These findings require careful consideration. The current study was done by pulmonology specialists with a high level of expertise in thoracentesis. It excluded loculated effusions, and the inclusion criteria restricted this study to free-flowing effusions ≥ 500 mL. In speaking directly with the authors of this study, they carefully monitored for symptoms of overly negative pleural pressures and were strategic in stopping their procedures before complications became likely. This is likely why they did not observe the same risk with vacuum drainage as previous groups.
How does this change my practice?
I have a high thoracentesis volume in my inpatient practice and have begun to cautiously use vacuum-drainage in large volume effusions. In line with this study, I monitor the patient for symptoms (chest pain, dyspnea, cough), and I terminate procedures immediately if the risk for complications outweighs the marginal benefit of further drainage.
Source
Gravity- vs Wall Suction-Driven Large-Volume Thoracentesis: A Randomized Controlled Study. Chest. 2024 Dec;166(6):1573-1582. doi: 10.1016/j.chest.2024.05.046. Epub 2024 Jul 18. PMID: 39029784
