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Central line...bubble it


One of the more serious complications of central venous catheter (CVC) placement involves arterial puncture and cannullation with a large caliber dialator and catheter.  This occurs in up to 5% of all CVC placement attempts.  

Depending on the location of  CVC placement, inadvertent arterial placement may lead to bleeding, embolism, neurologic injury, airway loss and even death.  Verifying venous placement prior to dilatation, cannulation and infusion of vasoactive agents is essential.
One method of doing so in situations where placement is equivocal by standard methods is with the less-publicized but highly useful bedside echocardiography bubble test.
In order to employ this method during CVC placement, after the target vessel has been entered with the finder needle, insert the finder needle catheter.  Have an assistant place the echo probe in a subcostal position.  Through the finder needle catheter rapidly flush 10cc sterile saline (both agitated and non-agitated have been shown to work).  If the catheter is in the venous system, the right atrium and right ventricle will opacify almost immediately on echo.  If the catheter is in the arterial system, there will be a delay, and then the left atrium and left ventricle will be noted to opacify.
This method can help differentiate between arterial and venous cannulations prior to dilatation and placement of large bore catheters.  It can also be used once a catheter has been placed, to confirm venous placement.  By doing so the user to may confidently identify venous catheter placement prior to chest x-ray.  




Blaivas M.  “Video analysis of accidental arterial cannulation with dynamic ultrasound guidance for central venous access.”  J Ultrasound Med 2009;28:1239-44.
Ghadiali N, Teo LM, Sheah K.  “Bedside confirmation of a persistent left superior vena cava based on aberrantly positioned central venous catheter on chest radiograph.” Br J Anaesth 2006;96:53–6.
Prekker ME, Chang R, Cole JB, Reardon R.  “Rapid confirmation of central venous catheter placement using an ultrasonographic "Bubble Test.” Acad Emerg Med 2010;17(7):e85-6.




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