We already know it is helpful to use ultrasound to guide placement of central venous catheters.
How can we use ultrasound to help confirm proper placement of an internal jugular catheter?
There are several methods which have been described:
- Visualize the needle entering the vein (optimally in the long axis)
- Visualize the guide wire in the vein
- Visualize the tip of the triple lumen catheter in the right atrium, then pull back 2 cm
- Bubble test (more on this below)
In addition there are non-ultrasound-related methods to confirm placement (but who cares about those?):
- Chest x-ray
- Blood gas drawn through central venous catheter port
- Pressure transduction (quantitative- manometry)
- Pressure transduction (qualitative- attach IV tubing and check height of blood column)
So let’s get back to that bubble test. In order to confirm that the catheter has been placed in the superior vena cava, inject 5-10 cc normal saline through the catheter while visualizing the right heart on a subxiphoid 4-chamber view. When done right should look something like this :
Saline flush right heart from Sinai EM Ultrasound on Vimeo.
So this is a neat trick after the catheter is in, but the horse is out of the barn at that point. Ideally you should confirm proper venous placement prior to dilating the vessel and placing the central line. You could do this while the needle is in the vessel, but that’s a bit unstable. Instead consider using the long angiocatheter found in most central line kits to puncture the internal jugular vein.
After the flash (and ultrasound confirmation of venous puncture) advance the catheter and remove the needle. You then have an angiocatheter in the central venous system, which can be used for manometry, blood gas analysis, or the saline push necessary for the bubble test. Some people have used this angiocatheter during ACLS situations to administer a few doses of code medications in a shorter time than it would take to complete a “full” central line.
Once proper venous placement is confirmed, you can advance the guide wire through the angiocatheter and continue the procedure as normal.
For a great overview of central venous catheterization, check out this post by Haru Okuda and Scott Weingart at EMCrit.org.
Further Reading
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. (PMID: 20653578)
Hopefully you are using ultrasound to guide your insertion of central venous catheters. Once they are in, you still have to suture them at some point. Straight suture needles are often used to secure arterial and venous catheters to the skin. These types of suture needles have been demonstrated to be more dangerous than curved or blunt suture needles, with up to seven times higher rate of injury for health care workers. By utilizing the plastic needle sheath present in most central venous line kits as a “thimble,” counter pressure and skin puncture may be achieved without bringing the fingers near the sharp end of the suture. Here’s an image from Bret Nelson’s article on the technique.
