Now I know that many of you may already be using ultrasound to help guide your needle when obtaining central venous access, but when a governing body announces its importance, it’s a big deal! If any of you are like me, you learned how to place all central lines using the “blind” technique – despite your eyes being wide open – but now that the ultrasound machine is your eyes beneath the skin, there is no longer a reason to be so blind about it! Isn’t it nice to know where “big red” is? Here, I’ll answer for you – Heck YEAH! So why am I excited? Well…
The American Society of Anesthesiologists (ASA) has introduced new guidelines recommending the use of ultrasound in central line placement, which are different than prior ones in that they recommend static and dynamic ultrasound not only for catheter placement but for venous catheter location as well.
The static method for central venous access involves identifying and visualizing the location of the vein (usually in transverse orientation), making careful note of its depth from the skin surface/top of the screen. You then insert your needle at a 45 degree angle at the same distance from the linear probe as the vein is deep. You do not move your probe and will next see the needle enter the center of the vein as a bright white dot. You’ll also notice a flashback in your syringe. Put down the probe and continue central line placement with the Seldinger technique. You can also use the in plane approach, visualizing the longitudinal vein, inserting the needle at the end of the probe (some even use a needle guide), allow you to see the needle enter the vein.
The true dynamic method involves direct visualization of the needle tip traverse through the subcutaneous tissue and enter the vein in transverse view. With this method, you do not need to note the depth of the vein as you will puncture the skin at the site of the probe and immediately see the needle tip on the top of the screen. As you slowly advance your needle, you either change the angle of your probe or slide your probe away from you in order to keep your needle tip in view at all times, watching while it enters the vein.
In case you were wondering about a way to confirm catheter placement after the wire is in, simply turn longitudinal on the vein and visualize the wire or catheter traversing through the vein (video). Also, the absence of the catheter in the right atrium on your echo also confirms that its not there 🙂
And, if you want to know the reason for why the Valsalva maneuver is great – just see what happens to the internal jugular vein: makes sense as to why people syncopize on the toilet, doesn’t it?
SonoSpot: Topics in Bedside Ultrasound 