Peripheral IV insertion may be one of the most underrated ultrasound-guided procedures in medicine.
Mastery of this skill is a testament of needle finesse.
Mastery of this skill is a testament of needle finesse.
The golden rules of US-guided PIVs
STAY CALM Once the needle has pierced the skin, breathe. The most painful part for the patient is now over and you have nothing but time to focus on the task at hand. ONE AT A TIME If you are moving the transducer, don't move the needle & vice versa |
FIND THE TIP Can you get away with not doing this? Yes, by using the static method where the US acts largely as a "crosshair". This method is suboptimal for a number of reasons, the most obvious being that you cannot verify what your needle is actually piercing. Case in point, those who drop a lung or dilate the carotid during an ultrasound-guided central line did not keep track of their needle tip during the procedure. THREAD The challenge is not over once the needle has pierced the vein. Threading is the final step in mastery. More on this below. |
Step-by-step instructions
1 Identify the target
The best veins to practice on when you are starting off are those ~1 cm deep. (1) Compress the vessel to ensure it's venous AND to rule out the presence of thrombus (not demonstrated in clip).
(2) The next step is to appreciate the direction that the vein runs under the skin. Slide the probe (positioned at 90 degrees to the skin) back and forth in a straight line over the vein. Adjust the direction until the vein remains in the center of your screen. This verifies a few things:
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2a Find the tip
Style points for piercing the dermis quickly and confidently as this is the most painful part of the procedure! Approach at 30-45 degrees. Once you are through the skin, stop, breathe, and FIND THE TIP: (1) Slide the transducer up against the needle where it enters the skin (2) Angle the probe 90 degrees to the needle. You will notice in the clip that the vein has essentially disappeared or become blurry. This is to be expected due to the physics of ultrasound (LINK). (3) Slide away from the site of insertion while maintaining 90 degrees to the needle. The shaft of the needle will appear as a hyperechoic dot that shadows. Continue sliding until the bevel flashes into and then out of view. The bevel's relatively large and flat reflective surface will appear as a horizontal signal 2-3 times the thickness of the shaft. (4) When the bevel disappears, slide back towards the needle a few millimeters and voila, you have found your true needle tip. |
2b Optimize the view
In this clip the transducer is being tilted back and forth (90 degrees to skin, 90 degrees to needle). Notice again how the vein becomes quite blurry when the transducer is perpendicular to the needle. There is a middle ground (angle) here, as you will see in the next clip, where both the vein and needle tip are visualized in the sub-Q simultaneously but that is not always the case. In certain patients you will be hard pressed to locate your needle tip without sacrificing the view of your vein. Visuospatial ability plays a role in those tougher cases. |
3 Advance the needle
After you have identified the needle tip, advance the probe a few millimeters ahead of your tip. You will then advance your needle into this frame while aiming for your target in 3-dimensional space. This takes a little practice. Fine movements are key. This method guarantees that you never lose site of your tip and cause accidental trauma to other tissues. |
3b Did you lose the tip? Re-find it!
If you get lost, go back to step 2 and re-find your tip. This is a key habit to adopt. When sliding away from your site of insertion, makes sure to continue sliding until the needle disappears from view. Only then will you know where the needle truly ends. Seeing a hyperechoic dot on the screen and wiggling it does NOT equal knowing where your tip is. |
4 Tenting
The archnemesis of PIVs. We've all been in the following hypothetical scenario. The view above is obtained, you look down and there's flash, so you advance the catheter. It doesn't draw but it flushes easily. Thirty minutes later the nurse calls and tells you the IV infiltrated. Problem = the catheter was not advanced into the lumen. Notice the following two things in the clip above: (1) Tugging of the vein as the bevel moves in and out of view (2) In the last couple of frames there is a hyperechoic "pie" shape to the right side of the needle tip. What you are seeing is the catheter getting stuck on the thin, weakly elastic venous wall (Figure 2) and tenting it. This leads to the tugging you see above as it fails to pass through into the lumen. Usually, there is tactile feedback when the needle-catheter complex "pops" into the lumen but the way to really guarantee successful access is by threading. |
5 Threading
In this step you will essentially weave the needle into the lumen of the vein for a distance to guarantee placement. Continue advancing the needle for a centimeter or two using the technique described in Step 3. You can further practice this skill by trying to hub the IV under ultrasound guidance. |