Your patient needs emergent dialysis. To expedite the proceedings, you agree place the dialysis catheter. You look on the shelf, but there is more than one length of catheter. Which one do you grab? Do you know?

Why do we have different length dialysis catheters but only one length of central lines?

We place central venous catheters frequently, but we only place dialysis catheters occasionally. The insertion procedures are similar, but the devil is in the details. In our department, we only keep one central venous catheter on the shelf: 20 cm triple lumen. We can use that catheter on any adult because of an accessory in the kit called a catheter clamp and fastener.

The catheter clamp allows us to not put the entire length of the catheter in the patient. We can pull it back a few centimeters (particularly at the right IJ) and still secure it where it enters the skin.

So, since we can vary how deep the catheter is inserted, we don’t need to be picky about the length. A 20 cm catheter can be a 14 cm catheter if we leave 6 cm outside the skin. It’s customizable.

Dialysis catheters allow no such luxury.

You have to pick the correct size and fully insert the catheter to the skin every time. It is, therefore, important to know which size goes where.

Where should I place the dialysis catheter?

The length we choose is based on the insertion site, so let’s clear that up first. Dialysis needs very high flow rates, so we want the shortest possible catheter with the straightest course. That makes the right IJ the prime candidate. Femoral veins are reasonable in patients that are going to be permanently supine (i.e. intubated), however the length of the catheter has to be longer (i.e. flow limiting) to to be sure the tip is reliably in the IVC. The left IJ is therefore considered the second best option. It needs a longer catheter than the right and has a less direct path, but at least it doesn’t confine the patient to bed. Subclavian veins are generally avoided due to their flow limiting curvature and their proclivity for scarring and developing stenosis when used for dialysis.

So, in order of preference, the sites for dialysis catheters are:

1. Right IJ
2. Left IJ
3. Femoral

What length should I use for each site?

There is a little room for variation here based on what length of catheters your hospital stocks and the preference of the nephrologists you work with, but common practice is that the right IJ gets a 15 cm catheter, the left IJ gets a 20 cm catheter, and the femoral gets a 24 cm catheter.