Monday, June 6, 2011

Seldinger Technique

One of the many pleasures of nephrology fellowship is learning how to put in temporary hemodialysis lines safely and efficiently using the Seldinger technique (the Swede is seen to the left). As an intern I constantly said to myself "don't let go of the wire, don't let go of the wire, don't let go of the wire." Having mastered this mantra I've now picked up a few more helpful tricks...

Always use the ultrasound. You just never know what the anatomy is going to look like and real time guidance really increases the number of single pass lines. Every central line I placed in residency used ultrasound localization but then landmarks without realtime guidance for placement. Realtime ultrasound definitely helps.

Lots of saline. It's great stuff. Really helpful if you're having a difficult time getting into the vein. The needle and syringe will sometimes become occluded with clotted blood from prior attempts. Flushing both the needle and syringe until the syringe plunger action is smooth helps avoid getting into the vessel but thinking you haven't because you can't aspirate due to clot. I like to keep the fresh and used saline pools separate so there's always some fresh saline handy.

Making sure the needle is in the venous lumen. Taking the syringe off and confirming the blood is dark and nonpulsatile is key to checking that the stick isn't arterial. If it's venous and your proceeding I've found it helpful to slightly drop the angle of the needle (to avoid going though the opposite wall of the vein "through and through") and advancing it 5mm or so further to get the needle tip fully within the lumen. Sometimes, if just the bevel has gotten in just a slight release of pressure moves it out of the vessel and you can't pass the wire.

Passing the guide wire. Not infrequently you'll be able to pass the guide wire to a point that clearly is beyond the tip of the needle and then encounter resistance (if it doesn't seem to have gotten past the needle tip you may be out of the vessel and need to start over). In the case of having gotten past the needle tip and then encountering resistance, sometimes flipping the circular plastic holder that houses the wire 180 degrees (which rotates the wire 180 degrees) will move the curled tip into a more favorable position and allow you to proceed.

The skin incision. Key to a smooth initial dilator insertion is a large enough skin incision along the trajectory of the wire. I've found that holding the guide wire steady along it's natural exit trajectory and then making the incision along this same angle is very helpful. The cutting edge of the scalpel should be directed away from the artery (cutting edge facing medial for the femoral, lateral for the internal jugular).

Trying not to kink the guide wire. Again, I've found that holding the guide wire firm and steady along it's natural exit trajectory then with the other hand advancing the dilator from as close to the skin as possible reduces the chances of kinking. If the wire does kink and you are unable to advance the dilator further, try pulling the guide wire back a centimeter or so while leaving the dilator in place. This will pull the kink into the dilator and then using the same techniques as above you can often complete the dilation.

Lots of 4x4s. When the dilator comes out, lots of blood. Having a 4x4 ready keeps the field clean and minimizes blood loss.

The catheter is in but now a port won't flush or pull back. Most catheters rotate freely in the wings used to suture them in place. If a port isn't functioning try rotating the catheter 180 degrees by twirling it in the wings, this will often move the distal port off the vessel wall and allow pull back and flush.

11 comments:

Anonymous said...

Thanks for a nice practical review. An additional important point is that patient position is crucial. Therefore time spent before gowning up, getting the patient into position and scanning to find the best angle (or indeed vein) to approach is time very well spent.

Matt Sparks said...

Nice practical review

Graham Abra said...

Thanks Matt.

Completely agree with the first comment. 10 minutes spent positioning can save 30 minutes of flail.

Graham Abra said...

As a supplement to the above there are two very nice previous RFN posts from Nate and Gearoid on catheter site selection and its impact on catheter associated infections and catheter function.

KODS said...

Very Good practical points.
Just want to emphasize on the fact that, if any doubt that artery has been entered, even if less than 1% doubt, please remove needle and start afresh. Never ever dilate the artery with dilator.

Graham Abra said...

Agreed.

In the hypotensive patient who is oxygenating poorly it is sometimes difficult to tell if dark relatively nonpulsatile blood is venous or arterial.

In these cases the ultasound can again be helpful to confirm that the needle is in the compressable nonpulsatile vein and that the artery is a separate, pulsatile, noncompressable structure.

Anonymous said...

I've also sent the blood, from murky needle placement in sick hypotensive patients, for a quick blood gas analysis before dilating.

m said...

During subclavian and internal jugular vein catheterization, aspiration of air into the central circulation is possible when syringes, guidewires, and tubing are exchanged........

____________
Mitchell Brown

Graham Abra said...

Thanks for the comment.

We do not typically place temporary subclavian dialysis catheters due to the higher rates of central venous stenosis with catheters at this site.

Agree that as nephrology fellows it's important for us to educate housestaff about the danger of air embolism during internal jugular dialysis catheter removal.

Placing the patient in trendelenburg, having them hum during removal and immediately placing an occlusive dressing with pressure over the exit site as the catheter comes out minimizes the risk.

Graham Abra said...

Was reminded of another point from a line this week: If you have one, be aware of the CVP.

If it's high, a venous stick may look more pulsatile than you're used to (My patient was in the mid 20s).

Sending off a blood gas as nicely suggested above or having a sterile CVP line ready to hook up to the hub of the needle can help sort it out.

DocInKY said...

Found the blog through whitecoat's link list. Good post. As a vascular surgeon who places many lines (temporary and tunnelled) in more locations than I care to admit, I can offer a few more tips. Consider using a short IV tube extension and hook up to your needle and hold it up. It will settle out at the CVP (in cm of water roughly) and vary with patient breathing when in the vein, it will climb up and out if in the artery. This is called the Fabian test. If your hold in the vessel is tenuous with the wire and needle, place a 18 gauge angiocath over the wire (not the dialator) - it will stay in better than the needle if you need to get an ABG to know, or to hook up that IV tubing. Try to have as steep a Trendelenburg as the patient can tolerate. Look even before prepping with ultrasound to avoid any suprises.

Be very careful in the patient with severe decompensated right heart failure (Right heart pressures 70-90mm+ by cath or echo estimate) - That jugular vein will bleed and pulsate just like an artery, with increased rates of site hematoma no matter how clean the entry and passage was. That patient can lose a lot of blood! This also can happen with a jugular on the side of a functional AV access in the arm.

Lastly - the wire never lies - don't force it.

DocInKY