Midline insertion question

I don't know if it's true in this case, but sometimes when I insert an iv that is the same size as a venous lumen, I won't get any blood return, but it will flush quite easily. My understanding is that the iv itself or in your case possibly the Midline, is blocking bloodflow past iteslf, and any suction pulls against proximal valves, hence no blood return. I've flushed an iv 3-4 times just to convince myself it was fine after not getting any return.

That makes a lot of sense. The catheter occupied around 42% of the vessel by my ultrasound measurement at the insertion site but it was much smaller farther up. Another nurse later was able to do a wire exchange for a picc through the midline I placed, so that confirmed I was in the vein, which made me feel better.

My question would be this:

What vessel did you cannulate? At times, the cephalic vein narrows as it goes up the arm, while the basilic usually increases in size as it goes up the arm. My aim is to never take up more than 35% of the vessel, and at times, the actual catheter does take up to 45%... This increases the damage to the tunica intima and of course begins the process of phlebitis/thrombus. Another poster had said that they thought that their IV catheter was the same size as their blood vessel.. which wouldn't be the case unless I'm putting a 14 gauge in a neonate!! AUUUGGHHHH...LOL

All IV catheters MUST yield a brisk blood return. Why didn't you get one with your midline??? Was your pt in a hypercoagulable state? Did the IV catheter end up near a valve preventing backflo? Did a fibrin develop right after placement, and why? Did you try pulling back with a 5 cc syringe vs 10cc as there will be a decreased chance of collapsing the catheter from increased suction of the 10cc syringe?

Bottom line, I am glad there was a final resolution with the exchange of that catheter.

It was the basilic. This was a very sick patient and there had been multiple failed IV attempts and the ones we got, didn't last. It was nightshift, I'm midline certified, so I chose the best vein that I was able to find. We cannulate a vessel as long as it occupies

You must use a 10cc syringe barrel or larger to assess patency, but once it's open, use whatever syringe you need to give a medication. For instance, if you're giving 125 mcg of dig, draw it up into a 3 cc syringe, and once you're assured that it is open, DO NOT transfer the drug, but rather give it using a 3 cc syringe.

Now, upon aspiration, you are creating less suction on the catheter if you aspirate with a 3 or 5 cc syringe, then if you use a 10cc barrel.

That makes a lot of sense. The catheter occupied around 42% of the vessel by my ultrasound measurement at the insertion site but it was much smaller farther up. Another nurse later was able to do a wire exchange for a picc through the midline I placed, so that confirmed I was in the vein, which made me feel better.

Not sure which midline kit you are using, or what size (ours are 18 and 20 GA), but It seems that a PICC shouldn't be introduced into a vessel in which a midline already occupies 42% of its lumen. Even a 4fr single lumen PICC is slightly larger than an 18g IV. If this was an ICU patient I'm sure they would have insisted on a PICC with multiple lumens, meaning it would be an even larger 5fr possibly 6fr. In addition you mentioned that the vessel narrowed as you scanned it proximally. That narrowing may account for some of the lack of blood flow issue you mentioned as well. If the patient was as sick as you stated, she was likely hypotensive and hypovolemic as well which would tend to leave her peripheral veins more pliable and prone to collapse under the pressure of suction. It could just be that the vessel wall itself was collapsing onto the catheter lumen opening and occluding the blood return, especially under aspiration pressure. It seems as though your access and placement weren't the issue, it was much more likely patient anatomy and physiology that hindered blood return.