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There is a brief pause between the end of the contrast bolus and the post flush saline. If you look at your pressure graphs, you'll see a dip, a sudden rise, and then a steady decline in pressure back to saline levels.
There is still contrast to be pushed out of the patient connector tubing, so a sudden pressure spike happens on every post flush.
This sudden release and immediate pressure spike will usually be the most likely time for an extravasation to happen.
I agree with you. One place I worked at was absolutely dreadful at placing iv's in the ER. Despite CT hounding them to tighten the hubs all the way, they simply wouldn't screw the hub and extension together tight at all, I could wiggle the connection with my finger, and one night had every single patients iv come apart and leak and noticed it was always either within the first 5 seconds of contrast where the pressure was on the rise, or switching to the saline bolus. I have no science behind it, but 2 things helped me. 1, obviously tightening down the iv hub so it wouldn't come apart, but I also found that dropping the flow rate of the saline by half a cc/s helped too and I don't know why. It's hard to tell if it actually worked or was just a fluke but I started doing that for a while. Where I'm at now is pretty good with iv's so I dropped that strategie.
Cause they need the money?
Which cannula? Go with 20G at least. Our Nemoto system starts saline for a sec before contrast is done so we have combined pressure at start. It depends on more factors.
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2mo
Where is your IV located on the patient? That pressure also seems very high for 4ml/s through a 20.
350 psi is over the rated pressure for any peripheral iv that I have ever seen. Is the 20 Guage iv a diffusics with side holes? Is the contrast warm or room temperature. I would recommend using 18 g IV if you continue to have problems. For example, my psi doesn't exceed 30-50 on a good iv going at 4ml/sec.
Try contrast warmers? It reduces viscosity and the pressure is lower on the graph when we use them. We have the ones that attach to the back of the Bayer injectors and clip onto the syringes
Just because they have a 20 doesn’t mean it’s a good iv or vein. If you can’t slam a hand flush, then it can’t be used for an angio. Sometimes if it’s iffy, I’ll stop the bolus as soon as it triggers, and just manually flush the line when all is done. Or slow the contrast down to 3-3.5, and slow the 2nd saline bolus to 2.
I always test flush with the injector first to give me a proper idea of how it'll hold up.
The IV is a relatively short and flexible tube that is often curved when it hits the back wall of the vein (you enter the vein at an angle, the tissues hold it relatively straight until then, and then it straightens out when it enters the vein). If the straight intravascular part is not long enough, you get some recoil especially as pressure changes, like a large hose with a lot of water pressure. When the contrast is starting up it ramps slowly so there isn't as much recoil. But switching to pure saline can cause an abrupt change due do different viscosity.
You sometimes see a PICC flip up into the IJ after an injection because it takes an abrupt right turn as it dives into the SVC because of this pressure. The vein is not really blowing up (I.e. bursting) but the catheter is just flipping out of the vein.
This should be the top comment
What’s the pressure rating on your cannulas? Do you use diffusics for angio studies? Cant say I’ve encountered this.
Yeah, I can't think of anything other than luck.
You can also try dropping you post saline flush injection rate. When you switch from contrast to saline there is a big difference in pressures and viscosities. Typically when performing an angio your contrast is still being injected when imaging is triggered. Drop your saline injection by .5 to account for this. You’ll still get a good study but alleviate some of the pressure in the vein.
Not quite sure how to help regarding extrav ivs. Its up to you to test the iv flush with the same 4cc/sec flow rate push. If it feels like theres resistance, then you can either reposition the iv, or slow the speed down to 3.5/3cc and just tech note it.
As a wise man said, "veins are not your friends".
I don’t use dual syringes bc I like to stop the infection when the ROI is triggered, IVs blow on the backside just as much as in the beginning
Imo and experience, you’re maybe injecting the saline and contrast too quickly - slow that shit way down and go excruciatingly slow.
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2mo
I usually go 3.5 or maybe 3 if they're small enough for my angios, obviously depending on the patient and circumstances.
Just slow down the saline. Or stop the injector all together once it triggers if you’re not confident in the iv.
Can't with angios.
As queen and Bowie once put it "Pressure pushin' down on me Pressin' down on you, no man ask for"