I just came off on an ER externship with a preceptor whom I call "The Vein Whisperer." She's the one the other nurses call when they can't get a line in. She taught me a lot and starting IVs doesn't make me nervous anymore. She taught me to always go in with a 18-gauge unless it's completely clearly unreasonable, because you never know when a patient might need to have an MRI with contrast or a blood transfusion, and since those are thicker substances than NS or IVP meds, already having a larger catheter means the patient won't have to get re-stuck. The other day I was starting an IV line as a favor to a different nurse and had all my equipment set up when she walked in the room. She said that I shouldn't use an 18-gauge, I should use a 20-gauge unless the MD has specifically requested otherwise because it's big enough for contrast/blood and it hurts less for the patient.
I'm inclined to go along with my preceptor. I think it's gonna hurt a bit to get an IV start whether it's 18-gauge or 20-gauge, and either way it's only going to hurt for the 5 seconds or so that the needle is in. I wouldn't think the difference between 18 & 20 as far as pain goes would be significant. But I do think there's a big difference between the two when we're talking about the microscopic, as far as having a larger lumen for the blood/contrast to flow through, and decreasing the chances of clogging the catheter. The way my preceptor was talking, it made me think that it was standard to use 18-gauge for blood/contrast, that if we sent someone back with a 20-gauge for a procedure like that, they would automatically get a bigger catheter before the procedure. But she didn't use those words.
So! What do you all do! 18-gauge or 20-gauge? I never had a problem getting the 18-gauges in.
I like Daytonite's post it summarizes the recommendations on what size IV to use quite eloquently.
Here is the reasoning we are taught in anesthesia school to use larger bore IVs.
The resistance increases/decreases dramatically for every gauge IV you go up or down. The resistance through an IV catheter (or similar tube) increases/decreases by the radius to the 4th power.
Say there is a 2mm difference in the radius between a 20g and 22g IV catheter. The resistance to fluid increases by a factor of 16 in the 22g vs. 20g IV.
I like Daytonite's post it summarizes the recommendations on what size IV to use quite eloquently.
Here is the reasoning we are taught in anesthesia school to use larger bore IVs.
The resistance increases/decreases dramatically for every gauge IV you go up or down. The resistance through an IV catheter (or similar tube) increases/decreases by the radius to the 4th power.
Say there is a 2mm difference in the radius between a 20g and 22g IV catheter. The resistance to fluid increases by a factor of 16 in the 22g vs. 20g IV.
Again, as you point out, it varies by situation, what size a person will need. A person undergoing anesthesia and surgery has the potential to need rapid infusions of fluids and blood and a larger bore is necessary. We send our patients to the OR with 18g or 20g minimum...that's our standard. Three days later when that patient is almost ready to go home, but needs another 24 hours of antibiotics and is rock solid stable otherwise, and it's time to change the IV, I'm not going to put another 18g in the patient, I'm going with a 22g. :)
What really gets me is when you go to start and IV and the patient tells you "you are going to have to use a butterfly needle" it drives me nuts
Me too!!!!!!!!!!! This drives me up the wall! We don't even HAVE butterflies at my hospital, except for the 24g ones we use for SQ meds. But yet they always insist that we have to use a butterfly, nothing else will work. Then I guess you'll have to go somewhere else, sweetie, 'cause I don't have any!
BUT with IV contrast it must be in the AC or similar large vein because of the size of the vein NOT the size of the catheter in the vein (does this make sense?)
Yes vein size vs. catheter size makes perfect sense (and you stated it well), but contrast through an IV placed at a joint is a very scary thing to me - I know they do it, but I can't believe it's allowed. Pushing a vesicant through an "older" IV (meaning not a fresh start) at a joint is just asking for trouble, and I think a hospital would have a hard time winning a lawsuit from a pt with, say, compartment syndrome as a result of an IV contrast extravasation from an IV placed in a joint.
Well, I will tell you this. Someone tried to put an 18g in a little bitty vein in my mothers arm because "radiology" required it when she needed a radiology scan... because of the high rate of injection speed for the radiology contrast.
She had an infiltrate during the procedure. A hospital worker was sitting there during the procedure with her, holding the IV in place during the scan, because it was "positional" (should have been a tip off in my book).
She had to go to wound care for MONTHS and was in major, major pain when it happened and during the healing process. It was like a major burn. It was horrible. Her arm is still disfigured.
One of the ERs I work in demand an 18 g in every pt. Another one I work at does not allow bigger than 20 without permission. All the other ERs I work at allow everything in between.
I for one choose to use my critical thinking skills and make a decision based on pt health, reason for visit and possible things that will need to be done while in ER.
I have never once placed a 20 g and then found out it was not adequate.
If a trauma comes in we do go for 18g (maybe even multiple sites).
I follow the infusion nurse quidelines that have been stated above in detail by several nurses.
Well, I will tell you this. Someone tried to put an 18g in a little bitty vein in my mothers arm because "radiology" required it when she needed a radiology scan... because of the high rate of injection speed for the radiology contrast.
She had an infiltrate during the procedure. A hospital worker was sitting there during the procedure with her, holding the IV in place during the scan, because it was "positional" (should have been a tip off in my book).
She had to go to wound care for MONTHS and was in major, major pain when it happened and during the healing process. It was like a major burn. It was horrible. Her arm is still disfigured.
Exactly! Because it is a vesicant! When a vesicant medication infiltrates, it's called an extravasation, and can do seriouos damage to the surrounding tissue. That is why I firmly believe that there should be a nurse in radiology aat for IV starts and assessments - I really think they should have to start a new IV and give the contrast within just a few minutes of that in order to avoid problems like the one you described. And that means to start the IV in the department! Not have us start one on the floor and then send them down - you never know what can happen in transport. There's no excuse for what your mom went through. It's not like it's a secret that it can do that, so they should be able to recognize that if the IV is "positional", it's probably not good to use for a high pressure infusion, especially when there is a vesicant involved.
Specializes in Med/Surg since ‘96; PACU since ‘16.
i just came off on an er externship with a preceptor whom i call "the vein whisperer." she's the one the other nurses call when they can't get a line in. she taught me a lot and starting ivs doesn't make me nervous anymore. she taught me to always go in with a 18-gauge unless it's completely clearly unreasonable, because you never know when a patient might need to have an mri with contrast or a blood transfusion, and since those are thicker substances than ns or ivp meds, already having a larger catheter means the patient won't have to get re-stuck. the other day i was starting an iv line as a favor to a different nurse and had all my equipment set up when she walked in the room. she said that i shouldn't use an 18-gauge, i should use a 20-gauge unless the md has specifically requested otherwise because it's big enough for contrast/blood and it hurts less for the patient.
i'm inclined to go along with my preceptor. i think it's gonna hurt a bit to get an iv start whether it's 18-gauge or 20-gauge, and either way it's only going to hurt for the 5 seconds or so that the needle is in. i wouldn't think the difference between 18 & 20 as far as pain goes would be significant. but i do think there's a big difference between the two when we're talking about the microscopic, as far as having a larger lumen for the blood/contrast to flow through, and decreasing the chances of clogging the catheter. the way my preceptor was talking, it made me think that it was standard to use 18-gauge for blood/contrast, that if we sent someone back with a 20-gauge for a procedure like that, they would automatically get a bigger catheter before the procedure. but she didn't use those words.
so! what do you all do! 18-gauge or 20-gauge? i never had a problem getting the 18-gauges in.
i read in a nursing journal not that long ago that the smaller gauge is actually better. i wish i could remember which issue it was... i was surprised to read that a smaller gauge was better because it allowed for more blood flow "around" and therefore less irritation from vesicants. really opposite from what most think, "the bigger the better". also read separately that 22s are really okay for blood, if you can't get a 20 in, don't sweat it. from experience, i go for 20s or 22s. i don't think i've ever used an 18 (really!).
I prefer an 18 in myself-I've had extremely bad phlebitis caused by fluids and thick meds pushed through too fast in a too small catheter-I could literally feel the liquids swirling as they came shooting out of the catheter, it was awful. If they can get an 18 in a cat....
Everyone gets an 18. Unless you are a trauma you get a 14 or 16. Yes you can put blood through a 20 in a pinch, but 18 is ideal. Often with smaller gauges you end up with hemolyzed potassium. With a larger line you can often obtain specimens from the line much easier w/o them being hemolyzed.
wtbcrna, MSN, DNP, CRNA
5,128 Posts
I like Daytonite's post it summarizes the recommendations on what size IV to use quite eloquently.
Here is the reasoning we are taught in anesthesia school to use larger bore IVs.
The resistance increases/decreases dramatically for every gauge IV you go up or down. The resistance through an IV catheter (or similar tube) increases/decreases by the radius to the 4th power.
Say there is a 2mm difference in the radius between a 20g and 22g IV catheter. The resistance to fluid increases by a factor of 16 in the 22g vs. 20g IV.