What's the Best IV Size and Site?

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Specializes in being a Credible Source.

When I teach IV skills to students and residents, I always start with this question: "What's the best size and site for an IV?"

I generally get myriad answers that involve considerations of c/c, VS, etc... and people generally want to go with 18s out of the gate.

My response to the question, though, is, "In an emergency, the best line is the line you can get... even with a 24 in the thumb, I can push ACLS drugs and RSI drugs and buy us time to get a more definitive line."

Don't become dogmatic in your approach to securing venous access.

Specializes in Emergency Department.

The best size IV is one that works because that will always be far more preferable than one that doesn't. As a paramedic, I usually prefer 20g or 18g catheters because they can flow fluid or medication as fast as I'd ever likely need to push them (adenosine is the only one I had to push really fast, for obvious reasons) but if all I can get is a 24g, then I'm good with it. Normally I start small-ish and work to a larger size as needed.

Incidentally, because I have 2 other larger sizes available (16g and 14g), if I need to place a large bore IV in a patient, that means the patient really needs to have a LOT of fluid as rapidly as possible. In those rare situations, I'll start at 14g and go down from there to maximize fluid flow. That being said, I've only ever had to place such a large bore IV twice, maybe 3 times.

Specializes in PACU, pre/postoperative, ortho.

Had this discussion with a coworker last week. She wanted help with an IV (she's the anxious sort & hadn't even tried because she couldn't find anything but I hadn't even received report yet)

She was so worried about managing to get a 20g in for surgery the next day but the pt only needed fluids @ 100 mls & prn morphine. I told her "Just get what you can get. Surgery can put in a 20g tomorrow if they aren't happy."

Specializes in Case mgmt., rehab, (CRRN), LTC & psych.

My workplace only supplies us with 18 gauge, 20 gauge and 22 gauge IV lines. We do not carry the 24 gauge catheters since we do not deal with pediatric patient populations, nor do we stock anything larger than the 18 gauge.

So unless we're planning to administer blood products, we are free to select whatever size we wish to pick. Per our facility policy, we are to utilize nothing smaller than a 20 gauge line when administering blood products.

Specializes in burn ICU, SICU, ER, Trauma Rapid Response.

The proper IV is the smallest possible to get the job done. In the old days most everybody got a large IV on the chance they may need to recieve a lot of fluids fast. Today that is no longer a consideration since we can always IO them if there is am emergency need for drips or fluids.

If the IV is for medication, especialy drips like Dilt, amioderone, NTG, or antibiotics etc the goal should be to achive hemodilution as quickly as possible. That means a small IV in a larg vein. For example a 22ga in one of the larger forearm veins for adult patients.

In the old days a 20 or 18ga IV was standard in my hospital. About 8 years ago they changed the standard to a 22ga adults, 24ga in kids) except for cases like GIB or sepsis where a lot of fluids is going to be indicated, subject to nurse's discretion.

We are supplied with IVs in size 14ga all the way down to 24ga on the adult units. We will place 14 & 16ga for use with the rapid infuser or similar uses.

There is some good EBP out there to support smaller is better when it comes to IVs.

Specializes in burn ICU, SICU, ER, Trauma Rapid Response.
Per our facility policy, we are to utilize nothing smaller than a 20 gauge line when administering blood products.

I always find this interesting when the claim is made that at least a 20ga is required for blood products, despite all the evidence to the contray out there.

Specializes in Emergency, Telemetry, Transplant.

I agree with what have been said already. I have to say, however, that we have one doctor who can convince himself that even the "simplest" patient might have a PE…that, of course, means 20 ga above the wrist. :down:

Specializes in Critical Care, ED, Cath lab, CTPAC,Trauma.
I always find this interesting when the claim is made that at least a 20ga is required for blood products, despite all the evidence to the contray out there.
MANY places hang on to that sacred cow unfortunately. I told one facility...how do you think babies get blood....and 18 gauge in a #24 vein?

Was just thinking about this on the shift I just came off of... Pt comes in ALOC... tox vs psych vs sepsis vs rhabdo, or a blend thereof... My partner placed a sound 20... flows but no blood draw... I find a little vein and slip in a 22 which fills all the tubes I need... hang a liter on each line and, as is sometimes the case, the smaller line ran better... all kinds of reasons why that might be the case but the point is, it was more than sufficient for what we needed.

Patient came perilously close to being intubated and my wimpy little 22 would've been up to the challenge.

For a lot of patients, I'll take a single-stick 22 over a triple-stick 18, at least for my first line.

If the IV is for medication, especialy drips like Dilt, amioderone, NTG, or antibiotics etc the goal should be to achive hemodilution as quickly as possible. That means a small IV in a larg vein. For example a 22ga in one of the larger forearm veins for adult patients.
I'm amazed at how many of my colleagues don't seem to get that and always go with the 'bigger is better' idea by default.

In the old days a 20 or 18ga IV was standard in my hospital. About 8 years ago they changed the standard to a 22ga adults, 24ga in kids) except for cases like GIB or sepsis where a lot of fluids is going to be indicated, subject to nurse's discretion.
Man, the more I read about your joint, the more envious I become.
Specializes in Critical Care, ED, Cath lab, CTPAC,Trauma.

Man, the more I read about your joint, the more envious I become.

He works at a nice place...I worked sat a place like that in the Midwest once. I miss it everyday.
Specializes in Critical care.
MANY places hang on to that sacred cow unfortunately. I told one facility...how do you think babies get blood....and 18 gauge in a #24 vein?

Well duh, their RBC's are smaller, 'cause they're babies. Geez, I thought you was smarter than that.;) Guffaw!

Specializes in Trauma, Teaching.

For a lot of patients, I'll take a single-stick 22 over a triple-stick 18, at least for my first line.

I'll second that one. If I do need a big line, just filling the veins up a bit with the little 22 so they can tolerate the 18 if I end up needing it works for me.

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