18-gauge vs. 20-gauge

[solneeshka]

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.

[nickola]

Where I work surgery always wants 18g unless it is absolutely impossible to insert an 18g, then we have to double check w/anesthesia if they think it's OK b/f inserting- if not then they will come do it. They like to know they can give a large volume quickly if needed- not always possible w/20's. Our blood transfusion policy throughout the facility is 18g preferred. The ED, of course likes at least an 18g. We do alot of traumas too.

[MIcrunchyRN]

Well I think some of it is that you were in the ER for your IV training. LOL not sure about other ER's but ours motto I swear is "bigger is better" and I"ve seen many patients come up with 16g in their hands.

Blood and IV contrast etc can be done with a 20g... 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?)

Theoretically if you put a 20g in same places they put central lines.. technically its not the size of the catheter that makes the difference its the size of the vein. The larger the place to put the meds the faster the blood flow and the quicker it gets circulated. A talented nurse can put an 18-20g in anything.. even super teeny veins in the hand. However using those veins for blood or contrast or large voumes isn't feesable because the vein itself isn't large enough to support what your putting into it.

LOL am I making any sense?

[Boston-RN, RN]

Infusion Nurses Society guidelines (based on research) state smallest gauge in the largest vein that will do the job.

Unless otherwise indicated, the smallest cath in the largest vein.....blood can go into a 22 (depending on policy)

[mandasueRN]

Even in an emergency-if I have veins that are questionable, I'll take 2-20g or 2-22g over no access and extensive bruising due to blown veins. Any access is good access-and I have used a pressure infuser with 20 and 22 g-THEY WORK.

I am so glad to hear another ER nurse say that! I can't tell you how many times I have seen inexperienced ER nurses say, "I can't get a line on so and so, they just don't have good veins," and its because they've been trying to stick an 18 gauge in someone with crappy venous access. I'm sorry, but contrary to popular ER nurse belief, not every patient has veins that can tolerate an 18 gauge and like Maisy said, I would much rather have a 20 gauge than no IV at all.

[ruralnurs]

I am going to jump in. In my ER we always try to do a blood draw with IV start (it is even on our chest pain standing orders). And pts LOVE it if you tell them you are going to try to do just one poke instead of 2. And it is just easier to get blood out of an 18, but I have done it even out of a 22 on a kidlet. To draw our "rainbow" I need 20 ccs of blood and that is alot easier to get out of an 18 and have it set there for a few seconds while I am getting it in the tubes and not clot off before I can flush it.

[Kojak]

I always use a 20 or 22 gauge catheter for infusions and transfusions. A smaller catheter will cause less damage to the vein wall and will also allow more blood to flow around the catheter. It will decrease the risk of phlebitis and increase the "life" of the IV. If you are concerned about delivering high flow rates, the newer catheters have thinner walls which will accomodate higher rates.

Here are three sources to use to get a definitive answer:

1. Your facility's standard procedure manual.

2. Infusion Nurse Society guidelines (already mentioned above).

3. Technical Manual from the American Association of Blood Banks. (Your blood bank should have the latest version.)

[GilaRRT]

Hmmm, ER nurses get your flame throwers out. Why oh why in the world of today does every patient need a large bore IV? Sure, 20 year old with massive pipes, throw in a 14 or 16 to boost your ego.

However, the days of bilat 14 ga IV's in every trauma patient and pressure infused LR until they have a pressure over 100 systolic are near the end. We are killing our trauma's with crystalloids and "adequate" blood pressures. The ER should be a place where the EMT's can grab a cup of coffee and wave at the nurses on the way to the OR.

In addition, the old "I need at least an 18" to do a CT " complaint is a really poor excuse. A patent 20 will work.

Go with a size that will both function well and can be successfully placed. With the popularity of IO devices, we should always have the ability to establish patent emergency access, so I see no problem with dropping a 20 if I am confident it will provide patent access. Remember, potent meds such as pressors should eventually go into a central line regardless of the size of your peripheral line.

I simply see the large bore madness as either ignorance or ego boosting. Neither do any real good for our patients IMHO.

[CRNA2007]

If you use lidocaine to numb the insertion site then everything else is a non issue. If someone is sick enough to be in the ER then they are sick enough for an 18 gauge IV if needed. Especially if they are going to CT. If there are some sort of finding that require that patient to go to surgery then they have a nice large bore access site already in place. Go big or Go home!

[Daytonite, BSN, RN]

Choosing the same size IV catheter for every patient all the time lacks critical thinking problem solving skill and rational thinking.

I was an IV therapist for many years. A 20g is more than adequate and unless needed a 22g will do. If someone told me they were starting me with an 18g because that's what they always start with I'd send them out of my room and ask for another nurse to do the IV.

1. larger IVs irritate the veins faster and phlebitis occurs quicker. An IV is a foreign body that evokes the inflammatory response--I don't care what the product manufacture tells you about the material their IV catheter is made out of.
   
2. blood can be transfused through a 20g catheter
   
3. the idea of IV therapy is to preserve the good veins you do have for when you really need them

With proficiency in inserting IVs it doesn't matter what size you put in, does it? You can easily put in the size catheter you need for the problem of the moment.

I'm curious what this "Vein Whisperer" would do when faced with an infant. Can't get 18g catheters in them.

[solneeshka, BSN, RN]

Choosing the same size IV catheter for every patient all the time lacks critical thinking problem solving skill and rational thinking.

I was an IV therapist for many years. A 20g is more than adequate and unless needed a 22g will do. If someone told me they were starting me with an 18g because that's what they always start with I'd send them out of my room and ask for another nurse to do the IV.

1. larger IVs irritate the veins faster and phlebitis occurs quicker. An IV is a foreign body that evokes the inflammatory response--I don't care what the product manufacture tells you about the material their IV catheter is made out of.
   
2. blood can be transfused through a 20g catheter
   
3. the idea of IV therapy is to preserve the good veins you do have for when you really need them

With proficiency in inserting IVs it doesn't matter what size you put in, does it? You can easily put in the size catheter you need for the problem of the moment.

I'm curious what this "Vein Whisperer" would do when faced with an infant. Can't get 18g catheters in them.

Well, I definitely didn't mean to imply that she puts an 18 in all patients, all the time, regardless of patient status, circumstances, or possible infancy. Her point was to get an 18 if you can, because you never know when it's going to be needed. If a patient is in the ER, then at least in theory they are medically unstable and potentially critical, and if you get a decent sized IV started in the AC, then they should be set if they need blood, or contrast, or surgery, or whatever. Chances are, they won't need to be stuck again. BTW, she did indeed get a catheter in a 3-day old infant, not an 18 of course (I think it was the yellow one? not sure of the size), in order to get a blood draw without having to do a heel stick and then milk the poor guy's foot for half an hour, as a different nurse had done the day before. Because she had the confidence, the baby only cried for a moment and then was fine for the minute or two it took to get the blood, and then was back in his mom's arms. I hope that none of us advocating 18s mean to put your head in a box and do an 18 no matter what under any and all circumstances. What I meant by opening the discussion was do you get an 18 if you can, or do you only do it if you specifically know that you have to. I've learned a lot from the discussion and it's clear that what I really need to do is check with the facility and find out if they have a policy.

[Daytonite, BSN, RN]

i hope that none of us advocating 18s mean to put your head in a box and do an 18 no matter what under any and all circumstances. what i meant by opening the discussion was do you get an 18 if you can, or do you only do it if you specifically know that you have to.

no. you do not get an 18g if you can. there's absolutely no rationale to support doing that. place an 18g iv because you have good, sound reasoning for doing so.

"the intravenous nurses society recommends that the shortest length, smallest gauge cannula be used to accommodate the therapy prescribed." (page 4, intravenous therapy: clinical principles and practice, by judy terry, leslie baranowski, rose anne lonsway and carolyn hedrick) "this. . causes less trauma to the vessel, promotes proper hemodilution of the infusate, and allows adequate blood flow around the catheter walls. all of these factors lengthen the cannula dwell time. . .veins can be preserved by initiating therapy on the distal area of the upper extremity. . .in emergency situations, larger catheter access is necessary to accommodate rapid infusion of fluids. cannulas inserted in emergency situations should be restarted as soon as the patient has stabilized but within 24 hours of the emergency. . .the diameter of the vein and the therapy to be delivered determine the size of the cannula inserted. a smaller-gauge catheter allows greater blood flow around the catheter, which promotes less irritation to the vessel wall. small veins should not be used for vesicants or irritants. if a larger-gauge needle cannula is required, then a larger vein should be selected.

recommendations for cannula selection

14-18 gauge

- trauma, surgery, blood

20 gauge

- continuous, intermittent infusions, blood

22 gauge

- intermittent or general infusions, children and elderly patients

24 gauge

- fragile veins for intermittent or general infusions"

(page 383-4,

intravenous therapy: clinical principles and practice

)

iv therapy is a highly evolved skill. you can become nationally certified in this specialty. many facility iv policy and procedures are based on the ins standards. there is complex critical thinking and decision making connected to its performance. there are solid principles of assessment connected to why certain size needles are used and placed in certain locations over others.

if you want more practical advice on inserting ivs see this thread in the emergency nursing forum: https://allnurses.com/forums/f18/iv-tips-tricks-3793.html - iv tips and tricks

[iluvivt, BSN, RN]

Just ask yourself the big question..."What will the line be used for or potentially used for in the next 48 hours and then you will have your answer. If the pt just needs some fluids and a dose of abx and will be dischaged I would use a 22 gauge. Yes you should always use the shortest smallest catheter that will meet the patients needs,as this will keep all the complications related to IV therapy to a minimum.If you have a patient that wilol need to be admitted try to get at least a 20 gauge in. My favortie rule also is...get what you can get...if you have tried to get a 20 gauge in and can not you have 2 options....get another to try or put in a smaller gauge. The reason CT techs want a large gauge IV site in is because they need a catheter that will allow a rapid flow rate through a power injector (these power injectors can administer the contrast at 2-5 ml per second0. The reason you need a rapid injection is to get a good picture,especially in the chest. I always ask "What type of CT scan" and I place the 18 gauge generally only in these cases and then the CT scan tech will not bug me anymore....