iv catheter/needle gauge selection

  1. how do you know what gauge IV catheter to choose to insert in someone?

    i know that the larger the gauge #, the smaller the diameter/thinner the needle, but does anyone have any tips based on pt chief complaint and symptoms? i'm new and not quick at anticipating what future labs/studies a pt may require down the line yet.

    when drawing labs off a fresh IV start, to prevent hemolysis of the samples, is there a threshold of gauge to not use to avoid hemolysis? i hear 22G at most for most cases, is that true?

    if a pt ends up being admitted to the ICU from the ED, for example, i have read that ICU RNs do not appreciate IVs in the AC bc of alarms going off for pump occlusion when the arms bend. i mean depending on what is available, i may have no other choice, but i want to try to be considerate iahead of time n case a pt does get admitted to another floor from the ED.

    does IV access in the AC only matter if the pt is getting a CT scan w/ contrast to r/o PE or are there other scenarios? is there a certain gauge needed? is the AC where they are administering the IV contrast dye?

    do IVs have to be restarted in 72 hours anyway at a new site? idk if this just varies by hospital policy.

    in case a pt needs a blood transfusion do you need at least a 22G or below?
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  2. 15 Comments

  3. by   snowflower2016
    For adults on my unit...

    OR requires 18G

    CT requires at least a 20G

    18G or 20G is preferred for administration of blood products (on our unit)

    22G is a last resort if the patient has difficult veins or is a "hard stick"

    I typically go with a 20G for all of my admits unless I know that they are going to the OR. I also avoid the AC, if I can, because it does get annoying for the patient who can't talk on the phone or bend their arm whenever their infusion is running.

    Our hospital policy is 72 hours for peripheral IVs, which can be extended with MD order if the patient is being discharged or if the patient is an especially hard stick.
  4. by   ~Mi Vida Loca~RN
    Quote from socoamaretto
    how do you know what gauge IV catheter to choose to insert in someone?

    For me it varies on the chief complaint. I will mostly just use a 20guage. But if someone is coming in with chest pain or appears pretty sick I will most likely go for an 18 first and get 2 lines. Maybe an 18 and a 20. Depends on the situation. But I am a huge advocate of 2 lines on any truly sick patient.


    i know that the larger the gauge #, the smaller the diameter/thinner the needle, but does anyone have any tips based on pt chief complaint and symptoms? i'm new and not quick at anticipating what future labs/studies a pt may require down the line yet.

    I touched on this a little above. Honestly I will never start anything smaller then a 20 unless it is obvious that I am going to just have to go for a 22. I am really good at IV's though and can gauge it pretty well. Trauma patients you're going to want a larger needle, hypovelemic patients, GI Bleeds, you're going to want as big as you can get. Just think in your head is this person going to need a lot of fluid, be it blood or regular fluid and are they going to need it fast.

    when drawing labs off a fresh IV start, to prevent hemolysis of the samples, is there a threshold of gauge to not use to avoid hemolysis? i hear 22G at most for most cases, is that true?

    I truly feel like this has more to do with operator error. Although the smaller the needle the more likely it can "break" the blood cells. There are many things that can factor into hemolysing the sample. One hospital I worked at it was common for the nurses to start the line, then take 2 10mL syringes and draw their blood and then transfer it into the tubes. I had never done it that way so I did it the way I always had. I would hook the connector to the IV and draw my blood straight into the tubes like you do when you do a straight stick. Guess who had the lower rate of hymolysis?? I felt like them drawing into one device and then having to transfer into a second is probably what caused this. Also the pressure of having to pull back and stuff especially with a 10mL syringe.Hemolysis was not a common issue I faced. It did happen but it was very rare.


    if a pt ends up being admitted to the ICU from the ED, for example, i have read that ICU RNs do not appreciate IVs in the AC bc of alarms going off for pump occlusion when the arms bend. i mean depending on what is available, i may have no other choice, but i want to try to be considerate iahead of time n case a pt does get admitted to another floor from the ED.

    If the patient is sick enough to go to the ICU I am thinking they probably should be having a central line or the ICU nurses should be pretty good at placing lines as well. However, it is true many floor and unit nurses are not a fan of AC IV's, In the ER we go with what we can get quickly and with a large needle in emergent situations, or when we don't have time to go looking around. For me though; as I said, I am really good at IV's so I will try somewhere else first if there is one easily accessible. I personally can't stand hand IV's and out of thousands and thousands of IV's I have placed, I have only had to go into a hand because I had no other options maybe 2 dozen times. I feel a lot of people go for them because they can be seen easily (don't even get me started on that) but I feel they are a terrible place for an IV, especially on a truly sick person.


    does IV access in the AC only matter if the pt is getting a CT scan w/ contrast to r/o PE or are there other scenarios? is there a certain gauge needed? is the AC where they are administering the IV contrast dye?

    This is going to vary on on your hospital's policies and procedures. If someone is coming in for abdominal pain and they are getting a line. Go ahead and assume they will get a CT with contrast and go above the wrist and a minimum of 20.

    IF someone is coming in with chest pain or breathing difficulties, go ahead and assume they will get a CTA (good chance they won't but better to avoid having to go start another line again and delay things) and start an 18 if you can in AC or forearm. A lot of places will allow for a 20 if it's high enough. But it's pretty standard in a lot of places for CTA's. Some hospitals will have high pressure injectable 22's and even 24's, I recently saw. for the patients with very very difficult veins that need the high pressure injectable contrast CT. But don't bank on that as I have worked at 6 hospitals and only seen them at 2.



    do IVs have to be restarted in 72 hours anyway at a new site? idk if this just varies by hospital policy.

    This varies by hospital and I am not sure what the standard is because I work in the ED

    in case a pt needs a blood transfusion do you need at least a 22G or below?
    This again depends on hospitals policy. I have worked at some places that say 20 and some 22.


    Please note these are all from my experience only. I say this because there always seems to be people that want to come in not seeming to grasp that different regions and facilities have different standards and norms and policies. People assume what's done where they are is the way it is everywhere or the way it has to be everywhere. IV's are my favorite thing to do as a nurse.

    If you think about it when it comes to tasks it is one of the most important life saving things we have to get. Without a patent IV it's nearly impossible to save people or diagnose or treat.
    Last edit by ~Mi Vida Loca~RN on May 4
  5. by   OlivetheRN
    Quote from snowflower2016
    For adults on my unit...

    OR requires 18G

    CT requires at least a 20G
    Holy cow, your OR REQUIRES an 18?! When I worked in our OR we didn't hate having an 18 but in no way did we require it. I'm trying to imagine what our SDS pre-op nurses would say if we told them every pt had to have an 18 lmao

    It's always interesting to me to hear other hospitals policies. For us, CTs don't need a 20, unless it's a PE study. Then it has to be a 20 above the wrist, preferably close to the AC but it doesn't have to be in the AC, which the floor nurses love because then if they're admitted the pumps aren't going crazy, but it could be anywhere in the forearm as long as it flushes well and with a lot of force. If it's an abd/pelvis CT with contrast it can be a 22 in the hand.
  6. by   soutthpaw
    Funny thing is that Nurses think 18ga is big. Check out what every patient that is bought in by paramedics has... 18 is standard, 20 is small and 22 or smaller is for kids and infants. 14 ga is considered a large bore IV by medics.
  7. by   ~Mi Vida Loca~RN
    Quote from soutthpaw
    Funny thing is that Nurses think 18ga is big. Check out what every patient that is bought in by paramedics has... 18 is standard, 20 is small and 22 or smaller is for kids and infants. 14 ga is considered a large bore IV by medics.
    Majority of patients brought in by medics have a 20 or 18.

    5 states, 8 hospitals that I have personally seen working on average 60-72 hrs a week on all shifts and majority of patients will have a 20 and I would say about 30% a 18 (if they are brought in with access, sometimes they can't get access and it's not emergent enough for the medic to need to start an IO) that are brought in by medics. Funny thing is I am a nurse and am well aware that a 14gauge is large bore. As is a 16 and 18,

    When starting IV's common sense should be utilized by both medics and nurses. If there is no indication to start a 14 or 16. then one should not be started. I love starting a 14 or 16 of EJ or IO, but I am not going to do it just to puff up my chest and say "look at me and what I did" if it's not needed. Most times a 20 can handle all the jobs needed on your average patient.

    In fact there is starting to be pretty heavy consequences for 14 and 16g IV's being started "just cause" or for "personal" reasons.
  8. by   OlivetheRN
    Quote from soutthpaw
    Funny thing is that Nurses think 18ga is big. Check out what every patient that is bought in by paramedics has... 18 is standard, 20 is small and 22 or smaller is for kids and infants. 14 ga is considered a large bore IV by medics.
    I don't think an 18 is big but the majority of patients brought in by EMS around here don't come in with 18s either.
  9. by   MikeyT-c-IV
    I believe the Infusion Nurses Society recommends placing the smallest gauge catheter needed for the prescribed therapy. They also removed the recommendation for routine site rotation but based on assessment. My hospital has a 72-96 hour site rotation policy.

    I generally place peripheral IV's in the forearm or the upper arm cephalic vein (rarely the basilic, brachial, or jugular.) I admit that I use ultrasound for all PIV's so I can see exactly what I need to see when assessing a patient. Since I can see the larger veins I usually place a 20g 1.75" catheter.

    Our CT guys like 20g in the forearm or higher for injection. And as far as drawing labs in a fresh IV, just experiment. Most of the time a 22 or 20 will work fine but sometimes they don't.

    The A/C isn't the best place for an IV not only because of the annoying pump beeping thing but if the patient is moving and bending then the catheter will "rub" on the internal lumen of the vessel which can lead to vessel damage (phlebitis.) One item that we need to be concerned with when performing IV therapy is: vessel preservation.

    And I completely agree with Mi Vida Loca... Just because we *can* do something doesn't mean we should.
  10. by   Double-Helix
    INS standards recommends using the smallest gauge catheter that will accommodate the prescribed therapy. The reason for this is because a smaller needle causes less trauma to the vessel and blood flow around the catheter decreases irritation to the vessel and reduces phlebitis.

    Catheter Size (Gauge) /Clinical Applications (according to INS)

    24g – Fragile veins; for intermittent and continuous infusions
    22g – Children/Older adults; intermittent general infusions
    20g – Adults/continuous infusions
    14g, 16g, 18g – Trauma and surgery
  11. by   Meriwhen
    I'm in psych, so IVs are few and far between. But when a patient has to have an IV or a saline/hep lock, it's generally a 20 gauge since it's a good all-purpose size. 22 gauge if it's being placed in the hand. We'll try to avoid the AC but if it's got to go there, it's got to go there.

    If they're needing a blood transfusion, they're too medically unstable for psych, even the psych/med unit.
  12. by   NerdyMedSurgNurse
    A lot of the nurses I work with were taught in school to start with a 22g. They're easier to put in than a larger gauge needle, and cause you less hassle. Personally, I always try to get at least a 20g in my patients. You never know when they might need to have a transfusion or have fluids run full force. With that being said, it's not always easy to get a 20 in an elderly patient, or someone who has small veins that are hard enough to feel for. As far as the IV change time, I do think it depends on the policy of the facility. Our tubing has to be changed every 72 hours, and the IV itself has to be changed to a new site every 96 hours.
  13. by   LovingLife123
    We do 18 or 20s. In ICU, if they are going to be there for a bit, we get a PICC. Peripherals go bad so quickly and we are usually drawing labs at the very least daily.

    Each hospital has their own policies regarding IVs. I do hate ACs. Not just for the beeps, but that is part of it. In ICU patients are hooked up to blood pressure cuffs constantly. Sometimes when I get a patient from ED, they have bilateral ACs. Then I'm stuck doing radial cuffs and if the patient needs restraints and all the jazz it's just not convenient.

    Forearms are where I look first if I'm in need of additional access. Then hands.

    If somebody is in need of a lot of blood, they get a central line. Most of our really sick ones get a central line.
  14. by   That Guy
    20 and smaller - most people most complaints

    18 - possible/potential need for rapid fluids/circle the drain

    16 - need fluids NOW

    14 - Oh yeah daddy gets to come out and play

    IO - I lose my mind because I love them so much

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