Having trouble understanding the different types of NG tubes

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    I am reading and reading on NG tubes trying to make sure I understand how they work and what they are used for. I find that if I don't truly understand the why of things I won't be able to learn the steps for the skills. What is the difference between large bore and small bore? I kind of get the differences, but can't really understand why you would choose one over the other. We have mostly worked with salem sump tubes. What I can't understand is if you can feed with this tube and suction, why you would want to use other tubes for feeding? Salem sump is a large bore tube correct? I guess I'm not really getting the purpose of small bore tubes. If NG tubes for feedings are for short term (which I'm assuming they would be or they would insert a G tube or something more permanent) then why would you choose another type besides the salem sump? Wouldn't you want to use a feeding tube that you could suction with too if you ran into problems? I don't know. I am still so new at all of this that I feel like I am not getting it. I am also having trouble knowing how to identify the different parts of the NG tubes and caps that come with them and where they should go. Any tips for that would be helpful too.
  2. 23 Comments so far...

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    The salem sump tube is double lumen, I believe, one lumen is large for suctioning and feeding/meds and the other lumen is small to equalize the pressure after suctioning. I'm guessing that you would want to use different types of NG's for different patients because not all NG's are for suctioning so the double lumen would be pointless for those cases.

    As far as the caps for NG's, I don't think we ever learned about those so I'm useless there.

    Sorry if I wasn't much help.
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    Tubes of various sizes have been used and selection of an appropriate size is largely dependent on the intended use for the tube and the anticipated duration it will be in situ.

    Soft, flexible, small-diameter (8-14 Fr) tubes are frequently used for patients who require enteral feeding for less than 6 weeks. However firmer, less flexible, large-diameter tubes (16 Fr or larger) are used to administer medications, gastric decompression, and for short-term feeding (usually shorter than 1 week).

    Reported advantages of small-bore NG tubes compared to large-bore tubes include less trauma to the nasal mucosa both during insertion and better patient tolerance


    large bore for decompression


    small bore feeding or pedi

    The different ports and cap vary product to product and product maker....what NGTs are you talking about and I will try to help.
    pmabraham likes this.
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    Okay, let me clarify my question some more. I bought a salem sump tube to practice with, but feel like I'm missing something.

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    Took a pic for you of what was in the package. What is the clear/white cap piece in the picture? The directions on the package say make sure blue end of Anti-Reflux valve is firmly seated in blue air lumen vent. Is the anti-reflux valve just not included in the package or is something in this pic the anti-reflux valve. The package also says seat 5-in-1 adapter snugly to prevent suction loss. Is the clear/white cap thing in the picture the 5-in-1 adapter maybe?

    Also still not sure why you would want to use a small bore NG tube if a salem sump can do the same thing.
  6. 1
    We must have been posting at the same time Esme12
    Esme12 likes this.
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    a removable 5-in-1 connector and a capping system with sump vent lumen cap, suction lumen adapter and suction lumen adapter cap.


    The long narrow "opaque white" is a suction connector to connect the NGT to the suction tubing. The white and blue is the the stonamh anti reflux valve which allows air to flow which prevents the NGT from sucking up against the stomach mucosa causing ulceration and injury
    pmabraham likes this.
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    Thank you so much Esme12! You were very, very helpful. To clarify I got this all right here is what I am understanding.

    1. The air vent is not necessarily a blue pigtail? I thought it had to be blue, but now I realize it can be clear like the main/suction tube. What differentiates the two tubes is the main tube is larger and the vent tube splits off and is smaller.

    2. The anti-reflux valve I have a good idea now what this should look like and where it should be placed. Thank you.

    3. Small bore NG tubes are used when suction is not anticipated to be needed because they cause less trauma to the mucosa and are tolerated better by the patient.
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    To amplify what my friend Esme said:

    It's very important to understand what that NG tube, probably a Salem sump tube with the little blue pigtail, is, how it works, and why we care.


    Before Salem sump tubes were invented, all we had were single-lumen tubes to suck out stomach contents. What's the problem there, you say? Well, if suction has removed all liquid stomach contents and it keeps sucking, what you get are little punch biopsies of the stomach mucosa, and this is not a good thing. So, some clever person (perhaps a Salem witch) figured out that if there were a way for the suction to have something else to suck on, to break the vacuum in the stomach, like air (and any other fluid that happened to accumulate too, of course), then this would protect the stomach from having vicious little hickies from suction at the eyelets down below and bleeding and such.


    The air vent on the salem sump is that solution. Air should always be going down the blue lumen. How do you know if that's happening? Well, you can put your ear near it and hear it, or put your thumb over the end of it briefly and feel suction there, but the best way to see is that there should always, always, always be air bubbles coming up the main lumen to your suction cannister. Now you know something important: if it isn't, there's hickifying going on down there, and that's a bad thing.


    The air vent lumen should always be patent (open) all the way down. If it isn't you can do a couple of things (after you have determined that some fool has not turned off your suction outlet). One is to untape the tube and pull it back an inch or so, and then put it back. You can also push some air (not fluid) down the blue lumen. Yes, you may have to do this all dang day long, but you will often be rewarded by a gush of gastric goo, which is what you wanted anyway.


    What's going on if there is no air coming up the main lumen and there's goo coming out of the air vent? Well, (assuming your suction is still turned on and plugged in properly) your main lumen is probably occluded and goo has nowhere else to go but up the air vent, and you should probably think about replacing the whole tube. But before you do that, if it's not otherwise contraindicated, shoot some NS down both lumens, and follow that with air down the air vent lumen. See if that doesn't get things moving properly. If not, do the wiggling thing as above. If that doesn't work, get the ok to replace it (or have the physician or NP come and replace it).


    Some Salem sumps come with little plugs in the blue lumen. They're supposed to allow air entry and prevent backflow but they don't always really do a great job of it. If you can still verify air entry past that plug and bubbles are going up the main lumen, it's fine. but if it's gotten grubby and acts like an actual plug, get rid of it, or what you have is now a gastric mucosa-grabbing single-lumen tube.
    pmabraham, Stcroix, Hygiene Queen, and 3 others like this.
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    I think I actually got this now. One more question if anyone happens to come back along. You've already been so helpful!

    Do you ever close the air vent? I know they usually plug the connector into the air vent and then into the main lumen during lab to close the whole thing off when not in use. I also know they had us pinch the main lumen when administering meds (before hooking up the syringe and then releasing to allow the meds to go through. The only question I have is if you hook the main tubing up for use for feeding do you just leave the air vent open or do you need to close it off? I know why you wouldn't close it during suction, but if it's not attached to suction then you wouldn't need the vent function. (I wouldn't think anyway.) So does the air vent need to be closed during feedings? I'm thinking no, that it never needs to be closed, but I don't know for sure. Do you ever cap the air vent end? I can't wait until I have lots of life experience on this.
  11. 1
    It needs to be closed for feedings.....feeding will migrate up the "vented" side into the bed and onto your patient.
    pmabraham likes this.


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