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How does an intercostal tube or any surgical drain work?

  1. Dec 22, 2013 #1
    Hello guys,

    Ok lets say there is a man with fluid in his lungs. You put a chest drain (intercostal tube). How does it drain?

    1. Since the container is below the chest, when the guy expirates due to high pressure does fluid just flow to container? Can there be any retrograde flow (since container is below on the floor does gravity prevent this)

    2. The article I read says with intercostal tubes, look at the water level of the container. In inspiration it must rise, and it must fall in expiration. If this doesn't happen tube is not working. What water are they talking about and also why does this phenomenon happen.

    Thanks :smile:
  2. jcsd
  3. Dec 22, 2013 #2
    The fluid/gas will drain by gravity and/or by pressure differentials if suction is being used. Prevention of back flow is done by keeping the box low to the ground, as you mentioned, but also by making the tubing long enough that the fluid will not rise too high. For the case of pneumothorax, the water seal container is used as a "check valve" of sorts to prevent the gas from returning to the patient's pleural cavity.

    They are referring to the water level in the water seal compartment which is sensitive to the pressure differentials arising from respiration. Are you familiar with the typical three compartment set up for chest tube drainage?

    Here is a pretty decent article about the medical aspects, though it doesn't go into the physics too much. I'm still trying to figure out exactly how the suction control compartment works, I haven't had the time in the last few years to work it out for myself. Maybe I'll do it in the next few days if time permits.

    Chest Tube at eMedicine
  4. Dec 23, 2013 #3
    Thanks Yanick :smile: . I understand it somewhat now.


    I also don't understand how suction works, but get the concept now.

    This is how I understood it, please correct me if I'm wrong at any stage. I have highlighted the questions

    1. Ok if a person just has a pneumothorax, you can use the water seal chamber only. If you use a drain with no water, air will go back into pleural place in inspiration . Water acts as a valve. Water can go back into pleural cavity in inspiration, but that would not happen it to gravity and long length of tube. So it would only rise a bit. My question here is if you just use a water seal chamber should it be opened to the atmosphere to prevent air pressure increasing in seal.

    2. If a person has a haemothorax also, you can't use this method because, blood and water would collect in chamber and fluid level will rise altering pressure differences I think. I'm not exactly clear about the reason here can anyone explain it.

    3. So you use 3 way chamber. This is how I think it works

    * During expiration air and fluid(eg blood) drain into tube.
    * Fluid collects in collection tube, air goes to water seal
    * Suction tube enhances the capacity to suck air. Can this system work without suction?

    4. My question is what happens if you have a chamber with collection and water seal, but no suction. Then should the water seal tube be opened to the atomsphere, if not wouldn't the pressure increase causing fluid to flow back.

    Thanks again :smile:
    Last edited: Dec 23, 2013
  5. Dec 23, 2013 #4
    Yes. You always need to give the system an ability to vent otherwise you risk back flow due to the higher pressure in the drain system relative to the pleural space.

    Do you mean just having one chamber? That would not be an ideal set up for a chest tube which would need to drain fluid. From what I have seen and read, the standard is the three chamber system. You can try to google "pleuravac" for more information on what is actually used in a hospital, the principles are exactly the same but the whole thing comes in a self contained box which is portable and user friendly.

    Yes but less efficiently I would imagine.

    Yes as I said earlier, you need the system to be opened somewhere to avoid building pressure in the drainage system and risking backflow.

    You're welcome, I'm rusty on this stuff but I enjoy refreshing my knowledge and using my newer knowledge of physical science to make sense of the jumble of words I memorized years ago.
  6. Dec 29, 2013 #5
    Thanks Yanick :smile:
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