chest tube question

[lightthelamp4]

I feel like perhaps I am thinking to hard about this and not getting something very obvious but can any of you explain to me how the third chamber of a standard chest tube drainage system works? I know the first chamber collects air and fluid, the second chamber is the water seal with 2 cm h20 to allow air out but not back in, and I know the third chamber is the suction chamber....but I dont understand how it works....I know that the amount of suction applied is determined by the height of the column of water that you fill and that when you attach the system to wall suction the amount of wall suction you set does not matter because the water column determines it anyway; but I dont understand how/why this is?
sorry if this question is silly

thanks in adance

---

Members don't see this ad.

 

[ThoracicGuy]

In the chest tube kits that I use, the amount of suction is determined by the dial on the side of the box. You do need to have the wall suction at a high enough level that it can still provide suction through the distance of tubing. Setting the wall suction to 20 will usually give too weak of a suction at the end of the tubing you connect to the chest tube box. You have the chamber that collects fluid that is contiguous with the water chamber that provides the seal. There is no third chamber that any of my chest tube boxes have. Perhaps you have some unusual sort at your hospital.

 

[Winged Scapula]

I'm guessing OP is thinking of the traditional "three bottle" chest tube system depicted in books, since that's usually how we teach them to conceptualize it even though modern pleurevacs accomplish the same thing in a single closed unit :

"Pre modern" Pleuravacs had 3 chambers in the box; the chambers were for fluid, waterseal, and suction. Maybe his program got a sweet deal on some old military surplus devices.

 

[ThoracicGuy]

I'm guessing OP is thinking of the traditional "three bottle" chest tube system depicted in books, since that's usually how we teach them to conceptualize it even though modern pleurevacs accomplish the same thing in a single closed unit :

Perhaps so. I have enough problem with nursing being able to take care of just one box. I can only imagine the horrors if we had to deal with the old three bottle system...

 

[Dr.LeoSpaceman]

The answer to the question just has to do with the physics of adding that 3rd bottle above. The "-20cm" is the measurement of the vacuum being applied (instead of PSI, barr, etc.). The reason it works is that the wall suction pulls air out of the space above the water level, creating a vacuum that draws on the tube to the right. When the vacuum exceeds -20cm of (negative) pressure, atmospheric air is drawn into the bottle through the middle straw to keep the pressure at -20cm. The reason why it works is simply that air is harder to draw into the chamber as you increase the water level...in other words, it's harder to suck air through 40 cm of water than through 20cm. Thus, it requires more suction.

Also note that the total amount of suction is the amount in the left bottle PLUS the volume in the water seal bottle. So if you wanted -20cm of suction and you had 5cm of water in the water seal chamber, you would add 15cm of water to the left hand bottle.

And the "wet" Pleur-Evavs certainly still exist...our VA was using them up until like 3 years ago and they are still marketed. The newer ones that replace use a dry seal with a pressure selector are not only easier to adjust, but much less annoying. I couldn't imagine being a patient and hearing that thing bubbling all night.

 

[Winged Scapula]

"And the "wet" Pleur-Evavs certainly still exist...our VA was using them up until like 3 years ago and they are still marketed. The newer ones that replace use a dry seal with a pressure selector are not only easier to adjust, but much less annoying. I couldn't imagine being a patient and hearing that thing bubbling all night."

So the new ones don't bubble anymore? I always found it sort of soporific.

 

[ThoracicGuy]

We use the Atrium system pictured here:

http://www.atriummed.com/en/chest_drainage/images/oasis-3600-popup.jpg

The suction regulation is a dry seal. The only bubbling comes from an ongoing air leak (if present).

Come to think of it though, I'm pretty sure our VA system has the old ones too.

And we all still call it "water seal" when we take it off suction.

That's our system as well. I've used that model at all but one hospital that instead used this one that was absolutely horrible. If it got knocked over, you could completely lose your water seal.

 

[lightthelamp4]

thank you very much for your replies guys, especially faytIND