a pulmonary puzzler

[Agnus]

This is just too weird.

This is a real situation that I encountered, see if you can figure it out. A patient had emypema. He has had a chest tube in for some time. He had gone home with the tube and is now back.

All this time the tube is open to air At home his wife flushed it with N/S and now we are flushing the cavity with N/S and all the time the patient is conversing with up and experiencing no pain.

Why has his lung not collasped?

Good luck!

I would love it if someone could figure it out. I know the answer but the doc had to tell me. Give it a try and I'll share the answer.

All the while I'm irrigating I hear my teacher's voice Yelling at me that you NEVER put anything in a chest tube and you NEVER let a chest tube be open to atmsopheric pressure.

[Agnus]

Kian,

I'm adding this post to pull this thread forward. Kian responded to this same thread under a diffrent forum. And I need to bring this to the front of this form so she can find it when I refer her.

[Dyno]

Very interesting post Angus. I have had to flush pleural cavities also. Usually a pt with empyema following lobectomy or chest injury. Betadine flush used, 100mls (1/2 water) in & let drain into UWSD. Heimlich valve would have been my guess also or adherence created by inflammation.

Cheers, Dyno

[mario_ragucci]

Yes, very interesting indeed! I put some serious thought power into my reason before I read these responces. It is a great way to "play pretend" and then read and see what the "real nurses" say. With what I learned so far, and with the spirit of DaVinci, I knew it has to be related to the special mechanics of the lung. The lung is an organ that doesn't "collapse" unless it is diseased from the inside, or punctured. Normal diaphragm contractions would keep it open, I imagine.

Now I want to see an autopsy like you can't imagine. Just seeing a lung and a diaphragm would speak volumes to me.

[mario_ragucci]

Mario's super virgin question. :-)

I know what empyema, pus, and our pleural cavity is. And I read this thread with super curiousity. However, I know, from actual experience, if I am drinking water, and even a drop gets past my epiglottis, and heads down my trachea, my reflex causes me to stop what I am doing and cough.

Now, please tell me that a person who has a tube inserted into their pleural cavity is on serious medication to inhibit that reflex. Right?

[Dyno]

Mario, have a look at an anatomy book, the pleural cavity (a potential space) is NOT connected to the trachea. In fact, it is not connected to any other structure. The visceral pleura lines the lungs & the parietal pleura lines the thoracic cavity. between the two, a lubricating fluid is present, this is sectreted by the membranes. This fluid reduces friction and helps the lung to stay expanded (try pulling apart 2 pieces of glass that have a drop of water between then. They can slide easily but it is difficult to pull them apart) Hope this helps.

Cheers, Dyno

[aus nurse]

Ah well done kids-r-fun.......ROCK ON GIRL!!!!

I have seen the irrigation thing done here...but never seen it left open to air, even with recurrent empyema.

We do pleurodesis here on chest tubes where you instill a combination of antibiotic and something else which I can't remember!!! to cause the pleural linings to stick together and prevent further pleural effusions.. It is usually for lung Ca where this effusion tends to reoocur. The doc instills it then the tube is clamped and 30 min position changes to allow coating all over.

Mario, a chest tube is in the pleural space and does not cause any tracheal irritation so no need for cough suppresion. In fact you get them to take a deep breath and have a good cough to check for swinging of drainage fluid in tubing to check for position of tube and reinflation of lung. All to do with intra-thoracic pressures. What they do need is analgesia with what I always call a garden hose in their chest!!!

[Agnus]

Mario,

The contraction of the diaphram does not keep the lungs expanded. Just the opposet. The Thorasic (not pleural) cavity which contains the lungs and heart is a negative pressure space. The pressure in this cavity is lower than atmospheic pressure. Thus the lungs expand as air enters them to fill this "vacuum" In causing the diaphram to expand (streatch) THe diaphram's relaxed state is a contracted state. (picture a rubber band) So when the diaphram relaxes it contracts. THis makes the space in the thorax smaller and forces air out of the lungs. Then the atmospheric pressure is once again higher and rushes in. The diaphram is a unique muscle in that its normal resting state is contracted.

Breathing is therefore a matter of simple physics. Atmospheric pressure causes lungs to fill putting pressure on the diaphram causing it to streatch. Once pressure is equalized the atmosphere no longer puts a higher pressure on the diaphram it relaxes and forces air out. streatch a rubber band then remove the force that is causing it to streatch and it snaps back.

Remember the bellows jar experiment back in elementary or high school. This is what is happening.

Normally our lungs do not collaspe. Even when we exhale. That is due to a coulpe of things. First normally when we exhale all of the air does not leave the lungs, second there is a natural luberacant that lines the alveoli called surfactant that keeps them slippery so they do not stick together. Mostly though it is due to the fact that only part of the air leaves on exhalation. Think of your bellows jar again. the baloon in the jar deflates but not to the point that the sides of the baloon stick together. This would be a complete vacume. The baloon only collaspes to the point that there is no tension on the rubber baloon so there is some air in the baloon. However you could create a total vaccum and collaspe it completely. The sides would probably stick together and be harder to inflate next time. Surfactant keeps the inside of the alveoli slippery so they dont stick.. So there is alway some air in the lungs. Unless the negative pressure in the thorasic cavity were to increase. For example plural space (a potential space becomming an actual space) filling with air or fluid and pressing into the thorasic space.

When you are dead the lungs are not inflated because the rubberband has relaxed.

When a baby is born his thorax is squeeded in the birth cannal. this force out any fluid that is in the airway or lungs so when he come in contact with atmospheric pressure air rushes in causing his lungs to expand. This is also why C-Section babies often are bluer at first as they need to be suctioned to clear their airways and allow the air in. (note here there is no diffrence in pressue on the lung in utero r/t no atmosphere) Hope this helps

[mario_ragucci]

It helps a great, great deal. It's hard to make an anatomy book talk to you. I learn the best when someone talks to me. All of you...are wonderful people and i am forever in your debt. Thise are heavy words, but the science you drop on me is serious.

Thank you so much.

Especially dyno's first explanation of the pleura. I openly admitted to being a virgin, and you didn't shoot me down for not understanding the pleura, membranes, etc. You all are great for putting this stuff down because now i am more sure of my knowledge. Eternal thanks! (Mario begins to gently weep happy tears of joy) :-)

[Agnus]

You are a joy Mario