CAGE and pneumothorax?

[Wildcard]

"During a pneumothorax, inhaled gas leaks into circulation via a break in the lung linings and can cause AGE. In normal lungs gas and blood do not mix, they are separated by a gas permeable membrane, with the whole lung wrapped in an air tight sheath. Either the sheath or the membrane ruptures and cause the gas leaks."

Explain to me how air in the plural space can enter the blood stream?

 

[Saturation]

"During a pneumothorax, inhaled gas leaks into circulation via a break in the lung linings and can cause AGE. In normal lungs gas and blood do not mix, they are separated by a gas permeable membrane, with the whole lung wrapped in an air tight sheath. Either the sheath or the membrane ruptures and cause the gas leaks."

Explain to me how air in the plural space can enter the blood stream?

There are supposed 2 mechanisms.

If visceral pleura rupture by overpressure it includes ruptured alveoli, and gas forces its way into ruptured blood vessels [mainly empties into the pulmonary vein hence the arterial side], the pleural space or may track between tissues as subcutaneous and mediastinal emphysema [SE,ME]. The inter-tissue gas can then be forced by building pressure into capillaries and hence into venous, more likely, than arterial circulation.

If rarely the problem is purely a pneumothorax, then gas that enters the pleural space expands on ascent, often with a resulting marked tension pneumothorax, then the expanding gas and pressure may track the gas into soft tissues causing SE and/or ME.

While SE or ME are normally benign, at depth the compressed gas expands as diver ascends, providing more gradients for bubbles to enter circulation, and worse, arterial circulation.

Case studies are here:

http://www.ncbi.nlm.nih.gov/entrez/...ve&db=PubMed&dopt=Abstract&list_uids=95300523

 

[Wildcard]

It would seem to me that if the aveoli rupture then the escaping and expanding air/gas would expand and not only partaly close the capillary bed but the resulting air "bubbles" would be too large to reenter anyway? Is air under pressure able to recross the membrane INTO the capillaries? I haven't ever realy though about it before I guess.

 

[Saturation]

It would seem to me that if the aveoli rupture then the escaping and expanding air/gas would expand and not only partaly close the capillary bed but the resulting air "bubbles" would be too large to reenter anyway? Is air under pressure able to recross the membrane INTO the capillaries? I haven't ever realy though about it before I guess.

Bubbles look and act like balloons when modelers describe them, but they aren't balloons. Faced with a smaller orifice, bubbles simply break up, diffuse, give up their gas in a dissolved phase and renucleate ... many phenomena possible. Gas under pressure always crosses into capillaries from most membranes in the human body, its not the gas that's the problem, its its bubble phase.

 

[Wildcard]

So in the case of a pnumo, wouldn't the escaping gas be more likley to stay inbetween the plural layers or go SQ rather than back into the capilaries?

I understand the physo part of this well but the UW aspect is fairly new to me, thanks for your insite.

 

[Saturation]

So in the case of a pnumo, wouldn't the escaping gas be more likley to stay inbetween the plural layers or go SQ rather than back into the capilaries?

I understand the physo part of this well but the UW aspect is fairly new to me, thanks for your insite.

In can go either way. If the gas leaks at the bottom of a dive, its more terrible than if it occurs shallower. With ascent the gas expands, and the pressure exerted by the gas on a fixed volume maybe the impetus to go SQ or elsewhere, and or cause tension pneumothorax.

 

[Wildcard]

So if I understand what your saying, with SQ or a tension pnumo, the gas can be forced back into the cap bed as bubbles not in solution?

 

[Saturation]

So if I understand what your saying, with SQ or a tension pnumo, the gas can be forced back into the cap bed as bubbles not in solution?

With sq movement of gas it gets forced back into tissues and hence in venous circulation.

Tension pneumothorax is a problem all its own and has nothing to do with DCI, its purely barotrauma.