I am searching for an answer to this important question; what can possibly replace breathing as a function?
I don't believe there's a good answer for that. To be best of my knowledge, nothing else is as good at direct O2/CO2 exchange as lung tissue.
The machine is a large cylindrical metal drum into which a patient is admitted by opening the left end and rolling out a flat metal bed. The patient's head extends through the plastic collar and reclines on the headrest at left. After the patient has been installed, the bed is rolled back into the drum and clamped into place. A motor and pump mechanism underneath the body of the iron lung raises and lowers the air pressure within. Four windows on the top, and six rubber lined openings on the sides, provide access to the patient. Whenever the patient needed bathing or other medical care, a plastic dome was installed over his or her head which took over breathing automatically. The Iron Lung Please Register or Log in to view the hidden image!
Why is it an "important question"? Some animals, frogs I think, get a significant fraction of the gas exchanges thru their skin. Possibly resting humans with some "wetting agents" applied to skin and placed in a very high pressure atmosphere O2 rich gas could meet their O2 intake requirements, but the CO2 in their blood would need to greatly increase to "exhale" it thru their skin. That high level of CO2 would, I am almost sure, kill them if only the effect on their blood's pH is considered. I.e. getting rid of CO2 is probably the harder problem to solve.
