Thanks. I was just curious why such a steep diffusion gradient across the lungs was necessary. The ventilator takes care of the mechanics of breathing (or lack thereof) but why the hyperbaric environment? Reduced O2/CO2 exchange due to damaged lung tissue?
Yes, exactly. Damaged lungs are inefficient at gas exchange, so higher O2 levels are required. Also, if there is brain or heart damage, or even if you want to prevent damage, it is essential to get as much O2 to those tissues as possible. A healthy paO2 level is 95-100%. (That’s what they measure with the little finger clip in the doc’s office.) That’s monitored constantly in ventilated patients, and the ventilator settings are calibrated to keep it within that range.