Lung volumes

When I showed up this a.m. at the nursing home, Mom was sleeping deeply, and her color looked bad. As usual, she'd thrown off her oxygen, so it was no surprise that her oxygen saturation was low. But 71% low?!?!? A normal level is greater than 90%--no wonder she was totally out to lunch.*

Why so low? My mother suffers from osteoporosis, and her curved spine restricts the expansion of her lungs. In addition, everyone, curvy backbone or no, restricts their lung volume when lying down, particularly if they carry a lot of weight around their midriff which she does not. She'd also recently had a dose of pain meds (having torn a chunk of her forearm out when reaching for an item on her bedside stand), and was breathing shallowly in her drugged sleep. Finally, she had radiation to her lungs many years ago (take that you stupid lung cancer) which left stiff scar tissue in place of elastic lung. All together--twisted back, lying down, drugged sleep, and radiation fibrosis--equals a low lung volume also known as restrictive lung disease.

So what then of the barrel-chested folks with obstructive airway disease? These people, generally ex- or current smokers, have destroyed tissue so that their lungs which once had the even sort of holes of a synthetic sponge now have wildly uneven air spaces like a natural sponge. The tissue no longer springs back into place as they breathe out. In fact, the expanded airspaces start to push on the tiny airways during the course of exhalation which shuts off the exit route for the used up air.

As a result, their lungs are hyperexpanded (increased lung volume), but the extra volume is made up of old, dead air that is devoid of fresh oxygen. While their total lung volume is up (as opposed to the patients with restrictive lung disease), their vital capacity--i.e. the amount of air exchanged with every breath--is way, way down.

Gotta love your lungs. Don't smoke, hold your breath during high pollution days, and save your spine from collapsing through exercise and proper nutrition.
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*Speaking of idioms, I went to the nurses' station at the home one day and informed the wonderful French nurse on duty that my Mom was completely out to lunch. She rose in alarm, "Non, non, she had lunch in her room! She should be there!