Measuring the effective operation of the lungs requires measuring peripheral blood oxygenation. Pulse oximeters, which shine red light throught the finger or earlobe, measure the saturation of red blood cells by color. I bought one at walgreens for about $40. This will let me know if I, or the 88 and 98 year old in my care, are decompensating. Lets me give the 911 operator a better idea of what's going on.

Course of illness of first 12 patients with Covid-19 :
None required a vent, apparently. Caveat:if any of the information in the article is confusing to you, you probably shouldn't be playing around with a ventilator.

Successful use of a ventilator requires aintubation with a cuffed endotracheal tube. Anesthesiologists created field expedient et tubes with condoms. If you do not have intubation supplies and skills, see Caveat.

Successful use of a ventilator requires
-a large supply of medical grade oxygen
-access to anesthesia, sedation, and analgesic drugs
-IV access and fluids
-assessment skills sufficient to diagnose misplaced et tube, subcutaneous emphysema, pneumothorax, pneumo-mediastinum, esophogeal intubation.
-arterial blood gas monitoring capability to detect alkalosis/acidosis, pH and HCO3 levels.

If you don't have these things, see caveat. I worked with patients on vents in ICU's and ers for a long time. It's complicated. Moreover, vents don't save everybody. If the lung tissue is thoroughly compromised,ventlators don't work. The alternative is ECMO Which is so difficult to use that no one is even talking about it.

Most of the patients who heve respiratory distress need supplemental oxygen: it might be productive to look into builing a home oxygen concentrator

If you want to go to the moon, you don't start by building a rocket ship: you start by studying physics.

IMHO/YMMV
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Dance like you have never been hurt, work like no one is watching,love like you don't need the money.