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Diagnosis

Pulse oxymeter

can rapidly detect even small changes in how efficiently oxygen is being carried to the extremities furthest from the heart.
a small, clip-like device that attaches to a body part, like toes or an earlobe.
Small beams of light pass through the blood in the finger, measuring the amount of oxygen - by measuring changes of light absorption in oxygenated or deoxygenated blood.
Healthy lungs keep the blood oxygenated at a level between 95 and 100 percent – if it dips below 92 percent, it’s a cause for concern and a doctor might decide to intervene with supplemental oxygen.