3. Snap the left and right “index fingernails” together.
Lightly bend the first joints of the index fingers of both hands and try to snug them together so that the nails are facing each other. If it is healthy, a “diamond-shaped gap” will form at the base of the nail. But if there is no gap at all, and the entire nail is sticking together, be careful. This may be a phenomenon where not enough oxygen reaches the blood vessels in the fingertips, causing the fingertips to curl and swell. This could be a sign of insufficient oxygen due to lung or heart problems, so please try this test, which takes only a few seconds.
