I had to have a lab test done the other day at the hospital. As part of the test, they put one of the new pulse/oximeters on my right 1st finger. Because I had just come in from the cold, my hands were freezing as usual. Because of this, they could not get a reading on that finger. They tried my thumb; no success. The middle finger of my left hand; no success. Then they felt my hands and were shocked at how cold they were. Once they warmed up slightly, they were able to get a reading and,…amazingly, confirmed I was alive with a pulse and excellent O2 intake.
I suggest that this may be an initial test for the possibility of the presence of Raynaud’s and might bear at least a minimum trial to see if there is a correlation.