[Osage Orange]

I'm guessing they had a finger Pox. They are not always reliable. Cold fingers, poor circulation...Some digits pick up better than others...Meaty digits, etc....

If your wife's SPO2 was 89-90...and that was a true reading...I wouldn't panic.

I work in the biz...but 80-84 gets my attention.

FWIW-

[Responsibility2nd]

Dittos. When I had Covid, I would take my pulse ox reading. Even sitting perfectly still it would bounce between 90 and 98.