Update
Thank you all for responding.
First of all, I want to apologize for not having responded as often as I should have, over the years, to those of you that have had personal tragedies like this. I realize now that it is not what you say its that someone cared enough to respond. I am so sorry for not replying when I should have.
At 4pm-ish, St. Louis time, the nurses checked on mom and she was fine, resting, but fine. Then about 15 minutes later, Dad walked in and wasn't able to wake her for supper. The nurses couldn't wake her either.
In that short period of time, her oxygen levels had dropped from around 95% to 72% and was still dropping.
They informed Dad that an ambulance would not get there in time to get her to a hospital. They removed her oxygen mask and told Dad that she could still hear him (I don't know if that is true, but it was important that Dad got a chance to say goodbye.) She died 5 minutes later.
I married a wise woman, she awaited until I was home from work to tell me, instead of calling me while driving.
I am babbling now, so I am going to stop typing.
James
