Reason for low blood oxygen levels

[EmJa]

My husband suddenly developed shortness of breath while exercising. He was given an EKG, CT of his lungs to rule out a blood clot and then a systemic stress test with dye and xrays. Everything was normal.  Then he went for a pre-scheduled colonoscopy and they were concerned because his blood oxygen levels were in the low 80's both before and after the colonoscopy.  The family doctor was consulted and he was sent to the ER.  There they monitored his heart, took blood tests to check for low  iron among any characteristics  of a heart attack, did a chest xray and after 5 hours, sent home with no answers.  He is in no pain and only has shortness of breath during exertion.  He has had sleep apnea and was on a c-pap and bi-pap until he had surgery to remove his tonsils, uvula, adnoids, etc.  He stopped using the machines about 2 years ago, after the throat operations because he was getting chest pains when using the machine.  He does have an appointment with a cardiologist early next week and we hope to get some answers but I was just wondering if anyone has had anything similar.  He is over-weight but is a non-smoker.  I would like to think it could be something like asthma.  No one has suggested a lung function study which seems to me to be a simple way to discover whether the problem is with his lungs vs. his heart.  Thank you to anyone who can give us some suggestions before consulting the cardiologist.

[EmJa]

Just as you suggested. The cardiologist scheduled a cath on Friday and we are waiting word from a pulmonary specialist for an appt.
Thanks again.

[EmJa]

Thank you for your suggestions regarding my husband. Hopefully we will know something tomorrow after the cardiologist appt. Thanks again!

[Sunny602]

I think it is a good idea that he is seeing a cardiologist. There are additional tests that can be done to accurately tell if he has cardiac problems such as a heart cath for instance. If they rule out the heart, then they will probably look to the lungs. That is just a guess though, I am not a doc just a former RN.
I hope he gets answers soon
Sunny