Arterial blood gases and crohns?

[mindiemonster]

So I was diagnosed with sleep apnea (not a huge surprise as my anesthesiologist was pretty sure I have sleep apnea and firmly instructed me to get that looked in to). I go in for another sleep study, and to be fitted with a c-pap machine in a couple of weeks. The confusion is that my doctor also is having my blood gases checked. I had never even heard of that test (oh, the things I've learned since getting diagnosed with crohns!), so I did some research and now I'm wondering if there are any lung problems associated with crohns disease?