I had colon cancer and now have colonoscopies every year. Ugh! I was diagnosed with bronchiectasis in 2010 and no one (doctor) has ever mentioned any concern including for the 7 hours I was sedated for colon cancer surgery in 2015. The sedatives used for colonoscopies are similar to the ones used for bronchoscopies and I had one of those last summer. Colonoscopies take little time and you are soon awake.
I ALWAYS remind the anesthesiologist and/or my gastroenterologist, who has performed many many colonoscopies on me, that I have lung diseases and they have always said that they saw that in my records and they have always been reassuring. Colonoscopies are preventive and diagnostic. Please get it done on the schedule recommended by your doctor. No half measures. Get your whole colon looked at.