shortness of breath

My 82 year old father has COPD which has escalated significantly following a serious bout if pneumonia this spring.  He is on oxygen almost all of the time, and rarely moves from his chair due to concerns that he is going to loose his breath.  He had colon cancer last year; he had extensive chemo and radiation, and his rectum was removed.  4 years ago he had an aorta aneurysm which was repaired with a stent. I am aware that the blood flow to one of his kidneys was compromised when the stent migrated a little after the surgery.

My question is this: at this time, his shortness of breath is exacerbated when he urinates. His shorthness of breath is terrible - very frightnening, when he urinates. I am wondering if the shortness of breath associated with kidney disease could be manifested when he passes his water?  He is also very cold all the time and is getting out of bed later and later every morning because he is more comfortable lying down.  

Mostly, we are concerned about the terrible impairment in his breathing when he goes to the bathroom.
Thanks for any input.