Try having them give him benadryl during the treatment. I get it each time. It'll knock him out, but it might help. Also it sounds like he is WAY over loaded on fluid. Dialysis pulls it out and what isnt filtered may go back into his lungs. Only other thought is that I use to get a bad cough while on my catheter because of what it did to my heart. Some places to start. Good luck and welcome.