The terminal stage of a congestive cardiac failure is very annoying for any family member. I understand and sympathize.
The main problem with any CCF is water retention. Water retention in lungs will cause breathlessness and cough
. Some patients will respond to diuretics and water retention will be reduced.
Muttering is because of dementia
. CCF per se will not cause severe pain
for anyone. Yes, discomfort will be there, but not pain.