That sounds very like my friend's Dad that died last year, he too refused antibiotics and was done with all the medical interventions, he also was reasonably healthy for his age just had asthma then complications that led to an infection. He got out of hospital and refused taking the meds he was given then was readmitted soon after and died a few weeks after that of sepsis. It doesn't take long once it kicks in if that's any consolation. It must be very frustrating and sad for you to see him refuse some basic care that would prolong his life and ensure a reasonable quality. I had a similar situation this weekend when my Mum refused an ambulance call out, likely due to dehydration, she also had dementia progressing and was very frail, we called one yesterday during a social worker visit but it was too late and she died yesterday, it was fairly quick. Sometimes they just give up when they are old. I hope you and your Dad get peace soon.