I've never wanted to be the patient in such a roleplay, but I have thought about being the caretaker/nurse/boyfriend who has to caretake. Thing is, I don't want to marry, anyway, and in reality, this kind of scenario might not work too well, because I also am disabled.
I was once friends with a girl who had cystic fibrosis, and thus eventually had a lung transplant. I still fantasize about her every day, even 12 years on (and 4 years on from her death). Part of that revolves around my fetish for girls who medically have to wear masks, which was her reality. I fantasize that I am allowed by her to put her mask on her face for her before she goes out for the day or does housework (usually in real life she wore a North 5500 half mask cartridge respirator, but she also had disposable earloop and tie-on masks, and a white lace fashion mask from I Can Breathe).
And of course I fantasize that she'd wear the mask during sex (including masturbating with me next to her in bed).
But, as far as reality goes, I couldn't just let my fetish lead the way. In cystic fibrosis, there is eventual death. As well, sputum makes me gag. I have no problem with a girl's normal saliva, but CF sputum looks different.
So, I guess the answer, for just practical reasons, is mostly "no". There's only so many ways I could "help" with my own physical disability, and I have no desire to be a "patient".