His doc is best placed to advise him, as he has all the data to make a diagnosis/plan.
Potassium at 6 is too high and I suppose they will target reduction of it. HR Is a bit high and his EF is low at 20%. (Normal is 55 - 70% ). I suppose they will try target the infection, then work on the rest. Its important to find the cause of the reduced EF, How is his BP ? As raised BP over time can reduce EF. He may have symptoms of Short Breath and exercise tolerance as a result of the reduced pump function.
The dialysis will help the body to continue to get rid of toxins and hopefully things will improve. He has issues with 3 main organs, so its important that things are got under control. approach his doctor for advice, make a list of questions first and hopefully you will get an idea of whats going on. Best of luck, keep us posted.