Mary Epp awoke from a deep sleep to the shrill sound of her dialysis machine’s alarm. Something was wrong.

It was 1 a.m. and Mrs. Epp, 89, was alone at home in Marion Junction, Ala. No matter. Mrs. Epp has been on home dialysis since 2012, and she knew what to do: Check the machine, then call the 24/7 help line at her dialysis clinic in Birmingham to talk to a nurse.

The issue: Hours before, a woman who helps her had put up two small bags of dialysis solution instead of the large ones. The solution had run out.

The nurse reassured Mrs. Epp that she’d had enough dialysis. So, Mrs. Epp tried to unhook from the machine, but she couldn’t remove a cassette, a key part. A man on another 24/7 help line run by the machine’s manufacturer helped with that.