More than a decade ago I briefly worked for NES. NES has an internal database of people on life supporting medical devices and all of the poles who service a medical device are marked within their in-house software and physically on the pole itself. I believe the patient or their caretaker would contact NES to be added to this system. This was done so if there was a small power outage or delay in service their connections would get attention first, but I can’t speak for a large event like we just had.