I like how the chart includes a description of a dead duck. Very helpful.
Imminent means "about to happen". The reason for the cruel description is because people often bring their birds into the vet and soon after the birds die, most often due to stress/dehydration, but to the point, oftentimes the owner blames the practitioner in charge because the bird died in the care of their hands. So if one were to receive a bird in such critical condition the veterinarian could then warn the owner the bird's chance of survival is grim. Often times, dehydration kills the bird before the disease/condition itself.
In other words, keeping a bird hydrated can't be stressed enough.
I would suggest examining the bird's skin, mouth, and eyelids as suggested in the graph to see if there is any sign of dehydration going on. Is the graph the best way to determine dehydration (?) No, ideally, and this is what I do here on some of the sick birds, and is what most vets will do, is a PCV (Packed cell volume). Basically, a sample of blood is taken from the bird, it's then sucked into a capillary tube, and centrifuged to separate the plasma from the RBC's. It's then set on a microhematocrit reader, and where the plasma and RBC meet is where you read. Here is one I performed on the farm, the reading reads 59% PCV. A high PCV reading suggests dehydration.
If you have a humidifier, I would put that in her pen. Keep us posted on her condition.