The main use of ORS is for diarrhea. The pioneers of the 1800s certainly could have used it. It wasn't the cholera that killed them, the dehydration got them first. The disease caused people to have diarrhea in the quantities of two to five GALLONS a day.

Water and other fluids after heavy blood loss just keep your blood pressure up. It doesn't replace the need for whole blood, the red blood cells of which carry oxygen to the brain and other organs.

When I had heavy blood loss (5 units replaced), I think they were giving me fluids as well as blood.

Sue