What were the useful medical discoveries made by Nazi experiments on prisoners?

Question:

What were the useful medical discoveries made by Nazi experiments on prisoners?

Best Answer - Chosen by Asker: There's only one I heard of, that people die quickly in freezing cold water if their neck is in the water. Life vests were changed to keep necks out of the water.
That could have been discovered without experimenting on Humans if those monsters had had the slightest bit of decency or humanity.