When air space in the lung tissue becomes flooded with fluids it's called Hape. When the brain cells fill with too much fluid, it prevents the brain from working normally. This is called Hace. AMS stands for Acute Mountain Sickness. You can stop breathing when you're having altitude sleeping problems.
Dehydration is another problem.
Some Mt. Everest climbers get frost bite because they take off their mask. Extreme cold can cause hypothermia, which slows the heart and can lead to death. You can get frostbite like Seaborn Beck Weathers did. They drink liters of water before climbing. High altitudes can affect the brain, creating confusion, bad judgement, and other problems.