I WAS THERE! How David Blaine flew helium balloons to the height of jets (and jumped)

https://www.pnas.org/content/114/24/6382 breathing techniques dont help you combat HAPE or HACE alpinists use a technique called climb high sleep low to acclimatize properly to ensure their red blood cell count can compete with the lack of atmospheric pressure. Sherpas actually have amazing genetics that allow them to persist in lower pressure environments without succumbing to the bodies natural response processes of increased membrane permeability at low pressures that normally results in fluid build up. Breathing exercises cannot allow you to escape the physics of lipid membranes under lower atmospheric pressure.