text: <unk>  is a breathing gas that is composed of a mixture of helium (He) and oxygen (O2).<unk>  has been used in a medical context since the 1930s, and although the medical community adopted its use initially to alleviate the symptoms of upper airway obstruction, its range of medical uses has since expanded greatly, most of which are dependent on the low density of the gas.<unk>  is also used in saturation diving and sometimes during the deep phase of technical dives.
option_0: Heliox
option_1: Benzyl
option_2: Arsine
option_3: ADME
option_4: Phencyclidine
option_5: Benzidine
option_6: Opiate
option_7: Opium