denitrogenate

transitive verb

de·​ni·​trog·​e·​nate (ˌ)dē-ˌnī-ˈträj-ə-ˌnāt 

denitrogenated; denitrogenating

: to reduce the stored nitrogen in the body of by forced breathing of pure oxygen for a period of time especially as a measure designed to prevent development of decompression sickness

denitrogenation

-ˌträj-ə-ˈnā-shən 

noun