ðɪ ˈɛɹ pɹˈɛʃɚɹ ɪz ɐdʒˈʌstᵻd sˌoʊ ðˌɐɾɪt ɪz dʒˈʌst ɪnˈʌf tə meɪntˈeɪn ðɪ ˈɑːksɪdʒən sˌætʃɚɹˈeɪʃən lˈɛvəlz ɪnðə blˈʌd.
The air pressure is adjusted so that it is just enough to maintain the oxygen saturation levels in the blood.