Fig 3.

Pa_o2 and Pa_co2 change over time during apnoea. Change in arterial oxygen and carbon dioxide tension during apnoea. TA, onset of apnoea; TA+x, apnoea duration where x denotes min after TA. Each line represents an individual participant (purple: high flow nasal oxygen group; blue: facemask group). Light lines represent participants whose oxygen saturation level remained >92% during apnoea throughout the 18 min period. Dark lines represent participants who desaturated to 92% during the study period.