Table 2.

Half-times T_1/2 of ^81mKr gas clearance in the anterior and posterior parts of the nasal cavity, pharynx, and trachea regions of interest of healthy volunteers during 15, 30, and 45 l/min of nasal high flow

	Half-Time T1/2, s
ROI	NHF 15 l/min	NHF 30 l/min	NHF 45 l/min
Nasal1	0.70 ± 0.26	0.53 ± 0.17	0.39 ± 0.11
Nasal2	0.91 ± 0.34*	0.69 ± 0.24*	0.48 ± 0.11*
Pharynx	7.80 ± 2.96	6.19 ± 3.82	4.43 ± 2.92
Trachea	23.73 ± 6.63	14.30 ± 13.43	10.53 ± 9.85

Values are means ± SD. In all compartments, half-times correlated with NHF (Nasal1, cc = −0.55, P < 0.01; Nasal2, cc = −0.57, P < 0.01; pharynx, cc = −0.41, P < 0.01; trachea, cc = −0.51, P < 0.01). Nasal1 and Nasal2, anterior and posterior parts of nasal cavity, respectively.

^* P < 0.05 Nasal2 vs. Nasal1, paired t-test.