Table 1 MAP, AMP, PaO₂ and PaCO₂ values during the experiment, FiO₂, 0.5; Frequency, 15 Hz, Values represent mean ± SD. * P < 0.05,

Carried Gas

Nitrogen50

Heliox50

Nitrogen50

Heliox50

Nitrogen50

SV (mL)

16

16

16

25

16

MAP (cmH₂O)

14 ± 0.55

11.5 ± 0.72*

13.8 ± 0.6

11.9 ± 0.85*

13.8 ± 0.88

AMP (cmH₂O)

40.1 ± 0.61

28.7 ± 0.51*

39.8 ± 1.22

38.4 ± 0.95

39.8 ± 0.61

PaO₂ (mmHg)

207 ± 8.6

196 ± 15.5

210 ± 26.8

204 ± 18.4

214 ± 24.3

PaCO₂ (mmHg)

43 ± 13

47 ± 14

45 ± 11

33 ± 5*

43 ± 6