Table 1.

Lung volume, weight and distribution of aeration in supine and prone positions

	Supine	Prone	p value
Total lung weight (g)	345 ± 26	358 ± 44	0.420
Aerated lung weight (g)	330 ± 24	353 ± 43	0.156
Functional residual capacity (ml)	380 ± 82	459 ± 60	0.025
Non-aerated lung tissue (% of total)	4 ± 3	1 ± 1	0.004
Poorly aerated lung tissue (% of total)	47 ± 13	30 ± 9	0.005
Well-aerated lung tissue (% of total)	49 ± 15	68 ± 10	0.003
Over-aerated lung tissue (% of total)	0 ± 0	0 ± 0	0.432

Lung CT scan-derived values: lung volume, lung tissue weight and lung tissue compartments in prone and supine positions. Aerated lung weight was defined as lung weight having a density <−100 H.U. Lung tissue compartments were divided based on their densities (see text), and the weight of each compartment was expressed as a percentage of the total lung weight. The difference between non-aerated lung tissue weights in the two positions expressed as a percentage of the total lung weight corresponds to lung recruitment (see text)