Table 2.

Thoracic dimensions at end-inspiration and end-expiration, and their expansion in the supine and semi-prone positions.

Measurement axes	Supine			Semi-prone			Expansion p-value
	End-insp (mm)	End-exp (mm)	Expansion (mm)	End-insp (mm)	End-exp (mm)	Expansion (mm)
Right H-F	216 ± 20	131 ± 21	84 ± 20	191 ± 23	125 ± 23	66 ± 20	0.029
Left H-F	220 ± 13	138 ± 16	81 ± 18	230 ± 14	161 ± 18	69 ± 16	0.036
Bilateral R-L	261 ± 13	257 ± 13	4 ± 1	259 ± 17	251 ± 14	8 ± 5	0.036
Right A-P	140 ± 17	126 ± 13	14 ± 10	135 ± 18	126 ± 16	9 ± 4	0.063
Left A-P	140 ± 9	126 ± 10	14 ± 10	143 ± 14	127 ± 13	16 ± 10	0.205

Data are presented as mean ± standard deviation. P-values were obtained using the Wilcoxon signed-rank test (paired, two-sided) to compare thoracic expansion between the supine and semi-prone positions, adjusted for multiple comparisons by the Benjamini–Hochberg procedure. H-F, head–foot; R-L, right–left; A-P, anterior–posterior; End-Insp, end-inspiration; End-Exp, end-expiration. Expansion = End-Insp—End-Exp.