Figure 5.

Total lung capacity in a sitting position predicted according to Quanjer and colleagues [9,12]. Total lung capacity (TLC) measured in a supine position as a function of computed tomography (CT) scan. (A) According to Quanjer and colleagues [9,12]: TLC (ml) (sitting) = 3,409 + 0.60 × CT scan (supine). P <0.0001, r² = 0.50. (B) Bland-Altman plot of the previous correlation. The average difference between the TLC predicted by Quanjer and colleagues [9,12] (sitting) and the CT scan TLC (supine) was 1,779 ± 849 ml (930 to 2,628). The difference between the predicted sitting TLC and the measured supine TLC decreased with the total gas volume increase. The difference between predicted TLC (Quanjer and colleagues) and measured TLC = 2,770 - 0.20 × (predicted TLC + measured TLC) / 2. P <0.001, r² = 0.05.