Figure 2.

Spearman’s correlation coefficient of the volume of trapped gas (VTG) over residual volume % from the 5 inspiratory capacity breaths (5IC) method (left) and 5 vital capacity (5VC) method (right) with trapped air % from spirometry-controlled computed tomography. There is a clear under-read of the of VTG/residual volume (RV)% from both 5-breath methods compared with the trapped air %. Straight black line is a linear regression line, with dashed lines either side the 95% confidence intervals.