How to compare two different metered-dose inhaler-valved holding chambers in the administration of salbutamol.

D lco and the D lco VA ratio change with lung volume as would be expected with changes in surface area for diffusion. Percent predicted for D lco adjusted for lung volume (D aco ) and D lco VA ratio adjusted for lung volume (K aco ) also should be reported, using the following equations: D aco predicted 5 D lco predicted 3 (0.58 1 0.42 3 VA VAtlc) and K aco predicted 5 K co predicted 3 (0.42 1 0.58 (VA VAtlc)), where Kco 5 carbon monoxide transfer coeffi cient and VAtlc 5 predicted VA at total lung capacity. 3 It also would be helpful to know whether CMS affects spirometry (FEV 1 and vital capacity) and lung volume (total lung capacity or VA). I hope that the authors will reanalyze their data and report percent predicted D lco , K co , and D aco (which 5 K aco ); VA; and, if spirometry was measured, FEV 1 and vital capacity. Finding comparable percent-predicted D aco in patients with and without CMS would strengthen their argument that CMS does not impair pulmonary microcirculation.