Assessment of the alveolar volume when sampling exhaled gas at different expired volumes in the single breath diffusion test

Table 2 Coefficients of repeatability (defined as 2.77 × SD) for VAst (standardalveolar volume obtained following the ERS-ATS recommendations) and VAq (alveolar volume measured according to the method of subdividing the wholeexpirate into quintiles) between two consecutive tests for healthy individuals and patients with COPD using the method of Bland-Altman (24) and comparison of the repeatibilities between groups (healthy individuals and COPD patients)

Coefficients of repeatability (defined as 2.77 × SD) for VAst (standard alveolar volume obtained following the ERS-ATS recommendations) and VAq (alveolar volume measured according to the method of subdividing the whole expirate into quintiles) for healthy individuals and patients with COPD using the Bland-Altman method (24), in order to examine the variation between two consecutive tests. The level of statistical significance in terms of probability (p) has been reported. It is evident that the variation in the calculated alveolar volume between two tests appeared statistically significant for the VAst of COPD patients. In the healthy individuals it resulted approximately close to the level of significance. On the contrary, for the alveolar volumes calculated by the quintile method, the variation between two consecutive tests was only significant in the 2nd quintile of the COPD patients. In addition, no differences were observed in the comparison in repeatibilities between groups at each VAq (and VAst).
level of significance related to the comparison between coefficients of repeatibilities within two measurements for healthy individuals (°p < ) and COPD patients (*p < );
level of significance of the repeatibilities by the analysis of variance between groups (healthy individuals and COPD patients) (** p < )

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