Assessment of concordance between diffusion of carbon monoxide through the lung using the 10 s breath-hold method, and the simultaneous NO/CO technique, in healthy participants

•DLCO measured during the double diffusion test deviates from 4,6 mL.min−1.mmHg−1 or 15% of the DLCO measured by classical 10 s breath hold time.•Reproducibilities for DLCO, DLNO, DmCO and Vc was respectively 1.2 (11 %), 6.8 (13%), 16.5 (32 %), 12.5 (17 %) mmol. min−1 kPa−1.•Discrepancies between the two measurements techniques may be an indication that the Roughton and Forster interpretation is inadequate. There is limited, large sample size, healthy control data comparing measurement of diffusing capacity of the lungs for carbon monoxide (DLCO) via the 10 s single-breath carbon monoxide uptake method (DLCO10) and using a DLCO-DLNO double diffusion test performed with a 5 s time of apnoea (DLCO5). The primary objective was to compare DLCO5 and DLCO10 in healthy participants. The secondary objective was to evaluate the reproducibility of DLCO5. We included medical students at Caen University Hospital, from 2008 to 2011. We performed a standard single-breath carbon monoxide uptake and combined DLCO and DLNO measurement for each participant. The combined test was repeated one week later. Among the 153 study participants, there was no statistically significant difference between the mean values of DLCO10 (10.2 ± 2.2 mmol.min−1 kPa−1) and DLCO5 (10.3 ± 2.2 mmol.min−1 kPa−1; paired t-test p = 0.19). Corrected for the same FiO2, DLCO5 was calculated at 10.5 ± 2.3 mmol.min−1 kPa−1 and was significantly different from DLCO10 (paired t-test p