TY - JOUR T1 - Measurements of carbon monoxide (CO) in exhaled air and calculation of alveolar-capillary membrane diffusion capacity JF - European Respiratory Journal JO - Eur Respir J VL - 42 IS - Suppl 57 SP - P1292 AU - Evgeny Babarskov AU - Evgeny Stepanov AU - Yury Shulagin AU - Alexander Cherniak AU - Zaurbek Aisanov AU - Alexander Chuchalin Y1 - 2013/09/01 UR - http://erj.ersjournals.com/content/42/Suppl_57/P1292.abstract N2 - Background: We found earlier [Babarskov E. at al. ERJ 2010; 36,suppl.54:504s] that lung diffusion capacity, DL, calculated by increasing rate of integral measured CO concenration, CM, in exhaled air at successive increasing breath holding time, corresponds membrane diffusion capacity, Dm. Measurements were performed in breathing regimes, when total dead volume (instrument+anatomic), VD, was much less than respiratory volume, ΔV, at maximal alveolar volume, VA.Aim: To determine the influence of VD on CM and to estimate the relationship beetwen DL and current alveolar volume,V.Methods: Mathematical modeling of CO gas exchange in lung and experimental data analysis.Results: Two models were considered: linear model (LM) when CO gas exchange in changing V takes place at constant DL (DL=Dm), and model of elastic membrane (MEM) when DL at breathing is changed proportionally to membrane surface area and inversely to its thickness (DL=Dm*(V/VA)4/3). Calculations were performed for two different breathing regimes at equal VA=7.0 L and Dm=60 mL/min/mmHg. Spontanios breathing, when alveolar volume is changed from V0=3.0 L to V1=4.0 L at equal mean inspiration and expiration flow rate, Q=20 L/min, and deep forced breathing at V0=2.0 L, V1=7.0 L and Q=100 L/min. Both models demonstrate strong dependence of CM from VD in case of spontanios breathing, but MEM more correctly aproximates experimental data, so at increasing VD from 0 to 0.5 L, CM is decreased by 1.7 fold.Conclusion: The dependence of CM from Dm was found for different breathing regimes taking into account VD. This allows to solve inverse task - to calculate DM using known CM values. ER -