Optimizing the Calculation of DMCO and VC viathe Single Breath Single Oxygen Tension DLCO/NOMethod

摘要

Alveolar-capillary membrane conductance (DM,CO) and pulmonary-capillary blood volume (VC) are calculated via lung diffusing capacity for carbon monoxide (DLCO) and nitric oxide (DLNO) using the single breath, single oxygen tension (single-FiO2) method. However, two calculation parameters, the reaction rate of carbon monoxide with blood (θCO) and the DM,NO/DM,CO ratio (α-ratio), are controversial. This study systematically determined optimal θCO and α-ratio values to be used in the single-FiO2 method that yielded the most similar DM,CO and VC values compared to the ‘gold-standard’ multiple-FiO2 method. Eleven healthy subjects performed single breath DLCO/DLNO maneuvers at rest and during exercise. DM,CO and V_C were calculated via the single-FiO₂ and multiple-FiO₂ methods by implementing seven θ_CO equations and a range of previously reported α-ratios. The RP θ_CO equation (Reeves and Park,Respiration physiology 88:1–21, 1992.) and an α-ratio of4.0–4.4 yielded D_M,CO and V_C values that were mostsimilar between methods. The RP θ_CO equation and anexperimental α-ratio should be used in future studies.