TY - JOUR T1 - Impact of the use of a finite value of NO conductance on Hb in the interpretation of TLNO and TLCO transfer in homogenous groups of patients JF - European Respiratory Journal JO - Eur Respir J VL - 44 IS - Suppl 58 SP - P2121 AU - J.B. Martinot AU - C. Kays AU - A. Chambellan AU - H. Guenard Y1 - 2014/09/01 UR - http://erj.ersjournals.com/content/44/Suppl_58/P2121.abstract N2 - Rationale.The single breath NO/CO method in its original design makes the assumption of infinity for the NO conductance on Hb (ΘNOinf). Yet this assumption of infinity seems uncorrect. The ratio ΘNO/ΘCO would be 7.7.Compared to the original method the use of this ratio decrease Vc by 24% and increase DmCO sharply in a proportion depending on both TLCO and TLNO values.The aim of the study was to analyse the impact of the use of a fixed ΘNO on DmCO in 3 groups of patients and 1 group of healthy. DmCO7.7 (computed with ΘNO/ΘCO=7.7) and DmCOinf (with ΘNO/ΘCO =infinity) were compared.The specific question raised was: can value in DmCO be safely inferred from the calculation of DmCOinf or should we use DmCO7.7 ?Methods. 1 group of 307 healthy people, 3 groups of patients : 62 patients with diabetes and near normal lung function, 64 patients with pulmonary hypertension, 59 patients before lung surgery with mild obstruction. All patients and subjects performed 2 maneuvers.Results. Linear correlations between Dm7.7, and Dm inf (Eq 1), Dm7.7 and Vc 7.7 (Eq2) were calculated . R² values were taken as indexes of variability. DmCO and Vc were calculated taking either θNO as infinite (Dm inf, Vc inf) or with θNO/θCO=7.7 (Dm 7.7, Vc 7.7).In patients the correlations between Dm 7.7 and Dm inf were tight in diabetes group (R²=0.79) but scattered in the 2 other groups (R² 0.35 and 0.11 for PAH and preop groups respectively) even more for Eq 2(R² 0.03 and 0.11 respectively).ConclusionIn patients with mild or severe alterations in lung function the calculation of Dm 7.7 is recommended as Dm value cannot be accurately inferred from Dm inf. ER -