Pulmonary diffusing capacity measured by NO/CO transfer in Tunisian boys

International audience Background The diffusing capacity, which measures gas-exchange, uses reference values based on data from American or European studies. There are currently no reference values of pulmonary diffusing capacity (TL) and its components, such as the conductance of the membrane (Dm) and capillary lung volume (Vc) for healthy North African children. Objectives We determined the prediction equations-reference values for TL, Dm, Vc and the alveolar volume (VA) in healthy Tunisian boys. Methods Values of Vc, Dm, TL, and VA were measured by the NO/CO transfer method, using a single breath maneuver in 118 Tunisian boys (8-14 years old) at rest. We performed linear regression analysis of the pulmonary parameters and independent variables, such as height, weight, and age. Results The reference equations for pulmonary diffusing capacity for carbon monoxide (TLCO) was 0.201 x weight (kg) + 8.979; for TL(NO)was 0.76 x height (cm)-24.383; for Dm was 0.388 x height (cm)- 12.555 and for VA was 0.34 x height (cm)-3.951. Vc increased significantly with weight (P < .05) but not with age (P > .05). Conclusions References norms for TL(CO)and TL for nitric oxide and its components in young Tunisian boys are similar to data from other countries. The prediction equations we developed can be extended to clinical practice in Tunisia and can be considered for use in neighboring North African countries.