Abstract: Abstract Objective:To investigate the changes of volumetric capnography(VCap) in patients with Idiopathic pulmonary fibrosis. Methods: Ventilatory function, diffusing capacity and Vcap were determined in 35 patients with idiopathic pulmonary fibrosis and 38 healthy controls.SPSS11.0 were used for statistical analysis. Results： IPF group showed restrictive ventilation and reduced diffusion capacity; VC, DLCO were significantly lower than the controls( p <0.01). VCap parameters of the slope than in normal group Ⅱ no difference, p> 0.05; VT was significantly lower than the normal group, p <0.01; VDB / VT and the slope was significantly higher than in stage Ⅲ, p <0.01; VDB slightly higher than normal, p < 0.05. FEV1% and VCap parameters showed no significant correlation; VC, DLCO were significantly positively correlated with the VT, with the VDB / VT, Ⅲ of the slope was significantly negative correlation, p <0.01, with VBD and Ⅱ was no correlation of the slope, p> 0.05. Conclusions：Patients with idiopathic pulmonary fibrosis, changes in volumetric capnography showed: VT decreased; VDB increases; VDB / VT increased; Ⅱ on the slope of the normal; Ⅲ disappearance of the platform, the slope increased significantly.

Key words: Idiopathic pulmonary fibrosis, respiratory function tests, volumetric capnography