The mechanistic model that can estimate respiratory parameters from capnography. Previous studies have correlated morphological features of the capnogram to respiratory parameters and used these features for classification of obstructive lung disease. In the that time-based capnography, which is noninvasive, effort-independent, and in ubiquitous use, has the potential to complement existing pulmonary function tests, such as spirometry, for screening and diagnosis of obstructive lung disease. results with healthy subjects and patients with obstructive lung disease suggest that a model-based approach to extracting respiratory parameters can be of practical diagnostic interest time-based capnography, which is noninvasive, effort-independent, and in ubiquitous use, has the potential to complement existing pulmonary function tests, such as spirometry, for screening and diagnosis of obstructive lung disease.