Influence of Bag Volume Variation in Inert Gas Rebreathing Pulmonary Blood Flow Measurements on the Reproducibility in Patients With Pulmonary Diseases

Non-invasive inert gas rebreathing (IGR) based on the Fick Principle showed promising results in the determination of pulmonary blood flow (PBF). The volume of the rebreathing bag (Vbag) is proposed by the system, however, elderly patients or those suffering from high grade pulmonary diseases might be unable to entirely rebreathe this volume and therefore fail to completely mix the test gases. The aim of our study is to evaluate the effect of adapting Vbag on the reproducibility of IGR measurements in patients with obstruction (group A), restriction (group B) and pulmonary healthy controls (group C).