Comparison of the 1-min Sit-to-Stand Test to the 6-minute Walk Test in the Respiratory Functional Assessment of Pulmonary Fibrosis

Fibrosing interstitial lung diseases or pulmonary fibrosis represent a heterogeneous group of progressive pulmonary pathologies, responsible for a significant morbi-mortality. They are defined by an infiltration of the pulmonary interstitium associating in a variable way an inflammatory component (deposit of inflammatory cells) and a fibrosing component (deposit of collagen). Idiopathic pulmonary fibrosis (IPF) is the most common and most severe pulmonary fibrosis. Other pulmonary fibroses are mainly represented by non-specific interstitial lung disease, pulmonary fibroses associated with connectivites, hypersensitivity pneumonitis, certain pneumoconiosis (occupational diseases) and sarcoidosis. The process of fibrosis is responsible for a loss of elasticity of the lung, leading to a decrease in lung volumes associated with an alteration of gas exchange. In these diseases, the clinician must be able to rely on reliable means to assess the severity of the disease based mainly on the measurement of lung volumes and gas exchange, at diagnosis and in the follow-up of the patient, in order to propose the most appropriate management. Lung volumes are assessed by respiratory function tests. Forced vital capacity is the reference volume value used. Impaired gas exchange is assessed at rest by measuring carbon monoxide diffusion capacity, arterial oxygen saturation and arterial blood gases. The functional capacity to exercise is also a very important evaluation criterion in terms of prognosis and in the follow-up of the patient. It is assessed by means of ergocycle tests which mainly determine the maximal oxygen consumption. These are relatively complex tests that require special equipment and are not routinely performed. Simpler field tests have been developed to assess functional capacity during exercise, the most widely used and validated being the 6-minute Walk Test (TM6). Other field tests to assess functional capacity to exercise have been developed, such as the 30-