TI

TI is an acronym for Tiffneau's index. Tiffneau's index (TI) is the ratio between FEV1 and FVC. In spirometry, we measure Forced Vital Capacity (FVC), which represents the volume of exhaled air after a maximum long inhale. When performing FVC, Forced Expiratory Volume in the first second (FEV1) is also measured, which is the volume of air that a person exhales in the first second of FVC. The ratio between FEV1 and FVC is called Tiffneau's index, which in a healthy person is above 75%, meaning that a person with healthy lungs can exhale 3/4 of the air from the lungs in the first second of forced exhalation. These values may vary depending on various factors, such as age, gender, and body height and weight.