lung and airway disorders
Pulmonary Function Testing (PFT)
Lung volume measurement
Lung volume measurements reflect the stiffness or elasticity of the lungs and rib cage as well as the strength of Respiratory muscles . The lungs are abnormally stiff in disorders such as Lung volume measurements made using spirometry are only estimates. More accurate measurements can be made using Body plethysmography Gas dilution In body plethysmography, a person sits inside an airtight plastic box. Because the box is airtight, the volume of air the person breathes in and the change in air pressure during breathing can be measured. A computer calculates lung volumes based on these measurements. Using gas dilution, a person breathes in a known amount of a gas, usually helium. A computer calculates lung volume based on how much gas the person exhales. 