To set up a pulmonary function laboratory that can measure all standard and dynamic lung vol-umes, which of the following equipment is necessary?

a. Screen pneumotachograph and inductive plethysmograph
b. Fleisch pneumotachograph and peak flowmeter
c. Vortex ultrasonic flowmeter and inductive plethysmograph
d. Stead-Wells spirometer and con-stant-volume plethysmograph

ANS: D
The Stead-Wells spirometer measures volumes and flows, whereas the constant-volume plethys-mograph (the most common plethysmograph used) measures functional residual capacity. These two devices are able to measure all the volumes and flows necessary for full pulmonary function studies. The screen, Fleisch, and vortex ultrasonic pneumotachographs are unidirectional and are not able to measure inspiratory and expiratory flow simultaneously. Inductive plethysmography will provide respiratory rate and volume only, and is used in sleep laboratories.