Photoelectric-helicoidal spirometer

This paper describes a photoelectric-helicoidal spirometer that has been designed in our laboratory. It includes a cylindrical helix (or turbine) partitioned in each of its blades by means of opaque plates transversally disposed. These plates obstruct the ray of light emitted by a diode, preventing it from reaching a photoreceptor located at the opposite side of the turbine. These basic elements are located in a module that can be adjusted to a mask that covers nostrils and mouth. Control software for this device is also described. The software facilitates a graphical representation of respiratory activity, as well as its storage in the computer. Software has been designed to be adaptable to any digital-to-analog converter. Both the device and the software have several advantages over traditional spirometers, as well as other nonspirometric techniques for studying respiratory activity.