A pneumograph, also known as a pneumatograph or spirograph, is a device for recording

velocity Velocity is the directional speed of an object in motion as an indication of its rate of change in position as observed from a particular frame of reference and as measured by a particular standard of time (e.g. northbound). Velocity is a ...

and force of chest movements during

respiration Respiration may refer to: Biology * Cellular respiration, the process in which nutrients are converted into useful energy in a cell ** Anaerobic respiration, cellular respiration without oxygen ** Maintenance respiration, the amount of cellula ...

Principle of operation

There are various kinds of pneumographic devices, which have different principles of operation. In one mechanism, a flexible rubber vessel is attached to the chest. The vessel is equipped with sensors. Others are impedance based. In these methods, a high frequency (tens to hundreds of kHz) low amplitude current is injected across the chest cavity. The voltage resulting from this current injection is measured and the resistance is derived from the application of Ohm's law (R = V/I). Current flows less easily through the chest as the lungs fill, so the resistance rises with increasing lung volume.Grenvik et al., (1973). "Impedance Pneumography: Comparison between Chest Impedance Changes and Respiratory Volumes in II Healthy Volunteers", ''Chest'', 62:439-443.

References

External links

Detailed article on pneumography (1905)

Measuring volume and flow
Respiratory system procedures Medical testing equipment {{medical-equipment-stub