Vitalograph has used many different precision technologies for measuring flows and volumes. In the early days of office spirometry these included measurement of volume by water displacement and the displacement of volumes by mechanical movement, including bellows, rolling seals and precision syringes which are still used as reference devices.
Today, flow measuring technology predominates in modern office spirometers and respiratory monitors because the technologies tend to be less expensive and of smaller size.
Lilly or Fleisch technologies are used in professional grade flow measuring spirometers. Lilly type, which may be single or multi-screen, are no longer used in Vitalograph devices.
Stator-rotor devices are used for less robust and accurate devices such as screeners and monitors. Such devices are also difficult to clean and their limited life makes them unsuitable for satisfactory spirometry examinations, although they are ideal for screening and are cheap to replace.
Vitalograph have used and explored many other flow measuring technologies including heated pneumotachs, platinum wire anemometers, ultrasonic ‘time of flight’ flowmeters, orifice plates, vortex shedders, variable orifice flowmeters and others, many of which can perform well in metrology laboratory conditions with frequent recalibration and linearity setting, but none of these perform satisfactorily in the conditions encountered in routine office spirometry.
The preferred flow measuring technology used today by Vitalograph in diagnostic spirometer devices is the Fleisch pneumotachograph.
The Fleisch pneumotachograph is an established technology, developed by Professor Alfred Fleisch in Lausanne in 1953. It makes an accurate, linear and reliable type of flow measurement spirometer as the linear signal is simple to process and the device is extremely robust.
The flow measuring technology used by Vitalograph in its monitoring and screening devices is the stator rotor. Stator-rotor devices are used for less robust and accurate devices such as screeners and monitors.