The coming of age of "fluidics" (fluid amplifiers, fluid logic) has resulted in the application of this new technology to the construction of mechanical ventilators. The most sophisticated fluidic apparatus presently available weighs less than 5 kg and is 6 × 14 × 24 cm in size. Basically, it consists of six fluid-logic cells which permit tidal volume and respiratory frequency to be adjusted independently. The unit is driven by compressed gas, and only 500 ml/min in excess of the desired minute volume are consumed during operation. This unit has been readily adapted to the clinical requirements of humidification, adjustment of inspired oxygen concentration, and monitoring of expired volume and airway pressure. Tested under rigorous laboratory control, during normal use and under stress conditions, this ventilator performed as well as other conventional, well-accepted machines.
Weitzner SW, Urban BJ. A New Ventilator Utilizing Fluid Logic. JAMA. 1969;207(6):1126–1130. doi:10.1001/jama.1969.03150190048010