F. Grianti et al., A VERSATILE MECHANICAL VENTILATOR (DIGIT) WITH HIGH-FLOW STABILITY AND A PROGRAMMABLE INSPIRATORY PHASE FLOW PATTERN, IEEE transactions on biomedical engineering, 43(11), 1996, pp. 1062-1072
The paper describes the general characteristics of a newly developed n
onconstant-flow generator for automatic ventilation of the lungs, It i
s known that the application of very high pressure to high internal re
sistance leads to a very stable flow; in that the flow itself is unaff
ected by external load (patient) variations. The stability of the how
means that the inspiratory process can be controlled by means of the v
entilated volume, thus extending DIGIT utilization to high resistance
patients, The modulation of the flow is implemented via a digital elec
tromechanical system, which allows the ventilator functions to be accu
rately programmed, The desired how waveform is obtained by means of a
series of pneumatic valves, the apertures of which are digitally contr
olled. The design is innovative in that it allows the flow waveform in
each of the ten digitalized time steps into which each inspiratory ph
ase is divided to be both programmed and controlled. Other ventilators
commercially available and currently in use do not have this function
al capability, as they are all designed to model the integral flow of
the inspiratory waveform without being able to modify the subunit time
steps of a single inspiratory phase. The paper also discusses the res
ults of fundamental tests concerning the performance characteristics o
f the ventilator.