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Figure3-2 Presentation of the data: (a) Flow; (b) Pressure; (c) Volume

 A close up on a few breaths in Figure 3-2 allows us to analyze the data: the time

series exhibits two different types of breath. As it was recorded from a patient under

assisted ventilation, it is composed of a sequence of segments belonging to two different

regimes: switching between the two regimes occurs rapidly: the patient either breathes in

one mode or the other.

 The first breath shown has a plateau in pressure and a flow at zero after the end of

the inspiration: it means that the inspiratory phase is finished, but the volume of air

delivered to the lungs is held inside by blocking the exhalation valve shut. The expiratory

phase is halted to create a distinctive shape that allows physicians to measure the

patient's lungs parameters. Indeed, as can be seen from (3.1), an analogy can be made

between this model and a simple electrical RC circuit. Therefore, the same methods used

for estimating values of components in an RC circuit from voltage waveforms can be


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