1
The lung resistance R and its compliance C =
 E


are considered constant, although


in reality they are not and their variations actually are one source of non-stationarity.


Figure3-1 Real world data set: (a) Flow; (b) Pressure; (c) Volume

 Figure 3-1 shows the four basic descriptive parameters of mechanical ventilation:

flow, pressure, volume and time. The data set is not shown in its entirety (30,000

samples) but the extract is representative. The series was composed of two sensors'

recordings (flow and pressure) and a computed quantity (volume) performed at a rate of

100 Hz, which can be an oversampling when the "periodicity" of the signal is often less

than a breath per second. The original data was oversampled for a fitting by a linear filter,

therefore we chose to downsample it to 50 Hz (to be able to perform linear modeling and

still have enough data for non-linear model training). The volume graph will only be

shown in this chapter, since it is usually not a measurement but a calculated integration of

the values shown in the flow graph, and therefore it does not bring any more information.


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