Biomedical Engineering Reference
In-Depth Information
Fig. 12.17 Target ( dotted
line ) and generated ( solid
line ) medium inspiratory
profi le for a DPI to validate
the breathing simulator-
mixing inlet-CI measurement
system described by Olson
et al. ( From [ 55 ] —used with
permission )
80
60
Flow
Rate
(L/min)
40
20
0
0
1
2
Time (s)
3
4
Fig. 12.18 Schematic diagram of the Miller mixing inlet interfaced with an MDI and associated
VHC
breathing [ 56 ]. Such a system is illustrated in Fig. 12.18 , where it should be noted
that there is two-way fl ow into and out of the breathing simulator, refl ecting the
incorporation of the expiratory portion of the breathing cycle. In this setup, the
selected breathing profi le, Q br-sim ( t ), which could be either patient-generated or an
idealized waveform, is shown with maximum inspiratory fl ow rate defi ned by the
PIFR. The precise form of the exhalation profi le is less important, as its function is
to close the inhalation and open the exhalation valve (if equipped) of the VHC on
test. However, its duration should refl ect the expected duty cycle (inspiratory time
as a percentage of the total time for the breathing cycle) for the patient age group
being modeled (i.e., 33 % for an adult, 25 % for a child).
 
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