Gas supply
The O2 gas supply (or medical gas) is purified by filter 1
and regulated by pressure regulator 2 to a constant
pressure. The 3/2-way solenoid valve »Insp./Exp.« 3
releases the inspiratory gas flow in IPPV/SIMV in time
with ventilation frequency. Flow is regulated by the
electrically controlled flow valve 10.
The gas supply is routed to the 3/2-way solenoid valve
»Insp./Exp.« 3 and to demand valve 6 via the 3/2-way
valve »IPPV/CPAP« 4. The system pressure is routed via
solenoid valve 7 to PEEP valve 8 and monitored by
pressure sensor 9.
IPPV/SIMV / SIMV
Inspiration
The 3/2-way solenoid valve »Insp./Exp.« 3 releases the
gas flow. Flow is regulated by the electrically controlled
flow valve 10 and reaches ventilation hose 13 via the
2/2-way valve 11 or injector 12, as well as the patient
connection via breathing valve 14 and flow sensor 15.
Depending on the switching position of the 3/2-way
valve 16, 100% O2 is applied or the gas supply is diluted
to 60% O2. For this purpose, injector 12 takes in ambient
air via non-return valve 17, the 2/2-way valve 18 and air
inlet 19. The position of the »Air Mix / No Air Mix« switch
is monitored by pressure sensor 20.
The controlled 2/2-way valve 21 prevents the inspiratory
gas from escaping to the mechanical PEEP valve 8. The
pressure limiting valve 22 limits the inspiratory pressure
to a maximum value independently of the Pmax regulating
unit.
Ambient air can be drawn in additionally via the extra
valve 23 if the gas supply fails. The airway pressure is
measured by pressure gauge 24 and pressure
sensor 25.
The expiratory flow generates a proportional differential
pressure on flow sensor 15, which is measured by
differential pressure sensor 26 and used to determine the
minute volume.
Automatic zero calibration of differential pressure sensor 26
is carried out with 3/2-way valve 27. The 3/2-way solenoid
valve »Insp./Exp.« 3 interrupts the gas flow either time-
cycled – at the end of the inspiration time determined by
the ventilation frequency and ratio TI : TE – or pressure-
controlled when the set pressure Pmax is reached.
Expiration / PEEP
The gas in the ventilation hose 13 is released via the
2/2-way valve 21 to the end expiratory pressure set on
the PEEP valve 8.
The patient can exhale into the ambient air via flow
sensor 15 and breathing valve 14. The PEEP pressure
set on PEEP valve 8 is superimposed by the breathing
valve 14.
49
Description of operating principles
Gas supply
IPPV/SIMV / SIMV
P
E
P
E
E
P
P
E
∆P
E
PEEP
Paw
Paw
Flow
15
14
13
24
2322
6
25 26
5
IPPV/
SIMV/CPAP
4
21
87
10
O2
AIR
12
3
9
11
12
17
18
19
20
16
Insp./Exsp.
Air Mix/
No Air Mix
100%O
2
50%O2
27
04329033_2
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