Dräger 84 13 050, Operating Instructions Manual

Page: 60 / 68

CPAP
Monitored by pressure sensor 5, 3/2 way valve 4
releases gas flow to demand valve 6 .
Inspiration/Expiration
Controlled by the patient's inspiratory effort, demand
valve
6 supplies the appropriate volume to the patient.
This supply is stopped when the patient decides to start
expiration.
The demand valve generates the desired CPAP pres-
sure in the patient circuit, using the PEEP/CPAP set
with PEEP valve
8 .
Pressure Support
During spontaneous breathing, the patient can trigger
pressure support which is controlled by a flow trigger
and 3/2-way valve
28 .
Demand valve 6 produces the desired pressure support
with the pressure set on PS-valve 29 .
Base flow
A base flow of about 5 L/min is supplied to the brea-
thing system.
If the gas supply fails, additional ambient air can be
drawn via an additional valve
23 . Airway pressure is
measured by pressure gauge 24 and pressure
sensor 25 .
Expiratory flow generates a proportional differential
pressure within flow sensor
15. It is measured with
differential pressure sensor 26 and used to determine
minute volume.
The automatic zero calibration of pressure sensor
26 is
carried out with 3/2 way valve 27 . The bi-stable 3/2 way
solenoid valve "Insp./Exp." 3 interrupts gas flow either
in a time-cycled fashion (at the end of inspiratory time)
or pressure controlled (when the set pressure P
max
is
reached).
Expiration/PEEP
The gas in the control line to the expiratory valve is
released via 2/2 way valve
21 to the endexpiratory
pressure level set with PEEP valve 8 .
The patient can then exhale via flow sensor 15 and
expiratory valve 14 to ambient air. The PEEP pressure
set with PEEP valve 8 is superimposed on expiratory
valve 14 .
CPAP
Pressure Support
Theory of Operation
60
Operating Instructions MicroVent
P
E
E
P
P
E
∆
P
E
PEEP
Paw
Paw
Flow
24
23 22
6
25 26
5
IPPV/
SIMV/CPAP
4
21
13
11
12 15
Patient
14
8 7
10
O
2
AIR
Gasmischer
O
2
/ AIR
1 2
3
9
Insp./Exsp.
27
28
ASB
29
O2/Air
Blender
Press.
Control
CMV
SIMV/CPAP