Siemens Servo Ventilator 300, Service Manual

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Servo Ventilator 300/300A Description of functions
E382 E380E 061 01 03 01 Siemens-Elema AB 49
2
6 Reference & Timing
This main block consists of the board
PC 1605
REFERENCE
&
TIMING
including its
PC 1588
MICROPROCESSOR MODULE
.
6.1 Mode CPU including REF-
PROM functions
This block includes the board PC 1588 with a
REF
-
PROM
. Some details of the Microprocessor
module PC 1588 are mentioned in section
General in this chapter. The
REF
-
PROM
functions
contain the different algorithms for the
breathing pattern in different Modes.
The description of this block function is
divided below into two principle block parts:
• 6.1.1 Reference generation
• 6.1.2 Respiratory timing.
6.1.1 Reference generation
A reference signal is generated for inspiratory
control. During Inspiration time the signal is in
principle a constant level according to front
panel settings. This level is reached via a
linear slope which covers a certain rise time
according to Insp rise time %, Front panel
setting. During Expiration time the signal is
another constant level.
The signal is handled in one of two different
ways depending on if flow regulation or
pressure regulation is used. The same signal
is therefore referred to with two different
signal names in the block diagram. The signal
names are:
•
FLOW REGULATION FLOW REF
for flow regulation.
•
PRESSURE REGULATION PRESSURE REF
for pressure
regulation.
Flow regulation
For flow regulation the signal
FLOW REGULATION
FLOW REF
is directly used by the block 7.3
MIXER
in the main block 7
INSPIRATORY CONTROL
as
reference for the total flow.
Flow regulation is used during expiration time
in all modes. The constant flow during
expiration time depends on the selected
patient range. Ref. block 1.1 Patient range
selection.
Flow regulation is used during inspiration time
in Volume Control mode and during
inspiration time for the mandatory breaths in
SIMV (Vol. Contr.) mode as long as ”on
demand flow” is not activated. As long as
flow regulation is active
FLOW REGULATION
FLOW REF
=
Minute vol. (front panel setting)
Insp. time % (front panel setting)
Note – For the case when Insp rise time is in
use above formula actually gives the mean
value of
FLOW REGULATION FLOW REF
during the
time this flow regulation is active. This
implies that the constant (end insp.) value of
FLOW REGULATION FLOW REF
is somewhat higher.