Service manual

Service Manual Technical Overview 113
Capnography (CO
2
)
Two capnography (CO
2
) monitoring options are available—the mainstream -sampling CO
2
option (MCO
2
) and the sidestream-sampling CO
2
option (SCO
2
).
Both mainstream CO
2
and sidestream CO
2
options are available in one product. However,
only one sampling method may be monitored at any time—simultaneous monitoring of
MCO
2
and SCO
2
is not supported.
The mainstream CO
2
circuit board (MSP) supports all mainstream and Sidestream
applications and is the major interface between the printer and SpO
2
hardware in certain
configurations of the Expansion Module. The MSP board replaces the SCP board in SpO
2
applications with CO
2
. For sidestream-only applications, an MSP board version without
mainstream hardware is used. For both mainstream and sidestream applications, the
MSP board is mounted within the rear panel of the Expansion Module housing.
Mainstream CO
2
Option. In the mainstream sampling method, the CO
2
analysis
chamber (commonly referred to as the “bench”) is an integral part of the mainstream
sensor which is located in-line, between the patient’s airway and the ventilator circuit
via an airway adapter. The patient’s expired gas is sampled directly from the patient’s
airway. The MSP board interfaces the external mainstream sensor to the Propaq
monitor.
Sidestream CO
2
Option. In the Sidestream sampling method, the bench is located on
the Stick board within the Propaq monitor. A sample of the patient’s expired gas is
aspirated from the airway and is drawn to the bench through a sampling line
containing a water trap. The Stick board also contains pneumatic tubing that connects
to the SSP board. The Stick board is mounted on the Sidestream Processor board
assembly (SSP board) which interfaces the Stick board to the Propaq monitor. The
SSP/Stick board assembly is mounted within the front bezel of the Expansion Module
housing of the Propaq monitor.
System Interface. The SSP board power and communication is obtained via the extender
board that connects to the MSP board. The extender board routes datalines from the
MSP board and contains additional power supplies for powering the SCO
2
boards.
The Main Stream Processor circuit board (MSP board) is the major interface connection
between several subsystems in the Expansion Module. This circuit board connects
directly to the expansion connector, providing a direct interface to a Propaq Encore
Display Processor system.
The MSP board also supports:
•Main Stream CO
2
• an interface to the SpO
2
system
• an interface to the Printer option
• an interface to sidestream CO
2
Mainstream Board
The MSP board is divided into isolated and non-isolated circuitry. See the figure below.
Non-Isolated Circuitry. The Non-Isolated circuitry on the MSP board interfaces with the
Propaq Encore, the printer, the speaker, P6 and P7 expansion connectors, and with
the Main Stream Processor which resides on the isolated section of the MSP board.