GE Cardiocap 5 Service Manual

Measurement Parameters 
6.4.7 STP board—Invasive blood pressure measurement section 
Isolated +5 V voltage is supplied to the pressure transducer. From the bridge connection a differential 
voltage, which depends on pressure and supplied voltage, is calculated (see the formula below). 
Uout = Uin × Pressure × 5 V 
where Uin = 5 V 
Uout = 25 V × Pressure [mmHg] 
Pressure amplification is realized in the instrumentation amplifier. Gain of the amplifier is set so that 
the level of the signal transferred...

Cardiocap/5 Technical Reference Manual 
6.5 N-XOSAT or N-XNSAT optional pulse oximetry components 
6.5.1 Datex-Ohmeda enhanced pulse oximetry components (N-XOSAT option) 
The Datex-Ohmeda enhanced pulse oximetry option (N-XOSAT) consists of the following parts: 
• Sensor connector board and cable assembly 
• Datex-Ohmeda pulse oximetry board (OSAT board) 
• SpO2 interface board 
The measured SpO2, pulse rate values and status information are transmitted through the connector 
board/cable assembly to the...

Measurement Parameters 
6.5.2 Nellcor pulse oximetry components (N-XNSAT option) 
The Nellcor compatible pulse oximetry option (N-XNSAT consists of the following parts: 
• Sensor connector board and cable assembly 
• Nellcor pulse oximetry board (NSAT board) 
• SpO2 interface board 
Sensors can be plugged into the monitor directly or used with sensor extension cables available from 
Nellcor. Sensors plug into a 9-pin female connector (D-type) on the front of the monitor. This 
connector is mounted on a...

Cardiocap/5 Technical Reference Manual 
6.5.3 SpO2 interface board (for N-XOSAT or N-XNSAT option) 
 
Figure 6-18. SpO2 interface board block diagram 
NOTE:  Two switches located on the board are not used and have no function with the Cardiocap/5. 
RS485 drivers 
The SpO2 interface board contains drivers for data and for module reset functions. They drive the 
RS485-type serial communication bus between the pulse oximetry unit and the Central Unit. Data 
transmission speed of the bus is 500 kbps. 
In...

Measurement Parameters 
Opto isolation 
The serial communication bus signals between the pulse oximetry board and the Central Unit are 
transferred through the patient isolation section by high speed opto couplers. 
Microprocessor, UART, nonvolatile memory 
The microprocessor, with on-chip memory, converts and transfers data from the pulse oximetry board 
to the monitor.  
The UART provides bidirectional asynchronous serial communication between the pulse oximetry 
board and interface board CPU....

Cardiocap/5 Technical Reference Manual 
6.6 Airway gases and spirometry components 
Airway gas measurement involves the following components: 
• Gas sampling system 
• TPX measuring unit 
• OM measuring unit and OM board 
• PVX measuring unit and PVX board for Patient Spirometry (N-XV option) 
• CPU board 
6.6.1 Gas sampling system 
The gas sampling system draws a gas sample to the analyzers at a fixed rate. It also removes water 
and impurities from the gas sample. A sample line is connected to the...

Measurement Parameters 
 
Figure 6-20. Gas sampling system (N-XCO and N-XCAiO options) 
D-fendTM
The sample is drawn through a sampling line to the water trap, where it is separated into a main flow 
and a side flow. The main flow is drawn through into the analyzers. A hydrophobic filter separates this 
flow from the patient side. The side flow creates a slight subatmospheric pressure within the D-fend 
water trap, causing fluid removed by the hydrophobic filter to collect in the bottle. 
Zero valve...

Cardiocap/5 Technical Reference Manual 
Sample flow differential pressure transducer 
The sample flow differential pressure transducer measures pressure drop across the OM inlet restrictor 
and calculates sample flow from the pressure difference. 
Working pressure transducer 
The working pressure transducer measures absolute working pressure between the TPX unit and the 
OM unit. It is used for the “Occlusion,” “Check D-fend,” “Replace D-fend,” and “Check sample gas 
outlet” messages. 
Pneumatic unit...

Measurement Parameters 
6.6.2 TPX measuring unit  
The TPX unit is a non-dispersive infrared analyzer, measuring absorption of the gas sample at seven 
infrared wavelengths, which are selected using optical narrow band filters. The IR lamp is a 4W 
filament, surrounded by thermal isolation. A hole in the isolation passes the radiation to a conical,  
4 mm long measuring chamber.  
From the sample chamber, radiation goes into seven tubular light guides that have reflective inner 
surfaces. A thermopile...

Cardiocap/5 Technical Reference Manual 
6.6.4 PVX measuring unit and board (Patient Spirometry, N-XV option) 
NOTE: Never apply overpressure or negative pressure of more than 300 cmH2O to the flow and volume 
tubing. Differential pressure maximum is 25 cmH2O on one port at a time (when connecting tubes, for 
example). 
Patient Spirometry provides patient respiration monitoring capabilities using D-lite and Pedi-lite flow 
sensors. When Patient Spirometry is used, a special sensor (D-lite) replaces the...