Datex-Ohmeda S-5 Service Manual Datex S5
S/5
S/5
S/5
Datex-Ohmeda
Hemodynamic Modules
TM
PRESTN Module, M-PRESTN (Rev. 01)
TM
RESTN Module, M-RESTN (Rev. 01)
TM
PRETN Module, M-PRETN (Rev. 01)
Technical Reference Manual Slot
CAUTION: U.S. Federal law restricts this device to sale by or on the order of a licenced practitioner.
Datex-Ohmeda, Inc.
P.O. Box 7550, Madison
WI 53707-7550, USA
Tel: 1-608-221-1551 Fax: 1-608-222-9147
www.us.datex-ohmeda.com
mailto:product.support.ussub@us.datex-ohmeda.com
All specifications are subject to change without notice.
Outside the USA, check local laws for any restriction that may apply.
Document No. 8005571-1
Datex-Ohmeda Division, Instrumentarium Corp.
P.O. Box 900, FIN-00031
DATEX-OHMEDA, FINLAND
Tel: +358 10 394 11 Fax: +358 9 146 3310
www.datex-ohmeda.com
Instrumentarium Corp. All rights reserved.
April 2004
Table of contents
TABLE OF CONTENTS
S/5 Hemodynamic Modules
TABLE OF CONTENTS i
TABLE OF FIGURES iii
Introduction 1
1 Specifications 3
1.1 General specifications.......................................................................................................................... 3
1.2 Typical performance ............................................................................................................................. 3
1.2.1 NIBP ........................................................................................................................................... 3
1.2.2 ECG.............................................................................................................................................3
1.2.3 Pulse oximetry .............................................................................................................................4
1.2.4 Temperature................................................................................................................................4
1.2.5 Invasive blood pressure................................................................................................................5
1.2.6 Respiration.................................................................................................................................. 5
1.3 Technical specifications........................................................................................................................ 6
1.3.1 NIBP ........................................................................................................................................... 6
1.3.2 ECG.............................................................................................................................................6
1.3.3 Pulse oximetry .............................................................................................................................6
1.3.4 Temperature................................................................................................................................7
1.3.5 Invasive blood pressure................................................................................................................7
1.3.6 Respiration.................................................................................................................................. 7
2 Functional Description 8
2.1 Measurement principle......................................................................................................................... 8
2.1.1 NIBP ........................................................................................................................................... 8
2.1.2 ECG.............................................................................................................................................8
2.1.3 Pulse oximetry .............................................................................................................................8
2.1.4 Temperature..............................................................................................................................10
2.1.5 Invasive blood pressure..............................................................................................................10
2.1.6 Respiration................................................................................................................................ 10
2.2 Main components ..............................................................................................................................11
2.2.1 M-PRESTN/-RESTN/-PRETN modules .........................................................................................11
2.2.2 NIBP board................................................................................................................................ 12
2.2.3 ECG board in 12-lead measurement...........................................................................................15
2.2.4 ECG filtering...............................................................................................................................17
2.2.5 STP board..................................................................................................................................18
2.3 Connectors and signals ......................................................................................................................23
2.3.1 Module bus connector (on the NIBP board) ................................................................................. 23
2.3.2 Front panel connectors...............................................................................................................25
2.3.3 Test points on boards.................................................................................................................26
3 Service Procedures 29
3.1 General service information ................................................................................................................29
3.2 Service check..................................................................................................................................... 29
3.2.1 Recommended tools.................................................................................................................. 29
3.2.2 Recommended parts..................................................................................................................29
3.3 Disassembly and reassembly..............................................................................................................39
3.3.1 M-PRESTN/-RESTN/-PRETN modules .........................................................................................39
3.4 Adjustments and calibrations ............................................................................................................. 40
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Datex-Ohmeda S/5 monitors
3.4.1 NIBP calibrations....................................................................................................................... 40
3.4.2 Temperature calibration............................................................................................................. 42
3.4.3 Invasive pressure calibration...................................................................................................... 42
4 Troubleshooting 43
4.1 Troubleshooting charts ....................................................................................................................... 43
4.1.1 NIBP ......................................................................................................................................... 43
4.1.2 NIBP error code explanation....................................................................................................... 46
4.1.3 ECG .......................................................................................................................................... 47
4.1.4 Pulse oximetry (SpO2) ................................................................................................................ 47
4.1.5 Temperature.............................................................................................................................. 48
4.1.6 Invasive blood pressure ............................................................................................................. 49
4.1.7 Impedance respiration............................................................................................................... 50
4.2 Troubleshooting flowcharts................................................................................................................. 51
4.2.1 M-PRESTN module troubleshooting for NIBP parameter............................................................... 51
4.2.2 M-PRESTN module troubleshooting for parameters ESTPR........................................................... 52
5 Service Menu 53
5.1 NIBP service menu ............................................................................................................................. 54
5.1.2 NIBP demo menu....................................................................................................................... 55
5.1.3 NIBP calibration menu ............................................................................................................... 56
5.1.4 NIBP safety valve menu.............................................................................................................. 57
5.1.5 NIBP pulse valve menu .............................................................................................................. 58
5.1.6 NIBP buttons/leds menu............................................................................................................ 59
5.1.7 NIBP pneumatics menu ............................................................................................................. 60
5.1.8 NIBP watchdog menu................................................................................................................. 61
5.1.9 ECG service menu...................................................................................................................... 62
5.1.10 ECG setup menu.................................................................................................................... 64
5.2 STP service menu............................................................................................................................... 65
5.2.2 STP calibration menu................................................................................................................. 67
6 Spare Parts 68
6.1 Spare parts list................................................................................................................................... 68
6.1.1 M-PRESTN rev. 01, M-RESTN rev. 01, M-PRETN rev. 01 ............................................................... 68
7 Earlier Revisions 71
APPENDIX A 73
Service Check Form 1
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Table of contents
TABLE OF FIGURES
Figure 1 S/5 PRESTN Module, M-PRESTN........................................................................................................... 1
Figure 2 Absorption of infrared light in the finger probe parts layout and schematic diagram ................................. 9
Figure 3 Front panel of M-PRESTN....................................................................................................................11
Figure 4 NIBP board functional block diagram .................................................................................................. 12
Figure 5 NIBP pneumatics diagram ..................................................................................................................14
Figure 6 12-lead ECG measurement block diagram .......................................................................................... 15
Figure 7 STP board block diagram ....................................................................................................................18
Figure 8 Temperature measurement principle ...................................................................................................19
Figure 9 Pressure measurement principle.........................................................................................................20
Figure 10 Pulse oximetry measurement block diagram....................................................................................21
Figure 11 Serial communication of NIBP board............................................................................................... 22
Figure 12 Serial Communication and Isolation of STP board............................................................................22
Figure 13 Serial Communication and Isolation of ECG board ...........................................................................22
Figure 14 Module bus connector (X1) pin layout ............................................................................................. 23
Figure 15 ECG board connectors and test points............................................................................................. 26
Figure 16 NIBP board connectors and test points............................................................................................ 27
Figure 17 STP board connectors and test points ............................................................................................. 28
Figure 18 M-PRESTN module troubleshooting flowchart for NIBP Parameter..................................................... 51
Figure 19 M-PRESTN Module Troubleshooting Flowchart for Parameters ESTPR................................................52
Figure 20 Exploded view of M-PRESTN Module ...............................................................................................68
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INTRODUCTION
This Technical Reference Manual Slot provides information for the maintenance and service of the
hemodynamic modules S/5 M-PRESTN/-RESTN/-PRETN. The modules are double width modules
designed for use with S/5 monitors. Later in this manual modules may be referred to w/o the
system name S/5 for simplicity.
Please also refer to Technical Reference Manual of the S/5 monitor for information regarding
system specific information e.g. related documentation, conventions used, symbols on equipment,
safety precautions, system description, system installation, interfacing, functional check and
planned maintenance.
The M-PRESTN/-RESTN/-PRETN modules provide general hemodynamic parameters.
Auto
On/Off
NIBP
ECG
Start
Cancel
T1
SpO
P1
Zero
P1
S/5 M-PRESTN Modules
NOTE: Do not use identical modules in the same
Zero
P2
2
monitor simultaneously.
The following modules are considered identical:
M-ESTP/-EST/-ETP,
M-ESTPR/-ESTR/-ETPR,
M-NESTPR/-NESTR/-NETPR,
M-NE12STPR/-NE12STR/-NE12TPR
M-PRESTN/M-RESTN/M-PRETN
T2
P2
Figure 1 S/5 PRESTN Module, M-PRESTN
Table 1 Options of S/5 hemodynamic modules
Parameter PRESTN RESTN PRETN
P
R
E
S
T
N
Two invasive blood pressures
Impedance respiration
ECG
Pulse oximetry
Two temperatures
NIBP
•
• • •
• • •
• •
• • •
• • •
•
NOTE: 12-lead ECG measurement requires Display Controller, B-DISP or B-DISPX.
Intended purpose (Indications for use)
The Datex-Ohmeda PRESTN module (model family M-PRESTN) and accessories are indicated for
monitoring of hemodynamic parameters of all hospital patients. The hemodynamic parameters of
the module comprise ECG including ST-segment and arrhythmia, Impedance respiration, NIBP,
Temperature,SpO2 (including monitoring during conditions of clinical patient motion),and invasive
blood pressure.
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Impedance respiration measurement is indicated for patients aged 3 and up. The NIBP
measurement is indicated for patients who weigh 5kg (11 lb.) and up. This device is indicated for
use by qualified medical personnel only.
Monitor software compatibility
Datex-Ohmeda PRESTN rev. 01 module is designed for use with Datex-Ohmeda monitors using
software as follows:
AM: L-ANE01(A) or later versions;
CCM: S-00C01 rev. 10.5, S-00C02 rev. 10.5 or newer versions;
CAM: S-00A05 rev. 10.9, S-00A06 rev. 10.9, L-00A07 rev. 10.9, L-00A08 rev. 10.9 or newer
versions and
CCCM: S-00C03 rev. 10.9, S-00C04 rev. 10.9 or newer versions.
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1 SPECIFICATIONS
1.1 General specifications
Module size 75 × 180 × 112 mm
W × D × H 3.0 × 7.1 × 4.4 in
Module weight 0.7 kg / 1.5 lbs
Power consumption about 6 W
Operation temperature 10 to 40 °C / 50 to 104 °F
1.2 Typical performance
1.2.1 NIBP
NOTE: Non-invasive blood pressure measurement is intended for patients weighing over 5 kg (11
lb.)
S/5 M-PRESTN Modules
1.2.2 ECG
Oscillometric measurement principle.
Measurement range adult 25 to 260 mmHg
child 25 to 195 mmHg
infant 15 to 145 mmHg
Pulse rate range accepted 30 to 250 bpm
Measurement interval STAT (continuous 5 min), 1, 2.5, 3, 5, 10, 15, 30 and 60 min (1 h),
2 and 4 h
Typical measuring time adult 23 s
infant 20 s
Initial inflation pressure adult 170 ±10 mmHg
child 150 ±10 mmHg
infant 120 ±10 mmHg
Venous stasis adult 40 ±5 mmHg / 2 min
child 40 ±5 mmHg / 2 min
infant 30 ±5 mmHg / 1 min
Cuff widths please see User’s Guide
Lead selection, 12-lead ECG I, II, III, aVR, aVL, aVF, V1, V2, V3, V4, V5, V6
Lead selection, other modules I, II, III, aVR, aVL, aVF, V
Sweep speeds 12.5, 25, 50 mm/sec
DISPLAY FILTER
Diagnostic, 12-lead ECG 0.05 to 150 Hz
Diagnostic, other modules 0.05 to 100 Hz
Monitoring 0.5 to 30 Hz (-3 dB, with 50 Hz reject filter)
0.5 to 40 Hz (-3 dB, with 60 Hz reject filter)
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ST filter 0.05 to 30 Hz (-3 dB, with 50 Hz reject filter)
0.05 to 40 Hz (-3 dB, with 60 Hz reject filter)
HEART RATE FROM ECG
Range 30 to 250 bpm
Accuracy ±5 bpm or ±5 %, whichever is greater
Resolution 1 bpm
Update interval 5 s
Averaging time 10 s
ST LEVELS (in main software)
ST level range -9 to +9 mm (-0.9 to +0.9 mV)
Resolution 0.1 mm (0.01 mV)
Averaging calculated from 8 QRS
SYNCHRONIZATION
Direct ECG analog output of ECG, 1 V/1 mV
Pacer 5 V and 0.5 to 2.5 ms pulse, < 30 ms after pacer peak
Defibrillator 5 V and 10 ms pulse, < 35 ms after R-point synchronization
1.2.3 Pulse oximetry
Measurement range 0 to 100 %
Calibration range 70 to 100 %
Accuracy
1 100 to 70 %, ±2 digits
±3 digits during clinical patient motion
69 to 0 %, unspecified
Display resolution 1 digit = 1 % of SpO
2
Display averaging time 20, 10 sec, beat-to-beat
Pulse beep pitch varies with SpO
The monitor is calibrated against functional oxygen saturation SpO
2 level
func.
2
PULSE RATE FROM PLETH
Measurement range 30 to 250 bpm
Accuracy 30 to 100, ±5 bpm,
100 to 250, ±5 %
Resolution 1 bpm
Display averaging 10 s
Adjustable pulse beep volume.
PLETH WAVEFORM
Scales 2, 5, 10, 20, 50 mod%, Auto
Start up scale is 20 mod% if AUTO is not selected to be the default setting.
1.2.4 Temperature
Measurement range 10 to 45 °C (50 to 113 °F)
Measurement accuracy ±0.1 °C (25 to 45.0 °C)
1 Accuracy is based on deep hypoxia studies with volunteered subjects during motion and non-motion conditions over a wide range of arterial
blood oxygen saturations as compared to arterial blood CO-Oximetry.
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±0.2 °C (10 to 24.9 °C)
Display resolution 0.1 °C (0.1 °F)
Temperature test automatic (every 10 min)
Probe type compatible with YSI 400 series
Single use sensors ±0.2 °C (25 to 45.0 °C)
±0.3 °C (10 to 24.9 °C)
1.2.5 Invasive blood pressure
Measurement range -40 to 320 mmHg
Measurement accuracy ±2 mmHg or ±5 %
Zero adjustment range ±150 mmHg
Calibration range ±20 %
Scales upper limit is adjustable between 10 and 300 mmHg in steps of
10. Lower limit is 10 % of selected upper limit below zero.
Sweep speed 12.5, 25, 50 mm/s
DIGITAL DISPLAY
Range -40 to 320 mmHg
Resolution ±1 mmHg
S/5 M-PRESTN Modules
WAVEFORM DISPLAY
Range -30 to 300 mmHg
PULSE RATE FROM ARTERIAL PRESSURE
Measurement range 30 to 250 bpm
Resolution 1 bpm
Accuracy ±5 bpm or ±5 % whichever is greater
1.2.6 Respiration
NOTE: The respiration measurement is intended for patients over three years old
Measurement range 4 to 120 bpm
Accuracy ±5 bpm or ±5 %
Resolution 1 bpm
Averaging time 30 s
Update interval 10 s
RESPIRATION WAVEFORM
Sweep Speeds 6.25 mm/s and 0.625 mm/s
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Datex-Ohmeda S/5 monitors
1.3 Technical specifications
1.3.1 NIBP
Deflation rate, PR dep. 3 to 8 mmHg/s
Inflation time 20 to 185 mmHg, 1 to 5 s
Automatic software control, max. inflation pressure
adult 280 ±10 mmHg
child 200 ±10 mmHg
infant 145 ±5 mmHg
Over pressure limit, stops measurement after 2 seconds
adult 320 mmHg
child 220 mmHg
infant 160 mmHg
The safety circuit limits the maximum cuff pressure to 320 mmHg in adult/child mode or 160
mmHg in infant mode. Independent timing circuit limits pressurizing (>15 mmHg) time to 3 minutes
maximum in adult/child mode, and 90 seconds at (>5mmHg ) in infant mode.
Zeroing to ambient pressure is done automatically.
1.3.2 ECG
Inflation pressure is adjusted according to the previous systolic pressure, typically 40 mmHg
above. If the systolic pressure is not found, inflation pressure is increased typically 50 mmHg.
Max. measurement time adult 120 s
child 120 s
infant 75 s
Pressure transducer accuracy is better than ±3 mmHg or ±2 % whichever is greater.
Max. error ±4 mmHg.
Protection against electrical
shock Type BF defibrillation proof
Defibrillation protection 5000 V, 360 J
Recovery time 5 s
Input impedance >2.5 MΩ (10 Hz)
CMRR ≥95 dB (ST)
System noise <30 µV (p-p, RTI)
Allowable offset ±800 mVDC
Gain range 0.2 to 5.0 cm/mV
Pacemaker pulse detection 2 to 700 mV, 0.5 to 2 ms pulses
Protection against electrical
shock Type CF defibrillator proof
1.3.3 Pulse oximetry
Protection against electrical
shock Type BF defibrillation proof
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1.3.4 Temperature
Measurement accuracy ±0.1 °C (25.0 to 45.0 °C)
±0.2 °C (10.0 to 24.9 °C)
Protection against electrical
shock Type CF defibrillation proof
NOTE: The accuracy of the measurement may be different from the specified, depending on
transducer/probe used. Please refer to the transducer/probe specification.
1.3.5 Invasive blood pressure
DIGITAL DISPLAY AVERAGING
Digital displays Art and P1 are averaged over 5 seconds and updated at 5 seconds intervals. All
other pressures have respiration artifact rejection.
Accuracy ±5 % or ±2 mmHg, whichever is greater
Transducer and input sensitivity
5 µV/V/mmHg, 5 VDC, 20 mA max current
Filter 0 to 4 - 22 Hz adjustable
Zero set accuracy ±1 mmHg
Calibration resolution ±1 mmHg
Zero time less than 15 s
Protection against electrical
shock Type CF defibrillation proof
S/5 M-PRESTN Modules
NOTE: The accuracy of the measurement may be different from the specified, depending on
transducer/probe used. Please refer to the transducer/probe specification.
1.3.6 Respiration
Excitation frequency,
12-lead ECG 31.25 kHz
Breath detection automatic, range 0.3 to 6 Ω manually adjustable minimum
detection: 0.2, 0.4, 0.6, 0.8, 1.0
Input dynamic range 0.2 to 32 Ω
Input impedance range 100 to 5000 Ω
Respiration Rate min. 4 bpm
max. 120 bpm
Lead off detection >3 MΩ
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Datex-Ohmeda S/5 monitors
2 FUNCTIONAL DESCRIPTION
2.1 Measurement principle
2.1.1 NIBP
NIBP (Non-Invasive Blood Pressure) is an indirect method for measuring blood pressure.
The NIBP measurement is performed according to the oscillometric measuring principle. The cuff is
inflated with a pressure slightly higher than the presumed systolic pressure, and deflated at a
speed based on the patient’s pulse, collecting data from the oscillations caused by the pulsating
artery. Based on these oscillations, values for systolic, mean, and diastolic pressures are
calculated.
The following parts are necessary for the NIBP measurement:
• M-PRESTN/-RESTN/-PRETN module
• twin hose (adult or infant model)
• blood pressure cuffs (various sizes)
2.1.2 ECG
Electrocardiography analyzes the electrical activity of the heart by measuring the electrical
potential produced with electrodes placed on the surface of the body.
ECG reflects:
• electrical activity of the heart
• normal/abnormal function of the heart
• effects of anesthesia on heart function
• effects of surgery on heart function
See the User's Guide or the User’s Reference Manual for electrodes positions and other
information.
2.1.3 Pulse oximetry
A pulse oximeter measures the light absorption of blood at two wavelengths, one in the near
infrared (about 900 nm) and the other in the red region (about 660 nm) of the light spectrum. These
wavelengths are emitted by LEDs in the SpO
tissue and is finally detected by a PIN-diode opposite the LEDs in the probe. The pulse oximeter
derives the oxygen saturation (SpO
relative absorption at the two wavelengths and the arterial oxygen saturation SaO
In order to measure the arterial saturation accurately, pulse oximeters use the component of light
absorption giving variations synchronous with heart beat as primary information on the arterial
saturation.
probe, the light is transmitted through peripheral
2
) using an empirically determined relationship between the
2
.
2
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A general limitation of pulse oximetry is that due to the use of only two wavelengths only two
hemoglobin species can be discriminated by the measurement.
The modern pulse oximeters are empirically calibrated either against fractional saturation SaO
frac;
2
2
2
fracSaO
= Formula 1
HbO
2
++
binDyshemogloHbHbO
S/5 M-PRESTN Modules
or against functional saturation SaO
2
funcSaO
HbO
= Formula 2
Functional saturation is more insensitive to changes of carboxyhemoglobin and methemoglobin
concentrations in blood.
The oxygen saturation percentage SpO
against functional saturation SaO
measurement relative to SaO
carboxyhemoglobin in blood. Independent of the calibration method, pulse oximeters are not able
to correctly measure oxygen content of the arterial blood at elevated carboxyhemoglobin or
methemoglobin levels.
Plethysmographic pulse wave
The plethysmographic waveform is derived from the IR signal and reflects the blood pulsation at the
measuring site. Thus the amplitude of the waveform represents the perfusion.
Pulse rate
The pulse rate calculation is done by peak detection of the plethysmographic pulse wave. The
signals are filtered to reduce noise and checked to separate artifacts.
func;
2
2
HbHbO
2
+
measured by the Datex-Ohmeda module is calibrated
2
func. The advantage of this method is that the accuracy of SpO2
2
func can be maintained even at rather high concentrations of
2
Probe
The standard probe is a finger clamp probe which contains the light source LEDs in one half and the
photodiode detector in the other half. Different kinds of probes are available from Datex-Ohmeda.
SpO2 sensor connector
6
GND
7
ILED
4
GND
5
DEF_A
8
IS
9
DET_C
PRSTN_absorption_of_infrared.vsd
Emitter
Detector
SpO2 sensor cable
IRED
RED
Figure 2 Absorption of infrared light in the finger probe, parts layout and schematic
diagram
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Datex-Ohmeda S/5 monitors
2.1.4 Temperature
The temperature is measured by a probe whose resistance varies when the temperature changes,
called NTC (Negative Temperature Coefficient) resistor.
The resistance can be measured by two complementary methods:
• Applying a constant voltage across the resistor and measuring the current that flows
through it
• Applying a constant current through the resistor and measuring the voltage that is
generated across it.
In Datex-Ohmeda modules the two methods are combined in the form of a voltage divider. The NTCresistor is connected in series with a normal resistor and a constant voltage is applied across them.
The temperature dependent voltage can be detected at the junction of the resistors, thus producing
the temperature signal from the patient. The signal is amplified by analog amplifiers and further
processed by digital electronics.
2.1.5 Invasive blood pressure
To measure invasive blood pressure, a catheter is inserted into an artery or vein. The invasive
pressure setup, consisting of connecting tubing, pressure transducer, an intravenous bag of normal
saline all connected together by stopcocks, is attached to the catheter. The transducer is placed at
the same level with the heart, and is electrically zeroed.
The transducer is a piezo-resistive device that converts the pressure signal to a voltage. The monitor
interprets the voltage signal so that pressure data and pressure waveforms can be displayed.
2.1.6 Respiration
Impedance respiration is measured across the thorax between ECG electrodes. The respiration
signal is made by supplying current between the electrodes and by measuring the differential
current from the electrodes. The signal measured is the impedance change caused by breathing.
From these impedance changes, respiration rate is calculated, and the respiration waveform is
displayed on the screen.
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2.2 Main components
2.2.1 M-PRESTN/-RESTN/-PRETN modules
Auto
Start
Zero
On/Off
NIBP
ECG
Cancel
T1
T2
SpO
P1
P2
Zero
P1
P2
2
S/5 M-PRESTN Modules
Figure 3 Front panel of M-PRESTN
The M-PRESTN, M-RESTN, and M-PRETN modules contain three main PC boards, the STP board,
the ECG board, and the NIBP board. They work independently. Each of these has their own
processor and software in the processor flash memory.
There are two small boards, the SP input and the ECG input board attached to the front panel of the
module. The front panel has seven connectors and four keys. The connectors are two for
temperature measurement, two for invasive blood pressure measurement, one for ECG, one for
NIBP, and one for SpO
measurement. The keys are for NIBP Auto On/Off, NIBP Start/Cancel, P1
2
zero, and P2 zero.
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2.2.2 NIBP board
PATIENT AND NIBP CUFF
NIBP TUBING
NIBP CONNECTOR
NIBP PNEUMATICS
NIBP CONTROL KEYS
NV MEMORY
MAIN CPU
PRESSURE SENSORS
RS 485 COMMUNICATION POWER SUPPLY
DRIVERS FOR PUMP &
VALVES
SAFETY CPU
NIBP BLOCK DIAGRAM
Figure 4 NIBP board functional block diagram
Signal processing
Two signals from the pressure transducers are amplified and sent to the A/D converter. After the
converter, digitized signals are sent to the microprocessor for data processing.
The NIBP board is controlled with a H8/3052 microprocessor at 16 MHz oscillator frequency.
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MODULE BUS CONNECTOR
Memory
NIBP program memory (processor flash memory) size is 512k × 8. The processor has 4 kBytes RAM
and there is also an external RAM memory the size of which is 128k x 8. Variable values of the NIBP
measurement are stored into the external RAM. The EEPROM size is 512 x 8 and it is used to store
the calibration values for the pressure transducers, the pulse valve constants gained during
measurements, the PC board identification, and module serial number.
Software control
Software controls valves and pump. In addition to the individual on/off signals for each component
there is a common power switch for the valves and the pump that can be used at pump/valve
failures.
In addition to external RS485 reset line the microprocessor system is equipped with its own powerup reset. See the section in the ECG board’s description:
Safety circuit
The NIBP board is equipped with an independent safety circuit to disconnect supply voltages from
the pump and the valves if the cuff has been pressurized longer than the preset maximum
measurement time, or if the pressure of the cuff is inflated over the specified pressure limit. The
maximum measurement time values and pressure limits for different measurement modes have
been specified in the technical specification section of this manual.
S/5 M-PRESTN Modules
“RS485 communication”
Pneumatics
Pneumatics of PRESTN module has the following parts:
Intake air filter; for preventing dust and other parts to enter the air pump and the
•
valves.
Air pump: for pumping the measuring pressure of the cuff.
•
• (
•
•
•
Pulse) Valve; for producing a linear pressure fall (bleeding) in order to measure the
blood pressure of the patient.
Note that there has been used also two other names
designate pulse valve in service menu.
Safety valve; The safety valve has been intended to be used for deflating the cuff in
single fault case, i.e. to prevent too long measurement time or too high inflation
pressure of the cuff.
Note that there has been used also
service menu.
Main pressure sensor; for measuring the pressure of the blood pressure cuff and
the pressure fluctuations caused by arterial wall movement.
Safety pressure sensor for detection of cuff hose type, cuff loose, cuff occlusion
situations etc.and recognising the pressure sensor fault.
Exh2 valve to designate the Safety valve in
Valve and Set valve to
Cuff connector; for connecting the cuff.
•
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Cuff connector
Safety pressure sensor
Proportional valve
Air pump
Main pressure sensor
Figure 5 NIBP pneumatics diagram
Power supply section of the NIBP board
All connections are established via 25-pin connector (D-type, female). The module needs +15 V
(dirty) power supply to operate. The supply voltage (+15V) is generated in the power supply section
of the S/5 monitor. The other voltages needed for the operation of the NIBP measurement are
made on the NIBP board.
Dump valve
Intake air filter
NIBP_pneum_diagr.vsd
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2.2.3 ECG board in 12-lead measurement
The 12-lead ECG measurement consists of the elements shown in Figure 6. All functions are
located in the ECG board except the ECG input unit .
PATIENT AND ECG ELECTRODES
ECG CABLE
- ECG LEAD SET
- ECG TRUNK CABLE
ECG INPUT UNIT
- ECG CONNECTOR
- INPUT PROTECTION RESISTORS
INPUT PROTECTION DIODES FOR ECG & RESPIRATION MEASUREMENT
INPUT FILTERING FOR ECG & RESPIRATION MEASUREMENTS
S/5 M-PRESTN Modules
RESPIRATION
MEASUREMENT
AMPLIFIERS
RS 485 COMMUNICATION POWER SUPPLY
ISOLATION ISOLATION
MODULE BUS CONNECTOR
RESPIRATION
MEASUREMENT CURRENT
SUPPLY
ECG CPU
ECG PREAMPLIFIERS &
RLD CIRCUIT
BASELINE
RESTORATION
NV MEMORY
ECG BLOCK DIAGRAM
LEADS OFF & PACER &
DEFIBRILLATION
DETECTION
Figure 6 12-lead ECG measurement block diagram
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ECG input unit
The ECG input unit consists of the front panel connector and the ECG input connector board with
the high voltage protection resistors. The connector for the 12-lead ECG cable is a green 11-pin
rectangle shaped connector.
Input protection and filtering
The input protection is implemented with high voltage protection resistors in the ECG input unit and
with protection diodes in the ECG board. The input filtering for ECG measurement is done with
passive RC filtering.
ECG preamplifiers
The buffer amplifiers are used for each lead. The “Leads off” detection is implemented by
measuring the output level of the input buffer amplifiers with A/D converter of CPU. The ECG signals
are measured using differential amplifiers.
ECG amplifiers and baseline restoration
The function of the ECG amplifiers and baseline restoration is to amplify the signal and to restore
the baseline of the signal in the middle of the display after the change of the signal level e.g. after
the change of the DC offset voltage.
Pacer detection
Pacer detection has been made by using three slew rate detector circuits. The pacer detection
amplifiers have been realized at the front of the slew rate detectors independently from the ECG
measuring channels.
Respiration impedance supply
The 31.25 kHz sine wave generator is used as the respiration measurement signal supply. Analog
switches are used for connecting the sine wave to the ECG leads to be measured.
Respiration impedance amplifiers
Buffer amplifiers are used in respiration measurement. Analog switches are used for selecting the
measurement leads. There are also additional amplifiers for increasing the respiration signal gain.
When ECG measurement is 5/12-lead, the respiration measurement is always done between R
and F, independently on the ECG lead selection. When ECG measurement is 3-lead, then the
respiration measurement is done at the same lead as the ECG measurement (I, II or III).
ECG CPU
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The CPU is a 16 bit H8/3052 single-chip microcomputer. It contains 128 kbytes of flash memory
and 4 kbytes of RAM. The clock frequency is 16 MHz.
RS485 communication
The communication to the CPU board of the monitor uses RS485 protocol. The RS485 driver
circuits are optically isolated from the processor of the module. PWM signal is used for direct ECG
signal. Direct ECG signal is available from the X2 connector of the UPI board or from the PT module.
Power supply
The ECG board has a driver controlled half bridge switching power supply with 5 kV isolation. The
supply voltages have been regulated with linear regulators.
2.2.4 ECG filtering
The S/5 monitors have three ECG filtering modes:
MONITORING 0.5 to 30 Hz (with 50 Hz reject filter)
0.5 to 40 Hz (with 60 Hz reject filter)
DIAGNOSTIC 12-lead ECG 0.05 to 150 Hz
ST FILTER 0.05 to 30 Hz (with 50 Hz reject filter)
0.05 to 40 Hz (with 60 Hz reject filter)
S/5 M-PRESTN Modules
The purpose of filtering is to reduce high frequency noise and low frequency (e.g. respiratory)
movement artifacts.
Monitor filter is used in normal monitoring. Diagnostic filter is used if more accurate diagnostic
information is needed. ST filter gives more accurate information of ST segment, but reduces high
frequency noise.
The high-pass filters 0.5 Hz and 0.05 Hz are done with software. The monitor sends a command to
the hemodynamic module determining which of the corner frequencies 0.5 Hz or 0.05 Hz is to be
used.
The 50 Hz and 60 Hz reject filters are both low-pass filters with zero at 50 Hz or 60 Hz
correspondingly. They are software based filters used for the mains supply filtering. With these
filters the 3 dB value for low-pass filter is 30 Hz or 40 Hz.
In diagnostic mode the upper frequency is 150 Hz and it is limited by software.
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2.2.5 STP board
PATIENT AND SpO2 PROBE
SpO2 TRUNK CABLE
SpO2 CONNECTOR
SpO2 PROBE RECOGNITION & LED
DRIVE SELECTION MATRIX
SpO2 LED DRIVE
SpO2 AMPLIFIER
PATIENT AND TEMPERATURE
SENSOR
TEMPERATURE CONNECTOR
TEMPERATURE
MEASUREMENT
AMPLIFIER
A/D CONVERSION
SENSOR
SIGNAL
CURRENT
SOURCE
PATIENT AND INVASIVE CANNULA
PRESSURE SENSOR WITH DOME
INV: PRESSURE
MEASURE MENT
OR CATHETER
FLUSHING KIT & INVASIVE
INV.PRESSURE CONNECTORINPUT PROTECTION CIRCUITRY
SENSOR SIGNAL
AMPLIFIER
VOLTAGE
SOURCE
STP CPU
NV MEMORY
RS 485 COMMUNICATION POWER SUPPLY
ISOLATION ISOLATION
MODULE BUS CONNECTOR
STP BLOCK DIAGRAM
Figure 7 STP board block diagram
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Microprocessor unit
The CPU is a 16 bit H8/3052 single-chip microcomputer. It contains 128 kbytes of flash memory
and 4 kbytes of RAM. The clock frequency is 16 MHz.
High speed I/O is used to obtain pulse control sequence necessary for pulse oximetry
measurement. Timing for the clock is from the oscillator.
Temperature measurement unit
The NTC-resistor value in the probe depends on the patient’s temperature. It is measured with the
following principle described below.
The constant current source is supplied about 7µA current through the temperature sensor (YSI
400-series NTC resistor). The constant current is caused a voltage over the temperature sensor
(NTC resistor). The voltage over the temperature sensor is amplified in a differential amplifier stage.
The amplified voltage is transferred to a controller of the STP board through an A/D converter.
Defibrillation/ESD protection
resistors and diodes
S/5 M-PRESTN Modules
constant
current
source
Temperature
sensor
Figure 8 Temperature measurement principle
100k
10k
0C:7k36
15C:3k54
25C:2k53
38C:1k30
45C: 984
10k
100k
Differential
amplifier
d/dt
0
0
0
0
To A/D
converter
temp_meas_principle.vsd
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Invasive blood pressure measurement unit
An isolated +5 V voltage is supplied to the pressure transducer. The differential voltage, which
depends on the pressure and the supplied voltage, is calculated from the bridge connection (see
the formula below).
U
= Uin × pressure × 5 V, where Uin is 5 V
out
⇒ U
= 25 V × pressure [mmHg]
out
Pressure amplification is realized in the instrumentation amplifier. The gain of the amplifier is set to
keep the level of the signal transferred to A/D converter within the measurement range even when
there are circumstantial offsets or offsets caused by the transducer. There is a filter before the
amplifier to attenuate high frequency disturbances.
Vin
Pressure
transducer
Vout
Figure 9 Pressure measurement principle
Pulse oximetry measurement section
LED control signals
The D/A converters of the microcontroller on STP board set the LED intensity adjustment values for
the infrared- and red LEDs of SpO2 probe. The microcontroller on the STP board switches ON ( to
the adjusted intensity ) and OFF the SpO2 probe LEDs according to the predetermined sequence.
Input
Filter
Instrumentation
amplifier
G
to AD converter
pressure_meas_principle.vsd
LED driving circuit
Differential amplifiers measure the LED currents (LED current indication) of SpO2 probe over the
shunt resistors placed in the LED current paths. The LED driving voltages (LED voltage indication)
are measured from the driver circuitry. The LED driving circuits also have MOSFET transistor matrix
to enable the use of different probe configurations.
Measured signal preamplification
The preamplifier is bipolar/single-ended current-to-voltage converter with adjustable gain. A higher
gain is used for measuring thin tissue. The preamplification stage has also ambient light reduction
and second amplifier stage.
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