S5 Hemodynamic Modules Technical Reference Manual Slot June 2001

Table of contents

TABLE OF CONTENTS HEMODYNAMIC MODULES TABLE OF CONTENTS

i

Table of figures

iii

Introduction

1

1

2

Specifications

1.1 General specifications ...2 1.2 Typical performance ...2 1.2.1 NIBP ...2 1.2.2 ECG ...3 1.2.3 Pulse oximetry...3 1.2.4 Temperature...4 1.2.5 Invasive blood pressure ...4 1.2.6 Respiration ...4 1.3 Technical specifications...5 1.3.1 NIBP ...5 1.3.2 ECG ...5 1.3.3 Pulse oximetry...6 1.3.4 Temperature...6 1.3.5 Invasive blood pressure ...6 1.3.6 Respiration ...6

2

Functional Description

7

2.1 Measurement principle ...7 2.1.1 NIBP ...7 2.1.2 ECG ...7 2.1.3 Pulse oximetry...7 2.1.4 Temperature...9 2.1.5 Invasive blood pressure ...10 2.1.6 Respiration ...10 2.2 Main components...10 M-ESTPR/-ETPR/-ESTR modules...10 M-NE12STPR/-NE12STR/-NE12TPR/-NESTPR/-NESTR/-NETPR modules ...11 2.2.3 NIBP board ...12 2.2.4 ECG board in 3-and 5-lead measurement...14 2.2.5 ECG board in 12-lead measurement ...16 2.2.6 ECG filtering ...18 2.2.7 STP board ...19 2.3 Connectors and signals...24 2.3.1 Module bus connector ...24 2.3.2 Front panel connectors ...25 2.3.3 Test points on boards ...26

3

Service Procedures

28

3.1 General service information...28 3.2 Service check ...28 i Document No. 800 1008-2

Datex-Ohmeda S/5 monitors 3.2.1 Recommended tools ...28 3.2.2 Recommended parts...29 3.3 Disassembly and reassembly...39 3.3.1 M-ESTPR, M-ESTR, and M-ETPR modules ...39 3.3.2 M-NE12STPR/-NE12STR/-NE12TPR/-NESTPR/-NESTR/-NETPR modules ...39 3.4 Adjustments and calibrations...40 3.4.1 Pressure safety level detection “OFFSET”...40 3.4.2 NIBP calibrations ...40 3.4.3 Temperature calibration ...42 3.4.4 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-NE12STPR and M-NESTPR module troubleshooting...51 4.2.2 M-ESTPR, M-ESTR, and M-ETPR module troubleshooting ...52

5

Service Menu

53

5.1 NIBP service menu ...54 5.1.1 NIBP demo menu...55 5.1.2 NIBP calibration menu...56 5.1.3 NIBP safety valve menu ...57 5.1.4 NIBP pulse valve menu...58 5.1.5 NIBP buttons/leds menu...59 5.1.6 NIBP pneumatics menu...60 5.1.7 NIBP watchdog menu ...61 5.2 ECG service menu ...62 5.2.1 ECG setup menu ...64 5.3 STP service menu ...65 5.3.1 STP calibration menu ...67

6

Spare Parts

68

6.1 Spare parts list ...68 6.1.1 M-ESTP rev. 01, M-ETP rev. 00, M-EST rev. 00 ...68 6.1.2 M-ESTP rev. 02, M-ETP rev. 01, M-EST rev. 01 ...69 6.1.3 M-ESTP rev. 03, M-ETP rev. 02, M-EST rev. 02 ...69 6.1.4 M-ESTP rev. 04, M-ETP rev. 03, M-EST rev. 03 ...69 6.1.5 M-ESTP rev. 05, M-ETP rev. 04, M-EST rev. 04 ...69 6.1.6 M-ESTPR rev. 01, M-ETPR rev. 01, M-ESTR rev. 01...70 6.1.7 M-ESTPR rev. 02, M-ETPR rev. 02, M-ESTR rev. 02...70 6.1.8 M-ESTPR rev. 03, M-ETPR rev. 03, M-ESTR rev. 03...70 6.1.9 M-ESTPR rev. 04, M-ETPR rev. 04, M-ESTR rev. 04...70 6.1.10 M-NESTPR rev. 00, M-NETPR rev. 00, M-NESTR rev. 00 ...71 6.1.11 M-NESTPR rev. 01, M-NETPR rev. 01, M-NESTR rev. 01 ...72 ii Document No. 800 1008-2

Table of contents 6.1.12 6.1.13 6.1.14 6.1.15

7

M-NE12STPR rev. 00, M-NE12STR rev. 00, M-NE12TPR rev. 00...72 M-NE12STPR rev. 01...72 Front panel stickers ...73 Front panel stickers for S/5 modules...74

Earlier Revisions

76

APPENDIX A

77

Service Check Form

A-1

TABLE OF FIGURES Figure 1

S/5 NE12STPR Module, M-NE12STPR ...1

Figure 2

Absorption of infrared light in the finger probe parts layout and schematic diagram...9

Figure 3

Front panel of M-ESTPR...10

Figure 4

Front panel of M-NESTPR ...11

Figure 5

NIBP board functional block diagram...12

Figure 6

3- and 5- lead ECG board block diagram ...14

Figure 7

12-lead ECG measurement block diagram...16

Figure 8

STP board block diagram...19

Figure 9

Temperature measurement principle ...20

Figure 10

Pressure measurement principle ...20

Figure 11

Pulse oximetry measurement block diagram ...21

Figure 12

Serial communication and opto isolation of M-NESTPR/-NE12STPR ...22

Figure 13

Serial communication and opto isolation of M-ESTPR...23

Figure 14

Module bus connector (X1) pin layout ...24

Figure 15

M-NE12STPR and M-NESTPR module troubleshooting flowchart...51

Figure 16

M-ESTPR Module Troubleshooting Flowchart...52

iii Document No. 800 1008-2

Datex-Ohmeda S/5 monitors

This page intentionally left blank.

iv Document No. 800 1008-2

S/5 Hemodynamic modules

INTRODUCTION This Technical Reference Manual Slot provides information for the maintenance and service of the hemodynamic modules. Please see also related Technical Reference Manual for information related to system e.g. related documentation, conventions used, symbols on equipment, safety precautions, system description, system installation, interfacing, functional check and planned maintenance. The S/5 M-ESTPR/-ESTR/-ETPR and S/5 M-NE12STPR/-NE12STR/-NE12TPR/-NESTPR/NESTR/-NETPR are double width modules designed for use with S/5 monitors. The modules provide general hemodynamic parameters. Later in this manual modules can be called w/o system name S/5. NOTE: Do not use identical modules in the same 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-MRI/-MRIP NOTE: 12-lead ECG measurement requires Display Controller, B-DISP. Figure 1

S/5 NE12STPR Module, M-NE12STPR

Table 1

Options of S/5 hemodynamic modules

Parameter

NE12STPR

NESTPR

NE(12) STR

NE(12) TPR

12

12-lead ECG

•

N

NIBP

•

•

E

ECG

•

S

Pulse oximetry

T

Two temperatures

P R

(•)

(•)

•

•

•

•

•

•

•

•

•

•

Two invasive blood pressures

•

•

Impedance respiration

•

•

•

ESTPR

ESTR

ETPR

•

•

•

•

•

•

•

•

•

•

•

•

•

•

•

•

•

1 Document No. 800 1008-2

Datex-Ohmeda S/5 monitors

1

SPECIFICATIONS

1.1 General specifications Module size W×D×H Operation temperature

75 × 180 × 112 mm 3.0 × 7.1 × 4.4 in 10...40 °C / 50...104 °F

@ M-ESTPR/-ETPR/-ESTR Module weight Power consumption

0.6 kg / 1.3 lbs 6W

@ M-NE12STPR/-NE12STR/-NE12TPR/-NESTPR/-NESTR/-NETPR Module weight Power consumption

1 kg about 9 W

1.2 Typical performance 1.2.1 NIBP Oscillometric measurement principle. Measurement range

adult child infant

Pulse rate range accepted

30...250 bpm

Measurement interval

from continuous to 1h, 2h, 4h

Typical measuring time

adult infant

23 s 20 s

Initial inflation pressure

adult child infant

185 ±10 mmHg 150 ±10 mmHg 120 ±10 mmHg

Venous stasis

adult child infant

80 ±10 mmHg / 2 min. 60 ±10 mmHg / 2 min. 40 ±10 mmHg / 1 min.

Cuff widths

please see User’s Guide

2 Document No. 800 1008-2

25...260 mmHg 25...195 mmHg 15...145 mmHg

S/5 Hemodynamic modules

1.2.2 ECG Lead selection @ 12-lead ECG Lead selection @ other modules Sweep speeds DISPLAY FILTER Diagnostic @ 12-lead ECG Diagnostic @ other modules

I, II, III, aVR, aVL, aVF, V1, V2, V3, V4, V5, V6 I, II, III, aVR, aVL, aVF, V 12.5, 25, 50 mm/sec

0.05...150 Hz 0.05...100 Hz

Monitoring

0.5...30 Hz (-3 dB, with 50 Hz reject filter) 0.5...40 Hz (-3 dB, with 60 Hz reject filter)

ST filter

0.05...30 Hz (-3 dB, with 50 Hz reject filter) 0.05...40 Hz (-3 dB, with 60 Hz reject filter)

HEART RATE FROM ECG Range Accuracy Resolution Update interval Averaging time

30...250 bpm ±5 bpm or ±5 %, whichever is greater 1 bpm 5s 10 s

ST LEVELS (in main software) ST level range -9...+9 mm (-0.9...+0.9 mV) Resolution 0.1 mm (0.01 mV) Averaging calculated from 8 QRS SYNCHRONIZATION Direct ECG Pacer Defibrillator

analog output of ECG, 1 V/1 mV 5 V and 0.5...2.5 ms pulse, < 30 ms after pacer peak 5 V and 10 ms pulse, < 35 ms after R-point synchronization

1.2.3 Pulse oximetry Measurement range Accuracy 1 (% SpO2 ±1 SD) Display resolution Display averaging time Pulse beep pitch

40...100 % 100...80 %, ±2 digits 80...50 %, ±3 digits 50...40 %, unspecified 1 digit = 1 % of SpO2 20, 10 sec, beat-to-beat varies with SpO2 level

The monitor is calibrated over the measurement range against functional saturation SpO2 func. HEART RATE FROM PLETH Measurement range Accuracy Resolution Display averaging 1

30...250 bpm 30...100, ±5 bpm, 100...250, ±5 % 1 bpm 10 s

1 SD (standard deviation) = 68 % of all readings in the specified range in stable conditions.

3 Document No. 800 1008-2

Datex-Ohmeda S/5 monitors 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...45 °C (50...113 °F) (In rev. ESTP 03/ EST 02/ETP 02 or earlier: 15...45 °C (59...113 °F)) Measurement accuracy Display resolution Temperature test Probe type

±0.1 °C (25...45.0 °C) ±0.2 °C (10...24.9 °C) 0.1 °C (0.1 °F) automatic (every 10 min) compatible with YSI 400 series

1.2.5 Invasive blood pressure Measurement range Measurement accuracy Zero adjustment range Calibration range Scales

-40...320 mmHg ±2 mmHg or ±5 % ±150 mmHg ±20 % 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 Resolution

-40...320 mmHg ±1 mmHg

WAVEFORM DISPLAY Range

-30...300 mmHg

HEART RATE FROM ARTERIAL PRESSURE Measurement range 30...250 bpm Resolution 1 bpm Accuracy ±5 bpm or ±5 % whichever is greater

1.2.6 Respiration Measurement range Accuracy Resolution Averaging time Update interval

4...120 bpm ±5 bpm or ±5 % 1 bpm 30 s 10 s

RESPIRATION WAVEFORM Sweep Speeds

6.25 mm/s and 0.625 mm/s

4 Document No. 800 1008-2

S/5 Hemodynamic modules

1.3 Technical specifications 1.3.1 NIBP Deflation rate, PR dep. Inflation time

5...13 mmHg/s 20...185 mmHg, 1...5 s

Automatic software control, max. inflation pressure adult 280 ±10 mmHg child 200 ±10 mmHg infant 150 ±10 mmHg Over pressure limit, stops measurement after 2 seconds adult 320 mmHg child 220 mmHg infant 165 mmHg Safety valve limits the maximum cuff pressure to 320 mmHg in adult/child mode or 165 mmHg in infant mode. Independent timing circuit limits pressurizing (>5 mmHg) time to 2 minutes 10 seconds maximum in adult/child mode, and 1 minute 5 seconds in infant mode. Zeroing to ambient pressure is done automatically. 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 child infant

2 min 2 min 1 min

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 Recovery time Input impedance CMRR System noise Allowable offset Gain range Pacemaker pulse detection

5000 V, 360 J 2s >2.5 MΩ (10 Hz) >100 dB (ST) <40 µV (p-p, RTI) ±300 mVDC 0.2...5.0 cm/mV 2...500 mV, 0.5...2 ms pulses

Protection against electrical shock

Type CF defibrillator proof

1.3.2 ECG

5 Document No. 800 1008-2

Datex-Ohmeda S/5 monitors

1.3.3 Pulse oximetry Protection against electrical shock

Type BF defibrillation proof

1.3.4 Temperature Measurement accuracy Protection against electrical shock

±0.1 °C (25.0...45.0 °C) ±0.2 °C (10.0...24.9 °C) Type CF defibrillation proof

NOTE: The accuracy of the measurement may be different from the specified, depending on transducer/probe used. Please check 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...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 NOTE: The accuracy of the measurement may be different from the specified, depending on transducer/probe used. Please check the transducer/probe specification.

1.3.6 Respiration Excitation frequency @ 12-lead ECG

62.5 kHz

Excitation frequency @ other modules

31.25 kHz

Breath detection

automatic, range 0.3...6 Ω manually adjustable minimum detection: 0.2, 0.4, 0.6, 0.8, 1.0

Input dynamic range Input impedance range Respiration Rate

0.2...6 Ω 100...5000 Ω min. 4 bpm max. 120 bpm >3 MΩ

Lead off detection

6 Document No. 800 1008-2

S/5 Hemodynamic modules

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-NE12STPR/-NE12STR/-NE12TPR/-NESTPR/-NESTR/-NETPR (or M-NIBP) module

•

twin hose (adult or infant model)

•

blood pressure cuffs (different 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 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 light spectrum. These wavelengths are emitted by LEDs in the SpO2 probe, the light is transmitted through peripheral tissue and is finally detected by a PIN-diode opposite to LEDs in the probe. Pulse oximeter derives the oxygen saturation (SpO2) using empirically determined relationship between the relative absorption at the two wavelengths and the arterial oxygen saturation SaO2. 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.

7 Document No. 800 1008-2

Datex-Ohmeda S/5 monitors A general limitation of the above pulse oximetry principle is that due to only two wavelengths used only two hemoglobin species can be discriminated by the measurement. The modern pulse oximeters are empirically calibrated either against fractional saturation SaO2frac; SaO2frac =

HbO2 HbO2 + Hb + Dyshemoglobin

Formula 1

or against functional saturation SaO2func; SaO2func =

HbO2 HbO2 + Hb

Formula 2

which is more insensitive to changes of carboxyhemoglobin and methemoglobin concentrations in blood. The oxygen saturation percentage SpO2 measured by Datex-Ohmeda module is calibrated against the functional saturation SaO2func. The advantage of this method is that the accuracy of SpO2 measurement relative to SaO2func can be maintained even at rather high concentrations of carboxyhemoglobin in blood. Independent of the calibration method, pulse oximeter is 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.

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 DatexOhmeda.

8 Document No. 800 1008-2

S/5 Hemodynamic modules

Intensity of transmitted light

I max (DC-component)

I max AC-component

I min

Variable absorption due to pulse added volume of arterial blood

Transmitted light

Arterial blood Venous blood

Tissue

No pulsation

Time

Pulsatile blood

Incident light

SpO 2 sensor connector SpO2 sensor cable 6 Emitter

IRED

5

GND

8

V B C

R Detector

I LED

4

RED

1 9

Figure 2

GND

7

IS GND

Absorption of infrared light in the finger probe parts layout and schematic diagram

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

9 Document No. 800 1008-2

Datex-Ohmeda S/5 monitors 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 a 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 signal of the respiration is made by supplying current between 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 respiration waveform is displayed on the screen.

2.2 Main components 2.2.1 M-ESTPR/-ETPR/-ESTR modules ECG Lead T1

P1

Start Wedge T2

ECG+ Resp

P2

Zero P1 SpO2

Zero P2

Figure 3

Front panel of M-ESTPR

The M-ESTPR, M-ETPR, and M-ESTR modules contain two main PC boards, the STP board and the ECG board. They work independently. Both of them have their own processor and software EPROM. Some components on the boards are not used in ETPR and ESTR modules. In M-ESTPR module, additionally, there are two small boards, the SP input and the ECG input 10 Document No. 800 1008-2

S/5 Hemodynamic modules boards, attached to the front panel of the module. The front panel has six connectors and four keys. The connectors are two for temperature measurement, two for invasive blood pressure measurement, one for ECG, and one for SpO2 measurement. The keys are for ECG lead, Start Wedge, P1 zero, and P2 zero. In M-ETPR module, there are two small boards, the ECG input board and the 2P input board attached to the front panel of the module. The front panel has five connectors and four keys. The connectors are two for temperature measurement, two for invasive blood pressure measurement, and one for ECG measurement. The keys are for ECG lead, Start Wedge, P1 zero, and P2 zero. In M-ESTR module, there are two small boards: the S input board and the ECG input board, attached to the front panel of the module. The front panel has four connectors and one key. The connectors are two for temperature measurement, one for ECG, and one for SpO2 measurement. The key is for ECG lead select. NOTE: M-ESTP rev. 03, M-ETP rev. 02 and M-EST rev. 02 and all earlier revisions have separate T and SP input boards.

2.2.2 M-NE12STPR/-NE12STR/-NE12TPR/-NESTPR/-NESTR/-NETPR modules

Auto On/Off NIBP

P1

Start Cancel T1

T2

ECG+ Resp

P2

Zero P1 SpO2

Zero P2

Figure 4

Front panel of M-NESTPR

The M-NESTPR, M-NETPR, and M-NESTR 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 EPROM. The M-NE12STPR, M-NE12TPR, and M-NE12STR contain three main PC boards, The STP board, the ECG board and the NIBP board. They work independently. Each of them has their own processor. The STP board and NIBP board have software EPROM. In the ECG board the software is in flash memory. The STP and NIBP boards are the same as in M-NESTPR module but the ECG board and ECG input board are different. In M-NESTPR module, 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 SpO2 measurement. The keys are for NIBP Auto On/Off, NIBP Start/Cancel, P1 zero, and P2 zero. The structure of M-NE12STPR is similar except the ECG board and ECG input board are different.

11 Document No. 800 1008-2

Datex-Ohmeda S/5 monitors In M-NETPR module, there are two small boards, the 2P input board and the ECG input board, attached to the front panel of the module. The front panel has six connectors and four keys. The connectors are two for temperature measurement, two for invasive blood pressure measurement, one for ECG, and one for NIBP. The keys are for Auto On/Off, Start/Cancel, P1 zero, and P2 zero. The structure of M-NE12TPR is similar except the ECG board and ECG input board are different. In M-NESTR module, there are two small boards, the ECG input board and the S input board, attached to the front panel of the module. The front panel has five connectors and two keys. The connectors are two for temperature measurement, and one for SpO2 measurement, one for ECG, and one for NIBP. The keys are for Auto On/Off, Start/Cancel. The structure of M-NE12STR is similar except the ECG board and ECG input board are different.

2.2.3 NIBP board EXHAUST VALVE 1 CUFF

ZERO VALVE

EXHAUST VALVE 2

BLEED VALVE

JOINING CHAM BER

PUMP

CHECK VALVE

M

B1

B2

PRESS URE TRAN S DUCERS

P UM P and V A LV E DR IV E R

OV E RPR E S S URE CO NT RO L WATCHDO G TIM ER

A D -C O N V ER T E R

POWER -UP RESET

+ 15 VD

ADDRESS BUS CPU 80C51FA ADDRESS DECODER

to/from module bus

RS485 INTERF. X1 EEPROM (Calibration Data)

INTERNAL WATCHDO G

ADDRESS LATCH

RAM

EPROM

FRONT PANEL KEYS

SOFTWARE CONTROL

DATABUS Write protect switch

Figure 5

NIBP board functional block diagram

Pressure transducers The NIBP board contains two pressure transducers. They are of piezoresistive type. One is used for measuring the pressure of the blood pressure cuff and the pressure fluctuations caused by arterial wall movement (B1). The other is used for detection of cuff hose type, cuff loose and cuff occlusion situations etc. (B2). The transducers are internally temperature compensated. They are supplied by a constant voltage and their output voltage changes up to 40 mV max. (50 kPa, 375 mmHg). 12 Document No. 800 1008-2

S/5 Hemodynamic modules

Signal processing Two signals from the pressure transducers are amplified and sent to A/D converter. After the converter, digitized signals are sent to microprocessor for data processing. Before the converter, one of the signals is used to adjust the offset to the pressure safety level. The NIBP board is controlled with 80C51FA microprocessor at 16 MHz oscillator frequency.

Memory NIBP program memory (EPROM) size is 128k × 8. RAM size is 32k × 8 bit and it stores variable values in NIBP measurement. EEPROM is size 64 × 16 bit and 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 ECG board’s description: “RS485 communication”

Watchdog timer The NIBP board is equipped with software independent safety circuit to disconnect supply voltages from the pump and the valves if the cuff has been pressurized longer than preset time. As soon as the cuff pressure rises over a specifiedpressure limit, timer starts counting. The timer is adjusted to stop the pump and open the valves in 2 minutes 10 seconds in adult/child mode and in 1 minute 5 seconds in infant mode.

Valves Exhaust valves are used for emptying the cuff and the joining chamber after the measurement. Exhaust valve 1 is also used as safety valve in infant mode. Valve opens at 165 mmHg. Exhaust valve 2 is also used as safety valve in adult mode and opens at 320 mmHg. Bleed valve is used for emptying the cuff during measurement. Zero valve is used for connecting the pressure transducer B1 to open air.

Power supply section All connections are established via 25-pin connector (D-type, female). The module needs +5 V, ±15 V, and +15 VD (dirty) power supply to operate. The pump and the valves use separate +15 VD power line. The supply voltages are generated in the power supply section of the S/5 monitor. The reference voltages ±5 Vref and +10 Vref are generated on the NIBP board.

13 Document No. 800 1008-2

Datex-Ohmeda S/5 monitors

2.2.4 ECG board in 3-and 5-lead measurement Patient signals are connected to overload protection circuits (resistors and gas-filled surge arresters) and analog switches to instrumentation amplifiers. Then the signals are amplified by 480 and limited by slew rate. Then they are A/D-converted, analyzed and transferred to module bus in digital form.

PATIENT OVERLOAD PROTECTION R DEFIBRILLATION DETECTOR

L

F

C

N LEAD SELECTION LOGIC Controlled by ECG lead selection signals from uP

ANALOG SWITCHES

uP

SLEWRATE DETECTOR uP

uP

HP Filter

SLEWRATE DETECTOR

SLEWRATE DETECTOR uP HP Filter

uP

uP ANTIALIAS

uP

HP Filter

uP

ANTIALIAS

SLEWRATE DETECTOR

31 kHz from uP

HP Filter

uP ANTIALIAS

ANTIALIAS

Resp amplifier

Sync. Rectifier

Amplifier A/D MICROPROCESSOR (uP)

SUPPLY VOLTAGES POWER SOURCE

OPTOCOUPLER

DIRECT ECG

POWER SOURCE

OPTOCOUPLER

DIRECT ECG

ISOLATION

to STP Board

Figure 6

3- and 5- lead ECG board block diagram

Analog ECG section ECG cable is connected to connector pins E1 to E6 on the input board which contains an overload protection circuit. Leads are connected to amplifiers via analog switches. States of the switches depend on the cable type. Lead-off, noise and pacemaker are detected by a slew rate detector. 14 Document No. 800 1008-2

S/5 Hemodynamic modules Lower frequency is determined by high pass (HP) filter 0.5 Hz (monitor bandwidth) or 0.05 Hz (diagnostic or ST- bandwidth).

Respiration section 3-lead cable

The analog switches control the current supply source of the impedance respiration measurement, and the lead selection for the 3-lead cable can be seen from the following table: Table 2

Lead selection and coding for the 3-lead cable

Selected lead

Signal measured from N

I

R-L

II

R-N

L

III

L-N

R

Position on body surface

5-lead cable

Current source between

IEC standard coding

AAMI standard coding

right arm

R = red

RA = white

left arm

L = yellow

LA = black

left leg

F = green

LL = red

When the 5-lead cable is used, the current source is between L-F and the signal is measured from the N, independently on the lead selection. The respiration amplifier consist of the operational amplifiers, and the components around them. There is an analog switch for controlling the gain of the first stage of the preamplifier. Synchronous rectifier consists of the analog switches, which are used for detecting the respiration signal from 31 kHz amplitude modulated raw signal. The amplifier stage consists of the differential amplifier and the last amplifier. The differential amplifier consists of the operational amplifiers and the components around them. This stage is AC-coupled on both sides for minimising the offset voltages. The last amplifier is used for amplifying the signal derived from differential amplifier stage. The respiration signal is zeroed at the beginning of the measurement. Zeroing is also used for fast recovering the measurement after the motion artefact. This is done in amplifier section. NOTE: The respiration measurement is switched OFF for 20 seconds when defibrillation is detected at the defibrillation detector.

Microprocessor section Microprocessor contains RAM and EPROM memories. The processor uses external EEPROM memory. The microprocessor’s internal 8-channel A/D-converter converts the ECG-signals to digital form. See the section in ECG board’s description: “RS485 communication

Serial communication Communication with the module bus is made through RXD and TXD pins. See the section in STP board’s description: “Serial communication”.

15 Document No. 800 1008-2