Datex-Ohmeda
Datex-Ohmeda S5 Monitor Series
S5 NeuroMuscular Transmission Module Technical Reference Manual Slot June 2001
Technical Reference Manual
30 Pages
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Datex-Ohmeda S/5TM NeuroMuscular Transmission Module, M-NMT (Rev. 02) Technical Reference Manual Slot
All specifications are subject to change without notice. Document No. 800 1018-1 June 2001
Datex-Ohmeda Inc. 3030 Ohmeda Drive 53707-7550 MADISON, WIS USA Tel. +1-608-221 1551, Fax +1-608-222 9147 www.us.datex-ohmeda.com
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.
Table of contents
TABLE OF CONTENTS NeuroMuscular Transmission Module, M-NMT TABLE OF CONTENTS
i
TABLE OF FIGURES
ii
Introduction
1
1
2
Specifications
1.1 General specifications ...2 1.2 Technical specifications...2 1.2.1 NMT...2 1.2.2 Stimulator...2 1.2.3 Regional block mode...2
2
Functional description
3
2.1 Measurement principle ...3 2.1.1 Nerve stimulation ...3 2.1.2 Response...4 2.1.3 Regional block ...4 2.2 Main components...4 2.2.1 NMT board ...4 2.3 Connectors and signals...6 2.3.1 Module bus connector ...6 2.3.2 Front panel connector...7
3
Service procedures
8
3.1 General service information...8 3.2 Service check ...9 3.2.1 Recommended tools ...9 3.3 Disassembly and reassembly...13
4
Troubleshooting
14
4.1 Troubleshooting chart ...14 4.2 Troubleshooting flowchart ...15
5
Service Menu
16
5.1 NMT menu...17
6
Spare parts
19
6.1 Spare part list...19 6.1.1 NMT Module, M-NMT rev. 00...19 6.1.2 NMT Module, M-NMT rev. 01...19 6.1.3 NMT Module, M-NMT rev. 02...19 6.1.4 Front panel stickers for AS/3 modules (square buttons) ...20 6.1.5 Front panel stickers for S/5 modules (round buttons)...20
7
Earlier revisions
APPENDIX A
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Service check form
A-1
TABLE OF FIGURES Figure 1
NeuroMuscular Transmission Module, M-NMT ... 1
Figure 2
Principle of response measurement ... 4
Figure 3
Serial communication and opto isolation... 5
Figure 4
Stimulator block diagram... 5
Figure 5
Module troubleshooting flowchart ...15
ii Document No. 800 1018-1
NeuroMuscular Transmission Module, M-NMT
INTRODUCTION This section provides information for the maintenance and service of the NeuroMuscular Transmission Module, M-NMT. The M-NMT module is a single width plug-in module designed for use with the S/5 Anesthesia and Compact Anesthesia Monitors. The module contains peripheral nerve stimulation and response measurement which supports electromyography EMG. The module can also be used as a nerve locator for regional nerve blocking with a regional block cable. However, in this case there is no response measurement.
Figure 1
NeuroMuscular Transmission Module, M-NMT
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1
SPECIFICATIONS
1.1 General specifications Module size, W × D × H Module weight Power consumption
37 × 180 × 112 mm / 1.5 × 7.1 × 4.4 in 0.37 kg /0.8 lbs 3.3 W
1.2 Technical specifications 1.2.1 NMT Stimulation modes
Train of four (TOF) Double burst (3.3) (DBS) Single twitch (ST) 50 Hz tetanus + post tetanic count (PTC) Measurement intervals for TOF and DBS Manual; 10 s, 12 s, 15 s, 20 s, 1 min, 5 min, 15 min Measurement intervals for ST Manual; 1 s, 10 s, 20 s
1.2.2 Stimulator Stimulus pulse Pulse width Stimulus current range Stimulus current accuracy Max. load Max. voltage
Square wave, constant current 100, 200 or 300 µs 10...70 mA with 5 mA steps 10 % or ±3 mA whichever is the greater 3 kΩ 300 V
1.2.3 Regional block mode Stimulation modes Intervals Stimulus pulse Pulse width Stimulus current range Stimulus current accuracy
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Single twitch 1 s, 2 s, 3 s Square wave, constant current 40 µs 0...5.0 mA with 0.1 mA steps 20 % or 0.3 mA whichever is the greater
NeuroMuscular Transmission Module, M-NMT
2
FUNCTIONAL DESCRIPTION
2.1 Measurement principle 2.1.1 Nerve stimulation There are three stimulus modes in the NeuroMuscular Transmission Module: Train of Four (TOF), Double Burst 3,3 (DBS) and Single Twitch (ST). In the Train of Four stimulus mode, four stimulation pulses are generated at 0.5 second intervals. The response is measured after each stimulus and the ratio of the fourth and first response of the TOF sequence is calculated (TOF%). NOTE: If the first response does not exceed a certain signal level, TOF% is not calculated due to poor accuracy. Double burst (3,3) stimulation includes two bursts with a 750 ms interval. Both bursts consist of three pulses separated by 20 ms intervals. The responses of both bursts are measured, and the ratio of the second and first response is calculated (DBS%). EMG responses are measured immediately after the first stimulus pulse of both bursts. In Single Twitch stimulation, one stimulation pulse is generated. The response is measured after the stimulus. In order to prevent decurarization of the stimulated area, the measurement is automatically stopped after 5 minutes stimulation in 1 sec cycle time.
Tetanic/PTC Tetanic/PTC (Post Tetanic Count) can measure deeper relaxation than TOF. The tetanic stimulation is produced when Start is chosen under Tetanic/PTC. The length of stimulation is 5 seconds. The stimulation generates pulses with a frequency of 50 Hz and with a selected pulse width and current. After tetanic stimulation and a three second delay, Single Twitch stimulation is produced to detect the post tetanic count (PTC). PTC describes the number of responses detected after tetanic stimulation. If there is no response, the measurement will be stopped. If responses will not fade away, a maximum of 20 responses will be calculated. If more can be detected, the PTC value is displayed only as '> 20' and measurement will be stopped. If the TOF, DBS or ST measurement cycle was on when tetanic stimulation started, the cycle will continue after the PTC. After completing the PTC measurement during 1 minute TOF, DBS or another PTC measurement is not possible. This is to avoid erroneous readings due to post tetanic potentiation.
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2.1.2 Response Before each stimulation, the sequence offset, noise and threshold for the response detection is measured. Offset is a baseline of the noise measurement. Noise is calculated by the same algorithm as the response signal itself. The response detection threshold is calculated based on the noise, and if the response is not greater than the threshold then it is interpreted as no response.
A/D & µP
EMG
Timing control EMG leads off Mechano Sensor Measurement
Figure 2
Principle of response measurement
EMG measurement The EMG response is measured as integrated muscle activity. The EMG measurement starts 3 ms after the stimulation and lasts 15 ms. The 3 ms delay helps to prevent the effect of stimulation artifact.
Mechano sensor measurement Response is measured as movement of the thumb, which is the area of positive signal.
2.1.3 Regional block A regional block cable can be used as a nerve locator in local anesthesia. A maximum current of 5.0 mA is given every, every other or every 3rd second. The response measurement is ocular.
2.2 Main components 2.2.1 NMT board The NMT Circuit Board consists of the following functional sections: •
constant current stimulator
•
measuring electronics for the EMG signals
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•
microprocessor for the stimulation and measuring control, and for counting the measuring results
•
serial communication
The serial bus speed is 500 kbps and the bus itself is half duplex, i.e. data can be transferred in both directions but only one way at a time.
Serial communication
Figure 3
Serial communication and opto isolation
Stimulator The constant current stimulator generates pulses whose amplitude is independent of the load. The main components of the stimulator are a transformer, a capacitor and a transistor. The transformer produces a high voltage which charges the capacitor and the transistor adjusts the pulse width and amplitude of the current. Power supply
Current adjustment Patient
Constant current generator
Current control
PWM
80C196KD
HSO
Continuous stimulation congestion
Figure 4
Stimulator block diagram
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2.3 Connectors and signals 2.3.1 Module bus connector
13
1
25
14
Table 1
Module bus connector (X1)
Pin No.
I/O
Signal
1 2 3 4 5 6 7 8 9 10 11 12 13 14 15 16 17 18 19 20 21 22 23 24 25
I I I I I/O I/O I I O I O I I I O I O I I
RESET_RS485 -15 VDC +15 VDIRTY +15 VDC -DATA_RS485 DATA_RS485 Ground & Shield -RESET_RS485 CTSB RTSB RXDB TXDB Ground & Shield +32 VDIRTY GroundDIRTY CTSC RTSC RXDC TXDC ON/STANDBY PWM_ECG RXDD_RS232 TXDD_RS232 +5 VDC +5 VDC
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2.3.2 Front panel connector NMT connector (NMT)
3 6 1 2
4
7
5
8
9
0
Pin No.
Signal
1 2 3 4 5 6 7 8 9 10
EMG Signal + EMG Signal Not Used Stimulus + Stimulus Ground Not Connected Sensor Identification +5 V Mechanical Signal
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3
SERVICE PROCEDURES
3.1 General service information Field service of the NeuroMuscular Transmission Module, M-NMT, is limited to replacing faulty circuit boards or mechanical parts. Faulty circuit boards should be returned to Datex-Ohmeda for repair. Datex-Ohmeda is always available for service advice. Please provide the unit serial number, full type designation, and a detailed description of the fault. The Datex-Ohmeda NMT Stimulator (order code 871251) is recommended for functional checks.
CAUTION
Only trained personnel with appropriate equipment should perform the tests and repairs outlined in this section. Unauthorized service may void warranty of the unit.
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3.2 Service check These instructions include complete procedures for a service check. The service check is recommended to be performed after any service repair. However, the service check procedures can also be used for determining possible failures. The procedures should be performed in ascending order. The instructions include a check form (Appendix A) which should be filled in when performing the procedures. The mark
? in the instructions means that the check form should be signed after performing
the procedure.
The procedures are designed for monitors with S/5 monitor software of revision 01. However, most of the procedures also apply to monitors, which contain some other monitor software type/revision.
3.2.1 Recommended tools Tool
Order No.
NMT simulator M-NMT ElectroSensor M-NMT MechanoSensor M-NMT Sensor Cable 3 kΩ resistor
871251
Notes
Screwdriver
•
Detach the module box by removing the two screws from the back of the module. Be careful with the loose latch and spring locking pin.
1.
Check internal parts: −
screws are tightened properly
−
cables are connected properly
−
the EMC cover is attached properly
−
there are no loose objects inside the module
? 2.
Check external parts: −
the front cover and the front panel sticker are intact
−
connectors are intact and are attached properly
−
the module box, latch and spring locking pin are intact
? •
Refit the module box and check that the latch moves properly. 9 Document No. 800 1018-1
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•
Turn the monitor on and wait until the normal monitoring screen appears.
•
Configure the monitor screen so that information regarding the NMT measurement is shown, for example:
Monitor Setup - Screen 1 Setup - Digit Fields - Field 4 - Nmt •
Preset the NMT measurement settings:
Others - NMT - Stimulus Mode - TOF Set Cycle Time - 10 sec NMT Setup - Current - S(70 mA) Pulse Width - 200 µS Stim. Beep Volume - 2 3.
Plug in the module. Check that it goes in smoothly and locks up properly
4.
Check that the module is recognized, i.e. the NMT header with related information appear in the chosen digit field.
? ?
5.
Enter the service menu:
Monitor Setup - Install/Service (password 16-4-34) - Service (password 26-23-8) Take down the information regarding NMT software by selecting SCROLL VERS and turning the ComWheel.
? 6.
Enter the NMT module service menu: Parameters - NMT Check that the “Timeouts”, “Bad checksums” and “Bad c-s by mod” values are not increasing faster than by 50 per second. Check that the module’s memories have passed the internal memory test, i.e. “RAM”, “ROM” and “EEPROM” all state OK.
?
7.
Check the front panel START-UP and STOP/CONTINUE membrane keys. Press each key for at least one second and check that the key being pressed is identified, i.e. the color under the corresponding text on the menu turns blue.
?
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8.
Check that the message “Cable off” is shown in the digit field and that “Cable” in the service menu states OFF. Plug the M-NMT Sensor Cable with the M-NMT ElectroSensor into front panel connector NMT. Check that the message in the digit field changes to “Measurement OFF” and “Cable” on the service menu states EMG and ELECTR. OFF.
? 9.
Perform the stimulus current test. Connect a 3 kΩ resistor between the ElectroSensor’s stimulus electrode leads (brown and white). Start the test by highlighting START CURR. TEST on the service menu and pressing the ComWheel. Check that the test was successful with all three test currents, i.e. the “Current test (mA):” on the menu states 30 OK, 50 OK and 70 OK.
?
•
Connect the M-NMT ElectroSensor leads to the NMT simulator. Set the switch on the simulator to “Fade off” and turn the knob to “max”. Check “Cable” on the service menu now states only EMG.
10.
Start NMT measurement (TOF) by pressing the START-UP key on the module. When the message “Supramax search” changes to “Setting reference” in the digit field, check that the supramaximal current detected is less than 70 mA, i.e. the “Current set” value on the service menu is less than 700.
? 11.
Check that the module gives four successive stimulus pulses with 10 second intervals. A small asterisk (✼) should be shown in the digit field during each of the stimulus pulses and simultaneous sound signals should be heard from the loudspeaker. Check that on the service menu the values for “T1%”, “T2%”, “T3%”, “T4%” and “Ratio%” are all within 950-1059. Check also that in the digit field the “TOF%” value is within 95-105, “Count” is 4 and “T1%” is within 95-105.
?
12.
Check that the “Noise” value on the service menu stays under 50.
13.
Change the stimulus pulse width to 100 µs through the NMT service menu:
?
NMT Setup - Pulse Width - 100 µS 11 Document No. 800 1018-1
Datex-Ohmeda S/5 monitors Check that the “TOF%” value is still within 95-105, “Count” is 4 and “T1%” is within 95-105 in the digit field. Check the same parameters with a stimulus pulse width of 300 µs.
? 14.
Turn the knob on the NMT simulator to “0”. Check that on the service menu the values for “T1%”, “T2%”, “T3%”, “T4%” turn to 0 and the “Ratio%” states - - -. In the digit field “TOF%” should also state - - - , and “Count” and “T1%” should show 0. Turn the NMT simulator knob back to “max”.
?
15.
Change the stimulus mode to Double Burst Stimulation (DBS) through the service menu: NMT Setup - Stimulus Mode - DBS Check that the module now gives only two stimulus pulses with a 10 seconds interval. Check that on the service menu the values for “T1%”, “T2%”, and “Ratio%” are still within 950-1059. In the digit field the “DBS%” value should be within 95-105, “Count” is 2 and “T1%” is within 95-105.
?
16.
Change the stimulus mode to Single Twitch Stimulation (ST): NMT Setup - Stimulus Mode - ST Check that the module starts to give only one stimulus pulse with a 1 second interval. Note the time when the ST stimulation started. Check that on the service menu the value for “T1%” is within 950-1059. In the digit field the “Count” value should be 1 and “T1%” within 95-105. Let the monitor continue to give single twitch stimulation.
?
17.
Check that the NMT measurement stops and the message “Measurement OFF” appears in the digit field for NMT five minutes after the start of the ST stimulation.
?
18.
Replace the M-NMT ElectroSensor with the M-NMT MechanoSensor and check that “Cable” on the service menu states PIEZO.
?
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NeuroMuscular Transmission Module, M-NMT 19.
Perform an electrical safety check and a leakage current test.
?
20.
Check that the module functions normally after performing the electrical safety check.
21.
Clean the module with suitable detergent.
•
Fill in all necessary documents.
? ?
3.3 Disassembly and reassembly Disassemble the NeuroMuscular Transmission Module, M-NMT, in the following way. See the exploded view of the module. 1.
Remove the two screws from the back of the module.
2.
Pull the module box slowly rearward and detach it from main body. Be careful with the loose latch and spring locking pin.
3.
Detach the NMT board by removing the two screws located near the front panel frame, disconnect the cables and pull out the front panel frame.
To reassemble the module, reverse the order of the disassembly steps.
CAUTION
When reassembling the module, make sure that the cables are reconnected properly.
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TROUBLESHOOTING
4.1 Troubleshooting chart Trouble
Cause
Treatment
Check the stimulus electrodes.
Loose electrodes or loose stimulus clip.
Change or attach the electrodes or clip.
Loose electrodes or loose stimulus clip.
Change or attach the electrodes or clip.
Stimulus electrodes attached to wrong place.
Change the place of the stimulus electrode.
EMG electrode off. Supramax. not found.
Patient is relaxated. Response too weak.
Loose stimulus electrodes.
Change or attach the electrodes.
Measuring electrodes attached to wrong place.
Change the place of the meas. electrodes.
Patient is relaxated. Ref. not stable.
Patient is relaxated. Movement artifact.
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4.2 Troubleshooting flowchart Possible fault in NMT module
Open NMT Service Menu
Check Timeouts, Bad checksums, Bad c-s by mod no OK?
yes
Does another module work in the same slot?
Replace NMT board
no
yes
Fault not in NMT module
Check RAM,ROM,EEPROM no
Replace NMT board
OK? yes Test stimulus current no OK?
Does the test pass with another sensor?
no
yes yes
no Does the test pass with another NMT sensor cable? yes
Replace the original sensor
Replace the original NMT sensor cable
yes Are the NMT input board wires connected? no
no Does the test pass with another NMT input board?
Replace NMT board
yes
Connect the connector
Replace the original NMT input board
Check that sensor is identified
OK? no
Does the test pass with another sensor?
yes Replace the original sensor
yes no
Does the test pass with another NMT sensor cable?
yes
Replace the original NMT sensor cable
no
Does the test pass with another NMT input board?
yes
Replace the original NMT input board
no Replace NMT board Connect ElectroSensor to NMT stimulator and start measurement
yes Responses OK? no yes
Does the test pass with another sensor?
Replace the original sensor
no yes Does the test pass with another NMT sensor cable
Replace the original NMT sensor cable
no yes Does the test pass with another NMT input board?
Replace the original NMT input board
no Replace NMT board Check front panel key functions
OK? no
Is the keypad connected?
no
Connect the keypad
yes
Does the test pass with another keypad?
yes Replace the original keypad
no Replace NMT board
Figure 5
Module troubleshooting flowchart
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SERVICE MENU
1.
Press the Monitor Setup key.
2.
Select Install/Service (password 16-4-34).
3.
Select Service (password 26-23-8).
4.
Select Parameters.
5.
Select NMT.
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5.1 NMT menu
Start Curr. test Start Curr. test is a test where the module itself checks the difference between a given current and the measured current. A 3 kΩ resistance should be connected between the stimulus electrodes before starting the test. All the currents checked will be displayed on the service data screen. After the current value, the status of the test is shown. If the test is not passed, send the module back to the factory for calibration. T1%/ref
T1% / ref gives a selection for changing settings related to the M-NMT MechanoSensor. A setting of 3 should always be used for normal monitoring. The settings 1 and 2 are for research purposes only.
Record Data
Record Data prints out the displayed service data and circuit board information (id., serial number, and software id.) onto the Recorder Module, M-REC.
Service Data Cable shows the type of cable being used. Cable check value shows the bit amount. From the following chart you can check the value for each cable: EMG
-100...+100
Cable OFF
>1950
Piezo
900...1100
Regional block
600...800
Module Keys checks the function of the module keys. A blue background appears at the back of the text when a key is pressed for more than one second. Stimulus mode shows the selected stimulus. Stimulus mode can be changed using the NMT Setup menu. Measurement indicates ON/OFF. T1%, T2% shows the measured response. A value of 1000 corresponds to 100%. 17 Document No. 800 1018-1