Siemens MULTIGAS Service Manual

s

MULTIGAS and MULTIGAS+ Modules

Service Manual

EM Guidelines, 1997-04-02

E341.E536U.061.01.02.02 Replaces/Ersetzt: E341.E536U.061.01.01.02 ASK-T876-02-7600

ADVISORY

Siemens is liable for the safety of its equipment only if maintenance, repair, and modifications are performed by authorized personnel, and if components affecting the equipment's safety are replaced with Siemens spare parts.

Any modification or repair not done by Siemens personnel must be documented. Such documentation must:

•be signed and dated

•contain the name of the company performing the work

•describe the changes made

•describe any equipment performance changes.

It is the responsibility of the user to contact Siemens to determine warranty status and/or liabilities if other than an authorized Siemens Service Representative repairs or makes modifications to medical devices.

Table of Contents

Chapter 1: Introduction . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . 1

1 Overview . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . 1

Figure 1-1 MultiGas and MultiGas+ Modules - Rear Views . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . 1

2 Hardware Installation . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . 1

3 Service Strategy . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . 2

4 Preventative Maintenance . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . 2

5 Recommended Tools & Test Equipment . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . 3

Chapter 2: Functional Description . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . .				5
1	Introduction		. . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . .	. 5
	Figure 2-1 Functional MGM Block Diagram . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . .			. 5
2	Overall Functionality . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . .			. 5
3	Method of Operation . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . .			. 5
	Figure 2-2 Anesthetic Gas Subsystem Functional Block Diagram . . . . . . . . . . . . . . . . . . . . . . . . . . . .			. 6
4	Subassemblies, Modules and Components . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . .			. 6
5	Anesthetic Gas Subsystem . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . .			. 6
6	Main System . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . .			. 6
7	Agent Measurement Analyzer . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . .			. 7
	Figure 2-3 Agent Measurement Analyzer Functional Block Diagram . . . . . . . . . . . . . . . . . . . . . . . . . .			. 8
	Figure 2-4 Agent Identification Analyzer (AIDA) Functional Block Diagram . . . . . . . . . . . . . . . . . . . . .			. 9
8	Agent Identification Analyzer . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . .			. 9
9	Oxygen Analyzer . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . .			10
	9.1	Paramagnetic O2 Measurement . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . .		10
	9.2	Electrochemical O2 Measurement . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . .		10
10Pneumatic System . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . .				10
	Figure 2-5 Pneumatics Block Diagram (excerpt from Figure 2-2.) . . . . . . . . . . . . . . . . . . . . . . . . . . . .			11
		Table 2-1 Pump Flow Rates . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . .		11
11Self-Test . . .			. . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . .	12
12Calibration .			. . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . .	12
	12.1Factory Calibration . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . .			12
	12.2Field Span Calibration . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . .			12
	12.3Zero Calibration . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . .			12
	12.4Storage of Calibration Data . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . .			13
	12.5Calibration of Agent Measurement Analyzer . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . .			13
		12.5.1	Factory Calibration . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . .	13
		12.5.2	Field Span Calibration . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . .	13
		12.5.3	Zero Calibration . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . .	13
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MGM and MGM+ Modules	Service Manual

12.6Agent Identification Analyzer . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . 14 12.6.1 Factory Calibration . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . 14 12.6.2 Field Span Calibration . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . 14 12.6.3 Zero Calibration . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . 14 12.7Paramagnetic O2 Analyzer . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . 14 12.7.1 Factory Calibration . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . 14 12.7.2 Field Span Calibration . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . 14 12.7.3 Field Zero Calibration . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . 14 12.8Fuel Cell Type O2 Analyzer Calibration . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . 14 12.8.1 Factory Calibration . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . 14 12.8.2 Field Span and Zero Calibration . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . 15 12.8.3 Field Zero Calibration . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . 15 12.9Pneumatic System Calibration . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . 15 12.9.1 Factory Calibration . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . 15 12.9.2 Field Flow Rate Calibration . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . 15 13Software . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . 15 13.1AMA Data Acquisition . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . 15 Figure 2-6 Software Functional Block Diagram . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . 16 13.2AMA Signal Processing . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . 16 13.3AMA Compensation . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . 17 13.4Patient Data Derivation . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . 17 13.5Host System Communications . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . 17 13.6Anesthetic Gas Subsystem / Host System Communications . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . 18 13.7AIDA Communication . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . 18 13.8MGM/AMA Control . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . 18 13.9AIDA Data Acquisition . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . 19 13.10AIDA Signal Processing . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . 19 13.11AIDA Agent Identification . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . 19 13.12AIDA Control . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . 20

Chapter 3: Removing / Installing Parts . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . .

21

1 Introduction . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . 21

1.1 Opening Module . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . 21

Figure 3-1 Pump and Pneumatic Subassemblies in MGM+ . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . 22

2 MGM+ . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . 22

2.1 Pneumatic Tubing Subassemblies . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . 22

2.1.1 Removing Pneumatic Subassemblies . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . 22

2.1.2 Installing Pneumatic Subassemblies . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . 22

Figure 3-2 Pump and Pneumatic Subassemblies in MGM (Slo-O2) . . . . . . . . . . . . . . . . . . . . . . . . . . . 23

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Service Manual	MGM and MGM+ Modules

3 MGM (Slo-O2) . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . 23 3.1 Replacing Pneumatic Subassemblies . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . 23 3.1.1 Removing Pneumatic Tubing . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . 23 3.1.2 Installing Pneumatic Tubing . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . 24 4 Replacing Pump . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . 24

4.1 Removing Pump . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . 24 4.2 Installing Pump . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . 25 5 Pump Filter Removal/Replacement Procedure . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . 25 5.1 Removal . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . 25 5.2 Replacement . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . 25 6 Nafion® or other Tubing Removal/Replacement Procedure . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . 25 6.1 Removal . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . 25 6.2 Replacement . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . 25 7 Room Air Filter Removal/Replacement Procedure . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . 26 7.1 Removal . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . 26 7.2 Replacement . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . 26 8 AMA Analyzer Head Removal/Replacement Procedure . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . 26 8.1 Removal . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . 26 8.2 Replacement . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . 26 9 AMA Sample Cell Removal/Replacement Procedure . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . 26 9.1 Removal . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . 26 Figure 3-3 System PC Board . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . 27 9.2 Replacement . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . 27 10Agent ID Analyzer Removal/Replacement Procedure . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . 27 10.1Removal . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . 27 10.2Replacement . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . 27 11MGM System Board Removal/Replacement Procedure . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . 27 11.1Removal . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . 27 11.2Replacement . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . 28 12Fast O2 Sensor Assembly Removal/Replacement Procedure . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . 28 12.1Removal . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . 28 Figure 3-4 MGM Module Rear View . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . 28 Figure 3-5 Pneumatic Tubing Disconnection Points . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . 28 Figure 3-6 Rear Panel Subassembly . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . 29 12.2Replacement . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . 29 13CAN PC Board Removal/Replacement Procedure . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . 29 13.1Removal . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . 29 13.2Replacement . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . 30

ASK-T876-02-7600

Siemens Medical Systems, EM-PCS Danvers

iii

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MGM and MGM+ Modules	Service Manual

14Power Supply Removal/Replacement Procedure . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . 30 14.1Removal . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . 30 14.2Replacement . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . 30 15Solenoid #1 & #3 Removal/Replacement Procedure . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . 30 15.1Removal . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . 30 15.2Replacement . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . 30 16Solenoid #2 Removal/Replacement Procedure . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . 30 16.1Removal . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . 30 16.2Replacement . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . 30 17NVRAM Transfer Procedure . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . 31 17.1Introduction . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . 31 17.2Equipment required . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . 31 17.3NVRAM Transfer procedure . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . 31

Chapter 4: Adjustment / Calibration . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . .

33

1 Recommended Tools & Test Equipment . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . 33 2 Leakage Check Procedure . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . 33 3 Pump Test . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . 34 4 O2 Calibration . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . 34 5 Pump Flow Rate Adjustment Procedure . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . 35 6 Agent Detection and Analysis Calibration . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . 35

Figure 4-1 Gas Calibration / Test Setup . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . 36

Chapter 5: Troubleshooting . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . .		. . . . . . . . 37
1	Agent Measurement Analyzer Head) . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . .	. . . . . . . . . . 37
	Table 5-1 AMA Analyzer Head Problems	37
2	Agent Measurement Analyzer Optical Path . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . .	. . . . . . . . . . 37
	Table 5-2 AMA Optical Path Problems . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . .	. . . . . . . . . . 37
3	Agent Identification Analyzer Head . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . .	. . . . . . . . . 38
	Table 5-3 AIDA Analyzer Head Problems . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . .	. . . . . . . . . 38
4	Power Supply . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . .	. . . . . . . . . 39
	Table 5-4 Power Supply Problems . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . .	. . . . . . . . . 39
5	O2 Sensor . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . .	. . . . . . . . . 39
	Table 5-5 O2 Problems . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . .	. . . . . . . . . 39
6	Sample Delivery Subsystem . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . .	. . . . . . . . . 41
	Table 5-6 Sample Delivery Subsystem Problem . . . . . . . . . . . . . . . . . . . . . . . . . . . . . .	. . . . . . . . . 41
7	Gas Flow Problems . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . .	. . . . . . . . . 41
	Table 5-7 Gas Flow Problems . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . .	. . . . . . . . . 41
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8	Bad MGM System Board suspected . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . .	. . . . . . . . . . . . . . . . . 41
	Table 5-8 MGM System Board Problems . . . . . . . . . . . . . . . . . . . . . . . . . . . .	. . . . . . . . . . . . . . . . 41
9	MGM System Board Test Points, Jumpers, & Connectors . . . . . . . . . . . . . . . . . . .	. . . . . . . . . . . . . . . . 42
	Table 5-9 MGM System Board Test Points . . . . . . . . . . . . . . . . . . . . . . . . . .	. . . . . . . . . . . . . . . . 42
	Table 5-10Connector Functions . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . .	. . . . . . . . . . . . . . . . 43
	Table 5-11Jumpers, Functions, and Settings . . . . . . . . . . . . . . . . . . . . . . . . . .	. . . . . . . . . . . . . . . . 44
	Table 5-12O2 Jumper Configuration . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . .	. . . . . . . . . . . . . . . . 44

Chapter 6: Functional Verification . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . 45

1 Pneumatics Leakage Check . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . 45

2 Pump Flow Rate Verification . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . 45

3 Gas Identification Verification . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . 45

4 Safety Tests . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . 46

4.1 Resistance Test . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . 46

4.2 Chassis Leakage Current Tests . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . 46

Figure 4-2 Leakage Current Tests Block Diagram . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . 46

Appendix A: Spare / Exchange Parts . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . 47

Figure A-1 MultiGas Module (Fuel Cell Type Sensor) Pneumatics . . . . . . . . . . . . . . . . . . . . . . . . . . 49 Figure A-2 MultiGas+ Module (Paramagnetic Sensor) Pneumatics . . . . . . . . . . . . . . . . . . . . . . . . . 49 Figure A-3 MultilGas Module (Fuel Cell Type Sensor) Cable Interconnections . . . . . . . . . . . . . . . . . 50 Figure A-4 MultilGas+ Module (Paramagnetic Sensor) Cable Interconnections . . . . . . . . . . . . . . . . 51 Figure A-5 MGM / MGM+ Selected Component Locations . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . 53 Figure A-6 MGM / MGM+ Cover and Mounting Feet . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . 53 Figure A-7 MultiGas / MultiGas+ Modules . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . 54

Appendix B: Exploded-View Drawings . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . 55

Figure B-1 MultiGas Module - Exploded View . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . 55 Figure B-2 MultiGas+ Module - Exploded View . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . 56 Figure B-3 MultiGas Module Rear Panel Subassembly . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . 57 Figure B-4 MultiGas+ Module Rear Panel Subassembly . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . 57 Figure B-5 Agent Measurement Analyzer / Agent Identification Analyzer Subassembly . . . . . . . . . 58 Figure B-6 MGM Top Cover and Mount . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . 58 Figure B-7 MGM System Board Layout . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . 59

Appendix C: Functional Verification . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . 61

Appendix D: Disease Prevention . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . 63

1 Siemens Disease Prevention Policy Statement . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . 63

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2	Know the Facts . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . .		. . . . . . . . . 63
	2.1	Types of Viruses . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . .	. . . . . . . . 63
	2.2	Facts About ARC, AIDS, Hepatitis B, and TB . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . .	. . . . . . . . 63
3	Environmental Controls . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . .		. . . . . . . . 64
4	Protocol for Servicing the MGM . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . .		. . . . . . . . 65
	4.1	Preparation for Repair . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . .	. . . . . . . . 65
	4.2	Precautions During Repair . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . .	. . . . . . . . 65
	4.3	After Repair . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . .	. . . . . . . . 65
	4.4	Disposing of Pneumatic System Components . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . .	. . . . . . . . 66
5	Accidental Skin Puncture Procedure . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . .		. . . . . . . . 66
6	Disease Prevention Supplies . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . .		. . . . . . . . 66
Appendix E: Supplemental Documentation . . . . . . . . . . . . . . . . . . . . . . . . . . .			. . . . . . 67
1	Introduction . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . .		. . . . . . . . 67
2	Hardware Installation . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . .		. . . . . . . . 67

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Chapter 1 Introduction

1 Overview

MULTIGAS™ and MULTIGAS+™ Modules (MGM) are free-standing units that perform sidestream measurements of respiratory and anesthetic gases. The modules automatically identify and measure five common anesthetic agents (Isoflurane, Halothane, Enflurane, Sevoflurane, Desflurane), and report the agent detected and its measurement data to the host device (such as an SC 9000, SC 7000, SC9000XL, or SC 8000 Patient Monitor, or KION). The modules also monitor respiratory gases CO2, N2O, and O2, and report measurements to the host as waveforms (except N2O) and parameters.

MULTIGAS and MULTIGAS+ Modules differ only in the way that they measure O2. The basic MULTIGAS Module measures O2 using a galvanic cell, and calculates average inspiratory values for O2 (labeled iO2). The MULTIGAS+ Module Incorporates a faster-acting paramagnetic sensor that provides both inspired and expired O2 measurements (iO2 and etO2). The outward appearance of the modules differs only in the rear view. The O2 galvanic cell is visible on the rear panel of the MULTIGAS Module. The paramagnetic cell is internal in the MULTIGAS+ Module. See Figure 1-1. In this service manual, the term MULTIGAS is used synonymously with MULTIGAS+ unless specifically stated otherwise.

	Fan Filter	Exhaust Port	Grounding Stud	Fan Filter	Exhaust Port	Grounding Stud
	(covered)			(covered)
			Hardware Version			Hardware Version
			Label
						Label
			RS232 Connector			RS232 Connector
			Software Version			Software Version
			Label
						Label
O2 Cell	O2 Cell	Power Connector			Power Connector
	Connector
		MULTIGAS Module			MULTIGAS+ Module

Figure 1-1 MULTIGAS and MULTIGAS+ Modules - Rear Views

2 Hardware Installation

X12
CPS Connectors
X12
IDS Connectors	CAN

MGM connects to the host (monitor) via an INFINITY Device Communication Power Supply (CPS) or INFINITY Docking Station (IDS) or SC 8000 Patient Monitor. A cable connects the RS232 port on the rear of the MGM to the SC 8000 or to X12 on the CPS/IDS. (The IDS must have a MIB Option installed; SC 8000 requires installed Adv Com Option.) See illustrations at left. The host displays parameter and setup information, only while the module is actually connected. When the module is disconnected, all parameters, waveforms, and setup menus remain on the display until the host is powered off. If host is powered on again without MGM connected, gas parameters and waveforms do not reappear.

SC 8000 ADV COM Option

Refer to the User Guide for the software version installed in the monitor, for applicable Technical Data, and for procedures to access the MGM menu structure in the monitor.

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3 Service Strategy

In light of the state-of-the-art technology used in the manufacture of Siemens' equipment, proprietary nature of the software, and specialized equipment required for replacement of most individual parts, Siemens’ policy is for the MGM to be serviced only to the field-replaceable subassembly level, after expiration of the warranty period. While in the warranty period, an MGM found to be malfunctioning should be returned to the factory for repair or replacement. After expiration of the warranty period, replacement of components other than those listed in Spare / Exchange Parts should be performed only at Siemens service depots.

4 Preventative Maintenance

Siemens recommends that the following preventative maintenance procedures be performed annually.

Warning

All parts of a MultiGas/+ module that come in contact with the patient’s airway (such as all internal and external tubing, water trap and water trap manifold, and filters) may be contaminated. Handle according to the hospital’s procedures and guidelines for handling infectious substances. Also, see Disease Prevention.

Before initiating preventative maintenance procedures, do the following:

•With MGM running with host, verify that the reported revision of the software and hardware is up to date in accordance with the Software Compatibility Chart for the INFININTY NETWORK (or with the installed software in the host if the host is operating in standalone mode). If not, the unit can be updated later in this procedure.

•Verify status that no errors are flagged. If any errors are flagged, troubleshoot and repair the MGM before completing the following procedure.

1.Turn off power to MGM.

2.Unscrew top cover, and gently remove cover.

3.Inspect and replace the following, if necessary (expected replacement rate of these parts is once per year):

•Internal Nafion® Tubing Assy (qty=2)

•Room air filter

•Pump filter

•Internal Bacterial filter (qty=2)

•Water trap seals (qty=2)

•Fan filter

•Water trap

4.Clean and remove any excess dust, etc.

5.If necessary, update software and/or hardware.

6.Power up MGM.

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7.Perform Leakage Check Procedure.

8.Perform Pump Flow Rate Verification Procedure.

9.Perform Span Verification Procedure.

10.Turn unit off and replace top cover.

11.Power up unit and verify status is okay.

5Recommended Tools & Test Equipment

•SC 9000, SC 7000 / SC 9000XL Patient Monitor with CPS or IDS (with installed MIB Option + CAN), or SC 8000 (with installed Adv Com Option), or KION

•Appropriate communication cables (from host to MGM).

•Siemens Calibration Kit - SVC TOOL MGM/MGM+ CAL KIT, Art. No. 52 07 415 E536U, containing the following:

Calibration gas - contains 3.00% Isoflurane, 5.00% CO2, 40.00% N2O, 52% Oxygen (with a 1% gas concentration accuracy), Siemens Art. No. 57 36 322 E536U.

Gas Regulator

Tubing w/ Luer-lock fittings T-Piece w/ Luer-lock fittings Two-way valve w/ Luer-lock fittings Gas collection bag

•Flow meter with a range of minimum 0 - 350 ml/min, accuracy ±5% or better, (Sierra Flow Control Model 822-13-OV1-PV1-V1 calibrated for “standard - l/min” is recommended

•Pressure Gauge

Recommended: Setra Digital Pressure Gauge, Model 370 or equiv.

Note: Pressure gauge required only if verifying and/or calibrating the pressure channel. The hospital and/or a local weather station or airport may be able to provide a reading.

•Exhaust system (for exhausting calibration gas).

•Digital Voltmeter w/ 3½ digit resolution (minimum)

•Oscilloscope (optional)

•Hand tools:

—Medium sized Phillips screwdriver

—Medium sized flat head screw driver

—Wire cutters

—Non - serrated needle nose pliers

•Loctite adhesive or equivalent

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Chapter 2 Functional Description

1 Introduction

Both THE MULTIGAS and MULTIGAS+ Modules provide a non-dispersive infrared measurement of respiratory and anesthetic gases. The O2 analyzer subsystem of the MULTIGAS module uses an electrochemical fuel cell, and the MULTIGAS+ module uses a paramagnetic cell. Both modules are designed to work with the host monitor through a serial digital interface. The MGM is intended for measuring airway gases of ventilated patients, within the anesthesia workplace, during the induction and maintenance of, and emergence from, general anesthesia.

Breathing
Circuit
		Main System &	Central
		Subsystem Hardware	Processing
			(Firmware)
		Pneumatic System	Host Unit
			Communications
	Airway	Agent Analyzer	Data Processing
		Oxygen Analyzer	Flow Control
	Adapter	Agent Identification
		Sample Gas
		Exhaust
Figure 2-1	Functional MGM Block Diagram

2 Overall Functionality

The MGM pulls the sample gas off the endotracheal tube of a ventilated patient and leads the sample gas through three analyzer subsystems: the Agent Measurement Analyzer (AMA), the Oxygen (O2) Analyzer, and the Agent Identification Analyzer (AIDA). The computational processing unit in the MGM derives waveform data for CO2, anesthetic agents (one out of Halothane, Enflurane, Isoflurane, Sevoflurane, and Desflurane), and O2, together with airway respiration rate and inspired and end-tidal values for the gases, and also including N2O. The derived data is transmitted to the host system which derives alarms from the received data, displays all the alarms and data, and communicates them to other functional modules in the monitoring system.

3 Method of Operation

The airway gases measurement technique used in the AMA subsystem and the AIDA subsystem are based on the non-dispersive infrared absorption of light by molecular gases.

The airway gases measurement technique used in the oxygen analyzer subsystem of the Anesthetic Gas Subsystem is dependent on the type of O2 transducer used.

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Figure 2-2 Anesthetic Gas Subsystem Functional Block Diagram

4 Subassemblies, Modules and Components

This document describes the subassemblies, modules, and components of the MGM, how they are controlled by the central processing unit, how the CPU processes the data received from the analyzer subsystems, and how communication between the MGM and the host system (SC 9000, SC 7000, SC 9000XL, or SC 8000 Patient Monitor) works.

5 Anesthetic Gas Subsystem

Figure 2-2 shows a functional block diagram of the Anesthetic Gas Subsystem, which houses the system board and the following major components:

•Agent Measurement Analyzer (AMA)

•Agent Identification Analyzer (AIDA)

•Oxygen (O2) Analyzer

•Pneumatic System

•Power Supply

These components are typically built into a metal box whose dimensions, weight, and additional features meet the unique requirements of the SC9000, SC 7000, SC 9000XL, SC 8000 or similar host. Typically it includes a power switch, a power connector, an RS-232 connector, a gas inlet, and an exhaust tube.

6 Main System

The Pneumatic System (consisting of the pump, tubing system, solenoid valves, and flow control components) pulls the gas from the gas inlet through the analyzer subsystems at a well-defined flow rate. The second solenoid valve is used when both the Oxygen (O2) Analyzer and the Agent Identification Analyzer are installed.

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The Agent Measurement Analyzer determines the concentration of CO2, N2O and one anesthetic agent in the gas sample. The AMA is plumbed “first in line,” so that CO2 data is not distorted and capnographic waveforms can accurately be displayed by the host monitoring system.

The O2 Analyzer determines the oxygen concentration in the gas sample.

The Pressure Transducer measures the differential pressure of the gas contained in the pneumatic system. During a Zero calibration this equals the ambient environmental pressure. This pressure transducer is physically housed in the AMA, but plumbed after the O2 Analyzer.

The Agent Identification Analyzer determines which anesthetic agents, if any, are contained in the gas sample.

The Power Supply provides the Anesthetic Gas Subsystem and all of its components with the power necessary to keep the system working. It operates at an input voltage range of 100 - 240 Vac, and is certified to be in compliance with the applicable requirements of UL544 (Patient Care Equipment), CSA 22.2 No. 234 (Level 3), IEC 601-1 (1988), EN60601, and VDE 0750/5.82.

The Electronics Subsystem, with memory (ROM and RAM), multiplexers, A-D converter, and power line supervision, is responsible for the following functions:

•Acquisition and processing of data from, and control of, the AMA

•Acquisition and processing of data from the Oxygen Analyzer

•Controlling the Pneumatic System

•Controlling the communications between the Anesthetic Gas Subsystem and the host monitoring system

•Controlling the communications between the Anesthetic Gas Subsystem and the Agent Identification Subsystem.

The MGM/AMA Electronics Subsystem has two communications channels -- one connected to an external RS-232 port and the other connected to the AIDA Electronics Subsystem.

The AIDA Electronics Subsystem, with memory (ROM and RAM), multiplexers, A-D converter, and power line supervision, acquires and processes data from agent identification and controls the AIDA. The only communications channel in the AIDA Electronics Subsystem is the one connected to the MGM/AMA Electronics Subsystem.

Full functionality of the Anesthetic Gas Subsystem is controlled by its firmware.

7 Agent Measurement Analyzer

The proven, known, and widely used technology of non-dispersive infrared gas analysis is used by the AMA in the Anesthetic Gas Subsystem.Figure 2-3 on page 8 is a functional block diagram of this analyzer subsystem.

The infrared light source is constructed of tungsten powder metal which is embedded in an Al2O3 ceramic. This source is electrically heated to an operating temperature of 600°C. Infrared emission from this source is distributed as a blackbody radiator.

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Metal Cavity
								Infrared
	Filter Wheel							Detector
Wideband								With TE
	With IR Optical		Sample Cell				Sample Cell
								Cooler
Light Beam					Thermistor
	Bandpass Filters		Window				Window
Containing
Infrared
								Preamp
								Circuits
				Gas
Infrared			Gas	Sample		Gas
		Mot or		Cel l
Light			Input			Output
Source
								NVRAM
	Filter Wheel							Memory
	Cavity Heater	Thermistor
								AMA Preamp
								Board Assembly

Figure 2-3 Agent Measurement Analyzer Functional Block Diagram

	The sample cell is constructed of a stainless steel tube with a reflective
	inside surface which serves as a light pipe. The sample cell length has been
	designed to provide an adequate absorption length to obtain the desired
	signal-to-noise ratio for the weakest anticipated absorption. Sapphire serves
N2O	as the sample cell window material for the two ends of the sample cell.

Agent

Reference

CO2

Blank

Filter Wheel

The gas sample to be analyzed enters the sample cell through the gas inlet and leaves it through the gas outlet. While in the cell, the gas sample is penetrated by light from the infrared light (IR) source. This light is filtered by coated optical bandpass filters mounted on the filter wheel (see illustration at left). The attached brushless DC motor spins the filter wheel so that the appropriate filter for each gas type (CO2, N2O, agent) comes into place one after the other. The filter wheel cavity heater maintains the metal cavity at 65°C under control of a thermistor. The wavelengths used are --

•4.3µ for CO2

•3.6µ for N2O

•3.3µ for anesthetic agents

The thermistor attached to the sample cell wall provides a measure for the sample cell temperature. Knowledge of sample pressure and sample temperature is vital to accurately determine gas concentrations in the gas sample. Sample pressure is provided by a pressure transducer housed in the AMA but actually plumbed behind the O2 Analyzer. It is therefore its own gas connection.

The photoresistive lead selenide (PbSe) infrared detector, mounted on the preamplifier board assembly, converts the IR radiation not absorbed by the gas sample to an electrical signal. The transmittance of IR radiation is a measure of the total number of molecules of a given gas in the sample cell. The detector’s output signals are preamplified and consist of a pulse stream, one pulse for each IR filter, corresponding to the fraction of this gas type in the sample. The IR detector temperature is kept at 2°C by a thermoelectric cooler to enhance signal-to-noise ratio.

A calibration mechanism guarantees long-term stable measurements and eliminates filter variations.

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Sample Cell	Thermopile
Window	Infrared
	Detectors
	(4 of 7 illustrated)

				Specific
		Chopped		IR Wavelengths
Wideband	Light	Wideband
		Infrared	Sample Cell
Light Beam	Chopper
		Light	Window
Containing
Infrared
			Gas
			Sample
			Cell
Infrared		Motor
Light
Source
			Gas	IR Optical
			Input	Bandpass
				Filters
			Gas	(4 of 7 illustrated)
			Output

Thermistor

Preamp

Circuits

NVRAM

Memory

AIDA Preamp

Board Assembly

Figure 2-4 Agent Identification Analyzer (AIDA) Functional Block Diagram

8 Agent Identification Analyzer

The agent identification function identifies which of the following anesthetic agents is being used:

•one agent out of Isoflurane, Halothane, Enflurane, or

•one agent out of Isoflurane, Halothane, Sevoflurane, or

•one agent out of Isoflurane, Halothane, Desflurane.

Like the AMA, the AIDA in the Anesthetic Gas Subsystem uses the technology of non-dispersive infrared gas analysis. Figure 2-4 shows a functional block diagram of this analyzer subsystem.

Infrared light from the IR light source (which is identical to the AMA IR light source) is modulated using a rotating chopper wheel driven by a stepping motor which is speed controlled by the Electronics Subsystem.

Narrow band filtering and demodulation techniques greatly enhance the quality of the signal generated in the infrared absorption process.

The sample cell is made of thermoplastic, and has a conical shape and nonreflective walls. The cell window material is silicon.

Seven thermopile IR detectors which do not require cooling, each output an analog signal whose magnitude is inversely proportional to the infrared light absorption at the corresponding frequency. These frequencies are determined by the bandpass filters (4 of 7 illustrated in Figure 2-4) operating in the wavelength region from 10µ to 13µ. The thermistor output is used to compensate for the effect of IR filter temperature changes. The analog signals are directly related to the anesthetic agent gas concentrations in the sample cell.

The IR detector outputs are measured during both chopper wheel phases. Measurements taken when the IR light beam is interrupted provide the dark level reference needed by the signal processing software.

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9 Oxygen Analyzer

9.1ParamagneticMeasurement O2

9.2Electrochemical O2 Measurement

10Pneumatic System

These signals are amplified, filtered, and digitized by the pre-amplifier on the pre-amplifier board assembly. The digitized waveform is then demodulated by the electronics subsystem to obtain a transmission value for each detector.

The following transmission data is used to obtain the gas concentration values used by the agent identification routine.

•The seven preamplified IR detector outputs

•The thermistor output

•The Zero calibration constants

•Factory characterization constants

•Gas concentration algorithms

•Primary agent ID thresholds

•Secondary agent ID thresholds

•Primary to secondary agent ID crosstalk factors

A calibration mechanism guarantees long-term stable measurements and eliminates filter variations.

In the MULTIGAS+ Module, the Paramagnetic Oxygen Transducer provides “fast” O2 measurement. In the MULTIGAS Module, the electrochemical type sensor provides O2 measurement with a slower response time. Both the paramagnetic sensor and the electrochemical cell deliver an analog signal linearly proportional to the oxygen concentration in the sample gas.

O2 is paramagnetic, which means that a magnetic field induced in O2 will be in the same direction as, and in greater strength than, the magnetizing field. In the paramagnetic oxygen transducer, O2 is placed in two sealed spheres of a dumb-bell assembly, which is suspended on a spring device in a symmetrical non-uniform magnetic field. The assembly assumes a position away from the most intense part of the field.

Sample gas surrounds the dumb-bell assembly, and when the surrounding gas contains O2, the dumb-bell spheres are pushed further out of the field by the relatively stronger paramagnetic O2. The strength of the torque acting on the dumb-bell is proportional to the paramagnetism of the surrounding gas, and is converted into an analog voltage which is likewise proportional to the oxygen concentration.

The electrochemical O2 analyzer operates like a battery. O2 in the gas sample, in contact with an electrolyte, generates a voltage proportional to the concentration of O2.

The Anesthetic Gas Subsystem includes a gas sampling system which accurately controls the flow rate of gas through the analyzer system. Nafion® tubing, a hygroscopic material made from Teflon and polypropylenesulfonic acid copolymer, is added to the sampling line inside the Anesthetic Gas Subsystem to eliminate residual water. Anesthetic agents, N2O, and CO2 are impermeable to the tubing.

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Figure 2-5 Pneumatics Block Diagram (excerpt from Figure 2-2.)

As illustrated in Figure 2-5, pneumatic solenoid valves are incorporated in the gas stream to switch between the patient gas stream (normal operation) and room air (during Zero calibration). The selected gas (patient or room air) is directed to the Agent Measurement Analyzer, O2 analyzer, and Agent Identification Analyzer.

A servo controlled pump is attached to the exhaust of the analyzer. The pump generates the flow through the system and pulls the gas from the airway adapter through the analyzers to the exhaust outlet. It also delivers the Zero calibration gas to the sample cells of the analyzer subsystems for the periodic zero procedures, and exhausts the patient’s sample gas, zero calibration and field calibration gases. The pump can be operated at four different flow rates, which are hardware-adjusted during factory calibration of the MGM. See Table 2-1.

Table 2-1 Pump Flow Rates

	Flow	Flow	Description
	Type	Rate
	Idle	No Flow	Pump switched off
	Low	120	With Paramagnetic O2	With Electrochemical O2
		ml/min	analyzer	analyzer
			Used for analysis of	Optionally used for
			patient gas samples	analysis of patient gas
				samples.
	High	200	With Paramagnetic O2	With Electrochemical O2
		ml/min	analyzer	analyzer
			Used for purging	Used for normal analysis
			Agent Measurement	of patient gas samples
			and paramagnetic O2
			analyzers before and
			after zero calibration
	Purge	350 ml/	With Paramagnetic O2	With Electrochemical O2
		min	analyzer	analyzer
			Used for purging the	Used for purging the
			Agent Identification	Agent Measurement and
			Analyzer before and	Agent Identification
			after Zero calibration	Analyzers before and
				after Zero calibration

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A flow sensor, consisting of a differential pressure transducer, a dampener, and a flow restrictor, is used to determine, stabilize and limit the flow rate of the sampled gas. The output from the pressure transducer is used in a servo system to control the drive power to the pump. The dampener (a 15cc container) isolates the sample cells of the analyzer subsystems from pulsations, enabling a smooth flow through the system. The flow rate control logic works as hard as necessary to maintain the selected flow rate. A partial occlusion, or an inefficient pump, result in the pump being driven harder. A serious occlusion results in the pump being driven at or near its maximum drive. A sense circuit is then triggered to report an occlusion.

11Self-Test

A power-up self-test is performed to validate the contents of firmware memory (ROM), read/write memory (RAM) and non-volatile memory (NVRAM), and to verify errorless access to these storage devices for read and write operations.

12Calibration

12.1Factory Calibration

12.2Field Span Calibration

12.3 Zero Calibration

In order to guarantee long-time stable measurement performance the MGM must be enabled to cope with three types of conditions that can lead to measurement errors:

•Small differences among the components of a subsystem (e.g., caused by limitations in manufacturing precision)

•Changes of the physical properties of some components over time (e.g., caused by aging or pollution)

•Limitations in the compensation for certain effects (e.g., changes in cell temperature/pressure or cross-gas interference)

Each of these conditions can be handled by an appropriate calibration process performed either during original manufacture, as part of normal preventive maintenance, or during normal use.

During factory calibration, the individual performance of each subsystem unit is measured. Polynomial coefficients are then calculated from these individual response curves and stored in the unit itself. These coefficients are later used to compensate for possible unit-to-unit component differences.

During field Span calibration, accurately known concentrations of each gas of interest are introduced into the AMA and O2 Analyzer sample cells and measured. Differences between the known and the measured values are used to calculate the appropriate coefficients for compensation of these differences.

Field Span calibration of the anesthetic agent, CO2 and N2O channels is typically part of preventive maintenance.

The paramagnetic O2 analyzer typically does not require Span calibration.

When an electrochemical O2 sensor is in use, the O2 channel must periodically be Span calibrated.

During Zero calibration, the analyzer subsystems are purged with room air or nitrogen to eliminate any gas of interest (concentration of these gases is “zero”). Oxygen or nitrogen are convenient “Zero calibration gases” since they do not absorb infrared radiation in the wavelengths used by the AMA and AIDA. Since atmospheric air is composed primarily of oxygen and

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nitrogen, with small amounts of water and CO2, normal room air is used for zeroing the MGM system. Optionally, the MGM can be Zero calibrated with 100% dry nitrogen.

Since changes of physical properties of subsystem components have the same effect on room air measurement performance, this is used as a reference and therefore to calculate new coefficients which help compensate for such changes. Zero calibration of the MGM analyzer subsystem is requested by the MGM as follows:

12.4Storage of Calibration Data

12.5Calibration of Agent Measurement Analyzer

•after certain time intervals

•after certain changes in operation

•after certain operational failures have been detected.

The Zero calibration process measures the infrared signal strength (transmittance) when no IR absorbing gases are in the sample cell. AMA and AIDA field calibration software compensates for the small absorption from atmospheric CO2.

With one exception, all Zero calibration data is stored in and used from volatile RAM memory. The Zero calibration data calculated by the first successful Zero calibration after is stored in non-volatile NVRAM memory for use after subsequent resets.

All Span calibration data is stored in non-volatile NVRAM memory. Critical data is replicated into a second location in both RAM memory (for immediate use) and NVRAM memory.

Block checksums are used to confirm continued validity of NVRAM and RAM data. Power cycling does not affect this data

Both the AMA and AIDA subsystems have their own NVRAM memory for storing their own calibration data, enabling interchangeability of these subsystems with system boards.

Calibration data for the oxygen analyzer is stored in AMA NVRAM memory.

12.5.1	Factory Calibration	Factory calibration compensates for small differences among the following
		components: pressure transducer, infrared (IR) light source, sample cell
		thermistor, filter heater element, filter cavity thermistor, each of the IR
		bandpass filters, IR detector, and thermo-electric cooler. Near the end of
		the manufacturing process, binary gases are used to characterize each
		AMA. The characterization process also analyzes individual cross-gas
		interference. The last function performed during characterization is to
		verify performance by sampling cocktail gases. Each unit ends up with is
		own unique set of response curves, and the ability to accurately report gas
		concentrations based on its individual parts and characteristics.
12.5.2	Field Span Calibration	The AMA should be calibrated by trained service personnel once every 12
		months using precision calibration gases. The resulting Span calibration data
		is stored in NVRAM memory. The host system can replace field calibration
		data with the original factory calibration data via software command.
12.5.3	Zero Calibration	To maintain the highest gas concentration measurement accuracy
		possible, the MGM requests that the host command Zero calibration at the
		following time intervals The Zero calibration is performed automatically,
		requiring no user intervention.
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:

Zero Calibration	Time Interval
1st	8 minutes after power-up or reset
2nd	15 minutes after power-up or reset
3rd	30 minutes after power-up or reset
4th	45 minutes after power-up or reset
5th	90 minutes after power-up or reset
next	8 hours after previous calibration

12.6Agent Identification Analyzer

12.6.1	Factory Calibration	Factory calibration compensates for small differences among the following
		components: infrared (IR) light source, detector thermistor, each of the
		seven IR bandpass filters, and each of the seven IR detectors. Near the end
		of the manufacturing process, binary gases are used to characterize each
		AIDA. The last function performed during characterization is to verify per-
		formance by sampling cocktail gases. Each Analyzer ends up with its own
		unique set of response curves, and the ability to accurately measure and
		identify anesthetic agents based on its individual parts and characteristics.
12.6.2	Field Span Calibration	The function of the AIDA is to measure accurately very low gas
		concentrations, most critically in the range of 0.0% to 0.5% where
		identification thresholds are set. Since field Span calibration would not
		influence the performance of the Analyzer in this very narrow range, none
		is required.
12.6.3	Zero Calibration	As with the AMA, regular Zero calibration is required. The Zero calibration
		process is exactly the same as for the AMA, but the time intervals are
		slightly different. The first Zero calibration is performed automatically
		(without host involvement) 2 minutes after power-up. Other Zero cali-
		brations are requested of the host system as described in Section 12.5.3.

12.7Paramagnetic O2 Analyzer

12.7.1	Factory Calibration	The paramagnetic O2 analyzer is calibrated with potentiometers at the 0%
		and 100% point of its measurement range.
12.7.2	Field Span Calibration	The paramagnetic O2 analyzer may be Span calibrated in the field via Span
		calibration commands using appropriate precision calibration gases.
		The resulting Span calibration data is stored in NVRAM memory. The host
		can replace field calibration data with the original factory calibration data via
		software command.
12.7.3	Field Zero Calibration	Zero calibration of the paramagnetic O2 analyzer is performed with room
		air. This is done every time the AMA is Zero calibrated.

12.8Fuel Cell Type O2 Analyzer Calibration

12.8.1 Factory Calibration		The fuel cell type O2 analyzer does not require “characterization” or factory
		calibration. In the case where a fuel cell type O2 analyzer is installed prior
		to original equipment shipment, field Span and Zero calibration are
		performed.
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12.8.2Field Span and Zero Calibration

12.8.3Field Zero Calibration

The fuel cell type O2 analyzer must be periodically Span calibrated since its output is continually degrading during use. Fuel cell type O2 analyzer Span and Zero calibration is performed using the MGM 2-point Span calibration command as discussed in Section 12.7.2. The resulting O2 calibration data is stored in NVRAM memory.

Separate Zero calibration of the fuel cell type O2 analyzer is not required.

12.9Pneumatic System Calibration

12.9.1	Factory Calibration	The pneumatic system of the Agent Analyzer Subsystem is factory-
		calibrated by performing range adjustments. A flow meter is used to adjust
		the four possible flow rates in which the pump can operate. These values
		are set by appropriately adjusting three potentiometers.
		The specific flow rates listed below are representative of one MGM
		configuration. Other configurations may use slightly different flow rates.
			Flow Type	Flow Rate
			Idle	No flow
			Low	120 ml/min
			High	200 ml/min.
			Purge	350 ml/min.
12.9.2	Field Flow Rate Calibration	Trained service personnel may perform a field calibration of the pneumatic
		system. A field calibration consists of the same range adjustments done
		during the factory calibration.

13Software

13.1AMA Data Acquisition

Figure 2-6 on page 16 shows a functional block diagram of MGM software. Each bubble indicates a submodule of that software and represents a functional task that is described in more detail below. Each box indicates a hardware part controlled by the firmware. Figure 2-6 also shows that the AIDA Control and Data Processing submodules run on its own AIDA Electronics Subsystem while all remaining submodules are executed by the MGM/AMA Electronics Subsystem, both shown in Figure 2-6.

The AMA Data Acquisition submodule, physically located on the AMA, acquires IR detector output signal pulses, sample cell pressure, sample cell temperature, filter wheel cavity temperature, and IR detector temperature data from the AMA. Additional data acquired by the submodule includes ambient temperature, pump flow rate, four MGM system board voltage measurements and the output of the O2 analyzer.

These analog signals are digitized by an A-D converter in the MGM/AMA Electronics Subassembly. The submodule stores this raw data in shared RAM memory so that the AMA Signal Processing and the Control submodules can access and further process them.

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Figure 2-6

Software Functional Block Diagram

13.2AMA Signal Processing

The AMA Data Acquisition and Control submodules send control signals to the AMA to control its IR source, TE cooler temperature, filter wheel motor speed, and filter wheel heater temperature.

Additional data acquired by the submodule includes ambient temperature, pump flow rate, four MGM system board voltage measurements and the output of the O2 analyzer.

These analog signals are digitized by an A-D converter in the MGM/AMA Electronics Subassembly. The submodule stores this raw data in shared RAM memory so that the AMA Signal Processing and the Control submodules can access and further process them.

The AMA Data Acquisition and Control submodules send control signals to the AMA to control its IR source, TE cooler temperature, filter wheel motor speed, and filter wheel heater temperature.

The Data Acquisition submodule checks the digitized data against A-D converter boundary conditions and issues an A-D limit error to the MGM/ AMA Control submodule if necessary.

The AMA Signal Processing submodule reads the AMA IR detector output data from RAM memory, takes an average of four samples and normalizes this average by multiplying the zero constant offset determined during the last Zero calibration of the AMA. This zero constant is read from the AMA RAM memory. The normalized data is stored in RAM memory from where it is read and further processed by the AMA Gas Concentration Algorithms submodule.

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