NORTH AMERICAN DRÄGER Primus User manual

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Technical Documentation

Primus Anaesthetic Workstation

Revision 6.0

5132.300 9036004

Because you care

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Contents

General

1 Symbols and Definitions 3

2 Notes 3

Function Description

1 General 7

1.1 Medical purpose ..................................................................................................................... 7

1.2 Product classification ............................................................................................................. 8

1.3 Protection classes .................................................................................................................. 8

1.4 Short description of Primus ...................................................................................................9

1.4.1 Ventilator .................................................................................................................. 9

1.4.2 Breathing system ...................................................................................................... 9

1.4.3 Mixer (fresh gas metering) .................................................................................... 10

1.4.4 Monitor control panel .............................................................................................. 11

1.4.5 Options ................................................................................................................... 12

1.5 Primus component structure ............................................................................................... 12

1.5.1 NEUTRAL POINT PCB .......................................................................................... 12

1.5.2 Graphical User Interface (GUI) ............................................................................... 13

1.5.3 Mixer ....................................................................................................................... 13

1.5.4 VGC (Ventilation and Gas Controller) .................................................................... 13

1.5.5 Power pack ............................................................................................................. 13

1.5.6 Cylinder pressure regulator .................................................................................... 13

2 NEUTRAL POINT PCB 15

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3 GUI 17

3.1 Monitor Control Panel (MoBi) ...............................................................................................17

3.1.1 MONITOR CONTROL PANEL PCB ....................................................................... 19

3.2 S-Box (interface box) ............................................................................................................20

3.2.1 BACKPLANE PCB ..................................................................................................21

3.2.2 SpO2 sampling function (option) .............................................................................22

4 Patient gas module 23

4.1 Version PGM2 ...................................................................................................................... 23

4.1.1 ILCA2 function ........................................................................................................26

4.1.2 PGM2 with Pato O2 sensor ....................................................................................28

4.1.3 PGM2 with Servomex O2 sensor ...........................................................................30

4.1.4 Pneumatics of the PGM2 ........................................................................................32

4.2 Version PGM ........................................................................................................................ 34

4.2.1 PGM pneumatic components ................................................................................. 37

4.3 Operating modes .................................................................................................................. 39

4.3.1 "Reduced Accuracy" mode (PGM only) .................................................................. 39

4.3.2 "ISO" mode (ISO accuracy) (PGM/PGM2) ............................................................. 39

4.3.3 "Full Accuracy" mode (PGM only) ..........................................................................39

4.3.4 "Standby" response of the Primus (PGM/PGM2) ................................................... 39

4.3.5 IRIA/ILCA2 calibration ...........................................................................................39

4.3.6 Auto-Wake-up function ..........................................................................................39

4.3.7 O2 sensor/Servomex ..............................................................................................39

4.4 PGM/PGM2 electronics ........................................................................................................40

4.4.1 MOPS PCB (PGM/PGM2) ......................................................................................40

4.4.2 AMO IRIA PCB (PGM) ............................................................................................40

4.4.3 AMO ILCA2 PCB (PGM2) .......................................................................................40

4.4.4 AMO O2 PUMP PCB (PGM) ..................................................................................40

4.4.5 AMO MFM PCB (PGM2) ........................................................................................40

4.4.6 AMO FLOW ILCA PCB (PGM/PGM2) .................................................................... 41

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5 Mixer 43

5.1 Operating modes .................................................................................................................. 46

5.1.1 10 VA mode ............................................................................................................ 46

5.1.2 'Normal' mode ........................................................................................................ 46

5.2 Layout ................................................................................................................................... 46

5.2.1 MIXER PCB ............................................................................................................ 46

5.2.2 PRIMUS CPU PCB (mixer) .................................................................................... 47

5.3 Gas inlet block (AIR, O2 and N2O) ...................................................................................... 48

5.3.1 Pneumatic components, gas inlet block ................................................................. 50

5.3.2 Pressure status LEDs ............................................................................................. 52

5.4 Mixer block ........................................................................................................................... 55

5.5 Pneumatic system ................................................................................................................ 56

5.5.1 VMIX valves ........................................................................................................... 57

5.5.2 PDMIX and RM ...................................................................................................... 57

5.5.3 PTANK (pressure sensor) ....................................................................................... 57

5.5.4 VTANK valve .......................................................................................................... 57

5.5.5 VMGS (fresh gas flow valve) .................................................................................. 57

5.5.6 PDMGSHI / PDMGSLO (differential pressure sensors) ......................................... 57

5.5.7 PSYS (pressure sensor) ......................................................................................... 57

5.5.8 VSWAK (A-cone valve) .......................................................................................... 58

5.5.9 VBAK (safety valve) ............................................................................................... 58

5.5.10 TEMPTANK / TEMPBLOCK (temperature sensors) ............................................... 58

5.5.11 VSFC (safety O2 adjuster) ..................................................................................... 58

5.5.12 VO2+ (flush button) ................................................................................................ 58

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III

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6 VGC 59

6.1 VGC electronics ....................................................................................................................61

6.1.1 VGC POWER PCB .................................................................................................61

6.1.2 PRIMUS ANALOG PCB .........................................................................................61

6.2 Piston cylinder unit (PCU) ....................................................................................................62

6.3 VGC pneumatic block ...........................................................................................................64

6.4 VGC pneumatic system ........................................................................................................65

6.5 Interface plate .......................................................................................................................67

6.6 Breathing system ..................................................................................................................69

6.6.1 Compact breathing system pneumatic components ............................................... 72

6.7 Automatic ventilation ............................................................................................................73

6.7.1 Inspiration ...............................................................................................................73

6.7.2 Expiration ................................................................................................................75

6.8 Manual ventilation .................................................................................................................77

6.8.1 Inspiration ...............................................................................................................77

6.8.2 Expiration ................................................................................................................78

6.9 Spontaneous breathing .........................................................................................................79

6.9.1 Inspiration ...............................................................................................................79

6.9.2 Expiration ................................................................................................................80

7 Ventilation modes with software version 2.n or higher 81

7.1 “Volume Mode” .....................................................................................................................81

7.2 “Pressure Mode” ...................................................................................................................84

7.3 “Pressure Support Mode” .....................................................................................................87

7.4 “Man./Spont Mode” ...............................................................................................................88

7.5 Switching ventilation modes .................................................................................................89

7.6 HLM mode ............................................................................................................................89

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8 Power pack 91

8.1 Power pack input .................................................................................................................. 91

8.2 Power switch ........................................................................................................................ 92

8.3 Output voltages and currents ............................................................................................... 92

8.4 Secondary connector ........................................................................................................... 93

8.5 UPS batteries ....................................................................................................................... 93

8.6 Power pack CAN communication ......................................................................................... 94

8.7 Power failure warning ........................................................................................................... 94

9 Operating modes 95

9.1 Cold start .............................................................................................................................. 95

9.2 Standby mode ...................................................................................................................... 95

9.3 Shutdown ............................................................................................................................. 95

9.4 Safety mode ......................................................................................................................... 95

9.4.1 Safety O2 flow ........................................................................................................ 95

9.5 Alarm system ........................................................................................................................ 96

10 Cylinder pressure reducer 97

11 Vaporizer 101

12 Bronchial aspirator 103

12.1 Intended use ....................................................................................................................... 103

12.2 Device types ....................................................................................................................... 103

12.2.1 Variants ................................................................................................................. 103

12.3 Bronchial aspirator with ejector .......................................................................................... 103

12.3.1 Pneumatics (ejector) ............................................................................................ 104

12.4 Bronchial aspirator with vacuum ........................................................................................ 105

12.4.1 Pneumatics (vacuum) ........................................................................................... 106

13 Block diagrams and pneumatic components layout 109

13.1 Introduction ......................................................................................................................... 109

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Maintenance Procedures

1 Safety precautions 123

2 Rear panel 125

2.1 Rear panel removal ............................................................................................................125

2.2 Rear panel fitting .................................................................................................................125

2.2.1 Rear panel final check ..........................................................................................125

3 Replacing bronchial suction device bacterial filter 127

4 Replacing filter mat on PGM fan 129

5 Replacing bacterial filter and Nafion tube in PGM 131

5.1 Removing the PGM ............................................................................................................131

5.1.1 Removing the PGM housing ................................................................................. 131

5.2 Replacing the bacterial filter ...............................................................................................133

5.3 Replacing the Nafion tube ................................................................................................. 133

5.4 Fitting the PGM housing (new) ...........................................................................................134

6 Cleaning or replacing filter mat in housing cover 137

6.1 Filter mat removal ...............................................................................................................137

6.1.1 Filter mat fitting .....................................................................................................138

7 Replacing filter mat in power pack 139

8 Replacing UPS batteries 141

8.1 Power pack removal ...........................................................................................................141

8.2 Removing UPS batteries ....................................................................................................142

8.3 Fitting UPS batteries ...........................................................................................................144

8.4 Fitting the power pack .........................................................................................................146

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9 Cleaning or replacing large and small filter mats in VGC 147

9.1 Removal of large filter mat ................................................................................................. 147

9.1.1 Fitting of large filter mat ........................................................................................ 149

9.2 Removal of small filter mat ................................................................................................. 149

9.2.1 Fitting of small filter mat ....................................................................................... 150

10 Replacing bag upper roller diaphragm 151

11 Replacing the lower rolling seal (VGC) 153

11.1 Removing the VGC ............................................................................................................ 153

11.2 Removing the piston-cylinder unit ...................................................................................... 158

11.2.1 Removing/Fitting the lower rolling seal ................................................................. 162

11.3 Mounting piston-cylinder unit .............................................................................................. 168

12 Replacing pressure regulators PRPN2O, PRPAIR, PRPO2 173

12.1 Removing gas inlet block pressure regulators ................................................................... 173

12.2 Fitting pressure regulators .................................................................................................. 174

13 Replacing CPU PRIMUS PCB lithium battery 179

13.1 Removing mixer ................................................................................................................. 179

13.2 Removing mixer cover ........................................................................................................ 182

13.3 Replacing the lithium battery .............................................................................................. 183

13.4 Fitting mixer cover .............................................................................................................. 184

13.5 Mixer fitting ......................................................................................................................... 184

14 Replacing PEEP diaphragm and MAN/SPONT diaphragm 185

15 Pressure regulator major overhaul 189

15.1 Safety precautions .............................................................................................................. 189

15.2 Required spare parts .......................................................................................................... 190

15.3 Service Equipment Required .............................................................................................. 191

15.4 Removing the pressure regulator ....................................................................................... 192

15.5 Replacing the “Major Overhaul” spare parts set ................................................................. 194

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VII

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Schematics and Diagrams

1 Primus pneumatic components diagram 203

2 Schematics and Diagrams 209

Annex

Parts catalog

Test List

Technical Information

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General

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Primus General

1 Symbols and Defini-

tions

WARNING

A WARNING statement provides important information about a potentially hazardous situation which, if not avoided, could result in death or serious injury.

CAUTION

A CAUTION statement provides important information about a potentially hazardous situation which, if not avoided, may result in minor or moderate injury to the user or patient or in damage to the equipment or other property.

NOTE

A NOTE provides additional information intended to avoid inconvenience during operation.

Definitions according to German standard DIN 31051:

Inspection = examination of actual condition

Maintenance = measures to maintain specified condition

Repair = measures to restore specified condition

Servicing = inspection, maintenance, and repair

2Notes

This Technical Documentation conforms to the IEC 60601-1 standard.

Read each step in every procedure thoroughly before beginning any test. Always use the proper tools and specified test equipment. If you deviate from the instructions and/or recommendations in this Technical Documentation, the equipment may operate improperly or unsafely, or the equipment could be damaged.

It is our recommendation to use only Dräger parts and supplies.

The maintenance procedures described in this Technical Documentation may be performed by qualified service personnel only. These maintenance procedures do not replace inspections and servicing by the manufacturer.

The information in this Technical Documentation is confidential and may not be disclosed to third parties without the prior written consent of the manufacturer.

This Technical Documentation is for the purpose of information only. Product descriptions found in this Technical Documentation are in no way a substitute for reading and studying the Instructions for Use/Operating Manual enclosed with the product at the time of delivery.

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General Primus

Know-how contained in this Technical Documentation is subject to ongoing change through research and development and Dräger Medical reserves the right to make changes to this Technical Documentation without notice.

NOTE

Unless otherwise stated, reference is made to laws, regulations or standards (as amended) applicable in the Federal Republic of Germany for equipment used or serviced in Germany. Users or technicians in all other countries must verify compliance with local laws or applicable international standards.

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Function Description

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Primus Function Description

1 General

1.1 Medical purpose

Primus is an anaesthetic workstation for automatic and manual ventilation and spontaneous breathing, usable for adults, children and infants.

Application:

– Inhalation anesthesia in rebreathing systems.

– Inhalation anesthesia in virtually closed systems for low-flow and mini-

mum-flow applications.

– Inhalation anesthesia in non-rebreathing systems with separate fresh gas

output for connection of “Bain” or “Magill” system, for example, with a fresh gas flow of 0.2 L/min to 18 L/min.

Changed ventilation modes (software 2.n or higher):

– Volume-controlled ventilation “Vol u m e Mode”. Switchable functions:

• Synchronization.

• Pressure support (optional).

– Pressure-controlled ventilation “Pressure Mode” Switchable functions:

• Synchronization.

• Pressure support (optional).

– Manual ventilation “MAN”.

– Spontaneous breathing “SPONT”.

– Pressure-assisted ventilation “Pressure Support” (optional).

Ventilation modes (up to software d1.06):

– Volume-controlled ventilation “IPPV, SIMV”.

– Pressure-controlled ventilation “PCV”

– Manual ventilation “MAN”.

– Spontaneous breathing “SPONT”.

Displayed values:

– Peak pressure “Ppeak”, mean pressure “Pmean”, plateau pressure

“Pplat, PEEP”.

– Expiratory minute volume “MV”, tidal volume “VT”, respiratory frequency

“f”.

– Inspiratory and expiratory concentrations of O2, N2O, anesthetic gas and

CO2.

– System compliance and leakage minute volume.

– Functional oxygen saturation “SpO2” and pulse rate (optional).

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Function Description Primus

Curve diagrams:

– Airway pressure “Paw”.

– Inspiratory and expiratory flow “V”.

– Inspiratory and expiratory concentrations of O2, CO2 and anesthetic gas.

– Plethysmogram (optional).

– P/V loops and flow/V loops (optional in software 2.n or higher).

Bargraph:

– Display of inspiratory tidal volume, expiratory tidal volume and leakage

tidal volume.

– Volumeter.

– Econometer (optional in software 2.n or higher).

Time trends of measured values (trends) are additionally available.

Monitoring:

– By programmable alarm limits which can be adjusted automatically to the

respective ventilation situation.

Monitored parameters:

– Airway pressure “Paw”.

– Expiratory minute volume “AMV”.

– Apnea (deactivated in heart-lung machine mode (HLM mode)).

– Inspiratory and expiratory anesthetic gas concentrations.

– Detection of anesthetic gas mixtures.

– Inspiratory O2 and N2O concentrations (breathing-phase independent

measurement in HLM mode).

– Inspiratory and expiratory CO2 concentrations (breathing-phase indepen-

dent measurement in HLM mode).

– Optional: Oxygen saturation (alarms deactivated in HLM mode), pulse

rate.

1.2 Product classification

– Class II b, according to rules 2, 9 and 11 of the Medical Products Direc-

tive.

1.3 Protection classes – Protection class I, type B according to EN 60601-1.

– With optional SpO2: Protection class I, type BF.

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Primus Function Description

1.4 Short description of Primus

1.4.1 Ventilator

The following sections provide an overview of the Primus components.

Figure 1 Ventilator with breathing system

The electronically controlled and driven ventilator has the following features:

– Tidal volumes of 20 mL (10 mL with software 2.n or higher) to 1400 mL at

frequencies of 3/min to 80/min.

– Peak flow of up to 150 L/min.

– Ventilation modes such as IPPV, PCB, SIMV (plus adjustable trigger, plus

adjustable PEEP) and MAN/SPONT (up to software 1.n).

– Ventilation modes such as volume mode, pressure mode, pressure sup-

port (optional) and MAN/SPONT with switchable synchronization and pressure assistance (optional).

1.4.2 Breathing system The breathing system comprises the following components:

– Integrated absorber, either reusable or disposable.

– Electronic interfaces for inspiratory and expiratory flow measurement.

– Direct patient section heating is integrated into the valve plate of the

breathing system.

– Pneumatic interface to ventilator.

– Fresh gas isolation and minimized compliance.

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Function Description Primus

1.4.3 Mixer (fresh gas metering)

The electronic mixer offers the following features:

– Gas metering for O2, N2O and AIR.

– Metering range from 200 mL/min to 18 L/min.

– Alarm monitoring for the pressure values of the central supply (CS) and

the cylinder supply. LEDs on the front panel indicate the pressure status.

– ORC function for low-flow and minimum-flow applications.

– O2 flush and mechanical safety O2 adjuster (see Figure 2).

Figure 2 O2 flush (O2+), mechanical safety O2 adjuster

– Double Vapor plug-in system with interlock.

– Optional external A-cone as fresh gas outlet.

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Primus Function Description

1.4.4 Monitor control panel

Figure 3 Monitor control panel

The parameters for fresh-gas flow control, ventilation, and gas monitoring are displayed on a 12-inch color screen.

The following parameters are monitored:

– Airway pressure.

– Inspiratory and expiratory flow.

– Circle system leakage.

– Inspiratory and expiratory O2 concentration.

– CO2 measurement and anesthetic gas measurement.

– Anesthetic gas detection.

– Quantitative measurement of mixed-gas values and MAC calculation

(age-relevant).

A data view, a trend view (graphical) and a log view can be selected.

As from software release 2.n the following settings are possible:

– Free configuration of 3 real-time curves and different numerical values.

– Body-weight-relevant ventilator presettings (Vt and frequency) and age-

relevant calculation of minimum alveolar concentration (MAC ) according to “Mapleson” as well as age-relevant scaling of volumeter and influence on ventilation monitoring.

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Function Description Primus

The safety concept incorporates the following tests:

– Automatic self-test with mixer test, ventilator test and test of the breathing

system.

– Test and automatic calibration of all sensors.

1.4.5 Options Primus is prepared for future upgrading with the following options:

– Integrated SpO2 measurement.

– Consumption-free O2 measurement (with software 2.n or higher).

– PAW preview – display of expected airway pressure curve when chang-

ing parameters.

– P/V and flow/V loops (with software 2.n or higher).

– Econometer function (with software 2.n or higher).

– Additional ventilation modes (e.g. autoflow, CPAP).

– Additional languages available for display texts.

1.5 Primus component structure

Figure 4 Primus component structure

In the “Block diagrams” section, you will find a detailed block diagram of the

Primus.

1.5.1 NEUTRAL POINT PCB The NEUTRAL POINT PCB connects the components of the Primus to the

power supply, additional signal wires and the CAN bus.

More details are given in the following section on the NEUTRAL POINT PCB.

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Primus Function Description

1.5.2 Graphical User Interface (GUI)

The GUI has the following components:

– On the Monitor Control Panel (MoBi) the ventilation mode is displayed.

Limit and target values are specified and the ventilation and anesthesia parameters are displayed.

– S-Box (Interface box). PC interfaces and optional measuring functions

such as SpO2 and BIS

– Patient Gas Module (PGM) for measurement of O2, CO2 and anesthetic

gas.

For more details refer to the section headed GUI.

1.5.3 Mixer The mixer comprises the following function units:

– Electronically controlled and monitored mixer.

– Vapor plug-in system for one or two conventional vaporizer types.

– External fresh gas outlet, A-cone (optional).

– Pressure monitoring for CS and compressed gas cylinders.

More details are given in the following section on the mixer.

1.5.4 VGC (Ventilation and Gas Controller)

The VGC comprises the following function units:

– Electronically controlled and driven ventilator.

– Integrated breathing system for “low flow” and “minimum flow” applica-

tions.

For more details refer to the section headed VGC.

1.5.5 Power pack The power pack comprises:

– Switched-mode power supply unit.

– Uninterruptible power supply (UPS) with one battery pack consisting of

two 12 V lead-gel batteries.

– Battery charging management.

For more details refer to the section headed Power pack.

1.5.6 Cylinder pressure regulator

The cylinder pressure regulators reduce the pressure of the optional compressed gas cylinders.

For more details refer to the section headed Cylinder pressure regulators.

The function description relating to the NEUTRAL POINT PCB follows.

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Function Description Primus

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Primus Function Description

2 NEUTRAL POINT

PCB

The NEUTRAL POINT PCB is the central signal and voltage distributor.

Figure 5 Location of the Neutral Point PCB

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Function Description Primus

Figure 6 Component mounting diagram, NEUTRAL POINT PCB, for leg-

end see Table 1

Table 1 Legend to Figure 6

Item Connector

1 Monitor Control Panel (MoBi).

2 Monitor Control Panel (MoBi).

3 Ventilation and Gas Controller (VGC).

4Mixer B.

5Mixer A.

6 Safety O2 flow valve (microswitch).

7 Power switch (main switch).

8 Halogen lamp

9 Jack plug (production tests).

10 PGM.

11 Power pack A.

12 Power pack B.

13 Not assigned.

The function description relating to the GUI follows.

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Primus Function Description

3GUI The following section describes the user interface (“GUI = Graphical User

Interface”).

Figure 7 GUI block diagram

3.1 Monitor Control Panel (MoBi)

In the “Block diagrams” section, in the block diagram of the Primus, you will find a block diagram of the GUI.

The GUI has the following components:

– MoBi (monitor control panel).

– S-Box (Interface Box).

– Patient Gas Module (PGM). The function description relating to the

Patienten Gas Module (PGM) follows.

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Figure 8 Position of Monitor Control Panel (MoBi)

In the “Block diagrams” section, you will find a block diagram of the MoBi.

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Function Description Primus

The user and Primus communicate via the MoBi. The MoBi display presents system and patient information. It is here that the user sets the parameters and ventilation modes.

The Patient Gas Module (PGM) is connected to the GUI.

Figure 9 Exploded view of MoBi, for legend see Ta b le 2

Table 2 Legend to Figure 9

Item Components

1 Front panel with membrane keypad. Includes keypad membrane

covering with design imprint, keys, LEDs (e.g. for CS gases), the carrier plate and the shielding, anti-glare glass screen.

2 12 inch color display (TFT, resolution: 800 x 600).

3 MONITOR CONTROL PANEL PCB (motherboard).

4 Backlight converter (display backlighting).

5 LCD800 PCB (adapter PCB for connection of different makes of

display).

6 Loudspeaker.

7 Rotary transducer.

8 Control knob (central operator control element).

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Primus Function Description

3.1.1 MONITOR CONTROL PANEL PCB

The following software is installed on the PCB:

– GUI software.

– Monitoring and evaluation software for the PGM.

– Software for Medibus connections and SpO2.

A 2-processor system is in operation on the PCB. It comprises a Display Master (DiMa) and a Communication Master (CoMa).

The powerful DiMa processor incorporates the following components:

– Motorola processor (MPC823) with 48 MHz clock frequency and 32-bit

address and data buses.

– Flash-PROM (program memory).

– RAM (data memory).

– CAN controller.

– RS232 interface for in-house development purposes.

– Serial communication channel for Ethernet.

The LCD controller is a programmable logic device (“PLD”). A “DRAM” serves as the video memory.

The CoMa processor system primarily controls communication with the other Primus components.

The CoMa incorporates the following components:

– Motorola processor (M68332) with 16.7 MHz clock frequency, internal 32-

bit bus and external 16-bit data bus.

– Flash-PROM (program memory).

– RAM (data memory).

– RS232 interface for communication with the SPO2, PGM and Medibus 1 -

3 modules.

– Real-time clock (RTC).

– Keyboard and rotary knob scan, LED actuation and sound output.

– CAN interface.

Both processor systems communicate by way of a Dual-Port RAM (DPR). This memory device is battery-buffered. The buffering is provided primarily by the UPS batteries of the Primus. If they fail, the lithium battery on the MONITOR CONTROL PANEL PCB ensures data is retained.

The operating voltage is provided by an unstabilized voltage of 20 V to 30 V (Vcc). DC converters on the MONITOR CONTROL PANEL PCB generate all other voltages on the PCB.

The MoBi is interconnected over the CAN bus with the other components of the Primus (power pack, mixer and VGC).

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Function Description Primus

3.2 S-Box (interface box)

Figure 10 Position of S-Box

In the “Block diagrams” section, you will find a block diagram of the S-Box.

Figure 11 Layout of the S-Box, for legend see Tab l e 3

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Primus Function Description

Table 3 Legend to Figure 11

Item Components

1 Drawer unit components fully mounted.

2 BACKPLANE PCB.

3 SpO2 ADAPTER PCB (SpO2 PCB not shown).

Figure 12 S-Box, block diagram

The S-Box as standard includes the BACKPLANE PCB and thus the externally available Medibus ports (COM 1-3), IV-System (Ethernet for TIVA) and a CAN port (SABUS exclusively for debug purposes).

The S-Box is prepared for the SpO2 option.

3.2.1 BACKPLANE PCB The BACKPLANE PCB is the base component for additional modules and

the insulated interfaces to external devices.

In the “Block diagrams” section, you will find a block diagram of the BACK-

PLANE PCB

The BACKPLANE PCB has the following functions:

– Electrical isolation and level conversion of the 3 Medibus ports (RS232).

– Connects the MoBi with the CAN (SABUS) and Ethernet (TCP/IP) con-

nectors.

– Connects the optional hardware (SPO2, IV-System) with the MoBi (as

from SW 1.n).

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Function Description Primus

3.2.2 SpO2 sampling function (option)

The SpO2 sampling function has the following tasks:

– Non-invasive measurement of functional oxygen saturation in the arterial

blood. The upper and lower alarm limits are monitored on the MONITOR CONTROL PANEL PCB by the CoMa processor.

– Measurement of pulse rate.

– Monitoring of the pulse rate with upper and lower alarm limits.

The SpO2 sensor essentially comprises two LEDs (light-emitting diodes) which alternatingly emit infrared light with typical wavelengths of 920 nm and 660 nm respectively. An opposing photodetector measures the radiant intensity. The sensor is placed on a part of the body on which arterial blood vessels can be X-rayed, such as the fingers, toes or bridge of the nose.

The new SpO2 sensor “DS-100A” incorporates a memory chip. The Nellcor module used in the Primus now detects only this SpO2 sensor. The new sensor is identifiable by the fact that all nine pins are present on the connector.

The SpO2 sensor is connected without a pre-amplifier to the module. The module communicates through a serial port with the MONITOR CONTROL PANEL PCB. On the BACKPLANE PCB the module is electrically isolated with 1.5 kV.

The function description relating to the Patienten Gas Module (PGM) follows.

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4 Patient gas module The PGM (patient gas module) or PGM2 is an integral part of the GUI func-

tional unit (see function description GUI.

There are two versions of the patient gas module:

–PGM.

–PGM2.

In the “Block diagrams” section, you will find the block diagrams of the

PGM/PGM2 electronics

Differences between PGM2 and PGM:

PGM PGM2

Anesthetic gas measurement.

O2 sampling. Electrochemical O2 cell. Servomex sensor or

O2 measurement electronics.

Pump flow. 150 mL 200 mL

Flush flow. 200 mL 250 mL

IRIA. ILCA2.

Pato sensor.

AMO O2 PUMP PCB AMO MFM PCB.

4.1 Version PGM2 The following illustration shows the location of the PGM2 (rear panel of unit is

open).

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Figure 13 Location of the PGM2

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Figure 14 Exploded view of PGM2, for legend see Tabl e 4

Table 4 Legend to Figure 22

Item Component

1 ILCA2 sensor head.

2 Solenoid valve V1.

3 Pump (200 mL).

4 Insulating foil.

5 MOPS PCB (central processor).

6 PCBs mounting frame.

7 AMO ILCA2 PCB (anesthetic gas analysis).

8 AMO Flow ILCA PCB (flow measurement, pump control, and valve

control).

9 AMO MFM PCB (O2 analysis).

10 “Servomex” O2 sensor or “Pato” O2 sensor.

11 Filter mat.

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Item Component

12 Bacterial filter.

13 Holder for WaterLock (water trap).

14 WaterLock.

15 Fan.

16 Solenoid valve V2.

17 Adapter board (connection board).

The PGM2 automatically detects and measures the anesthetic gas in use Halothane, Enflurane, Isoflurane, Desflurane or Sevoflurane. It also detects and measures mixtures of two of the above anesthetic gases. If it encounters a mixture of more than two anesthestic gases, the warning “AGas mixture” is delivered.

CO2, O2 and the anesthetic gas mixture are presented as a real-time curve.

Some of the parameters measured by the PGM2 (etCO2, inCO2 etN2O, inN2O, etO2 and inO2) are presented on the GUI as digital values.

One component of the PGM2 is the water trap. The water trap is accessible from the front panel. For position see following diagram.

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Figure 15 Position of water trap

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4.1.1 ILCA2 function ILCA2 is a gas measuring module for the analgesic N2O, the anesthetic

gases Halothane, Enflurane, Isoflurane, Desflurane and Sevoflurane, and for measurement of mixtures. ILCA2 conforms to the measurement accuracy specified by ISO standards.

The ILCA2 module is capable of automatically detecting the above mentioned gases.

ILCA2 module design

The ILCA2 module principally comprises the following components:

– Sensor head with double-optics, pressure sensor, and electronics.

– Diaphragm pump.

– Pneumatic low pass.

– Solenoid valve for zero calibration.

– Module rack with 3 PCBs.

In the “Block diagrams” section, you will find a block diagram of the ILCA2

module.

Sensor head

The sensor head houses 2 PCBs with the following functions:

– Pre-amplifier PCB for the two multi-channel detectors.

– Base PCB with emitter activation, temperature regulation, absolute pres-

sure measurement and a serial EEPROM holding the serial number, setting and calibration data for operation of the sensor head.

The module rack of the ILCA2 module contains 4 additional PCBs with the following functions:

– AMO FLOW ILCA PCB - Control of the diaphragm pump and the zero

calibration solenoid. A serial EEPROM stores the necessary data such as the serial number, hardware/software revision, control parameters etc.

– AMO ILCA2 PCB - Here the necessary supply voltages are generated

and the data transfer from the ILCA2 sensor to the MOPS PCB is implemented.

– AMO MFM PCB - This circuit board amplifies the signal from the Ser-

vomex sensor.

– MOPS PCB - Primarily delivers the data for further processing via an RS

232 interface.

Measurement principle

The measurement principle of the ILCA2 module is based on the absorption of infrared light by the various media (see Figure 16). The sensor head consists of a double measuring head with one emitter each which emits a broad spectrum of infrared light. The light beam passes through a cuvette, through which the gas being measured is also drawn by means of a diaphragm pump. Downstream of the cuvette the light beam hits a multi-channel detector with IR filters. The filters are dimensioned so that only the light in the absorption wavelength of the measured gases is transmitted. If a gas is present light is absorbed. The higher the partial pressure of the gas, the greater the absorption of the light and the smaller the sensor signal.

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Figure 16 Principle of multi-channel detector with IR filters

Table 5 Legend to Figure 16

Item Meaning

1 Infrared light.

2 Beam splitter.

3 Sensor chip.

4 Infrared filter.

5 Sensor window.

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4.1.2 PGM2 with Pato O2 sensor

The oxygen analyser measures the patient's O2 concentration at the Y-piece.

Measurement principle

The oxygen sensor uses the effect that oxygen molecules are attracted very much more strongly to a magnetic field (paramagnetism) than the molecules of other gases, which in some cases are repelled by the magnetic field (diamagnetism).

Layout

The Pato houses a cuvette containing a sensor system, the cuvette is located between two electromagnets.

Figure 17 Pato system structure

Table 6 Legend to Figure 17

Item Component

1 Magnetic system

2 Sensor system

3 Cuvette

4 Magnetic system

This sensor system comprises the gas path (cuvette) and the sensor inside the measurement compartment.

The measurement compartment is designed as a bulge in the gas path.

The sensor consists of a heating element and thermoelement assembly.

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Figure 18 Pato sensor system

Table 7 Legend to Figure 18

Item Name

1 Measurement compartment

2 Heating element and thermoelement assembly

3 Gas path

4 Sensor element

Function

The electromagnets generate an alternating field.

The sampling gas flows through the cuvette and the gas path in the sensor system.

The heating element heats up the sampling gas to operating temperature, the thermoelement measures the temperature.

The outer alternating magnetic field influences the mobility of the oxygen contained in the sampling gas.

The changing mobility alters the heat transfer in the sampling gas which results in the thermoelement measuring a changing temperature.

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The exent of the heat transfer variation depends on the oxygen concentration in the sampling gas.

The ILCA2 module converts the temperature change in an oxygen concentration value which is then displayed on the connected patient monitor.

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4.1.3 PGM2 with Servomex O2 sensor

The Servomex sensor uses the fact that oxygen molecules have a stronger paramagnetic characteristic (attracted to a magnetic field) than the molecules of other gases that are sometimes even diamagnetic (repulsed by a magnetic field).

The following position numbers refer to Figure 19.

The permanent magnets (7 and 12) in the sensor create a symmetric magnet field (11). The magnet field contains two nitrogen-filled quartz spheres (9) arranged in the form of dumbbells. The dumbbell is suspended rotating from a taut platinum band. A reel of platinum wire is wound around the dumbbell as a feedback coil (10).

When oxygen flows through the measuring cell (1 and 6), the magnetic field (11) changes based on the paramagnetic effect of the oxygen dependent on its concentration. This rotates the quartz spheres (9) of the dumbbells out of the magnetic field.

A mirror attached to the pivot of the dumbbell (8) reflects a light beam (5) onto a photocell pair (4). The photocells are connected to an amplifier (3) of which the output signal supplies the feedback coil (10) of the dumbbell. The dumbbell is rotated back by the current in the feedback coil (10) until the light beam (5) is illuminating both photocells (4) equally by means of the mirror (8). Then the system is at equilibrium. The current flowing through the feedback coil (10) is proportional to the paramagnetism of the oxygen and thus a measure of the oxgen concentration, which is displayed on the display instrument (2).

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Figure 19 Schematic representation of the Servomex sensor

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4.1.4 Pneumatics of the PGM2 In the “Block diagrams” section, you will find a schematic of the PGM2 pneu-

matic components.

Figure 20 Schematic of PGM2 pneumatic components, see legend Ta bl e

Table 8 Legend to Figure 24

Item Meaning

1 Sampling gas.

2 Goretex membrane (flow 20 mL).

3 Goretex membrane (flow 180 mL).

4 Water trap.

5 Teflon tube.

6 Nafion tube.

7 ILCA2 solenoid valve (pneutronics).

8 Room air (calibration).

9 Filter.

10 ILCA2 (anesthetic gas analysis).

11 O2 sensor.

12 Solenoid valve (pneutronics).

13 Filter.

14 OLC pump 200 mL (DC diaphragm pump).

15 Gas outlet.

C1 Volume.

R1 Restrictor.

P Differential pressure sensor.

The item numbers and abbreviations occurring in this section relate to Figure

24.

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The sample gas (1) enters the water trap (4). In the water trap are two Goretex membranes (1, 2). The moisture in the sample gas cannot pass through the Goretex membranes. This prevents water from reaching the ILCA2 (flow approx. 180 mL/min). Consequently no water can penetrate the bypass branch (flow approx. 20 mL/min) either. An approximately 10 cm long Teflon tube (5) serves as a resistor, and meters the flow in the bypass branch.

If the water in the water tank reaches to the level of the membranes, they are closed off by the water. An error message is displayed on-screen. A filling level detector is therefore no longer necessary.

The sample gas flows through the Nafion tube (6) and is additionally dried. The sample gas then passes on to the ILCA2 solenoid valve (7). Depending on the valve switching state, either the sample gas (1) or, during calibration, the room air (8) reaches the ILCA2. The sample gas is fed through the cuvette (10) of the ILCA2 and passes on to the “Servomex” O2 sensor (11).

When the Primus is in leak test mode, and the PGM2 in standby, the pump (14) is shut off. Whenever the pump is off, the solenoid valve (12) interrupts the gas flow to the system. This does not increase the leakage value.

The following low-pass filter comprises the restrictor (R1) and the volume (C1).

R1 is dimensioned as follows:

– R1 is small enough for the pump not to be placed under unnecessary

strain.

– R1 is large enough so that the pump pressure surges occurring in the

ILCA2 cuvette do not impair the signal ratio and noise ratio in gas sampling.

– The pressure drop at R1 is measured. The measured value is used for

pump control.

The pneumatic low-pass components are integrated into the module housing of the electronics. The low-pass minimizes the pressure surges generated by the pump. Downstream of the pneumatic low-pass filter the sample gas passes to the pump.

The flow through the pump (14) in measuring mode is approx. 200 mL/min (flush flow approx. 250 mL/min). The supply voltage of the pump is in the range from 2.5 VDC to 7.5 VDC at a current of up to 150 mA.

Dimensioning of R2:

In a calibration, the switching of the ILCA2 solenoid valve (7) is tested with the pressure sensor (in the sensor head). In this case the pressure drop via R2 and the filter (9) must be significantly less than the minimum pressure drop through the water trap and the sample gas tube. In the event of an error, an error log entry is generated.

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In substitution for a flowmeter, the pressure is measured with a differential pressure sensor (P) upstream and downstream of the low pass. The AMO FLOW ILCA PCB controls the pump with the pressure signal as the input variable.

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In order to ensure an adequate measurement accuracy, an automatic zero calibration is performed periodically. For this, room air is drawn in by the diaphragm pump through the ILCA2 solenoid (zero calibration valve) and passed through the sensors. The zero calibration valve is controlled by the AMO Flow ILCA PCB.

Further measures to safeguard measurement accuracy:

– Heating of the cuvette so the intensity of the light beam is not affected by

condensation. As the temperature also influences the measurement result, the cuvette temperature is kept constant by means of a control loop.

– The pressure in the cuvette likewise influences the result. So the pres-

sure is measured and entered as a correction variable into the system.

4.2 Version PGM The following diagram shows the position of the PGM with the rear panel

open.

Figure 21 Position of the Patient Gas Module (PGM)

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Figure 22 Exploded view of the PGM, legend Table 9

Table 9 Legend to Figure 22

Item Components

1 Connection board.

2 IRIA cuvette.

3 IRIA = “Infrared Rapidly Identifying Analyzer”. Sensor head of

anesthetic gas analyzer.

4 Bacterial filter.

5 Fan.

6 Water trap.

7 Filter mat.

8 O2 cell (fast O2 analysis).

9 MOPS PCB (electronics).

10 AMO IRIA PCB (anesthetic gas analysis).

11 AMO O2 PUMP PCB (O2 analysis).

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12 Pump.

13 ILCA solenoid valve (room air/sampling gas).

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Item Components

14 AMO FLOW ILCA PCB (actuation and monitoring of valve, pump

and flow values).

15 ILCA component carrier (for items 9 - 14).

16 ILCA solenoid valve (leakage).

17 Board (Teflon plate).

The PGM automatically detects and measures the anesthetic gas in use Halothane, Enflurane, Isoflurane, Desflurane or Sevoflurane. It also detects and measures mixtures of two of the above anesthetic gases. If it encounters a mixture of more than two anesthestic gases, the warning “AGas mixture” is delivered.

CO2, O2 and the anesthetic gas mixture are presented as a real-time curve.

Some of the parameters measured by the PGM (etCO2, inCO2 etN2O, inN2O, etO2 and inO2) are presented on the GUI as digital values.

One component of the PGM is the water trap. The water trap is accessible from the front panel. For position see following diagram.

Figure 23 Location of the water trap

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4.2.1 PGM pneumatic components

In the “Block diagrams” section, you will find a schematic of the PGM pneu-

matic components.

Figure 24 Schematic of PGM pneumatic components, legend Table 10

Table 10 Legend to Figure 24

Item Meaning

1 Sampling gas.

2 Goretex membrane (flow 15 mL).

3 Goretex membrane (flow 135 mL).

4 Water trap.

5 Teflon tube.

6 Nafion tube.

7 ILCA solenoid valve (pneutronics).

8 Room air (calibration).

9 Filter.

10 Electrochemical O2 cell (fast O2 analysis).

11 Solenoid valve (pneutronics).

12 Filter.

13 Pump (DC diaphragm pump).

14 Gas outlet.

C1 Volume.

R1 Restrictor.

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P Differential pressure sensor.

The item numbers and abbreviations occurring in this section relate to Figure

24.

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The sample gas (1) enters the water trap (4). In the water trap are two Goretex membranes (1, 2). The moisture in the sample gas cannot pass through the Goretex membranes. This prevents water reaching the IRIA (flow 135 mL/min). Consequently no water can penetrate the bypass branch (flow approx. 15 mL/min) either. An approximately 9 cm long Teflon tube (5) serves as a resistor, and meters the flow in the bypass branch.

The sample gas flows through the Nafion tube (6) and is additionally dried. The sample gas then passes on to the ILCA solenoid valve (7). Depending on the valve switching state, either the sample gas (1) or, during calibration, the room air (8) reaches the IRIA. The sample gas is fed through the IRIA cuvette and passes on to the O2 sensor (10).

When the Primus is in Leak Test mode, and the PGM in Standby, the pump (13) is shut off. Whenever the pump is off, the solenoid valve (11) interrupts the gas flow to the system. This does not increase the leakage value.

The following low-pass filter comprises the restrictor (R1) and the volume (C1).

R1 is dimensioned as follows:

– R1 is small enough for the pump not to be placed under unnecessary

strain.

– R1 is large enough so that the pump pressure surges occurring in the

IRIA cuvette do not impair the signal ratio and noise ratio in gas sampling.

– The pressure drop at R1 is measured. The measured value is used for

pump control.

The flow through the pump (13) in measuring mode is approx. 150 mL/min (flush flow approx. 200 mL/min). The supply voltage of the pump is in the range from 2.5 VDC to 7.5 VDC at a current of up to 150 mA.

Dimensioning of R2:

In a calibration, the switching of the valve is tested with the pressure sensor in the IRIA. In this case the pressure drop via R2 and the filter (9) must be significantly less than the minimum pressure drop through the water trap and the sample gas tube. In the event of an error, an error log entry is generated.

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4.3 Operating modes

4.3.1 "Reduced Accuracy" mode (PGM only)

The sampling bank of the PGM/PGM2 is in so-called “Reduced Accuracy” mode after approx. 5 minutes. During that time, the measured values are outside the specified accuracy. During that time, a calibration of the O-point is carried out every 2 minutes.

4.3.2 "ISO" mode (ISO accuracy) (PGM/PGM2)

4.3.3 "Full Accuracy" mode (PGM only)

Following “Reduced Accuracy” mode the sampling bank has ISO accuracy. After a maximum of 30 minutes the switch is made to “Full Accuracy” mode.

After power-up, the IRIA takes around 30 minutes to reach its operating temperature for maximum accuracy. During this time, a calibration of the O-point is carried out every 2 hours.

4.3.4 "Standby" response of the Primus (PGM/PGM2)

The filter wheel in the IRIA (PGM only) and the sampling gas pump are switched off after approximately 30 minutes. After 90 minutes the emitter and the heater are shut off. This is done to extend service life and reduce noise.

4.3.5 IRIA/ILCA2 calibration The IRIA/ILCA2 is calibrated automatically. The user cannot initiate manual

calibration. Nor is calibration possible during the ventilator leak test. This prevents a possible increase in volume resulting from intake of ambient air.

4.3.6 Auto-Wake-up function If the Primus is switched to a ventilation mode following a cold-start, the alarm

monitoring is initially disabled. This applies to all the parameters of the CO2 sampling bank except the alarm CO2/AGENT INOP. Alarm monitoring is activated when a respiration phase is detected.

4.3.7 O2 sensor/Servomex The electrochemical O2 sensor and the Servomex sensors are calibrated

during the cold start. In operation, the electrochemical O2 sensor is calibrated automatically every 8 hours. The Servomex sensor is calibrated every 2 hours. During calibration, the ILCA/ILCA2 solenoid valve is switched to room air.

When the zero point of the IRIA/ILCA2 is calibrated the plausibility of the electrochemical O2 sensor signal is also checked. The Servomex sensor is calibrated with 21% O2.

If non-linearity occurs, the user is offered a 100% O2 calibration. In 100% O2 calibration the user is responsible for connecting 100% O2 to the sampling line.

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4.4 PGM/PGM2 electronics

4.4.1 MOPS PCB (PGM/PGM2) In the “Block diagrams” section, you will find a block diagram of the MOPS

PCB

“MOPS” stands for “Modular Platform for Sensors”. It is a modular concept by which suitable sensor components (pneumatic and mechanical components) can be operated together by way of a processor board.

The resultant arrangements are supported by a software program with a uniform communications interface. In this way, the user is provided with a uniform view of the parameters on offer, irrespective of the components deployed.

The software is automatically configured for the connected components when the system starts up.

With this concept, different gas sampling modules (for example “ILCA2” and “IRIA”) can be configured for specific customer needs using standard components.

The MOPS PCB calculates the values of the patient parameters and controls the sensor head signals.

4.4.2 AMO IRIA PCB (PGM) “AMO” stands for “Adapter MOPS”. The PCB has the following tasks:

– Convert digital target values from the MOPS PCB into analog voltages for

the IRIA emitter.

– Generate the IRIA supply voltage.

– Data transfer from the IRIA sensor to the MOPS PCB (data evaluation).

4.4.3 AMO ILCA2 PCB (PGM2) “AMO” stands for “Adapter MOPS”. The PCB has the following tasks:

– Convert digital target values from the MOPS PCB into analog voltages for

the ILCA2 emitter.

– Generate the ILCA2 supply voltage.

– Data transfer from the ILCA2 sensor to the MOPS PCB (data evaluation).

4.4.4 AMO O2 PUMP PCB (PGM)

4.4.5 AMO MFM PCB (PGM2) The PCB has the following task:

The PCB has the following task:

– Transfer the O2 sensor data to the MOPS PCB (data evaluation).

– Transfer the O2 sensor data (Servomex) to the MOPS PCB (data evalua-

tion).

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4.4.6 AMO FLOW ILCA PCB (PGM/PGM2)

The AMO FLOW ILCA PCB controls the pump and the valves of the PGM/PGM2. The PCB is controlled and powered by the MOPS PCB. The actual regulation of the pump flow is handled by the software of the controller on the MOPS PCB.

The AMO FLOW ILCA PCB holds the following components:

– A DC/DC converter generates the pump voltage (2.5 - 7.5 V/DC). The

output voltage of the DC/DC converter is controlled with a digital potentiometer on the PCB. The digital potentiometer is regulated by the MOPS PCB.

– The output stage to operate the valve.

– Service LEDs for the pump voltage, the valves and the supply voltage

– The temperature-compensated differential pressure sensor for flow mea-

surement. The sensor offset is corrected with a digital potentiometer.

– The analog electronics for evaluation of the pump voltage, pump current,

valve current and differential pressure.

The flow is measured by way of the differential pressure of restrictor R1 plus the upstream (sintered-metal) filter. The measuring range is 0 mbar to 350 mbar.

The AMO FLOW ILCA PCB is connected directly to a 60-pin connector on the MOPS PCB and is detected automatically by the MOPS PCB.

The function description relating to the mixer follows.

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5 Mixer This section describes the mixer for the AIR, N2O and O2 gases. The newly

generated fresh gas is fed through the vaporizer to the VGC.

Figure 25 Mixer position, with rear panel open

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Figure 26 Mixer without hood, for legend see Tab l e 11

Table 11 Legend to Figure 26

Item Components

1 PRIMUS CPU PCB

2 Gas inlet block

3 Mixer block

4 A-cone valve

5 Fresh gas tank

6 MIXER PCB

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Figure 27 Block diagram of fresh gas metering, legend Table 12

Table 12 Legend to Figure 27

Item Component

1 Monitor Control Panel (MCP)

2 CAN bus

3 Mixer electronics (PRIMUS CPU PCB/MIXER PCB)

4 Fresh gas outlet

5 Fresh gas flow valve

6 Fresh gas tank

7 Gas inlet valves

8 Pressure regulator

The item numbers and abbreviations occurring in this section relate to Figure

27 .

On the MCP (1) the user selects the carrier gas AIR or N2O as well as the fresh gas flow and the O2 concentration.

A CAN bus (2) transfers the setup parameters to the mixer electronics (3). The mixer electronics generate the actuation signals for the gas inlet valves (7).

At the inlet of the fresh gas tank (6) the flow (V) is measured. With the measured flow value the switching times for the gas inlet valves (7) are calculated. The selected gas concentration is set in the fresh gas tank. The pressure in the tank (6) and at the fresh gas outlet (4) is measured and monitored.

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The fresh gas flow valve (5) delivers the selected fresh gas flow. The flowmeter at the fresh gas outlet (4) regulates the fresh gas flow valve.

5.1 Operating modes The operating mode is regardless of whether the Primus is powered from the

mains via its power plug or is powered up in battery mode.

5.1.1 10 VA mode Internal leakage may mean that the O2 concentration in the Primus is above

21% when operation is begun. “10 VA” mode prevents dangerous operating states from occurring.

When the power plug is connected to the mains power but the power switch is not yet switched on, the following safety rule applies:

– A supply voltage of only 10 VA is fed into the interior of the mixer (10 VA

is the product of the no-load voltage and short-circuit current of the supply voltage “24 V PLUG-IN”. Only the DC/DC converters (-15 V, +15 V) for the pressure sensor amplifiers are supplied).

– The pressure sensors for the gases from the central supply (CS) system

and the cylinder supply are read and the compressed gas supply status is indicated by LEDs on the front panel (see 5.3.2 Pressure status LEDs).

When the Primus is switched on at the power switch (mains or battery powered) the following safety rule applies:

– Before other modules receive operating voltage, the fan in the mixer is

switched on for at least 10 seconds. Only then is “Normal” mode activated.

5.1.2 'Normal' mode In this mode the mixer CPU PCB controls normal mixing. All DC/DC convert-

ers (+5 V, +24 V, -15 V, +15 V) are supplied with “24 V SWITCH”.

5.2 Layout

5.2.1 MIXER PCB In the “Block diagrams” section you will find a block diagram of the MIXER

PCB.

The MIXER PCB holds the following components:

– DC/DC converters (+5 V, + 15 V, - 15 V, +24 V) with voltage monitoring

– Amplifiers of the pressure and temperature sensors

– Valve power switch and monitoring circuits

– Fan actuation and monitoring

– Logic device for the safety O2 adjuster

A cable harness connects the mixer with the NEUTRAL POINT PCB and with the other unit components. By way of the cable harness the mixer receives the unstabilized 18 V to 30 V supply voltage and the 12 V fan power from the power pack as well as the CAN bus.

The mixer fan is switched on 10 seconds before the other components and is powered directly by the power pack (see 5.1.1 10 VA mode).

When the fan wheel rotates a proportional square signal is generated (approx. 90 Hz). This square signal is monitored by the PRIMUS CPU PCB.

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The valves on the mixer block are actuated by the Master CPU (PRIMUS CPU PCB). Power drivers on the MIXER PCB operate the valves. When one of the valves is actuated, the current flows through a shunt. The voltage drop at the shunt is evaluated by a comparator circuit and monitored by the supervisor processor on the PRIMUS CPU PCB. An exception to this is the fresh gas flow valve “VMGS”. The proportional valve cannot be monitored by this procedure.

For safety shut-off of all valves, the supply voltage can be cut to all valves.

5.2.2 PRIMUS CPU PCB (mixer)

In the “Block diagrams” section you will find a block diagram of the PRIMUS

CPU PCB.

The PRIMUS CPU PCB is based on a 2-processor system with Master and Supervisor. Both 16-bit processor systems are identical in structure. The peripherals are controlled by way of an interface.

Each processor has the following components:

–Quartz

– undervoltage detector

– External watchdog

– Flash-PROM

–RAM

– EEPROM (system configuration)

A Dual-Port RAM is placed between the two processor systems for data exchange. A logic circuit prevents both processors writing to a memory cell simultaneously.

Each processor system has an isolated serial port and a CAN bus.

Configuration options for the serial port by jumper:

– Independent serial ports, RS232 level, isolation on jack plug.

– Independent serial ports, TTL level, no isolation, output to connector strip.

7-segment displays are provided for visual indication of operating states of the Master and the Supervisor.

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5.3 Gas inlet block (AIR, O2 and N2O)

In the “Block diagrams” section you will find a detailed layout of the pneumatic

components of the Primus.

On the underside of the gas inlet block are the ISO ports for the CS gases (Figure 28/1) e.g. Nist or DISS and the compressed gas cylinder ports for N2O and O2 (Figure 28/2).

Figure 28 CS/compressed gas cylinder ports

Optional outlets for a bronchial suction device with AIR (Figure 29/1) and for a O2 flowmeter (Figure 29/2) are prepared.

Figure 29 Optional outlets AIR (1) and O2 (2)

The following specifications apply to the CS and the compressed gas cylinders:

– The pressure values of the CS gases must be between 270 kPa and

690 kPa (19 psi to 80 psi).

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– If the CS pressure falls below 270 kPa, the user must open the O2 or

N2O compressed gas cylinder, as appropriate. If the cylinder pressure is too low, the user is warned on the MCP display. The maximum cylinder pressure is 19000 kPa.

Figure 30 Detail, gas inlet block, for legend see Table 13

Table 13 Legend to Figure 30

Item Component

1 Pressure regulators (N2O, AIR, O2) regulate the input pressure to

the mixer to 2.3 r0.1 bar

2 Sintered-metal filter

3 ISO port (e.g. NIST for O2 cylinder supply)

4 Optional gas outlet (plug-in connection for AIR)

5 Non-return valve

6 Non-return valve for N2O gas inlet

7 CS sensor N2O

8 CS sensor AIR

9 CS sensor O2

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5.3.1 Pneumatic components, gas inlet block

Figure 31 Pneumatic components diagram, gas inlet block, for legend see

Table 14

Table 14 Legend to Figure 31

Abb./Item Component

PPO2 Relative pressure sensors with integral amplifier for CS

PPAIR

pressure measurement

PPN2O

PCO2 High-pressure sensor cylinder pressure O2

PCN2O High-pressure sensor cylinder pressure N2O

PRPO2 Pressure regulator, O2 line

PRPAIR Pressure regulator, AIR line

PRPN2O Pressure regulator, N2O line

PRCO2 Pressure regulator, O2 compressed gas cylinder

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Abb./Item Component

PRCN2O Pressure regulator, N2O compressed gas cylinder

1 Gas inlet block (complete)

2 HP ISO port O2 (NIST or DISS)

3 CS ISO port O2 (NIST or DISS)

4 Sintered-metal filter in CS ISO port

5 Non-return valve, CS inlet O2

6 ISO outlet O2 (optional)

7 ISO outlet AIR (optional)

8 To flush button and safety O2 adjuster

9 To the CS flow metering inlet valves

The item numbers and abbreviations occurring in this section relate to Figure

31 .

For the following description the O2 gas path was chosen.

The CS gas (3) passes through the ISO port to the gas inlet block.

By way of the sintered-metal filter (4) the gas passes to the pressure sensor “PPO2”. The relative pressure sensor delivers a signal proportional to the pressure.

The sintered-metal filter (4) prevents the non-return valve (5) from being contaminated by particles.

If the CS fails, no CS pressure is indicated. The non-return valve (5) prevents O2 from escaping out of the compressed gas cylinder (2) into the CS system.

The pressure regulator PRPO2 generates a constant input pressure for the mixer (2.3 bar r0.1 bar). The O2 pressure regulator additionally supplies (8) the flush button “VO2+” and the safety O2 adjuster “VSFC”.

An optional compressed gas supply for an external bronchial suction device (7) or an external O2 flowmeter (6) is provided for.

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5.3.2 Pressure status LEDs The mixer measures and monitors the pressure of the CS and the com-

pressed gas cylinders. Depending on the measured values, LEDs on the MCP indicate the pressure status.

Figure 32 Position of LEDs (front panel)

The CS pressure and the cylinder pressure is indicated by five LEDs on the front of the MCP. The sixth LED is intended for an optional AIR compressed gas cylinder.

The LEDs are lit either green or red or are unlit, depending on operating status. The LEDs are made to change colour by reversing the polarity of the supply voltage.

If the mixer is in “10 VA” mode, the LEDs are either green or unlit.

The initial condition for Table 15 is:

– Primus is off, but power is connected.

Table 15 LED status, Primus off

Gas supply Pressure value LED status

O2-CS p < 2.7 bar Off

p 2.7 bar Green

AIR-CS p < 2.7 bar Off

p 2.7 bar Green

N2O-CS p < 2.7 bar Off

p 2.7 bar Green

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Gas supply Pressure value LED status

O2 cylinder p < 20 bar Off

p 20 bar Green

Pressure sensor not connected Off

AIR cylinder p < 20 bar Off

p 20 bar Green

Pressure sensor not connected Off

N2O cylinder p < 10 bar Off

p 10 bar Green

Pressure sensor not connected Off

The initial condition for Table 16 is:

– Primus is on. The mixer is in normal mode.

Table 16 LED status, Primus in normal mode

Gas supply Pressure value LED status

O2-CS p < 2.7 bar Off

p 2.7 bar Green

Pressure sensor error Flashing green

AIR-CS p < 2.7 bar Off

p 2.7 bar Green

Error Flashing

N2O-CS p < 2.7 bar Off

p 2.7 bar Green

Pressure sensor error Flashing green

O2 cylinder p < 20 bar and CS O2 pressure

Off

is 2.7 bar

p 20 bar Green

p < 20 bar and the CS O2 pressure is < 2.7 bar

Flashing red at 1.4 to 2.8 Hz

Pressure sensor not connected Off

AIR cylinder p < 10 bar and the CS N2O

pressure is < 2.7 bar

Flashing red at 1.4 to 2.8 Hz

p 10 bar Green

Pressure sensor not connected Off

p < 10 bar and CS N2O pres-

Off

sure is 2.7 bar

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Gas supply Pressure value LED status

N2O cylinder p < 10 bar and CS N2O pres-

sure is 2.7 bar

p 10 bar Green

p < 10 bar and CS N2O pressure is < 2.7 bar

Pressure sensor not connected Off

Off

Flashing red at 1.4 to 2.8 Hz

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5.4 Mixer block

Figure 33 Mixer block, for legend see Table 17

Table 17 Legend to Figure 33

Item Component Short name

1 Differential pressure sensors with piezo mea-

2PDMGSLO

suring bridge

3 Absolute pressure sensors with integral ampli-

4PTANK

fier

PDMGSHI

PSYS

5 Tank vent valve VTANK

6 Temperature sensors TANKTEMP,

MGSTEMP

7 Connection for tank volume TANK

8 Gas inlet valves VMIXO2

9 VMIXAIR

10 VMIXN2O

11 Pressure inlets (N2O, AIR, O2) to the gas inlet

valves

12 O2 inlet to safety O2 adjuster and flush button

13 Differential pressure sensor with piezo measur-

PDMIX

ing bridge

14 Fresh gas flow valve (proportional valve) VMGS

15 A-cone valve VSWAK

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5.5 Pneumatic system

Figure 34 Pneumatic components diagram, mixer, for legend see Table 18

Table 18 Legend to Figure 34

Item Component/Meaning

1 Gas inlet block

2 A-cone valve (optional)

3 Mixer, flow metering

4 Vaporizer

I To compact breathing system

II To A-cone valve/compact breathing system switching valve (MV3)

for airway pressure measurement

III To A-cone outlet

In the “Block diagrams” section you will find a detailed layout of the pneumatic

components of the Primus.

The abbreviations occurring in the following sections relate to Figure 34 and

Figure 33.

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5.5.1 VMIX valves The “VMIX” valves mix the desired gas concentration. By way of the “VMIX”

valves the CS gas (N2O, AIR, O2) passes to the differential pressure sensor “PDMIX”, to the pressure sensor “PTANK” and to the flowmeter section “RM”.

The “VMIX” valves fill “TANK”. The pressure range in 'TANK“ is between 1 bar and 1.5 bar. The pressure difference of 0.5 bar and the “TANK” volume of

0.5 L produce a usable “TANK” volume of 0.25 L (0.5 bar x 0.5 L = 0.25 L).

At a fresh gas flow setting of 18 L/min, the “VMIX” valves are opened 72 times a minute. The following equation illustrates the TANK filling process (72 /min x 0.25 L = 18 L/min).

5.5.2 PDMIX and RM With the differential pressure sensor “PDMIX” and the flowmeter “RM” the

gas flow and volume of the gas flowing into the TANK are measured (flow x time = volume). If a constant usable 'TANK' volume of 0.25 L is used then any given gas concentration can be mixed.

The differential pressure sensor “PDMIX” and the absolute pressure sensor “PTANK” form a single functional unit. The output signal of the pressure sensor “PTANK” is used for the bridge supply voltage for “PDMIX”. The output voltage of “PDMIX” is evaluated on the PRIMUS CPU PCB (mixer).

5.5.3 PTANK (pressure sensor)

The pressure sensor “PTANK” has the following tasks:

– Tank pressure monitoring

– Compensation for effect of ambient pressure fluctuations on flow meter-

ing with “PDMIX”.

– Monitoring of flowmeter “RM” by means of the proportional pressure rise

in “TANK”.

The pressure sensor “PTANK” has a resolution of 2 mbar and a maximum measuring range of 2.558 bar absolute. The pressure sensor “PTANK” also has a second amplification branch to the AD converter of the PRIMUS CPU PCB (mixer). To be able to measure higher pressures for service purposes, the resolution is 4 mbar per digit. The maximum measured value is 4.092 bar absolute.

5.5.4 VTANK valve The tank vent valve “VTANK” opens when:

– O2 and AIR are missing.

5.5.5 VMGS (fresh gas flow valve)

The fresh gas flow valve is a proportional valve. It delivers a fresh gas flow of

0.2 L/min to 18 L/min. The flowmeter at the fresh gas outlet regulates the valve.

5.5.6 PDMGSHI / PDMGSLO (differential pressure

The differential pressure sensors each have a press-dependent resistance measuring bridge.

sensors)

The differential pressure sensors measure the flow through the flowmeter section “RMGS”. With the measured value the PRIMUS CPU (mixer) PCB regulates the fresh gas flow valve “VMGS”.

5.5.7 PSYS (pressure sensor) The pressure sensor “PSYS” compensates for the effect of ambient pressure

fluctuations on the flow metering of “PDMGSHI” and “PDMGSLO”.

The pressure sensor “PSYS” has a resolution of 1 mbar.

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5.5.8 VSWAK (A-cone valve) The A-cone valve actuated by the MIXER PCB has a bistable switching

response.

The valve is switched with a time-limited voltage pulse. The polarity of the voltage pulse determines the switching direction.

The valve position is detected by a proximity sensor in the valve and monitored by the PRIMUS CPU (mixer) PCB.

5.5.9 VBAK (safety valve) A mechanical safety valve for the A-cone valve. Opening pressure 80 mbar at

18 L/min +15%.

5.5.10 TEMPTANK / TEMPBLOCK (temperature sensors)

The volume of the gases “N2O, AIR, O2” is dependent on the temperature. Consequently, the measured values of the temperature sensors “NTC” are incorporated into the mixing process. The temperature sensors (“TEMPTANK”, “TEMPBLOCK”) used for temperature compensation generate voltages proportional to the temperature. The PRIMUS CPU (mixer) PCB compares and monitors the sensor voltages.

5.5.11 VSFC (safety O2 adjuster)

The safety O2 adjuster is located outside the mixer unit. With the manual safety O2 adjuster the user can set an additional O2 flow of 3 to 12 L/min r30%.

When the overall system power-up test is running the flow adjuster must be closed. The operating status is registered by a microswitch in the safety O2 adjuster. The microswitch is plugged into the NEUTRAL POINT PCB. The signal is transmitted via the cable harness to the mixer.

5.5.12 VO2+ (flush button) Mechanical flush button. Output min. 35 L/min.

The function description relating to the VGC follows.

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6VGC This section describes the VGC (Ventilation and Gas Controller). The VGC

consists of the ventilator and the compact breathing system.

Figure 35 VGC position

The patient is ventilated by the VGC according to the ventilation mode and parameters set on the MCP.

The VGC also measures the airway pressure and the inspiratory and expiratory flow (two flow sensors).

A cable harness connects the VGC with the NEUTRAL POINT PCB. From there, the VGC is connected to other Primus components.

By way of the cable harness the VGC receives the following voltages and signals:

– The unstabilized supply voltage of 18 V to 30 V.

– The 12 V for the VGC fan (there immediately).

– The 12 V for the pneutronics valves (there after approx. 10 seconds).

–CAN bus.

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Figure 36 Exploded view of VGC, legend Table 19

Table 19 Legend to Figure 36

Item Component

1 MV4 “Pneutronics”

2 MV2, calibration and venting

3 Electrical connections for inspiratory and expiratory flow sensor

4 Piston-cylinder unit.

5VGCPOWERPCB.

6 CPU PRIMUS PCB.

7 Electronics fan.

8 PRIMUS ANALOG PCB (VGC).

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Item Component

9 Bacterial filter.

10 Non-return valve RV3.

11 VGC pneumatic block.

12 Interface plate.

13 Interface plate fan.

14 Light barrier.

15 Breathing system heater contacts.

6.1 VGC electronics In the “Block diagrams” section, you will find a block diagram of the VGC

electronics.

The supply voltages required for the VGC to function (5 V, 15 V, +24 V) are generated by the VGC itself.

The interface plate holds the connecting pneumatic tubes and the plug-in flow sensor connectors.

The interface plate is the carrier for all other VGC components, and includes the breathing system lock. The complete interface unit is inserted from above into the VGC housing.

6.1.1 VGC POWER PCB The following functional units are provided on the PCB:

– 5 V voltage regulator (Imax 2 A).

– Driver for the DC motor (M2) of the piston cylinder unit (PCU).

–Valve control.

– Breathing system heater control. Temperature monitoring with 2 indepen-

dent NTCs in the heater mat.

– Control for the DC pump (M1). Output voltage 8 to 18 V.

– Monitoring of the PCB supply voltages.

6.1.2 PRIMUS ANALOG PCB The following functional units are provided on the PCB:

– +15 V voltage regulator (Imax 300 mA). 15 V is only connected if 5 V is

present.

– -15 V voltage regulator (Imax ca. 100 mA).

– PEEP valve control (0 to 430 mA).

– Pressure measurement with two airway pressure sensors and a vacuum

sensor.

– 12-bit A/D converter for the airway pressure sensors and the flow sen-

sors.

– Incremental encoder evaluation. Evaluation of direction of rotation, rota-

tion angle and velocity of the PCU motor (M2).

– Light barriers. One light barrier each for the end position of the PCU and

for detection of a fully inserted ventilator drawer unit.

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6.2 Piston cylinder unit (PCU)

Figure 37 Piston cylinder unit layout, for legend see Table 20

Table 20 Legend to Figure 37

Item Component

1 Breathing volume dependent on piston position.

2 Cylinder.

3 Rolling seal (loose).

4Piston.

5 Diaphragm (fixed).

6 Piston motor.

7 Perforated disk for incremental encoder.

8 incremental encoder.

9 Rubber buffer.

10 Light barrier.

11 Spindle nut.

12 Spindle.

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The items cited in the following text relate to Figure 37.

The ventilator unit consists of a piston cylinder unit and two diaphragms. The vacuum for the rolling seal (3) comes from the pneumatic system of the VGC and is generated in the space between the cylinder (2) and the rolling seal (3).

The spindle (12) is permanently fixed to the piston. The spindle nut (11) is permanently fixed to the hollow shaft axle of the piston motor. When the motor shaft, and thus the spindle nut, rotates the spindle is moved vertically. This sends a corresponding volume through to the compact breathing system and consequently to the patient. Also, the motor is permanently fixed with rubber buffers (9) to the drive housing.

When the spindle nut rotates once, a volume displacement of 38.5 mL is produced. So to achieve a volume change of 1400 mL, around 37 revolutions are required.

The piston motor (6) is powered by direct voltage and operated by way of the PCBs of the VGC. The actuator requires the signal from the incremental encoder (8). The incremental encoder has a resolution of 1024 pulses per motor revolution.

When the VGC is switched on, the counter of the incremental encoder must be set. To do so, the piston is lowered until it reaches the light barrier (10). This position is then recorded as the reference position.

Only when the vacuum is applied to the rolling seal is the piston motor activated. An exception is possible, however. If the roller diaphragm is not inserted, a vacuum may be created. The roller diaphragm can only be inserted without difficulty when the piston is at its bottom end position, however. If the control detects this state, it will slowly move the piston to the bottom end position in “Standby” mode. With software version 2.n or higher, the piston motor (6) is additionally switched on as an active brake as soon as the light barrier (10) is touched. This is to avoid that the spindle (12) gets stuck in the bottom end position.

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6.3 VGC pneumatic block

Figure 38 Exploded view of VGC pneumatic system, legend Table 21

Table 21 Legend to Figure 38

Item Components

1 PEEP valve “MV1”.

2 Restrictor “R2”.

3 Pump motor “M2” with vacuum pump “VP”.

4 Vacuum valve “Vu”.

5 Bacterial filter “BF”.

6 Volume “V” (2 containers).

7 Solenoid valve “MV3”“Pneutronics”.

The components of the pneumatic block are detailed in the following section.

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6.4 VGC pneumatic system

In the “Block diagrams” section, you will find a detailed schematic of the Pri-

mus pneumatic components.

Figure 39 VGC pneumatic system and breathing system, for legend see

Table 22

Table 22 Legend to Figure 39

Item Component/Meaning

5 VGC ventilator unit.

6 Breathing system.

I Fresh gas inlet.

II From A-cone valve (if fitted).

E Ejector.

BF Bacterial filter.

M2 Vacuum pump motor.

MV1 PEEP/Pmax valve.

MV2 Calibration and vent valve.

MV3 Breathing system/A-cone outlet switching valve.

MV4 PEEP valve/control valve.

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Item Component/Meaning

PAWe Expiratory airway pressure sensor.

Pu Vacuum sensor.

R1 Restrictor to smooth pressure peaks.

R2 Restrictor to reduce vacuum (when pump “VP” is off).

RV3 KZE vacuum non-return valve.

V Volume.

VP Vacuum pump.

The position numbers mentioned in this section refer to Figure 39.

The vacuum sensor “Pu” is connected to the intake side of the vacuum pump “VP”. In operation, the vacuum sensor “Pu” measures the vacuum for the roller diaphragm of the KZE. Another port is connected during operation to the switching valve “V2”“AUTO-MAN/SPONT”. When the vacuum pump is running, the software checks the pressure value at the vacuum sensor “Pu”. The drive motor is only activated if the vacuum pump is able to build up a vacuum of between 120 mbar and 250 mbar (hPA).

The vacuum pump “VP” draws the air in through the bacterial filter “BF”. The following valve “Vu” is preset to approx. 200 mbar. The air is pumped in two consecutive volumes “V”.

To smooth pressure peaks, the outlet of the volumes is designed as a fine hole “R1”. From there, the gas flows through the PEEP valve “MV1”. If the PEEP valve is not actuated, the integral ejector “E” generates a low-level vacuum in its control line. This smoothes the zero of the PEEP characteristic.

So that the vacuum is reduced when the vacuum pump is shut off, the vacuum valve is bridged by a restrictor “R2”.

When the user switches the ventilation mode from automatic ventilation to “MAN/SPONT”, the vacuum pump is switched off. The vacuum is reduced with “R2”. The non-return valve “RV3” prevents the vacuum in the diaphragm volume from being reduced too. This considerably reduces the switching time from automatic ventilation to “MAN/SPONT”. At the same time, “RV3” also prevents a reduction of the vacuum in the diaphragm volume in “MAN/SPONT” mode. The vacuum can then be built up faster when the user switches to an automatic ventilation mode.

With valve “MV2” the system is calibrated and vented.

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6.5 Interface plate

Figure 40 Layout of interface plate measuring points, for legend see Table

Table 23 Legend to Figure 40 and Figure 41

Item Connection/Meaning

1 Pressure sensor “Pz”.

2 Fresh gas outlet.

3 Anesthetic gas scavenging system AGSS.

4 ILCA suction device (optional).

5 PEEP valve “V1”.

6 APL bypass valve “V2”.

7 “PAWe” / “MV2”.

8 ILCA sampling gas return line (optional).

9 Expiratory flow sensor (electric).

10 IRIA sampling gas return line.

11 Inspiratory flow sensor (electrical).

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12 A-cone airway pressure.

13 IRIA sampling gas return line.

14 Fresh gas.

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Item Connection/Meaning

15 Piston of piston cylinder unit.

The following diagram Figure 41 permits allocation of the measuring points/connections on the interface plate to the pneumatic components diagram.

Figure 41 Allocation of measuring points/connections, for legend see Table

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6.6 Breathing system There can be two different types of breathing systems. The difference lies in

the design of the APL valve (adjustable pressure-limiting valve, see Figure

42).

Figure 42 APL valves, new type (1) and old type (2)

The new type (Figure 42/2) has a toggle mechanism for toggling between MAN and SPONT mode. The new type (Figure 42/1) uses a locking function.

This results in different types of breathing system covers (see breathing system cover Figure 43/1). The valve plate (Figure 43/5) and the breathing system block (Figure 43/6) remain unchanged.

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Figure 43 Overview of the breathing system, see legend Table 24

Table 24 Legend to Figure 43

Item Component

1 Breathing system cover with fixing screws.

2 Valve “RV1”.

3 Breathing system heater contacts.

4 Valve “RV2” (new design).

5 Valve plate.

6 Breathing system block.

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Item Component

7 Fixing screws.

8 Absorber canister.

9 Absorber element.

10 Expiratory flow sensor “Flowe”.

11 Connection for manual breathing bag “Bag”.

12 Expiratory socket.

13 Inspiratory socket with downstream inspiratory flow sensor “Flowi”.

14 APL bypass valve “V2”.

15 Valve “V1”, PEEP diaphragm.

16 Expiratory valve “Ve”.

17 Inspiratory valve “Vi”.

18 “APL” valve, new type.

19 “APL” valve, old type.

The compact breathing system permits the following ventilation modes:

– Manual ventilation.

– Spontaneous breathing.

– Automatic, pressure-limited ventilation modes (IPPV, SIMV and PCB) or

“Volume Mode” and “Pressure Mode” with optional synchronization and pressure support.

– (Optional) pressure-assisted ventilation “Pressure Support” for spontane-

ously breathing patients.

The switch of the APL valve can be set to MAN or SPONT.

In the “MAN” position, the breathing system is closed to atmosphere. The APL valve opening pressure can be adjusted from 5 to 70 hPa (mbar). This switch setting is the default for manual ventilation.

In the “SPONT” position the APL valve is open to atmosphere. This switch setting is the default for spontaneous breathing.

The pressure limitation “Pmax” can also be adjusted between 20 hPa (mbar) and 70 hPa (mbar) on the GUI during automatic ventilation.

The following section permits allocation of the components to the pneumatic components diagram.

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6.6.1 Compact breathing system pneumatic components

In the “Block diagrams” section, you will find a detailed schematic of the Pri-

mus pneumatic components.

Figure 44 Breathing system and VGC pneumatic components, for legend

see Table 25

Table 25 Legend to Figure 44

Item / Abbrevia-

Component

tion

6 Breathing system pneumatic components.

A Absorber

V2 APL bypass valve.

APL APL valve.

Ve Expiratory valve.

PAWe Expiratory pressure sensor.

FLOWe Expiratory flow sensor.

FG Fresh-gas port.

RV1 Fresh-gas decoupling valve.

BAG Breathing bag.

Vi Inspiratory valve.

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6.7 Automatic ventilation

6.7.1 Inspiration

Item / Abbrevia-

tion

Pz Inspiratory pressure sensor.

FLOWi Inspiratory flow sensor.

Piston cylinder unit Piston cylinder unit.

AGSS Anesthetic gas scavenging system.

V1 PEEP valve.

RV2 AGSS non-return valve.

A prerequisite for automatic ventilation (IPPV/PCV or “Volume Mode” and “Pressure Mode”) is that the patient is supplied with a sufficient amount of fresh gas.

The APL bypass valve “V2” is actuated by the VGC and is open. The setting of the APL valve has no effect in automatic ventilation. The pressure limit (Pmax) is adjustable on the GUI.

Component

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Figure 45 Block diagram of mandatory inspiration

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The abbreviations occurring in the following text relate to Figure 45 .

Mandatory inspiration process:

– The fresh gas isolation valve “RV1” is closed.

– The PEEP valve “V1” is closed during inspiration. Depending on the pre-

set maximum pressure “Pmax”, an appropriate control pressure is applied to the PEEP valve.

– The piston of the PCU rises according to the preset parameters (F, VT,

I:E...). The mixed gas (expiratory gas and fresh gas) flows through the inspiratory valve “Vi”, the flow sensor “Flowi”, the inspiratory patient tube, and through the Y-piece into the patient’s lung.

– The inspiratory pressure is measured.

– For inspiratory compliance only the volume between “RV1”, “Vi” and “V1”

is active.

– The manual breathing bag serves as a mixed gas reservoir.

If the ventilation pressure exceeds the maximum pressure (Pmax) set on the GUI, the PEEP “V1” opens. The gas from the patient's lung flows either into the manual breathing bag or through the open APL bypass valve “V2”. Depending on the non-return valve opening pressure “RV2”, the mixed gas flows into the anesthetic gas scavenging system AGSS.

Advantage of this method:

– The fresh gas isolation valve “RV1” minimizes the inspiratory compliance

(without absorber and manual breathing bag).

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6.7.2 Expiration

Figure 46 Block diagram of mandatory expiration

The abbreviations mentioned in this chapter refer to Figure 46.

Mandatory expiration process:

– The PEEP valve “V1” opens.

– The motor of the PCU is activated such that the piston follows the physio-

logical expiration curve. This means the patient is able to exhale at an optimum flow rate.

– The downward movement of the piston opens “RV1”.

– “Vi” is closed, and prevents breathing back into the inspiratory branch.

– The expiratory flow flows through the expiratory flow sensor “Flowe”, the

PEEP control valve “V1”, the expiratory valve “Ve” and the absorber and back into the piston chamber of the piston cylinder unit.

– The patient gas is additionally enriched with fresh gas.

– Surplus mixed gas flows into the manual breathing bag or through the

APL bypass valve “V2” and the non-return valve “RV2” into the anesthetic gas scavenging system AGSS.

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Advantages of flow-optimized piston guidance:

– The gas loss through the AGSS valve is minimized, because no non-

physiological overpressure is created in the expiratory phase.

– The fresh gas consumption via the absorber is high as long as the fresh

gas flow is lower than the minute tidal volume “AMV”.

– No non-physiological overpressure in the expiration phase. Consequently

there is also no intake of the diaphragm by “V1” (PEEP valve in breathing system).

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6.8 Manual ventilation During manual ventilation of the patient, the switch of the APL valve is set to

the MAN position.

Only the warnings/alarms for the lower O2 alarm, for the upper airway pressure (Paw) and for CO2 are enabled.

The piston of the VGC is in the upper end position in order to reduce the dead space volume of the ventilator.

The APL bypass valve “V2” is not actuated and is closed.

6.8.1 Inspiration

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Figure 47 Block diagram of manual inspiration

The expiratory valve “Ve” is closed during the inspiratory phase.

Manual inspiration process:

– When the manual breathing bag is compressed, the mixed gas (expira-

tory gas and fresh gas) flows through the absorber, the fresh gas isolation valve “RV1”, the inspiratory valve “Vi” and the flow sensor “Flowi” and then into the patient’s lung.

– The pressure sensor “PAWe” measures the airway pressure.

– The APL valve limits the ventilation pressure.

– The surplus mixed gas flows via the APL valve and the non-return valve

“RV2” into the anesthetic gas scavenging system AGSS.

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6.8.2 Expiration

Figure 48 Block diagram of manual expiration

The inspiratory valve “Vi” is closed, and prevents expiratory gas from flowing back into the inspiratory branch.

Manual expiration process:

– When the pressure is relieved from the manual breathing bag, the expira-

tory gas flows through the expiratory flow sensor “Flowe”, the PEEP control valve “V1” and the expiratory valve “Ve” and then into the manual breathing bag.

– At the same time, fresh gas flows continuously during inspiration and

expiration into the manual breathing bag.

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6.9 Spontaneous breathing

6.9.1 Inspiration

During spontaneous breathing of the patient, the switch of the APL valve is set to the SPONT position. No gas pressure builds up in the compact breathing system. Only the warnings/alarms for the lower O2 alarm, for the upper airway pressure (Paw) and for CO2 are enabled. The piston of the KZE is moved to the upper end position in order to reduce the dead space volume of the ventilator. The APL bypass valve “V2” is not actuated.

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Figure 49 Block diagram of spontaneous inspiration

The expiratory valve “Ve” is closed during the inspiratory phase, and so prevents inhalation of expiratory gas with CO2.

Inspiration process:

– The patient inhales independently. During inhalation, the gas flows out of

the manual breathing bag through the absorber and is additionally enriched with fresh gas. The enriched mixed gas passes through the fresh gas isolation valve “RV1”, the inspiratory valve “Vi” and the inspiratory flow sensor “Flowi” and then enters the patient’s lung.

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6.9.2 Expiration

Figure 50 Block diagram of spontaneous expiration

During expiration, the inspiratory valve “Vi” remains closed thus preventing the expiratory gas from flowing back into the inspiratory branch.

Spontaneous expiration process:

– During exhalation, the expiratory gas flows out of the patient’s lung

through the expiratory flow sensor “Flowe”, the PEEP control valve “V1” and the expiratory valve “Ve” into the manual breathing bag and the absorber.

– At the same time, fresh gas flows into the breathing bag.

– If the pressure in the manual breathing bag is greater than the opening

pressure of “RV2”, the surplus gas mixture flows into the anesthetic gas scavenging system AGSS.

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7 Ventilation modes

with software version 2.n or higher

7.1 “Volume Mode”

As of Primus software version 2.n, the ventilation modes terms for synchronization and pressure support of spontaneously breathing patients will be changed into the four following terms:

–“Volume Mode”.

–“Pressure Mode”.

–“Pressure Support Mode” (optional).

–“Man./Spont Mode”.

Ventilation mode Intended use

Volume-controlled ventilation mode with fixed mandatory tidal volume “VT” and frequency “Freq.”, including switchable synchronization and adjustable pressure support for spontaneous breaths (optional “Pressure Support”).

Anesthesia in relaxed or partially relaxed patients with healthy lungs and in patients with cranio-cerebral trauma. The goal is to maintain a constant volume or a constant “et CO2”.

Figure 51 Volume-controlled ventilation with constant inspiratory flow

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The following parameters determine the breathing cycle (see Figure 51):

– Frequency “1/freq”.

– Inspiratory time “Tinsp”.

– Inspiratory flow level.

– Inspiratory pause time “TIP:Tinsp”.

– Tidal volume “VT”.

Figure 52 Synchronization of volume-controlled ventilation and spontaneous breathing

Synchronization is activated as soon as a trigger sensitivity value is entered. The message “sync” is displayed in the ventilation mode status field on the screen.

The flow trigger sensitivity controls the synchronization. The maximum time delay between the controlled ventilation breaths is adjusted by means of the frequency. To keep the frequency constant in the event of a premature triggering, the time is equalized in the next ventilation cycle.

A ventilation breath triggered by the patient is indicated by a continuous line (Figure 52/1) in the pressure curve and in the flow curve (trigger indicator). The active flow trigger window (Figure 52/2) corresponds to the last 25% of the relevant expiratory time.

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Figure 53 Synchronization of volume-controlled ventilation and “Pressure Support” of spontaneous breathing

Pressure support is activated if, during volume-controlled ventilation, a value is entered for the level of the pressure support “'pps”.

The message “PressSupp” is displayed in the ventilation mode status field on the screen.

The flow trigger sensitivity and the “'pps” level control the synchronization or the pressure support. The maximum time delay between the controlled ventilation breaths is adjusted by means of the frequency. To keep the frequency constant in the event of a premature triggering, the time is equalized in the next cycle.

If, at the time of pressure support activation, the patient was being ventilated without synchronization, automatic activation of the synchronization is initiated with the last trigger setting used.

If pressure support is deactivated with “OFF”, the synchronization is maintained with the set value.

If the trigger is deactivated with “OFF”, then the pressure support will be deactivated automatically.

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7.2 “Pressure Mode”

Ventilation mode Intended use

Pressure-controlled ventilation with decelerating flow (PCB), with synchronization of mandatory breaths (SIMV-PC) and with pressure support of spontaneous breathing (“Pressure Support”).

Anesthesia in patients suffering from a lung disease (inhomogeneous lung), neonates, children mask ventilation, pulmonary fistulae, laryngeal masks, inversed ratio ventilation, in relaxed or partially relaxed patients.

Figure 54 Pressure-controlled ventilation with decelerating flow

Pressure-controlled ventilation with fixed pressure limit “Pinsp” and frequency “1/freq”. Synchronization and adjustable pressure support of spontaneous breaths (optional) are switchable.

A continuous flow is applied to the patient during the inspiratory time “Tinsp”. The curve's rate of rise can be preset with the slope increase time “TSlope”. The maximum time delay between the controlled ventilation breaths is adjusted by means of the frequency. To keep the frequency constant in the event of a premature triggering, the time is equalized in the next cycle.

Changes to the lung compliance and the ventilation parameters affect the tidal volume.

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Figure 55 Synchronization of pressure-controlled ventilation and spontaneous breathing

Synchronization is activated as soon as a trigger value is entered.

The message “sync” is displayed in the ventilation mode status field on the screen.

The flow trigger sensitivity controls the synchronization.

A breath triggered by the patient is indicated by a continuous line (Figure

55/1) in the pressure curve and in the flow curve (trigger indicator). The active

flow trigger window (Figure 55/2) corresponds to the last 25% of the relevant expiratory time.

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Figure 56 Synchronization of pressure-controlled ventilation and “Pressure Support” of spontaneous breathing

Activation of pressure support during pressure-controlled ventilation is initiated by entering a value for the pressure support level “'pps”. The message “PressSupp” is displayed in the ventilation mode status field on the screen.

The flow trigger sensitivity and the “'pps” level control the synchronization or the pressure support.

If, at the time of pressure support activation, the patient was being ventilated without synchronization, automatic activation of the synchronization is initiated with the last “trigger” setting used.

If pressure support is deactivated with “OFF”, the synchronization is maintained with the set value.

If the trigger is deactivated with “OFF”, then the pressure support will be deactivated automatically.

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7.3 “Pressure Support

Mode

”

The ventilation mode “Pressure Support Mode” is an optional feature that must be activated.

Ventilation mode Intended use

Pressure support for spontaneous brathing. This option can be used in all mechanical ventilation modes. At the same time, this option is an independent ventilation mode.

The patient's spontaneous breathing effort is supported by the following factors:

– The flow trigger sensitivity controls the syn-

chronization.

– The adjusted pressure setting is a measure of

the pressure support.

The curve's rate of rise can be preset with the slope increase time “Tslope”.

In addition, an apnea ventilation can be set via the minimum frequency “Freqmin”.

Anesthesia in spontaneously breathing patients with laryngeal masks during surgeries without muscle relaxants.

If the patient does not breathe spontaneously, the ventilator is activated automatically dependent on the set minimum frequency “Freqmin”. The subsequent ventilation breath is not a mandatory ventilation breath. The patient can always stop the mandatory ventilation breath by his/her own breathing activity.

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Figure 57 Spontaneous breathing support

The flow trigger sensitivity and the “'pps” level control the synchronization or the pressure support of the spontaneous breathing effort. The curve's rate of rise can be preset with the slope increase time “Tslope”.

In addition, an apnea ventilation can be set via the minimum frequency “1/freqmin”. “1/freqmin” controls the automatic triggering of the ventilator when the patient is not breathing spontaneously. It is not a mandatory ventilation breath from the ventilator. The patient can always stop the breath triggered by the ventilator by his/her breathing activity. This breath is not provided with a trigger indicator.

7.4 “Man./Spont Mode”

Manual ventilation or assisted ventilation and spontaneous breathing.

Ventilation mode Intended use

Anesthesia induction/recovery and in emergency situations.

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7.5 Switching ventilation modes

When switching to another ventilation mode, the presettings of the previous mode's parameters are transferred or usefully derived.

Identical parameters in both ventilation modes (Freq., TINSP, PEEP, 'pps, trigger) are transferred directly.

Switching ventila-

tion modes

Volume-controlled to pressure-controlled.

Pressure-controlled to volume-controlled.

Automatic ventilation modes to “Pressure Support” (optional).

The measured parameter “Pplat” is applied as new parameter “Pinsp”.

The new tidal volume “VT” is transferred from the measured minute volume “MV” and the set frequency “Freq.”. Only the mechanically applied minute volume is used in this case.

Pressure-supported breaths by the patients are not taken into consideration.

The set PEEP, “'pps” and trigger are transferred.

If “'pps” and/or trigger were set to “OFF”, the most recently used values are transferred to pressure support, otherwise the configured default settings.

Transfer of settings

Pressure support (optional) to automatic ventilation modes.

The set PEEP, “'pps” and the trigger are transferred.

The other parameters correspond to the most recently used settings, otherwise to the configured default settings.

7.6 HLM mode The HLM mode (“HLM” = heart-lung machine) enables an alarm-free patient

monitoring during extracorporeal oxygenization of the patient by means of a heart-lung machine.

The following conditions apply in the HLM mode:

– All gas concentrations are measured independent of the breathing phase.

– The CO2 apnea alarm, the pressure apnea alarm, and the SpO2 monitor-

ing alarms are deactivated.

The HLM mode remains active when switching from one ventilation mode to another. Switching to standby mode will deactivate the HLM mode.

The function description relating to the Power pack follows.

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