S5 Compact Airway Module Technical Reference Manual Slot Oct 2003

Table of contents

TABLE OF CONTENTS S/5 Compact Airway Modules TABLE OF CONTENTS

I

TABLE OF FIGURES

III

INTRODUCTION

1

1 SPECIFICATIONS

2

1.1 1.2

General specifications ...2 Typical performance ...2 1.2.1 CO2 ...2 1.2.2 O2...2 1.2.3 N2O ...2 1.2.4 Respiration Rate (RR) ...3 1.2.5 Anesthetic Agents (AA) ...3 1.2.6 MAC ...3 1.3 Gas specifications ...3 1.3.1 Normal conditions...4 1.3.2 Conditions exceeding normal...4 1.4 Patient spirometry specifications...5 1.4.1 Normal conditions...5 1.4.2 Conditions exceeding normal...6 1.5 Gas exchange specifications...6 1.5.1 VO2 and VCO2...6 1.5.2 RQ...6

2 FUNCTIONAL DESCRIPTION

7

2.1

Measurement principle ...7 2.1.1 CO2, N2O, and agent measurement ...7 2.1.2 O2 measurement ...9 2.1.3 Patient spirometry ...9 2.1.4 Gas exchange measurement...11 2.2 Main components...12 2.2.1 Gas sampling system ...12 2.2.2 TPX measuring unit ...16 2.2.3 OM measuring unit ...16 2.2.4 PVX measuring unit...17 2.2.5 Gas exchange ...18 2.2.6 CPU board ...18 2.2.7 OM board ...19 2.2.8 PVX board ...19 2.3 Connectors and signals...20

3 SERVICE PROCEDURES 3.1

21

General service information ...21 3.1.1 OM measuring unit ...21 3.1.2 TPX measuring unit ...21 3.1.3 OM, TPX, and PVX measuring unit...21 i Document No. 8001009-5

Datex-Ohmeda S/5 monitors 3.1.4 Serviceable or exchangeable parts ...21 Service check...22 3.2.1 Recommended tools...22 3.2.2 Recommended parts...22 3.3 Disassembly and reassembly ...30 3.3.1 PVX unit...30 3.3.2 Pump unit...30 3.3.3 CPU board ...30 3.3.4 Software of CPU board ...31 3.3.5 Instructions after replacing software or CPU board ...31 3.4 Adjustments and calibrations ...31 3.4.1 Gas sampling system adjustment ...31 3.4.2 Flow rate measurement...31 3.4.3 Flow rate adjustment...32 3.4.4 Gas calibration ...32 3.4.5 Flow calibration ...32 3.2

4 TROUBLESHOOTING

33

4.1

Troubleshooting charts ...33 4.1.1 CO2 measurement...34 4.1.2 Patient spirometry...35 4.1.3 Gas exchange ...37 4.2 Gas sampling system troubleshooting ...38 4.2.1 Sampling system leak test...38 TM 4.2.2 Steam test for the Nafion tubes...38 4.3 OM measuring unit troubleshooting...38 4.4 TPX measuring unit troubleshooting...39 4.5 PVX measuring unit troubleshooting ...39 4.5.1 Spirometry tubing leak test...39 4.6 CPU board troubleshooting ...39 4.7 Error messages ...39

5 SERVICE MENU 5.1 5.2 5.3

General menu ...42 Gases service menu ...43 Spirometry service menu ...45

6 SPARE PARTS 6.1

41

47

Spare parts list...47 6.1.1 M-C rev. 00, M-CO rev. 00...48 6.1.2 M-C rev. 01-02, M-CO rev. 01-03...50 6.1.3 M-CAiO rev. 00, M-CAiOV rev. 01...52 6.1.4 M-CAiO rev. 01-03, M-CAiOV rev. 02-04, M-CAiOVX rev. 00-02 ...54 6.1.5 M-COV rev. 01, M-COVX rev. 00 ...57 6.1.6 M-COV rev 02-04, MCOVX rev. 01-03 ...59 6.1.7 D-fend latch ...61

7 EARLIER REVISIONS

62

APPENDIX A

63

SERVICE CHECK FORM

A-1

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Table of contents

TABLE OF FIGURES Figure 1

TPX sensor principle...7

Figure 2

Absorbance of N2O and CO2 ...8

Figure 3

Infrared absorbance of AAs ...8

Figure 4

O2 measurement principle ...9

Figure 5

Absorber ...13

Figure 6

Gas sampling system layout, M-C...14

Figure 7

Gas sampling system layout, M-CAiOV, M-CAiOVX, M-CAiO, M-COVX, M-COV, M-CO...15

Figure 8

Gas tubing layout ...15

Figure 9

TPX measuring unit ...16

Figure 10

OM measuring unit ...17

Figure 11

PVX measuring unit...17

Figure 12

Signal processing...18

Figure 13

Control logic...19

Figure 14

Calibration data stored in EEPROM...19

Figure 15

Module bus connector pin layout ...20

Figure 16

Pneumatic unit and reference gas connection block...24

Figure 17

Front panel stickers ...47

Figure 18 Exploded view, M-C rev.00, M-CO rev.00, M-CaiO rev.00, M-COV rev. 01, M-CaiOV rev.01, M-COVX rev.00 48 Figure 19 Exploded view M-C rev. 01-02, M-CO rev. 01-02, M-COV rev.02, M-COVX rev.01, M-CAiO rev.01, MCAiOV rev. 02, M-CAiOVX rev.00 ...50 Figure 20 Exploded view, M-C rev.00, M-CO rev.00, M-CAiO rev.00, M-COV rev. 01, M-CAiOV rev.01, M-COVX rev.00 52 Figure 21 Exploded view M-C rev. 01-02, M-CO rev. 01-02, M-COV rev.02, M-COVX rev.01, M-CAiO rev.01, MCAiOV rev. 02, M-CAiOVX rev.00 ...54 Figure 22 Exploded view, M-C rev.00, M-CO rev.00, M-CAiO rev.00, M-COV rev. 01, M-CAiOV rev.01, M-COVX rev.00 57 Figure 23 Exploded view M-C rev. 01-02, M-CO rev. 01-02, M-COV rev.02, M-COVX rev.01, M-CAiO rev.01, MCAiOV rev. 02, M-CAiOVX rev.00 ...59 Figure 24

D-fend latch...61

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iv Document No. 8001009-5

Compact Airway modules

INTRODUCTION This Technical Reference Manual Slot provides information for the maintenance and service of the Datex-Ohmeda S/5 Compact Airway modules. The Compact Airway modules are double width plug-in modules. M-C, M-CO, M-COV, M-COVX, M-CAiO, M-CAiOV, M-CAiOVX and MCAiOVX/SERVICE are designed for use with the S/5 monitors. Later in this manual modules may be refered to without the S/5 system nomenclature for simplicity. Please also see theTechnical Reference Manual of the S/5 monitor for system specific information e.g. related documentation, conventions used, symbols on equipment, safety precautions, system description, system installation, interfacing, functional check and planned maintenance. The Compact Airway modules provide airway and respiratory measurements. Letters in the module name stand for: M = plug-in module, C = CO2 and N2O, O = patient O2, V = patient spirometry, X = gas exchange, A = anesthetic agents, and i = agent identification

About M-CAiOVX/SERVICE module The M-CAiOVX/SERVICE module is meant for service purposes only. It can be used as a loan module if the module in the hospital should be sent to the factory for repair. The specifications that apply to the M-CAiOVX apply also to the M-CAiOVX/SERVICE module. Module differences: the colour of the front mask is green, the front panel has a “SERVICE” text and there are no front panel keys equipped. Table 1 Modules

Options for Compact Airway modules Parameters/measurements CO2

M-CAiOVX M-CAiOV M-CAiO M-COV M-COVX M-CO M-C M-CAiOVX/SERVICE

N2O

O2

Anesthetic agents

Agent ID

Spirometry

Gas exchange •

•

•

•

•

•

•

•

•

•

•

•

•

•

•

•

•

•

•

•

•

• •

•

•

•

•

•

•

•

•

•

•

•

•

•

•

•

•

NOTE: Do not use identical modules in the same monitor simultaneously. The M-C, M-CO, M-COV, M-COVX, M-CAiO, M-CAiOV, M-CAiOVX , M-CAiOVX/SERVICE and M-miniC are considered identical modules. NOTE: The Compact Airway Module or Single-width Airway Module and Airway Module, G-XXXX, cannot be used simultaneously in the same monitor. NOTE: The Compact Airway modules cannot be used in the Extension Frame, F-EXT4. NOTE: Anesthetic agents and N2O values are not displayed with Critical Care main software, but when present in the module they are calculated for compensation of CO2 and O2.

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1

SPECIFICATIONS

1.1 General specifications Module size, W × D × H Module weight Operating temperature Storage temperature Atmospheric pressure

Humidity Power consumption

75 × 228 × 112 mm, 2.9 × 9.0 × 4.4 in 1.6 kg/3.7 lbs +10...+40 °C -25...+70 °C 666...1060 hPa / (67...106 kPa) (500...800 mmHg) (666...1060 mbar) 10...95 % non-condensing (in airway 0...100 %, condensing) 12.6 W Prms, 14.6 W momentary

Protection against electrical shock Type BF

1.2 Typical performance 1.2.1 CO2 Measurement range Measurement rise time Accuracy Gas cross effects

0...15 vol% (0...15 kPa, 0...113 mmHg) < 400 ms typical ±(0.2 vol% +2 % of reading) < 0.2 vol% (O2, N2O, anesthetic agents)

If CO2 concentration is below 0.1%, 0.0% is displayed.

1.2.2 O2 Measurement range Measurement rise time Accuracy Gas cross effects O2 Fi-Et difference

0 to 100 vol% < 400 ms typically ±(1 vol% +2% of reading) < 1 vol%; anesthetic agents < 2 vol%; N2O resolution 0.1 vol%

Measurement range Measurement rise time Accuracy Gas cross effects

0 to 100 %; N2O < 450 ms typically ±(2 vol% +2% of reading) < 2 vol%; anesthetic agents

1.2.3 N2O

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1.2.4 Respiration Rate (RR) Measurement range Detection criteria

4...60 breaths/min 1 % variation in CO2

1.2.5 Anesthetic Agents (AA) Measuring range Hal, Enf, Iso Sev Des

0 to 6 vol% 0 to 8 vol% 0 to 20 vol%

Measurement rise time Accuracy Gas cross effects

< 400 ms typically ±(0.15 vol% +5% of reading) < 0.15 vol% N2O

Resolution is two digits when the AA concentration is below 1.0 vol%. If AA concentration is below 0.1 vol%, 0.0% is displayed. Identification threshold Identification time

0.15 vol% typically < 20 s (for pure agents)

Mixture identification threshold for 2. agent: 0.2 vol% +10% of total conc.

1.2.6 MAC Range

0...9.9 MAC

Equation: MAC(AA) =

%(ETAA) %ETN2O + x(AA) 100

Formula 1

where x(AA): Hal=0.75 %, Enf=1.7 %, Iso=1.15 %, Sev=2.05 %, Des=6.0 %.

1.3 Gas specifications Airway humidity Sampling rate Sampling delay Total system response time Display update rate

0...100 %, condensing 200 ±20 ml/min. (sampling line 2-3 m, normal conditions) 2.5 seconds typical with a 3 m sampling line 2.9 seconds typical with a 3 m sampling line, including sampling delay and rise time breath-by-breath

Automatic compensation for pressure, CO2-N2O and CO2-O2 collision broadening effect. Warm up time

2 min. for operation with CO2, O2, and N2O 5 min. for operation of anesthetic agents 30 min. for full specifications

Autozeroing interval

Immediately after ‘calibrating gas sensor’ and 2, 5, 10, 15, 30, 45, 60 minutes after start-up, then every 60 minutes

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1.3.1 Normal conditions Accuracy specifications apply in normal conditions (after 30 minutes warm-up period): Ambient temperature 18...28 °C, within ±5 °C of calibration Ambient pressure 500...800 mmHg, ±50 mmHg of cal. Ambient humidity 20...80 % RH, ±20 % RH of cal. Non-disturbing gases − Ethanol C2H5OH(< 0.3%) − Acetone (< 0.1%) − Methane CH4 (< 0.2%) − Nitrogen N2 − Carbon monoxide CO − Nitric Oxide NO (< 200 ppm) − water vapor Maximum effect on readings − CO2 < 0.2 vol% − O2, N2O < 2 vol% − anesthetic agents < 0.15 vol% Effect of Helium decreases CO2 readings < 0.6 vol% typically

1.3.2 Conditions exceeding normal Accuracy specifications under the following conditions; ŒŽ: Œ Ambient temperature Ambient pressure Ambient humidity

10...40 °C, within ±5 °C of calibration 500...800 mmHg, ±50 mmHg of calibration 10...98 % RH, ±20 % RH of calibration

 During warm-up 2 to 10 minutes (anesthetic agents 5-10 minutes), under normal conditions Ž During warm-up 10 to 30 minutes, under normal conditions  N2O > 85%, under normal conditions Accuracy under different conditions (see above) Condition Œ and Ž

Condition 

CO2

±(0.3 vol% + 4 % of reading) (at 5 vol% error ±0.5 vol%)

±(0.4 vol% + 7 % of reading) (at 5 vol% error ±0.75 vol%)

O2

±(2 vol% + 2% of reading)

±(3 vol% + 3% of reading)

N2O

±(3 vol% + 3% of reading)

±(3 vol% + 5% of reading)

Agents: Hal, Enf, Iso,Sev, Des

±(0.2 vol% + 10% of reading)

±(0.3 vol% + 10% of reading)

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Condition 

± (2vol% + 8% of reading)

Compact Airway modules

1.4 Patient spirometry specifications 1.4.1 Normal conditions Accuracy specifications apply in normal conditions (after 10 minutes warm-up period): Ambient temperature Ambient pressure Ambient humidity Airway humidity Respiration rate I:E ratio Intubation tube

10...40 °C 500...800 mmHg 10...98 %RH 10...100 %RH 4...35 breaths/min (adults) 4...50 breaths/min (pediatric) 1:4.5...2:1 5.5...10 mm (adults), 3...6 mm (pediatric)

Airway pressures (Paw, Ppeak, Pplat, PEEPe, PEEPiStat, PEEPiDyn, Pmean) Measurement range Resolution Accuracy

-20...+100 cmH2O 0.5 cmH2O ±1 cmH2O

Measurement range (for both directions)

1.5...100 l/min (adults) 0.25...25 l/min (pediatric)

Measurement range Resolution Accuracy

150...2000 ml (adults), 15...300 ml (pediatric) 1 ml ±6 % or 30 ml (adult), ±6 % or 4 ml (pediatric)

Airway flow

Tidal volume

Minute volume Measurement range Resolution

2...20 l/min (adults), 0.5...5 l/min (pediatric) 0.1 l/min

Measurement range Resolution

4...100 ml/cmH2O (adult), 1...100 ml/cmH2O (pediatric) 1 ml/cmH2O (adult), 0.1 ml/cmH2O (pediatric)

Compliance

Airway resistance Measurement range Resolution

0...40 cmH2O/ l/s 1 cmH2O/ l/s

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Other parameters Specifications apply in conditions listed in patient spirometry specifications.

Dead space of the sensor 9.5 ml (adult), 2.5 ml (pediatric)

Resistance of the sensor 0.5 cmH2O @ 30 l/min (adult), 1.0 cmH2O @ 10 l/min (pediatric)

1.4.2 Conditions exceeding normal Accuracy specifications under the following condition (during warm-up 2 to 10 minutes):

Airway Pressure(Paw) Accuracy

±2 cmH2O

Accuracy

±10 % or 100 ml (adult), ±10 % or 10 ml (pediatric)

Tidal volume

1.5 Gas exchange specifications Mathemathical integration of airway flow and gas concentration for intubated, mechanically ventilated and/or partly spontaneously breathing patients. NOTE: These specifications apply only when a 2 meter gas sampling line is used, and a Y-piece with a physical dead space less than 8 ml. NOTE: These specifications only apply if the FiO2 level delivered to the patient is varing by less than 0.2 % during the inspiratory cycle at the measurement point.

1.5.1 VO2 and VCO2 Measurement range Resolution Accuracy

50...1000 ml/min 10 ml/min ±10 % or 10 ml; when FiO2 < 65 % ±15 % or 15 ml; when 65 % < FiO2 < 85 %

Measurement range Resolution

0.6...1.2 0.05

1.5.2 RQ

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2

FUNCTIONAL DESCRIPTION

2.1 Measurement principle 2.1.1 CO2, N2O, and agent measurement TPX is a side stream gas analyzer, measuring real time concentrations of CO2, N2O and anesthetic agents (Halothane, Enflurane, Isoflurane, Desflurane, and Sevoflurane). Temp sensor Sample chamber

Thermopile detectors

Sample Sample gas out gas in

Figure 1

TPX sensor principle

Anesthetic agents or mixtures of two anesthetic agents are automatically identified and concentrations of the identified agents are measured. TPX also detects mixtures of more than two agents and issues an alarm. TPX is a nondispersive infrared analyzer, measuring absorption of the gas sample at seven infrared wavelengths, which are selected using optical narrow band filters. The infrared radiation detectors are thermopiles. Concentrations of CO2 and N2O are calculated from absorption measured at 3-5 µm.

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Figure 2

Absorbance of N2O and CO2

Identification of anesthetic agents and calculation of their concentrations is performed by measuring absorptions at five wavelengths in the 8-9 µm band and solving the concentrations from a set of five equations.

Figure 3

Infrared absorbance of AAs

The measuring accuracy is achieved utilizing numerous software compensations. The compensation parameters are determined individually for each TPX during the factory calibration.

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Compact Airway modules

2.1.2 O2 measurement The differential oxygen measuring unit uses the paramagnetic principle in a pneumatic bridge configuration. The signal picked up with a differential pressure transducer is generated in a measuring cell with a strong magnetic field that is switched on and off at a frequency of 165 Hz. The output signal is a DC voltage proportional to the O2 concentration difference between the two gases to be measured.

Electromagnet Mixture out

Microphone

Switched magnetic field

Sample in Reference in

Figure 4

O2 measurement principle

2.1.3 Patient spirometry In mechanical ventilation breaths are delivered to the patient by a ventilator with a proper tidal volume (TV), respiration rate (RR), and inspiration / expiration ratio in time (I:E) determined by the settings of the ventilator. The Patient Spirometry monitors patient ventilation. The following parameters are displayed: − − − −

Expiratory and inspiratory tidal volume (TV) in ml Expiratory and inspiratory minute volume (MV) in l/min Expiratory spontaneous minute volume in l/min Inspiration/expiration ratio (I:E)

Airway pressure − − − − − − −

Peak pressure (Ppeak) Mean airway pressure (Pmean); available only in S/5 Critical Care and Compact Critical Care monitors End inspiratory pressure (Pplat) PEEPi, PEEPe; available only in S/5 Critical Care and Compact Critical Care monitors Total positive end expiratory pressure (PEEPtot); available only in S/5 Anesthesia and Compact Anesthesia monitors Real time airway pressure waveform (Paw) Static Positive end expiratory pressures (Static PEEPi and Static PEEPe); available only in S/5 Critical Care and Compact Critical Care monitors

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Datex-Ohmeda S/5 monitors

− −

Static Plateau pressure (Static Pplat); available only in S/5 Critical Care and Compact Critical Care monitors Static Compliance (Static Compl); available only in S/5 Critical Care and Compact Critical Care monitors

PEEP, Ppeak, Pmean, and Pplat are measured by pressure transducer on the PVX board. Atmospheric pressure is used as a reference in measurement. The pressure measurement is made from the airway part that is closest to the patient between patient circuit and intubation tube. PEEPi=intrinsic PEEP, PEEPtot-PEEPe Static pressure measurement maneuvres are automatically identified based on a increased zero flow period at the end of the inspiration or expiration. Static Compliance is calculated if Static PEEP and Static Pplat measurements were made within a 2 minute period.

Airway flow − − − − −

Real time flow waveform (V') Compliance (Compl) Airway resistance (Raw) Pressure volume loop Flow volume loop

The measurement is based on measuring the kinetic gas pressure and is performed using the Pitot effect. A pressure transducer is used to measure the Pitot pressure. The pressure signal obtained is linearized and corrected according to the density of the gas. Speed of flow is calculated from these pressure values and the TV value is then integrated. The MV value is calculated and averaged using TV and RR (respiratory rate) values. Compliance and airway resistance Compliance is calculated for each breath from the equation Compl =

TVexp Pplat − PEEPi − PEEPe

Formula 2

Compliance describes how large a pressure difference is needed to deliver a certain amount of gas to the patient. The airway resistance, Raw, is calculated using an equation, that describes the kinetics of the gas flow between the lungs and the D-lite. The equation states that the pressure at the D-lite can at any moment of the breath be approximated using the equation P(t) = Raw x V’(t) + V(t)/Compl + PEEPe + PEEPi

Formula 3

where P(t), V’(t) and V(t) are the pressure, flow and volume measured at the D-lite at a time t, Raw is the airway resistance, Compl is the compliance and PEEPe+PEEPi is the total positive end expiratory pressure (PEEPtot).

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Compact Airway modules

D-lite Patient Spirometry uses specific sensors called D-lite+/D-lite and Pedi-lite+/Pedi-lite flow sensors. Different types of sensors are available: adult sensor for measuring adults and pediatric sensor for children. Both are available as reusable and disposable versions. D-lite and Pedi-lite adapters are designed to measure kinetic pressure by two-sided Pitot tube. Velocity is calculated from pressure difference according to Bernoulli's equation. Flow is then determined using the calculated velocity.

2 × dP ρ

v=

(from Bernoulli's equation)

Formula 4

F =v×A, where: F = flow (l/min), v = velocity (m/s), A = cross area (m2), dP = pressure difference (cmH2O), ρ = density (kg/m3) Finally the volume information is obtained by integrating the flow signal.

2.1.4 Gas exchange measurement The gas exchange measurement uses the D-lite flow sensor and the gas sampler. The basic data which is needed to obtain O2 consumption and CO2 production are volumes and concentrations. Concentrations have been corrected for delay and deformation during the transport of the gas sample in a sidestream gas measurement sensor. To obtain the amount of O2 consumed in ml/min, the amount which is exhaled is subtracted from the amount that is inhaled. To obtain the amount of CO2 producted in ml/min, the amount which is inhaled is subtracted from the amount that is exhaled. These amounts can be obtained by multiplying each measured volume piece (dv) by the corresponding gas concentration: VO2 = ò fO 2dv − ò fO 2dv insp

Formula 5

exp

and VCO2 = ò fCO 2dv − ò fCO 2dv exp

Formula 6

insp

Using inspiratory and expiratory minute volumes MVi and MVe and volume-weighted inspiratory concentrations fi and fe these equations can be rewritten as: VO2 = fiO2 × MVi - feO2 × MVe [ml/min]

Formula 7

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Datex-Ohmeda S/5 monitors VCO2 = feCO2 × MVe - fiCO2 × MVi [ml/min]

Formula 8

To obtain results which are less sensitive to errors in volume measurements, the so-called Haldane transformation is used. This means taking advantage of the fact that the patient is not consuming nor producing nitrogen: the amount of nitrogen inhaled is equal to the amount exhaled fiN2 × MVi=feN2×MVe. VO2 and VCO2 can then be written as: VO2 = (fiO2 - fHald × feO2)MVi [ml/min]

Formula 9

VCO2 = (fHald × feCO2 - fiCO2)MVi [ml/min]

Formula 10

with fHald = (1-fiCO2 – fiO2 – fiN2O - fiAne1 – fiAne2) / (1-feCO2 – feO2 – feN2O - feAne1 – feAne2) EE=(5.5 × VCO2) + (1.76 × VO2) + (1.99 × Un) [kcal/day]

Formula 11

with Un=Urea Nitrogen Excretion = 13 g/day (for adults only).

2.2 Main components The compact airway modules consist of: • • • • • • •

Gas sampling system TPX measuring unit OM measuring unit PVX measuring unit CPU board OM board PVX board

2.2.1 Gas sampling system The sampling system takes care of drawing a gas sample into the analyzers at a fixed rate. The gas sampling system samples the measured air to the module, and removes water and impurities from it. A sampling line is connected to the water trap. The pump draws gas through the sampling line to gas measuring units. After the measurements, the gas is exhausted from sample gas out connector. The M-COVX and M-CAiOVX modules have a different gas sampling system compared to the other modules. A number of flow restrictors have been changed to create a bigger pressure difference with ambient pressure in the gas sensors. The sample flow is however about the same (200 ml/min). A larger pressure difference makes the deformations of the gas concentration curves less sensitive to high variations of the airway pressures thus meeting also the accuracy requirements of gas exchange for these applications.

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D-fendTM The sample is drawn through a sampling line. Then gas enters the monitor through the water trap, where it is divided into two flows, a main flow and a side flow. The main flow goes into the analyzers. This flow is separated from the patient side by a hydrophobic filter. The side flow creates a slight subatmospheric pressure within the D-fend water trap which causes fluid removed by the hydrophobic filter to collect in the bottle.

Zero valve and absorber The main flow passes through a magnetic valve before proceeding to the analyzers. This valve is activated to establish the zero points for the TPX and OM units. When the valve is activated, room air is drawn through the absorber into the internal system and the gas sensors. Paralyme is used as an absorbent. Figure 5

Absorber

NafionTM tubes 1) A nafion tube is used between the water trap and the zero valve to balance the sample gas humidity with that of ambient air. The tube will prevent errors caused by the effect of water vapor on gas partial pressure when humid gases are measured after calibration with dry gases. Another nafion tube is used between the absorper and the pneumatic unit to prevent humidity caused by absorb of CO2.

Gas analyzers After the zero valve and nafion tube the gas passes through TPX and OM units. The oxygen sensor has two inputs. One input accepts the main flow and the other draws in room air for reference. Both gas flows exit from a single port.

Sample flow differential pressure transducer The sample flow differential pressure transducer measures pressure drop across OM inlet restrictor and calculates sample flow from the pressure difference.

Working pressure transducer The working pressure transducer measures absolute working pressure between the TPX unit and OM unit. It is used for messages: ‘sample line blocked’, ‘check D-fend’, ‘replace D-fend’ and ‘check sample gas outlet’.

1)

Nafion is a trademark of Perma Pure Inc.

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Pneumatic unit The pneumatic unit contains zeroing valve, occlusion valve and tubing connections. There is a series of restrictors and chambers forming a pneumatic filter to prevent pressure oscillations from the pump to reach the measuring units. The occlusion valve connection to room air includes a dust filter and the zero valve connection to room air includes an absorber.

Connection block The connection block contains sample gas outlet connector and OM unit reference gas inlet. The inlet is equipped with a dust filter.

Occlusion valve The valve is activated when the sampling line gets occluded. The main flow is then diverted to the side flow of the D-fend water trap to faster remove the occlusion.

Sampling pump and damping chamber The gas sampling pump is a membrane pump that is run by a brushless DC-motor. Sample flow is measured with a differential pressure transducer across a known restriction. The motor is automatically controlled to maintain a constant flow, even when the D-fend water trap ages and starts to get occluded. It also enables use of sample tubes with varying lengths and diameters. The damping chamber is used to even out the pulsating flow and silence the exhaust flow. NOTE: In no occasion is the flow reversed towards patient. CO2 absorber Nafion tube

Pneumatic unit

D-fend Water trap

G F E D C B A

Nafion tube Pressure transducers

B1 Connection block

B2 TPX unit OUT

IN

IN OUT Damping champer Sampling pump

Figure 6 14 Document No. 8001009-5

Gas sampling system layout, M-C

Compact Airway modules

CO2 absorber Nafion tube

Pneumatic unit

P OUT

G

D-fend Water trap

OM unit

REF

F

IN

E D C B A

Nafion tube

Pressure transducers

B1

Connection block

B2 TPX unit OUT

IN

IN OUT

Damping champer Sampling pump

Front panel

Figure 7

Filter

Gas sampling system layout, M-CAiOV, M-CAiOVX, M-CAiO, M-COVX, M-COV, M-CO

Room air

Reference gas

1)

Filter Absorber

Zero valve 1)

D-fend Sample line

D-fend

Room air Occlusion valve

OM

TPX Pressure transducer p

Pressure transducer pdp

Pump

1)

Tubing marked with 1) is thinner in M-CAiOVX and M-COVX module. Figure 8

Gas tubing layout

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