Osmetech Opti 1 User manual

Contents
Service Manual – Osmetech OPTI™ Analyzer i
CONTENTS
1 INTRODUCTION
General Information .......................................................................................................1-1
Warnings .......................................................................................................................1-1
2 GENERAL DESCRIPTION
Specifications ................................................................................................................2-1
Principles of Operation ..................................................................................................2-7
Fluidics Block Diagram ................................................................................................ 2-11
Osmetech OPTI Cassette............................................................................................. 2-12
Osmetech OPTI Cassette Valve Positions .................................................................... 2-13
Assemblies .................................................................................................................. 2-14
Software Structure ...................................................................................................... 2-15
3 TEST PROGRAMS AND DIAGNOSTICS
Osmetech OPTI 1
Diagnostic 1 ........................................................................................... 3-1
Barometer .....................................................................................................................3-1
Battery ..........................................................................................................................3-1
Temperature..................................................................................................................3-2
Gas Pressure ................................................................................................................3-2
Cleaning........................................................................................................................3-2
Flow Test ......................................................................................................................3-3
Optics Test ....................................................................................................................3-3
Diagnostic 2 ........................................................................................... 3-4
Printer Test ...................................................................................................................3-4
Keypad Test ..................................................................................................................3-4
Display Test ..................................................................................................................3-4
Barcode Test .................................................................................................................3-4
RS232 Test ...................................................................................................................3-4
Cover Test.....................................................................................................................3-5
Fset...............................................................................................................................3-5
Diagnostic 3 ........................................................................................... 3-6
Valve Test .....................................................................................................................3-6
Valve Drive Test ............................................................................................................3-6
Peristaltic Pump Test .....................................................................................................3-6
LED Test .......................................................................................................................3-7
Memory Test..................................................................................................................3-7
Software Version ...........................................................................................................3-7
Reports .........................................................................................................................3-7

Contents
ii Service Manual – Osmetech OPTI™ Analyzer
Osmetech OPTI CCA
Diagnostic 1..........................................................................................3-10
Barometer....................................................................................................................3-10
Battery ........................................................................................................................3-10
Temperature ................................................................................................................3-11
Gas Pressure...............................................................................................................3-11
Version........................................................................................................................3-11
Reports .......................................................................................................................3-11
Barcode.......................................................................................................................3-14
Diagnostic 2..........................................................................................3-14
Printer Test..................................................................................................................3-14
Optics Test ..................................................................................................................3-14
LED Test .....................................................................................................................3-15
Interface Test ..............................................................................................................3-15
IR Test ........................................................................................................................3-15
Fan Test ...................................................................................................................... 3-15
Fset.............................................................................................................................3-16
Diagnostic 3..........................................................................................3-18
Valve Test ...................................................................................................................3-18
Flow Test..................................................................................................................... 3-18
Display Test ................................................................................................................3-19
VDrive Test..................................................................................................................3-19
Peristaltic Pump Test ...................................................................................................3-19
Keypad Test ................................................................................................................3-19
4 ADJUSTMENTS
Osmetech OPTI 1 Summary .........................................................................................4-1
Barometric Pressure ......................................................................................................4-1
Sample Measuring Chamber Temperature ......................................................................4-1
Osmetech OPTI CCA Summary ....................................................................................4-2
Barometric Pressure ......................................................................................................4-2
Sample Measuring Chamber Temperature ......................................................................4-3
5 TROUBLESHOOTING
Displayed Alarms / Message Summary ..........................................................................5-1
System Stop Messages..................................................................................................5-2
System Error Messages .................................................................................................5-4
System Warning Messages ............................................................................................5-8
System Information Messages......................................................................................5-12
Troubleshooting ...........................................................................................................5-14
Troubleshooting Flowcharts .........................................................................................5-24

Contents
Service Manual – Osmetech OPTI™ Analyzer iii
6 OSMETECH OPTI™ REPAIR PROCEDURES ........................... 6-1
Osmetech OPTI™ 1 Systems .........................................................................................6-1
Pump Cartridge ..................................................................................................................6-1
Printer Assembly................................................................................................................6-2
Analyzer Housing............................................................................................................... 6-5
Sample Measurement Chamber (SMC) Cover ...................................................................... 6-6
SMC Lower Module ........................................................................................................... 6-6
Osmetech OPTI 1 Handle ................................................................................................... 6-6
Pump Nipples..................................................................................................................... 6-6
Gas Manifold Module......................................................................................................... 6-7
Display Assembly .............................................................................................................. 6-8
Keypad .............................................................................................................................. 6-9
Exhaust Fan ......................................................................................................................6-10
Storage Compartment ........................................................................................................6-10
Peristaltic Pump Motor......................................................................................................6-11
Battery Receptacle ............................................................................................................6-12
Main Board Assembly .......................................................................................................6-13
Barcode Reader.................................................................................................................6-14
Osmetech OPTI™ CCA Systems S/N <4000 .................................................................6-15
Pump Cartridge .................................................................................................................6-15
Printer Assembly...............................................................................................................6-16
Analyzer Housing..............................................................................................................6-19
Sample Measurement Chamber Cover ................................................................................6-20
SMC Lower Module ..........................................................................................................6-20
Osmetech OPTI CCA Handle.............................................................................................6-20
Pump Nipples....................................................................................................................6-20
Gas Manifold Module........................................................................................................6-20
Display Assembly .............................................................................................................6-22
Keypad .............................................................................................................................6-23
Exhaust Fan ......................................................................................................................6-24
Storage Compartment ........................................................................................................6-24
Peristaltic Pump Motor......................................................................................................6-25
Battery Receptacle ............................................................................................................6-26
Main Board Assembly .......................................................................................................6-27
Barcode Reader.................................................................................................................6-27
Osmetech OPTI™ CCA Systems S/N >4000 .................................................................6-29
Pump Cartridge .................................................................................................................6-29
Printer Assembly...............................................................................................................6-30
Analyzer Housing..............................................................................................................6-32
Sample Measurement Chamber Cover ................................................................................6-33
SMC Lower Module ..........................................................................................................6-33
Osmetech OPTI CCA Handle.............................................................................................6-34
Pump Nipples....................................................................................................................6-34
Gas Manifold Module........................................................................................................6-35
Display Assembly .............................................................................................................6-36
Keypad .............................................................................................................................6-37
Exhaust Fan ......................................................................................................................6-38
Storage Compartment ........................................................................................................6-38
Peristaltic Pump Motor......................................................................................................6-39
Battery Receptacle ............................................................................................................6-40
Main Board Assembly .......................................................................................................6-41
Barcode Reader.................................................................................................................6-41
Table of Contents of Figures ........................................................................................6-43

Contents
iv Service Manual – Osmetech OPTI™ Analyzer
7 ILLUSTRATED PARTS LIST
Spare Parts List .............................................................................................................7-1
Main Upper Housing (Outer View) ..................................................................................7-2
Main Upper Housing (Inner View) ...................................................................................7-4
Lower Housing Assembly ...............................................................................................7-6
Printer Assembly............................................................................................................7-8
Gas Module Assembly..................................................................................................7-10
Display Assembly.........................................................................................................7-12
8 SERVICE SPARE PARTS
Spare Parts List .............................................................................................................8-1

SERVICE MANUAL REVISION LOG
(Please record any changes made to this manual)
Revision
Number Release Date Approved By Description
A Nov 94 Released
B Nov 95 Updated per CO 090226
C Aug 97 Updated per CO 970334
D Sep 98 Updated per CO 980329
E Mar 01 Updated per CO 010134
F Nov 01 Updated per CO 010614
G Nov 02 Updated per CO 020642
H Mar 04 Updated per CO 031357
Copyright 2004, Osmetech Inc. All rights reserved. Unless otherwise noted, the contents of this document may
not be reproduced, transmitted, transcribed, translated, stored in a retrieval system or translated into any language in
any form without the written permission of Osmetech Inc. While every effort is made to ensure its correctness,
Osmetech Inc. assumes no responsibility for errors or omissions, which may occur in this document.
This document is subject to change without notice.
Made in U.S.A.
Osmetech OPTI is a trademark of Osmetech Inc.
Osmetech Inc.
Critical Care Division
235 Hembree Park Drive
Roswell, GA 30076 USA
www.osmetech.com
PD7005-H

Important Information! Important Information!
This Service Manual contains important warnings and safety information to be
observed by the user.
This instrument is only intended for one area of application which is described in the
instructions. The most important prerequisites for application, operation and safety,
are explained to ensure smooth operation. No warranty or liability claims will be
covered if the instrument is applied in areas other than those described or if the
necessary prerequisites and safety measures are not observed.
The instrument is only to be operated by qualified personnel capable of observing
these prerequisites.
Only accessories and supplies either delivered by or approved by Osmetech Inc. are
to be used with the instrument.
Due to this instrument‘s operating principle, analytical accuracy not only depends on
correct operation and function, but also upon a variety of external influences beyond
the manufacturers control. Therefore, the test results from this instrument must be
carefully examined by an expert, before further measures are taken based on the
analytical results.
Instrument adjustment and maintenance with removed covers and connected power
mains are only to be performed by a qualified technician who is aware of the dangers
involved.
Instrument repairs are only to be performed by the manufacturer or qualified service
personnel.
Important Information! Important Information!

Operating Safety Information
•Overvoltage Category II when connected to a branch circuit.
•This equipment has been tested and found to comply with the limits for a Class B
digital device, pursuant to Part 15 of the FCC Rules.
Caution:
•The instrument is designed as a conventional device (closed, not waterproof
type).
•Do not operate the instrument in an explosive environment or in the vicinity of
explosive anesthetic mixtures containing oxygen or nitrous oxide.
•This instrument is suitable for continuous operation.
•The power plug is to be plugged into a ground socket only. When using an
extension cord, make sure that it is of the proper size and is properly grounded.
•Any breakage of the ground lead inside or outside the instrument or a loose
ground connection can cause a hazardous condition when operating the
instrument. Intentional disconnection of the grounding is not permitted.
•When replacing the fuses, make sure that they are of the same type and rating
as the original fuses. Never use repaired fuses or short-circuit the fuse holders.
This device is a Class 1 Laser product according to the requirements of IEC 60825-1.
The maximum energy output is as follows:
670 nm (LED): 40 Microwatts max. for 400ms
780 nm (Laser): 40 Microwatts max. for 400ms
850 nm (Laser): 40 Microwatts max. for 400ms
Caution - Use of controls or adjustments or performance of procedures other than
those specified herein may result in hazardous radiation exposure.
Operating Safety Information

Symbol Definitions
The symbols described below are used on the packaging of Osmetech OPTI related products.
Symbol Explanation
Attention Symbol – Refer to the Operator’s Manual or
Service Manual for further instructions. This symbol is
located on the inside of the instruments and product
packaging.
EXP
Expiration / Use By Symbol – Product to be used by the
expiration date indicated to the right of this symbol. This
symbol is located on all consumables, which are controlled
via an expiration or use by date.
Batch Code Symbol – Manufacturing lot number is located
to the right of this symbol. This symbol is located on all
products, which are controlled via a lot number.
Do Not Re-use Symbol – Identifies products which are not
to be used for more than the specified period of time as
defined in the product instructions. This symbol is located
on all applicable product packaging.
1
PFTG
Recycle Plastic Symbol - Identifies the clear plastic material
(polyethylene terephthalate glycol) used in the packaging of
the product. Containers identified with this symbol can be
considered recyclable. This symbol is located on all
applicable product packaging.
Green Dot Symbol - Indicates compliance with the German
Packaging Ordinance for the return of consumer packaging.
This symbol is located on all applicable product packaging.

Symbol Explanation
Bio-Hazard Symbol – Products and/or components
containing this symbol should be handled as bio-hazardous
material after use.
C
F
C
F
Temperature Symbol – Products and/or components which
contain this symbol must be stored between the specified
temperature range.
IVD
For in vitro diagnostic use
This product fulfils the requirements of Directive 98/79/EC
on in vitro diagnostic medical devices.
REF
Catalogue number
Please read pack insert. / Follow the instrument’s
instructions for use!
Manufactured by

1 Introduction
Service Manual – Osmetech OPTI™ Analyzer 1-1
1 Introduction
General Information
This Service Manual includes information and data necessary for repair and
maintenance of the Osmetech OPTI™ 1 and Osmetech OPTI™ CCA analyzers.
The manual is intended to be used with the Operator’s Manual where operating
instructions and procedures are described. In order to fully utilize the described
procedures in this manual, it is necessary to be familiar with the operation and
handling described in the Operator’s Manual.
To ensure proper operation and performance which meets the analyzer
specifications, maintenance and repairs must be performed according to the
instructions described in this service manual. The use of Osmetech original parts
and recommended materials is required to achieve performance specifications.
Spare parts and the proper order numbers are described in Chapters 7 and 8.
Product warranties may vary by country. Specific warranty terms and conditions
are described in documents provided at the time of installation.
Warnings
Warnings in this manual are marked with CAUTION and describe situations or
potential dangers that may be hazardous to personnel performing maintenance or
service activities. Information marked with NOTE describes situations or
hazards, which can cause damage or analyzer malfunction and should be
avoided. The following general operating conditions should be strictly adhered
to:
•Never operate the analyzer near flammable or explosive gases.
•Check the supply voltage before connecting the analyzer to local AC power.
•When operating the analyzer connected to primary AC power, always
connect it to a properly grounded 3-pole power receptacle.
•Replace damaged or worn power cables or plugs.
•Before opening the rear cover, turn off the analyzer, disconnect the power
cable from the primary AC source and remove the battery.

1 Introduction
1-2 Service Manual – Osmetech OPTI™ Analyzer
•Replace fuses with approved or original types only.
•Operate the analyzer away from sources of liquids such as sinks or wash
basins.
•Avoid leakage or spilling of fluids inside the analyzer, which may damage
the electrical assemblies.
•Clean the analyzer surfaces with only a mild soapy solution as necessary.
Avoid strong or harsh chemical cleaning agents that may damage the
analyzer housing and surfaces.
•Use proper tools and test equipment as described in this manual to complete
testing and repairs.
•Analyzer surfaces may be contaminated from contact with blood. Always use
precaution when coming into contact with these surfaces.
•Use approved protective gloves when handling blood specimens of contacting
contaminated surfaces.
•Adhere to local regulations when disposing of Osmetech OPTI cassettes or
contaminated parts.

2 General Description
Service Manual – Osmetech OPTI™ Analyzer 2-1
2 General Description
Specifications
Measurement Parameters
The specifications are described for both the Osmetech OPTI™ 1
and Osmetech OPTI™ CCA analyzers. Certain parameters are
specific only to Osmetech OPTI™ CCA analyzers.
The specifications listed below are valid for human whole blood,
human plasma, serum, and approved QC-material.
Parameter
Range
Display
Resolution
(Lo / Hi)
Units
Osmetech
OPTI 1
Osmetech
OPTI CCA
pH 6.6 - 7.8 0.01 / 0.001 pH units 99
PCO210 - 200 1 / 0.1 mmHg 99
PO210 - 700 1 / 0.1 mmHg 99
Na+ 100 - 180 1 / 0.1 mmol/L 9
K+ 0.8 - 10.0 0.1 / 0.01 mmol/L 9
Ca++ 0.2 - 3.0 0.01 mmol/L 9
Cl- 50.0 - 160.0 1 / 0.1 mmol/L 9
Glu 30 - 400 1 / 0.1 mg/dl 9
Glu 1.7 - 22 1 / 0.1 mmol/l 9
ctHb 5 - 25 0.1 g/dL 9
SO260 - 100 1 / 0.1 % 9
Barometer 300 - 800 0.1 mmHg 99
Input Values Range * Default
Value
Osmetech
OPTI 1
Osmetech
OPTI CCA
Patient Temperature Temp 14 - 44 °C
58 - 111 °F
37.0 °C
98.6 °F 99
Total Hemoglobin tHb 1 - 26 g/dL
1 - 16 mmol/L
1 - 260 g/L
15.0 g/dL
150 g/L
9
Total Hemoglobin ctHb 1 - 26 g/dL
1 - 16 mmol/L
1 - 260 g/L
15.0 g/dL
150 g/L
99
Hemoglobin type adult / fetal adult 99

2 General Description
2-2 Service Manual – Osmetech OPTI™ Analyzer
Input Values Range * Default
Value
Osmetech
OPTI 1
Osmetech
OPTI CCA
P50 15 - 40 mmHg 26.7 mmHg 99
FIO20.21 - 1.0 0.21 99
Respiratory Quotient, RQ 0.7 - 2.0 0.84 99
Patient Id 11 digits max. 9
Patient Sex male / female / ? ? (unknown) 99
Operator Id 11 digits max. 9
*SI units are also available. 3
Accession Number Blank to 999999999999 3
Puncture Site
LR/RR/LB/RB/LF/RF/
Cord/Scalp
Where:
LR = Left Radial
RR = Right Radial
LB = Left Brachial
RB = Right Brachial
LF = Left Femoral
RF = Right Femoral
LR
3
Cord = Cord
Scalp = Scalp
Bypass Off Pump / On Pump Off Pump 3
Sample Type Art, Ven, MixVen, Cap,
Cord, CPB
Where:
Art = Arterial
Ven = Venous
MixVen = Mixed Venous
Cap = Capillary
Cord = Cord
CPB = Cardio-Pulmonary
Bypass
Art 3
Mean corpuscular hemoglobin
concentration, MCHC% 29.0 to 37.0 33.3 3

2 General Description
Service Manual – Osmetech OPTI™ Analyzer 2-3
Input Values Range * Default
Value
Osmetech
OPTI 1
Osmetech
OPTI CCA
O2 Mode Rm Air, Mask, T-P, NC,
Vent, Bag, Hood or Other
Where:
Rm Air = Room Air
Mask = Mask
T-P = T- Piece
NC = Nasal Cannula
Vent = Ventilator
Bag = Bag (manual
resuscitation)
Hood = Hood
Other = Other
Rm Air 3
Vent Mode No, SIMV, PSV, PCV,
CMV/AC, CPAP, PCIVR
or BIPAP
Where:
No = None
SIMV = Synchronized
Intermittent Mandatory
Ventilation
PSV = Pressure Support
Ventilation
PCV = Pressure Control
Ventilation
CMV / AC = Controlled
Mechanical Ventilation /
Assist Control
CPAP = Continuous
Positive Airway Pressure
PCIVR = Pressure Control
Inverse Ratio
BIPAP = Bi – Level
Positive Airway Pressure
No 3
Tidal Volume (VT) 0 to 4000 0 3
Minute Volume (VE) 0 to 120 0 3
Peak Inspiratory Pressure
(PIP)
0 to 140 0 3
Plateau Pressure(Pplat) 0 to 100 0 3
Pressure Support Value (PS) 0 to 99.9 0 3
Positive End Expiratory
Pressure (PEEP)
0 to 50 0 3
Continuous Positive Airway
Pressure(CPAP)
0 to 50 0 3

2 General Description
2-4 Service Manual – Osmetech OPTI™ Analyzer
Input Values Range * Default
Value
Osmetech
OPTI 1
Osmetech
OPTI CCA
Rate (f) 0 to 155 0 3
Flow Rate (Liter Flow) (FR) 0 to 300 0 3
Inspiratory/Expiratory Ratio
(I/E Ratio)
1:9.9 0
3
Bi-Level Pressure 0 to 99.9 / 0 to 99.9 0 / 0 3
User Field blank to 999999999 Off 3
User Field 2 blank to 999999999 Off 3
User Field 3 blank to 999999999 Off 3
Calculated Values
Range
Display
Resolution Units
Osmetech
OPTI 1
Osmetech
OPTI CCA
Base excess in vitro BE -40 - +40 0.1 mmol/L 99
Base excess in vivo BEecf -40 - +40 0.1 mmol/L 99
Base excess actual BEact -40 - +40 0.1 mmol/L 9
Buffer base BB 0 - 100 0.1 mmol/L 99
Actual bicarbonate HCO3
-1 - 200 0.1 mmol/L 99
Total CO2TCO21 - 200 0.1 mmol/L 99
Standard bicarbonate stHCO3-1 - 200 0.1 mmol/L 99
Standard pH stpH 6.5 - 8.0 0.001 pH units 99
Oxygen saturation O2sat 0 - 100 0.1 % 99
Oxygen content O2ct 0 - 56 0.1 vol% 99
Hydrogen ion concentration cH+1000 - 10 0.1 nmol/L 99
Alveolar-arterial oxygen
partial pressure difference AaD O2
0 - 800
0.1 mmHg
99
P50 P50 15 - 35 0.1 mmHg 9
Anion Gap AnGp 3 - 30 0.1 mmol/L 9
Normalized Ca++ nCa++ 0.1 - 3.0 0.1 mmol/L 9
Hematocrit, Calculated Hct(c ) 15 - 75 1 PCV% 9

2 General Description
Service Manual – Osmetech OPTI™ Analyzer 2-5
Data Management Osmetech
OPTI 1
Osmetech
OPTI CCA
Printout built-in thermoprinter 33
Serial Interface 1x RS 232, 9-pin
SUBMIN D/F
ASCII or
ASTM
ASCII
only
3
Infrared Interface 1XIR (Unidirectional or
Bi-directional (Osmetech
OPTI CCA only))
ASTM 3
Gas Supply
Calibration Gas 14 % O2, 6 % CO2, balance N2,
max. pressure 140 psi (9.7 bar)
Operating Parameters
Sample type Heparinized whole blood, plasma/serum (pH only), Osmetech
approved quality control materials
Sample input device syringe, capillary, microsampler
Sample size Osmetech OPTI 1 80µL
Osmetech OPTI CCA 125µL
Sample input automatic aspiration
Analysis time < 2 minutes
Type of measurement Optical fluorescence and reflectance
Units conventional, standard international (SI)
Temperature / Humidity
Ambient temperature 15 °C - 32 °C (60 °F – 90 °F) – Osmetech OPTI 1
10 °C - 32 °C (50 °F – 90 °F) – Osmetech OPTI CCA
Measuring chamber
temperature
37 °C ±0.1 °C (98.6 °F ±0.18 °F)
(Osmetech OPTI 1 & Osmetech OPTI CCA)
Relative humidity
Altitude
5 - 95 % non-condensing (Osmetech OPTI 1 & Osmetech OPTI
CCA) up to 3048 m (10,000 ft)
Electrical Supply
Mains supply 100 ± 10% VAC to 240 ± 10% VAC
Frequency 50 - 60 Hz
Power consumption 45W max (7W standby)

2 General Description
2-6 Service Manual – Osmetech OPTI™ Analyzer
Overvoltage Category
Category II when connected to a branch circuit
Pollution Degree
Degree 2, normal indoor laboratory environment.
Air contains only non-conductive pollutants with
occasional condensation.
Classification
Approvals UL3101-1, CAN/CSA C22.2 NO.1010.1, CE
Mode of Operation Continuous operation
Laser Classification This device is a Class 1 laser device according to
IEC 60825-1
Explosion protection The device is not specified for operation inside
explosion hazardous areas.
Dimensions / Weight
Height 4.875 inches (12.4 cm)
Width 14.25 inches (36.2 cm)
Depth 4.75 inches (27.8 cm)
Weight 10.5 pounds (4.8 kg ) with battery
Acoustic Noise Level
standby 28 dbA
ready 28 dbA
wash/dry 60 dbA
measurement 43 dbA

2 General Description
Service Manual – Osmetech OPTI™ Analyzer 2-7
Principles of Operation
Luminescence is the emission of light energy resulting from "excited" molecules
returning to a resting state. When luminescence is initiated by light, it is
commonly referred to as fluorescence. When a fluorescent chemical is exposed
to light energy of an appropriate "color", electrons in the molecules of the
fluorescent chemical are "excited". A very short time later, the electrons return
to a resting state and in this process sometimes emit a small amount of light
energy. This energy is less than the excitation energy and thus has a different
color. That is, the emitted light (fluorescence emission), is red-shifted from the
excitation light and is much less intense.
Fluorescent optodes (from optical electrodes) essentially measure the intensity
of light emitted from fluorescent dyes. The emitted light is distinguished from
excitation light by means of optical filters. Because the excitation light energy
is kept constant, the small amount of light that results is changed only by the
concentration of the analyte. The concentration of the analyte is determined by
the calculation of the difference in fluorescence measured at a known calibration
point and fluorescence measured with the unknown concentration of analyte.
The PO2optode measurement principle is based upon luminescence, first
documented in the 1930's, and commercially utilized to measure blood PO2in
1983. The relationship of luminescence to PO2is quantified by the Stern-
Volmer equation which describes how the fluorescence emission intensity "I" is
reduced as the PO2"P" is increased. Unlike conventional electrochemical
"Clark" PO2electrodes, the oxygen optode does not consume oxygen molecules
during the measurement.
The pH optode measurement principle is based upon pH-dependent changes of
the luminescence of a dye molecule immobilized in the optode. Chemists have
used such pH indicator dyes for many years to perform acid-base titrations in
turbid media. The relationship of luminescence to pH is quantified by a variant
of the Mass-Action Law of chemistry that describes how the fluorescence
emission intensity increases as the blood pH is increased above the dye's
characteristic pKa. pH optodes do not need a reference electrode to measure pH;
however, they exhibit a small sensitivity to the ionic strength of the sample
being measured.
The PCO2optode measurement principle is based upon placing a pH optode
behind an ion-impermeable membrane, just as conventional PCO2blood gas
electrodes employ the Severinghaus CO2electrode construction. As such, PCO2
optodes suffer from non-selective interference from volatile acids and bases in
blood just as conventional PCO2electrodes.

2 General Description
2-8 Service Manual – Osmetech OPTI™ Analyzer
During the measurement, light originating from lamps in the analyzer is passed
through optical filters so that specific colors are transmitted to the sensors,
causing them to emit fluorescence. The intensity of this emitted light depends
upon the partial pressure of oxygen (PO2), carbon dioxide (PO2) or hydrogen
ion concentration (pH) of the blood in direct contact with the sensors, as
described above. The light emitted by the fluorescent sensors passes through
lenses and additional optical components. A filter is used to isolate specific
colors of interest from this returning light for measurement by a light detector.
The Na, K, Ca++ and Cl-ion optodes are based upon the principle of Ion
Selective Electrodes (ISEs). The optodes use ion selective recognition elements
(ionophores) similar to those used in ISE’s, however the ionophores are linked
to fluorescent dyes instead of electrodes. These types of dyes have been used
since the 1970s to visualize and quantify cellular ion levels in fluorescence
microscopy and cell counters. As the ion concentration increases, these
ionophores bind larger amounts of ions and cause the fluorescence intensity to
increase or decrease, depending on the particular ion. Like the pH optode, the
ion optodes do not need a reference electrode, however they do exhibit a small
pH sensitivity that is automatically compensated in the Osmetech OPTI using the
measured pH.
The glucose optode measurement is based on the enzymatic oxidation of glucose
glucose + O2 gluconic acid + H2O2
glucose oxidase
The sensor is constructed of an enzyme layer over an oxygen sensor. As a
sample containing glucose contacts the sensor this oxidation of the glucose
consumes the oxygen locally present in the sensor.
This decrease in oxygen is detected in the same manner (luminescence
quenching) as described for the PO2optode. The amount of glucose is
determined to be proporational to the rate at which the oxygen is consumed.
The measurement of total Hemoglobin (ctHb) and oxygen saturation (SO2) uses
the well-established principle of optical reflectance. Red and infrared light a
three wavelengths is directed at whole, non-hemolyzed blood within a precisely
defined part of the cassette over the O2optode. The photons are partially
absorbed and reflected by erythrocytes in a manner proportional to hemoglobin
level; at low hemoglobin levels the unabsorbed photons strike the O2optode’s
pink overcoat and are reflected back up through the blood a second time.
A portion of the reflected light exits the top of the cassette and is measured by a
detector in the instrument. The infrared wavelengths are selected for the
hemoglobin measurement because they are largely independent of SO2, that is,
the predominate forms of adult and fetal hemoglobin absorb similarly within the
750 – 850 nm wavelength range.

2 General Description
Service Manual – Osmetech OPTI™ Analyzer 2-9
The red wavelength is utilized for the SO2 measurement because it is much more
strongly absorbed by deoxyhemoglobin than all other hemoglobins, and is
picked close to the isobestic point for oxy- and carboxyhemglobin. Maintaining
high shear force just prior to measurement minimizes sensitivity to erythrocyte
aggregation (rouleau formation).
The optical signal of the detectors is converted by the microprocessor to a
numerical readout in conventional units of measure and displayed on the front of
the device. Other values commonly used for the assessment of oxygen and acid-
base status are calculated from these measured values.
The entire sample path of the Osmetech OPTI cassette is filled with storage
buffer to keep the sensors stable during storage. In addition, the cassette pouch
is filled with a CO2atmosphere, which keeps the pH of the storage buffer stable.
The cassette not only contains the sensors but also houses a distribution valve
(cassette valve), the sample fill port, an input/output port (I/O port), a reservoir
and a vent.
The function of the I/O port is to connect the cassette to the peristaltic pump
allowing sample aspiration and calibration gas to flow through the cassette.
The storage buffer in the reservoir ensures stability over the shelf life of the
cassette.
The distribution valve has 2 functions: its hollow body serves as a waste
container, referred to as “waste”, holding storage buffer and OPTI-trol.
In addition, the cassette valve incorporates small channels, called links that
connect the sensor channel, the fill port, the vent and the I/O port in different
combinations. These different connections are achieved by turning the cassette
valve to different positions. Each valve position has an assigned number. An
unused cassette is set to position 0, the home position. The diagram on page 2-9
shows the valve positions and the connections for each position. E.g., position 2
connects the fill port via the valve link to the sensor channel and the reservoir to
the I/O port.
The Osmetech OPTI 1 and Osmetech OPTI CCA analyzers are microprocessor-
based instruments measuring optical fluorescence. The disposable, single-use
cassette contains all the elements needed for calibration, sample measurement
and waste containment. After reading the calibration information specific to a
cassette into the instrument by 'swiping' the cassette package through a
convenient bar code reader, the cassette is placed in the measurement chamber.
While the analyzer warms the cassette to 37.0 ± 0.1 °C, the cassette valve is
turned to position 5. In this position, the I/O port is connected to the vent
allowing the pump to purge calibration gas. At the same time, readings are
taken from all sensors to ensure proper functioning. In addition, the fluid light
gates L1, L2 and L3 are calibrated.