Fluke Biomedical Index 2MF User manual

Index 2MF
SpO2 Simulator
Users Manual
PN 3341210
September 2008, Rev. 1
© 2008 Fluke Corporation, All rights reserved. Printed in USA. Specifications subject to change without notice.
All product names are trademarks of their respective companies.

Warranty and Product Support
Fluke Biomedical warrants this instrument against defects in materials and workmanship
for one full year from the date of original purchase. During the warranty period, we will
repair or, at our option, replace at no charge a product that proves to be defective,
provided you return the product, shipping prepaid, to Fluke Biomedical. This warranty
does not apply if the product has been damaged by accident or misuse or as the result of
service or modification by other than Fluke Biomedical. IN NO EVENT SHALL FLUKE
BIOMEDICAL BE LIABLE FOR CONSEQUENTIAL DAMAGES.
Only serialized products and their accessory items (those products and items bearing a
distinct serial number tag) are covered under this one-year warranty. PHYSICAL
DAMAGE CAUSED BY MISUSE OR PHYSICAL ABUSE IS NOT COVERED
UNDER THE WARRANTY. Items such as cables and nonserialized modules are not
covered under this warranty.
Recalibration of instruments is not covered under the warranty.
This warranty gives you specific legal rights, and you may also have other rights which
vary from state to state, province to province, or country to country. This warranty is
limited to repairing the instrument to Fluke Biomedical’s specifications.
Warranty Disclaimer
Should you elect to have your instrument serviced and/or calibrated by someone other
than Fluke Biomedical, please be advised that the original warranty covering your
product becomes void when the tamper-resistant Quality Seal is removed or broken
without proper factory authorization. We strongly recommend, therefore, that you send
your instrument to Fluke Biomedical for factory service and calibration, especially during
the original warranty period.

Notices
All Rights Reserved
©Copyright 2008, Fluke Biomedical. No part of this publication may be reproduced, transmitted, transcribed, stored in a retrieval
system, or translated into any language without the written permission of Fluke Biomedical.
Copyright Release
Fluke Biomedical agrees to a limited copyright release that allows you to reproduce manuals and other printed materials for usein
service training programs and other technical publications. If you would like other reproductions or distributions, submit a written
request to Fluke Biomedical.
Unpacking and Inspection
Follow standard receiving practices upon receipt of the instrument. Check the shipping carton for damage. If damage is found, stop
unpacking the instrument. Notify the carrier and ask for an agent to be present while the instrument is unpacked. There are no special
unpacking instructions, but be careful not to damage the instrument when unpacking it. Inspect the instrument for physical damage such
as bent or broken parts, dents, or scratches.
Technical Support
For application support or answers to technical questions, either email [email protected] or call 1-800- 850-4608or 1-
440-248-9300.
Claims
Our routine method of shipment is via common carrier, FOB origin. Upon delivery, if physical damage is found, retain all packing
materials in their original condition and contact the carrier immediately to file a claim. If the instrument is delivered in good physical
condition but does not operate within specifications, or if there are any other problems not caused by shipping damage, please contact
Fluke Biomedical or your local sales representative.
Standard Terms and Conditions
Refunds and Credits
Please note that only serialized products and their accessory items (i.e., products and items bearing a distinct serial number
tag) are eligible for partial refund and/or credit. Nonserialized parts and accessory items (e.g., cables, carrying cases,
auxiliary modules, etc.) are not eligible for return or refund. Only productsreturned within90 days fromthe dateof original
purchase are eligible for refund/credit. In order to receive a partial refund/credit of a product purchase price on a serialized product, the
product must not have been damaged by the customer or by the carrier chosen by the customer to return the goods, and the product
must be returned complete (meaning with all manuals, cables, accessories, etc.) and in “as new” and resalable condition. Products not
returned within 90 days of purchase, or products which are not in “as new” and resalable condition, are not eligible for credit return and
will be returned to the customer. The Return Procedure (see below) must be followed to assure prompt refund/credit.
Restocking Charges
Products returned within30 days of original purchase are subject to a minimum restocking fee of 15 %. Products returned in excess of
30 days after purchase, but prior to 90 days, are subject to a minimum restocking fee of 20 %. Additional charges for damage and/or
missing parts and accessories will be applied to all returns.

Return Procedure
All items being returned (including all warranty-claim shipments) must be sent freight-prepaid to our factory location. When you return
an instrument to Fluke Biomedical, we recommend using United Parcel Service, Federal Express, or Air Parcel Post. We also
recommend that you insure your shipment for its actual replacement cost. Fluke Biomedical will not be responsible for lost shipments
or instruments that are received in damaged condition due to improper packaging or handling.
Use the original carton and packaging material for shipment. If they are not available, we recommend the following guidefor
repackaging:
Use a double-walled carton of sufficient strength for the weight being shipped.
Use heavy paper or cardboard to protectall instrument surfaces. Use nonabrasive material around all projecting parts.
Use at least four inches of tightly packed, industry-approved, shock-absorbent material around the instrument.
Returns for partial refund/credit:
Every product returned for refund/credit must be accompanied by a Return Material Authorization (RMA) number, obtained from our
Order Entry Group at 1-800- 850-4608 or 1-440-248-9300.
Repair and calibration:
To find the nearest service center, goto www.flukebiomedical.com/service, or
In the U.S.A.:
Cleveland Calibration Lab
Tel: [phone]
Email: [email protected]
Everett Calibration Lab
Tel: [phone]
Email: [email protected]
In Europe, Middle East, and Africa:
Eindhoven Calibration Lab
Tel: [phone]
Email: [email protected]m
In Asia:
Everett Calibration Lab
Tel: [phone]
Email: [email protected]
Certification
This instrument was thoroughly tested and inspected. It was found to meet Fluke Biomedical’s manufacturing specifications when it
was shipped from the factory. Calibration measurements are traceable to the National Institute of Standards and Technology (NIST).
Devices for which there are no NIST calibration standards are measured against in-house performance standards using accepted test
procedures.
WARNING
Unauthorized user modifications or application beyond the published specifications may result in electrical shock hazards or
improper operation. Fluke Biomedical will not be responsible for any injuries sustained due to unauthorized equipment
modifications.
Restrictions and Liabilities
Information in this document is subject to change and does not represent a commitment by Fluke Biomedical. Changes made
to the information in this document will be incorporated in new editions of the publication. No responsibility is assumed by
Fluke Biomedical for the use or reliability of software or equipment that is not supplied by Fluke Biomedical, or by its
affiliated dealers.
Manufacturing Location
The Index 2MF Pulse Oximeter Analyzer is manufactured in Everett, Washington by Fluke Biomedical, 6920 Seaway Blvd.,
Everett, WA, U.S.A.

i
Table of Contents
Chapter Title Page
1 Introducing the Index 2MF.................................................................. 1-1
Capabilities ........................................................................................................ 1-1
Index 2MF Compatibility .................................................................................. 1-1
Index 2MF Features........................................................................................... 1-2
Package Contents............................................................................................... 1-2
F Version....................................................................................................... 1-2
FE Version..................................................................................................... 1-2
Registration Card........................................................................................... 1-2
Precautions......................................................................................................... 1-2
Electromagnetic Interference and Susceptibility ............................................... 1-3
EC EMC Directive 89/336/EEC.................................................................... 1-3
EN 50081-1, CLASS A-Emissions ............................................................... 1-3
EN 50082-1 Immunity................................................................................... 1-3
USA FCC CLASS A..................................................................................... 1-3
Canadian Department of Communications Class A...................................... 1-4
Safety............................................................................................................. 1-4
EC Directive 73/23/EEC, Low-Voltage Directive ........................................ 1-4
Getting Started................................................................................................... 1-4
Starting the Simulator and Using Menus....................................................... 1-4
Using the Optical Finger Probe (All Versions) ............................................. 1-5
2 Blood Oxygen and Pulse Oximeters.................................................. 2-1
Blood Pressure................................................................................................... 2-1
Gases in Blood................................................................................................... 2-1
Pulse Oximeters................................................................................................. 2-2
How Pulse Oximeters Work.......................................................................... 2-2
Spectrophotometry ........................................................................................ 2-2
References.......................................................................................................... 2-4
3 Index 2MF Overview............................................................................ 3-1
The Index 2MF "Finger".................................................................................... 3-1
Simulator Electrical Testing (MFE Version only)............................................. 3-1
Simulation Settings............................................................................................ 3-1
Running Tests.................................................................................................... 3-1

Index 2MF
Users Guide
ii
Evaluating Test Results ..................................................................................... 3-2
Simulator Functionality ..................................................................................... 3-2
4 The Main Menus .................................................................................. 4-1
Introduction........................................................................................................ 4-1
The Main Menu 1 .............................................................................................. 4-1
The Main Menu 2 .............................................................................................. 4-3
5 Configuring the Simulator.................................................................. 5-1
Configuring for Specific Oximeter Make.......................................................... 5-1
Accessing the Make Menu................................................................................. 5-1
Verified Oximeter Makes .................................................................................. 5-2
R-Curve Specifications...................................................................................... 5-2
Customizing a Make Not Included Within Index 2MF ..................................... 5-3
Operation ........................................................................................................... 5-4
6 Setting and Changing Simulation Factors........................................ 6-1
About Simulations and Presets .......................................................................... 6-1
Setting Simulations............................................................................................ 6-1
The Simulations Menu .................................................................................. 6-1
Changing the Default SpO2Setting .............................................................. 6-3
Setting the O2Saturation Level..................................................................... 6-3
Raising or Lowering the Pulse Rate .............................................................. 6-4
Returning to Main Menu 1............................................................................ 6-4
Using Preset Patient Conditions......................................................................... 6-4
Setting the Light Artifact................................................................................... 6-7
Setting 02and Pulse Rate Step Size .................................................................. 6-8
7 Testing the Pulse Oximeter Limits..................................................... 7-1
Introduction........................................................................................................ 7-1
Testing Pulse Oximeter Limits .......................................................................... 7-1
Simulating Oxygen Conditions.......................................................................... 7-1
Simulating the Pulse Rate.................................................................................. 7-3
Simulating Pulse Amplitude.............................................................................. 7-5
Simulating Asystole or No Pulse....................................................................... 7-7
8 Using Test Programs .......................................................................... 8-1
The AUTO Menus ............................................................................................. 8-1
Navigating Through the Programming Process............................................. 8-1
The Program Definition Cycle ...................................................................... 8-2
The Automatic Test Parameters .................................................................... 8-2
Accessing the Autosequences Menu (AUTO)............................................... 8-3
Creating a Custom Test Program (Autosequence)............................................. 8-4
Selecting a Test Program............................................................................... 8-5
Optionally Renaming the Test Program........................................................ 8-6
Configuring the Program............................................................................... 8-7
Selecting Print Settings............................................................................. 8-8
Setting the 02Level .................................................................................. 8-9
Setting the Pulse Rate................................................................................ 8-9
Setting the Simulation Cycle..................................................................... 8-10
Selecting the Make.................................................................................... 8-10
Choosing Your Tests................................................................................. 8-11

Contents (continued)
iii
Selecting Pulse Amplitude........................................................................ 8-12
Selecting Motion....................................................................................... 8-12
Selecting Presets........................................................................................ 8-13
Saving Your Program.................................................................................... 8-13
Running an Automatic Test Program ................................................................ 8-14
Returning an Automatic Test Program to Default State.................................... 8-15
9 Electrical Probe Test........................................................................... 9-1
Electrical Probe Testing..................................................................................... 9-1
Probe Test Selection .......................................................................................... 9-2
LED Testing .................................................................................................. 9-2
Photodiode Test............................................................................................. 9-3
Resistance Testing......................................................................................... 9-4
10 Adjusting the LCD Screen.................................................................. 10-1
Introduction........................................................................................................ 10-1
LCD Contrast Settings....................................................................................... 10-1
11 Manufacturers Mode ........................................................................... 11-1
Introduction........................................................................................................ 11-1
Automated Testing............................................................................................. 11-1
Manufacturer Parameters Available For Simulations........................................ 11-1
Mathematical Background................................................................................. 11-2
Notes on the Formulas................................................................................... 11-3
The R-Value Equation................................................................................... 11-3
Accessing Manufacturers' Tests......................................................................... 11-4
Setting the Signal Source............................................................................... 11-4
Setting the R-Value ....................................................................................... 11-5
Adjusting the Step Amount........................................................................... 11-6
12 Creating Your Own R-Curve............................................................... 12-1
Introduction........................................................................................................ 12-1
Generating an R-Curve from a Pulse Oximeter................................................. 12-2
Downloading an R-Curve into the Simulator .................................................... 12-2
Appendices
A Printing and Data Transfer.......................................................................... A-1
B Error Messages and Corrective Measures................................................... B-1
C Accessories List........................................................................................... C-1
D Specifications .............................................................................................. D-1
E Computer Control........................................................................................ E-1
F Typical Questions and Answers.................................................................. F-1
G Custom Probe Test Cables and Electrical Simulation Cables..................... G-1
H Glossary....................................................................................................... H-1

Index 2MF
Users Guide
iv

v
List of Tables
Table Title Page
5-1. Oximeters with Technology Options ..................................................................... 5-4
5-2. Oximeters with R-Curve Parameters...................................................................... 5-4
6-1. Simulations Menu Selections................................................................................. 6-2
6-2. Level 0 Presets ....................................................................................................... 6-5
6-3. Light Artifacts........................................................................................................ 6-7
8-1. Automatic Test Parameters .................................................................................... 8-2

Index 2MF
Users Guide
vi

vii
List of Figures
Figure Title Page
2-1. Sphygmomanometer .............................................................................................. 2-1
2-2. Formula for Determining Saturated Oxygen Level................................................ 2-2
2-3. Diagram of Sample Finger Probe for a Typical Pulse Oximeter............................ 2-3
2-4. Diagram of Light Absorbers in Tissue................................................................... 2-3
2-5. AC/DC Infrared and Red Absorption Ratio........................................................... 2-3
3-1. Basic Simulator Functions ..................................................................................... 3-2
8-1. The Program Creation Sequence............................................................................ 8-2

Index 2MF
Users Guide
viii

1-1
Chapter 1
Introducing the Index 2MF
Capabilities
The Index 2MF SpO2Simulator (hereafter the Simulator) allows accurate verification of
pulse oximeters by allowing you to test them in a variety of ways. The Simulator
provides simulations that allow thorough testing of the complete pulse oximeter,
including the optical sensors.
For the first time, there is now a reliable way to gauge the condition and performance of
standard pulse oximeters. Fluke Biomedical provided the Simulator to the medical and
health industry to allow measuring pulse oximeters currently on the market against
widely accepted performance standards.
Using the Simulator as a virtual patient's index finger, you set the the Simulator to
simulate a patient with virtually any combination of blood oxygen conditions. When the
pulse oximeter under test connects to the Simulator, measure its responses against a set of
predetermined readings for a patient with the preset saturation levels and pulse
conditions. This procedure matches the pulse oximeter's results against the simulations.
Electrically, the Simulator can verify probe diodes, wire continuity, LEDs, and oximeter
accuracy.
Like all of Fluke Biomedical's hardware and software systems, the Simulator is backed
by Fluke Biomedical's superior support system. If the Simulator ever fails to work
perfectly, please refer to the phone, fax, and Internet numbers at front of this book to
contact Fluke Biomedical's Technical Support Staff.
Index 2MF Compatibility
The Simulator can quickly establish the state of any given pulse oximeter and determine
the performance qualities of the device. The Simulator can test and evaluate most
oximeters in the market today.
Because each pulse oximeter manufacturer uses a slightly different technology and
algorithm to measure SpO2(Saturation of Peripheral Oxygen), Fluke Biomedical has pre-
programmed into the Simulator a number of different R-values versus SpO2curves for
specific manufacturers. This ensures that the Simulator provides the closest possible
simulation. It is also possible to download additional R-value curves directly into the
Simulator for non-volatile storage and use. Additionally, the MFE version of the
Simulator has adapter cables to test most popular oximeters and probes through electrical
simulations.

Index 2MF
Users Guide
1-2
Note
The Simulator is not intended to be a pulse oximeter calibrator.
Index 2MF Features
•Conduct saturated peripheral oxygen (SPO2) simulations with saturation levels
between 35% and 100% (in 1% increments)
•Complete probe and electronics assembly testing either optically or electrically (FE
version only)
•Probe continuity check (MFE version)
•Variable heart rate settings from 30 beats per minute to 250
•Preset simulations reproduce several patient conditions
•Alarm tests for response time, recovery time, and pulse amplitude
•Portable, weighing in at under 3 pounds, with a 10" x 10" footprint
•Programmable auto sequences
•Computer controllable
•Menu driven with softkey interface and 2-line by 24-character LCD (liquid crystal
display) supertwist, alphanumeric display
•Rechargeable lead acid battery, with 8 hours of continuous operation and built-in low
battery indicator
Package Contents
The contents of the Simulator package as shipped include:
F Version
•Index 2MF Pulse Oximeter Tester
•Battery Charger
•User's Guide and Registration Card
FE Version
•Index 2MF Pulse Oximeter Tester
•Battery Charger
•Users Guide and Registration Card
•Ohmeda and Nellcor Probe and Oximeter Adapter (electrical cables)
Registration Card
Once the the Simulator is successfully up and running, complete the postage-paid
registration card and mail it to Fluke Biomedical.
Precautions
Observe these precautions when using the Simulator; like any electronic equipment, it
should be adequately protected both when moving and in storage.
WCaution
When connecting the Simulator to a peripheral, such as a PC’s
RS232 serial port or printer, power OFF both the Simulator and
the peripheral device during connection and disconnection.
Failure to follow this precaution may result in damage to the
equipment.

Introducing the Index 2MF
Electromagnetic Interference and Susceptibility 1
1-3
The Simulator battery life can be seriously shortened by leaving
the instrument turned on for many hours after the low battery
alarm sounds. To avoid damage:
•Package and handle the Simulator to ensure that the power
switch cannot accidentally turn on during shipment.
•Always connect the Simulator to its charger when not in
use. The Simulator allows continuous charging, a practice
that ensures full power charge whenever needed. The
Simulator may also be used while charging.
•Always turn off the Simulator and connect it to its charger
when the low battery alarm sounds. The Simulator can be
used within about 1 minute of commencing charge. The
Simulator picks up two or more hours of battery run-time
for each hour of charger connect time, even when running
with the charger connected.
•Avoid placing the Simulator in contact with, or in close
proximity to, Electrosurgery units (ESUs), MRIs, and
defibrillators.
•Only use an appropriately rated battery charger to avoid
damage to the Simulator’s battery. Based on the testing
below, the Simulator bears the CE mark.
Electromagnetic Interference and Susceptibility
EC EMC Directive 89/336/EEC
EN 50081-1, CLASS A-Emissions
The Simulator has been type tested by an independent testing laboratory and found to
meet the requirements of EC Directive 89/336/EEC for Radiated Emissions and Line
Conducted Emissions. Verification was to the limits and methods of EN 55011. The
device is classified as EN 55011, Group 1, Class A.
EN 50082-1 Immunity
The Simulator was also tested and found to meet requirements for Electrostatic Discharge
Susceptibility, Radiated Susceptibility, and Electrical Fast Transient/Burst Susceptibility.
Verification of compliance was conducted to the limits and methods of EN 50082-
1:1992, IEC 801-2, IEC 801-3, and IEC 801-4.
Note
If using a battery charger while the Simulator is in the Electrical
Simulation Mode, the user may observe a spike in the voltage on the line to
the battery charger, thereby producing erratic results. If you suspect this
has occurred, retest the oximeter with the battery charger disconnected.
USA FCC CLASS A
This equipment has been tested and found to comply with the limits for a Class A digital
device, pursuant to Part 15 of the FCC Rules.
These limits provide reasonable protection against harmful interference when operating
the equipment in a commercial environment. Like similar medical equipment, this

Index 2MF
Users Guide
1-4
equipment generates, uses, and can radiate radio frequency energy and, if not installed
and used in accordance with the instruction manual, may cause harmful interference to
radio communications. Operation of this equipment in a residential area could cause
interference, in which case the user will be required to correct the interference.
Canadian Department of Communications Class A
This digital apparatus does not exceed Class A limits for radio emissions from digital
apparatus set out in the Radio Interference Regulations of the Canadian Department of
Communications.
Le present appareil numerique n'met pas du bruits radioelectriques depassant les limites
applicables aux appareils numerique de la Class A prescrites dans le Reglement sur le
brouillage radioelectrique edicte par le ministere des Communications du Canada.
Note
The Simulator, like many pulse oximeters, may have its operation affected
by strong electromagnetic sources, such as electrosurgery equipment. It
may also be affected by imaging equipment, such as Magnetic Resonance
Imaging (MRI). It is the user’s responsibility to verify performance of the
Simulator prior to use in these kinds of environments.
Safety The Simulator is a battery-powered device which operates at voltages that are considered
intrinsically safe. Independent laboratory approval to a test standard is thus not required.
The battery charger used must meet the safety requirements for your country.
EC Directive 73/23/EEC, Low-Voltage Directive
The Simulator operates below 75 VDC, thus EN 61010-1 is not applicable.
Getting Started
Unpack the Simulator from the shipping carton. Check that the shipment is complete and
all parts are intact.
Starting the Simulator and Using Menus
Slide the power switch to the "I" (on) position to power up the system. The LCD
sequentially displays the following screens for about two seconds each before ending on
the Main Menu 1 screen:
•Bio-Tek Instruments Inc. with model number and version
•Software version number and copyright years
•Make of last selected R-curve
•Main Menu 1 screen
esl001.eps

Introducing the Index 2MF
Getting Started 1
1-5
When the Main Menu 1 displays in the LCD, the following options are available:
esl002.eps
The Main Menu 1 consists of the primary test functions available to the Simulator, with
the softkeys SIM, LMTS, PRBE, CUST, and more. Press the up arrow below the
menu item to select a menu option, change a setting, or to advance to additional menus.
Note
If you see a message warning you that your battery is low, you need to
attach the battery charger. Call Fluke Biomedical for assistance if needed.
Toggle between Main Menu 1 and Main Menu 2 with the more softkey.
For example, you have these options at the Main Menu 1 screen:
Press the softkey SIM, and then MAN to open the Simulations menu. The menu
“Simulations:” appears in the Simulator LCD. This menu allows you to set oxygen
saturation levels and heart rate in beats-per-minute (BPM).
Press the softkey MAN to set the Sp02levels from 35 to 100%, and the heart rate from 25
to 250 BPM.
1. The LCD indicates current Sp02level and BPM. Additional softkey options now
available allow you to set the SpO2levels (02+ and 02-), as well as increase and
decrease the BPM (BPM+ and BPM-).
Return to the previous menu, Main Menu 1, by pressing the esc softkey. For detailed
information on using the test features, refer to the relevant chapter in this users guide.
Using the Optical Finger Probe (All Versions)
Connect the finger probe of the pulse oximeter under test to the Simulator finger probe
attachment. Position the pulse oximeter LEDs on the bottom of the Simulator finger
probe attachment.
From the Main Menu 1, select the SpO2and Heart Rate settings by pressing the
appropriate +or -(plus or minus) keys, and viewing the settings displayed on the the
Simulator LCD.
Note
Oximeters take from 5 to 20 pulses to respond to a change in simulated
SpO2or BPM.

Index 2MF
Users Guide
1-6

2-1
Chapter 2
Blood Oxygen and Pulse Oximeters
Blood Pressure
Blood pressure readings provide valuable information about the condition of our bodies,
indicating health or the lack of it. As the heart contracts (systole) and relaxes (diastole),
the volume of freshly-oxygenated blood increases and decreases measurably within the
artery walls. This action causes the artery walls to expand and contract in rhythm with the
heart. The force of the blood exerted upon the artery walls is what is called blood
pressure. Contraction produces the highest pressure, and relaxation the lowest.
A sphygmomanometer (shown in Figure 2-1) is one tool for measuring blood pressure.
When our blood pressure is taken, it is measured at the brachial artery in the forearm in
millimeters of mercury (mmHg). If our blood pressure reading is at or near 120 mmHg
(systolic) over 80 mmHg (diastolic), we are considered to be in peak health, all else being
normal.
esl003.eps
Figure 2-1. Sphygmomanometer
Gases in Blood
Blood pressure is not the whole story, however, since the exact concentration of gases
such as carbon dioxide and especially oxygen in your blood cannot be determined by a
simple blood pressure test.
To determine gas concentrations accurately, specifically saturated oxygen, a blood-gas
sensing device must be used, and must be capable of detecting the wide range of nominal
values for these gases. Gas concentrations in blood, specifically oxygen (O2) and carbon

Index 2MF
Users Guide
2-2
dioxide (CO2), can be expressed as milliliters of gas per liter of blood, and can be
indicated by the partial pressure that the gases exert in your blood at a given temperature.
Pulse Oximeters
Because of their ease of use in many hospital- and critical-care situations, pulse oximeters
have greatly increased in popularity since their introduction. Today, pulse oximeters are
virtually required equipment in situations where the monitoring of arterial oxygen
saturation (SaO2) is essential, such as when anesthesia is in use, both during an operation
and in post-operative recovery, intensive care, transport, and patient home care.
Pulse oximeters have proven to be capable and reliable, being highly accurate in
measuring blood SaO2 in the range of 80-100%, while at the same time needing little, if
any, calibration. No patient preparation is required before using the pulse oximeter; in
addition, the devices are so simple to operate that specialized training is unnecessary.
How Pulse Oximeters Work
Pulse oximeters are defined as non-invasive, arterial, oxygen-saturation monitors which
measure the ratio of two principal forms of hemoglobin in the blood: saturated arterial
hemoglobin (also called oxyhemoglobin), HbO2/SAT, to unsaturated (or reduced)
hemoglobin, Hb.
The arterial oxygen saturation, SaO2, is defined as the ratio of the concentration of
oxyhemoglobin (cHbO2) to the concentration of HbO2+ Hb (cHbO2+ cHb). Oxygen
saturation is commonly expressed as a percentage and is calculated according to the
formula in Figure 2-2.
esl004.eps
Figure 2-2. Formula for Determining Saturated Oxygen Level
Using this information, a correctly calibrated and operating pulse oximeter can accurately
predict the level of oxygen in the blood, which in turn provides valuable data about the
health of a patient, and in the case of anesthesia and post-operative recovery, the status of
the patient.
Spectrophotometry
Pulse oximeters operate on the principle known as spectrophotometry, using wavelengths
of light to determine the concentration of oxygen in the blood. Because we already know
the wavelengths for the light absorption of blood hemoglobin, we can mathematically
determine the arterial oxygen saturation in a patient's blood.
The light emitting diodes (LED's) of a pulse oximeters shine two types of light—near
infrared light (at 940 nanometers) and red light (at 660 nanometers)—wavelengths that
pass through the skin and which are absorbed by both the oxyhemoglobin and the
reduced hemoglobin. These light beams pass through the index finger of a patient to
photo detectors on the opposite side of the pulse oximeter.