Respironics 950 Service manual

English

Instruction and Service Manual

Model 950

Finger Pulse Oximeter

0459

About the Manual

Shaded boxes draw attention to contraindications, warnings, cautions

and notes.

The boxed messages are important. Be sure to read them.

The information in this manual has been carefully checked and is
believed to be accurate. In the interest of continued product
development, RESPIRONICS, INC. reserves the right to make
changes and improvements in this manual and the products it
describes at any time, without notice or obligation.

Caution: Federal Law (USA) restricts this device to sale by or on the
order of a physician.

Respironics Georgia

175 Chastain Meadows Court
Kennesaw, Georgia 30144-3724
USA
Telephone: [phone]
Fax: [phone]
Customer Service Telephone: [phone] (USA and Canada)
Customer Service Fax: [phone] (USA and Canada)
www.respironics.com

Respironics Deutschland

Gewerbestrasse 17
82211 Herrsching
Germany
Telephone: [phone]
Fax: [phone]

Respironics Asia Pacific

3/F, Microtron Building
38 Hung To Road
Kwun Tong, Kowloon, Hong Kong
Telephone: [phone]
Fax: [phone]

Copyright © 2002 Respironics, Inc. All rights reserved.

is a registered trademark of Respironics, Inc.

English

iii

Table of Contents

Contraindications, Warnings, and Cautions ........................ 1

Introduction ............................................................................. 3

Description................................................................................... 3

The 950 at a Glance ..................................................................... 4

Intended Use ................................................................................ 6

Operating Instructions............................................................ 7

Getting Started ............................................................................. 7

Lanyard and Lanyard Lock.......................................................... 8

Battery Requirements .................................................................. 9

Inserting New Batteries.............................................................. 10

Activating the 950...................................................................... 11

Verifying Operation................................................................... 12

Conditions That May Affect Use............................................... 13

Maintenance........................................................................... 14

Storage Requirements ................................................................ 14

Theory of Operation ............................................................. 16

Oximetry.................................................................................... 16

950 Averaging............................................................................ 18

Specifications ......................................................................... 19

Parts and Accessories............................................................ 20

Parts ........................................................................................... 20

Accessories ................................................................................ 20

Technical Support ...................................................................... 20

Warranty................................................................................ 21

Troubleshooting Guide ......................................................... 22

English

v

Figures

Figure 1. Top digital display illustration and bottom label. .... 4

Figure 2. Lanyard and lock. .................................................... 8

Figure 3. Inserting new batteries...........................................10

Figure 4. Applying the 950. .................................................. 11

Figure 5. Maintenance choices.............................................. 15

SYMBOL DEFINITION OF SYMBOL

NRTL/C

0459

Glossary of Symbols

Attention, Consult ACCOMPANYING
DOCUMENTS

Type BF Applied Part:
(Patient isolation from electrical shock).

Canadian Standards Association

Meets both Canadian and United States
Standards.
CE Marking indicating conformance to EC
directive No. 93/42/EEC concerning medical
devices.

Not for Continuous Monitoring
(No Alarm for SpO2)

vi

Contraindications, Warnings, and Cautions

Do not use the 950 in an MRI environment.

Do not operate the 950 in an explosive atmosphere.

Do not use the 950 on infant or neonatal patients.

Batteries may leak or explode if used or disposed of improperly.

Federal Law (USA) restricts this device to sale by or on the order
of a physician.

Read this entire manual carefully before using the Respironics 950
Pulse Oximeter.

The 950 determines the percentage of arterial oxygen saturation of
functional hemoglobin. Significant levels of dysfunctional
hemoglobin such as carboxyhemoglobin or methemoglobin may
affect the accuracy of the measurement.

Cardiogreen and other intravascular dyes, depending on the
concentration, may affect SpO2 accuracy.

The 950 must be able to measure the pulse properly to obtain
accurate SpO2 measurement. Verify that nothing is hindering the
pulse measurement before relying on the SpO2 measurement.
Some situations that may contribute to erroneous pulse
measurement are:

• inadequate perfusion,

• excessive patient movement,

• pulse oximeter and blood pressure measurement on the

The 950 may interpret motion artifact of sufficient amplitude and
regularity as good perfusion (green).

Do not use the 950 in situations where alarms are required. The
950 has no audible alarms.

The 950 is intended for spot-checking or continuous monitoring by
an attending health care professional. Because the 950 has no
audible alarms, international labeling requirements (ISO 9919)
dictate it be labeled, “Not for continuous monitoring”.

CONTRAINDICATIONS:

WARNINGS:

CAUTIONS:

same limb, etc.

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1

CAUTIONS: (Continued)

Check application site periodically (at least every thirty minutes) to
determine circulation, positioning and skin sensitivity.

The 950 may not work for all patients. If you are unable to achieve
stable readings, discontinue use.

Finger nail polish may reduce light transmission and thereby affect
SpO2 accuracy.

A flexible circuit connects the two halves of the 950. Do not twist or
pull on the connection.

Do not use different types of batteries at the same time. Do not mix
fully charged and partially charged cells at the same time. These
actions may cause the batteries to leak.

Batteries must be removed if the 950 is going to be stored for more
than one month or batteries may leak.

Do not immerse the 950 in liquid to clean.

2

Introduction

Description

Respironics, Inc. has integrated the finger clip sensor and the
electronics of the Respironics Model 920 hand held Pulse Oximeter
into one unit, the Model 950. The 950 is very small (1.3 inch W x 1.3
inch H x 2.2 inch L) and lightweight (2 ounces).

The 950 displays numerical values for functional arterial hemoglobin
oxygen saturation (%SpO2) in percentage and pulse rate (
beats per minute on light emitting diode (LED) digital displays.

With each detected pulse, the Perfusion  Display blinks. Patient
perfusion signals are graded as good, marginal or inadequate and are
indicated as such by the perfusion indicator changing color from green
to yellow or red respectively. This sophisticated, yet simple technique
provides a pulse-by-pulse visual indication of waveform signal
quality, without requiring the user to perform complex signal analysis
during critical patient care situations.

Two AAA battery cells power the 950 and operate it for
approximately 1,600 spot checks
between battery replacement. When the batteries are low, the digital
displays will blink once per second. (Refer to page 9 for battery
specifications and page 10 for battery replacement instructions.)

a

or 18 hours of continuous operation

) in

English

a

Calculated at 40 seconds per spot check using two AAA alkaline battery

cells.

3

N

The 950 at a Glance

%SpO2 Display

Heart Rate Display

Perfusion Display

Finger Grip

Figure 1. Top digital display illustration and bottom label.

Serial

umber

Battery
Polarity
Markings

4

• %SpO

Numeric LEDs display the value of percent oxygen saturation,
calculated using a four beat exponential averaging technique.
(Refer to page 16, Theory of Operation, for information on
averaging.)

Display

2

• Heart Rate Display

Numeric LEDs display the pulse rate in beats per minute,
calculated by an eight beat sliding averaging technique. (Refer
to page 18 for information on averaging.)

• Perfusion  Display

Provides a visual indication of the signal quality, while
blinking at the corresponding pulse rate. It is a method of
alerting the user to changes in the pulse waveform signal that
may affect the SpO2 data.

Green = good signal amplitude
Yellow = artifact or marginal signal amplitude
Red = inadequate signal amplitude

CAUTION:
The 950 may interpret motion artifact of sufficient amplitude and
regularity as good perfusion (green).

•

Battery Low

Numeric LEDs flash once per second when batteries are low.
Replace the batteries as soon as possible. Refer to page 10,
Inserting New Batteries.

• Finger Removal

A minus (-) sign appears in the left most digit of the %SpO2
display when the 950 senses that the finger has been removed.
The last measured SpO2 and pulse rate values freeze for ten
seconds, then the displays go blank.

• The label on the bottom of the 950 lists the model number,

serial number, CAUTION statement, and battery polarity
indicators.

English

5

Intended Use

The 950 is a portable device for spot-checking or attended-care
monitoring of adult or pediatric patients. Use the 950 with finger
thickness between 0.3 to 1.0 inches. The 950 is not recommended
where motion is expected or for relatively long-term monitoring, e.g.,
greater than 30 minutes.

CONTRAINDICATION:
Do not use the 950 on infant or neonatal patients.

CAUTION:
Do not use the 950 in situations where alarms are required. The
950 has no audible alarms.

CAUTION:
It is intended for spot-checking or continuous monitoring by an
attending health care professional. Because the 950 has no audible
alarms, international labeling requirements (ISO 9919) dictate it be
labeled, “Not for continuous monitoring”.

CAUTION:
Check application site periodically (at least every thirty minutes) to
determine circulation, positioning and skin sensitivity.

CAUTION:
The 950 may not work for all patients. If unable to achieve stable
readings, discontinue use.

6

Operating Instructions

Getting Started

1. Read this entire manual.

2. Thread the lanyard through the lanyard holes on the 950 following
the instructions on page 8, Lanyard and Lanyard Lock.

3. Insert the batteries following the instructions on page 10, Inserting
New Batteries.

4. Activate the 950 by inserting a finger.

5. Verify operation following the instructions on page 12, Verifying
Operation.

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7

Lanyard and Lanyard Lock

A lanyard is provided for the convenience of wearing the 950 around
the neck or wrist. The 950 will function with or without the lanyard.

1. Thread the ends of the lanyard through the lanyard holes as shown
below in Figure 2.

2. Push in the lanyard lock button, slide the lock onto the lanyard up
to the desired length.

3. Release the lock button to secure its position.

4. Reverse this procedure to remove the lanyard.

Figure 2. Lanyard and lock.

NOTE:
The lanyard must cross over the top of the 950 to permit full
opening of the sensor.

8

Battery Requirements

Respironics recommends using AAA alkaline batteries to power the

950. Two of these batteries are included with each new system.

Concerning the Use of Rechargeable Batteries:

Rechargeable nickel cadmium or nickel-metal hydride batteries may
be used. However, rechargeable batteries need more frequent
replacement as they have less capacity than non-rechargeable alkaline
batteries.

WARNING:
Batteries may leak or explode if used or disposed of improperly.

CAUTION:
Do not use different types of batteries at the same time or mix fully
charged and partially charged cells at the same time, as the
batteries may leak.

CAUTION:
Batteries must be removed if the 950 is going to be stored for more
than one month or batteries may leak.

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9

Inserting New Batteries

1. Loosen the screw at the end of the 950 using a coin or a standard
flat screwdriver and remove the battery door.

2. Remove the old batteries and dispose of them properly.

Figure 3. Inserting new batteries.

3. Insert two new AAA batteries following the polarity markings
indicated on the battery door or bottom label of the 950. Proper
positioning of the batteries is critical.

4. Carefully position the battery door and firmly, but gently tighten
the screw. Do not force the door into place. The door only fits
when properly oriented. To avoid stripping screw threads, do not
tighten excessively.

5. Insert your finger into the 950 and verify operation. If the unit
does not turn on, remove the finger and wait two seconds before
reinserting a finger.

6. If the 950 still does not work, reinstall the batteries.

10

Activating the 950

Activate the 950 by inserting the patient's finger into the pulse
oximeter as shown in Figure 4. (The 950 determines that a finger has
been inserted and then automatically activates the display.)

English

Figure 4. Applying the 950.

1. Insert the patient's finger into the 950 as shown above, until the
fingertip touches the built-in stop guide.

2. Center the finger.

3. Verify operation. Turn to page 12, Verifying Operation.

NOTE:
The 950 performs best when used on fingers other than the thumb.

NOTE:
If 950 does not turn on, remove the finger and wait 2 seconds
before reinserting a finger.

11

Verifying Operation

1. When a finger is first inserted, the 950 executes an initialization
sequence.

2. After completing this sequence, the 950 begins sensing the pulse
(indicated by the blinking Perfusion  display).

3. Allow the system to stabilize by observing at least ten seconds of
continuous green-colored Perfusion  display pulses (consistent
with the patient's pulse) before relying on the displayed values.

4. If the Perfusion  display blinks yellow or red, make sure
perfusion is not restricted. Try another finger.

5. If you are unable to achieve consistent green perfusion pulses and
stable readings, remove the 950 from the patient's finger and refer
to page 22, Troubleshooting Guide.

CAUTION:
The 950 may interpret motion artifact of sufficient amplitude and
regularity as good perfusion (green).

CAUTION:
Finger nail polish may reduce light transmission and thereby affect
SpO2 values.

NOTE:
If the pulse signal is inadequate for a 2-minute period the 950 will
automatically power down.

12

Conditions That May Affect Use

•

Environmental

Fluctuating or flickering light may affect measurements.

Use of the 950 outside stated temperature and humidity
specifications may affect measurements. Refer to page 1,
Contraindications, Warnings, and Cautions.

• Motion

Excessive or rapid movement may affect measurements.

• Sensor Position

Sensor position is critical for accurate SpO2 measurements.
All emitted sensor light must pass through the finger before
reaching the detector. Do not allow positioning such that

some or all of the emitted light can by-pass the finger as
this will result in inaccurate SpO2 values.

While on the finger, do not press the 950 against any surface
and do not squeeze or hold the 950. The external spring
provides the correct pressure on the finger; additional
pressure may affect measurements.

• Perfusion

The finger must have perfusion adequate to cause the
Perfusion Indicator  to blink green in order to give
accurate readings.

• Nail Polish

Fingernail polish may reduce light transmission which may
affect SpO2 values.

In addition, the following factors may degrade performance:

• an arterial catheter • moisture in the 950

• a blood pressure cuff • a finger outside the 0.3-1.0” size range

• an electrosurgical procedure • venous pulsations

• an infusion line • anemia or a low hemoglobin count

• cardiovascular dyes • the 950 not at heart level

English

13

Maintenance

The advanced digital circuitry within the Respironics 950 requires no
calibration or periodic maintenance other than battery replacement.
Field repair of the 950 circuitry is not possible. DO
open the 950 case or repair electronics. Opening the case will damage
the 950 and void the warranty. If the 950 is not functioning properly,
refer to page 22, Troubleshooting Guide.

CAUTION:
A flexible circuit connects the two halves. Do not twist or pull on
the flex circuit.

CAUTION:
Do not immerse the 950 in liquid to clean.

NOTE:
The 950 may be sterilized using ethylene oxide (EtO) (cold cycle).
Remove
Follow the instructions on page 10, Inserting New Batteries.

NOTE:
Hold the 950 top and bottom together when the spring is released.
The two halves are held together by the flex circuit only.

the battery door and batteries before EtO sterilization.

Storage Requirements

Store the 950 within the stated temperature and humidity storage
specifications. Refer to page 19, Specifications.

CAUTION:
Batteries must be removed if the 950 is going to be stored for more
than one month or batteries may leak.

NOT attempt to

14

y

y

Top

Half

Gripping

Flex

Circuit

SURFACES:

TO CLEAN THE INNER

soft cloth dampened with an

isopropyl alcohol solution or a

mild detergent solution.

to air dry.

• Wipe exposed surfaces with a

• Dry with a soft cloth or allow

Retaining

groove

BOTTOM

Insert

thoroughly dry before

• Surfaces should be

BACK

FRONT

re-engaging the spring.

Bottom

Half

1.14"

TOP

Finger

cavit

Pivot hole

e.

(Top

Half)

(Top

TO REPLACE THE SPRING:

TO REPLACE THE GRIPPING INSERT:

emove the old spring, carefully pulling the ends from the pivot holes on either sid

past the finger cavity, then seat the spring into the retaining groove.

R

Insert the ends of the new spring into the pivot holes and swing the spring up and

RE-ENGAGE THE SPRING

assembly.

design for proper

Distinguish spring

Retaining

SPRING DESIGN A

A gripping insert adhered to the upper interior surface of the 950 provides a more

secure fit to the finger. The 950 will function with or without the gripping insert,

however Respironics recommends that the insert be in place during normal

operation.

BACK

TOP

groove

BOTTOM

FRONT

Pivot hole

SPRING DESIGN B

Finger

cavit

Front

Edge

Half)

Carefully

peel from

surface

1.39"

TO DISENGAGE THE SPRING:

• Turn the 950 bottom side up.

spring up (to get it out of the retaining groove)

• Following the arrows on the label, gently pull the

• Carefully peel the old gripping insert away from the surface.

• Remove any residual adhesive with an isopropyl alcohol solution.

• Peel the backing paper off the new gripping insert, uncovering the adhesive back.

• Position the new insert as shown above and gently press it in place.

• To clean the inner surfaces.

• To replace the spring.

• To replace the gripping insert.

Figure 5. Maintenance choices.

Cleaning and replacing the spring and the gripping insert.

and then swing it forward, bringing the spring

past the finger cavity.

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15

Theory of Operation

Oximetry

The pulse oximeter shines red and infrared light through the tissue and
detects the fluctuating signals caused by arterial blood pulses. The
ratio of the fluctuation of the red and infrared light signals received
determines the oxygen saturation content. Conditions such as steady
venous blood flow, skin thickness, fingernail thickness, etc., do not
affect the saturation reading because they are constant and do not
cause fluctuations.

The function, f, depends on the physical properties of the LEDs
producing the light. These physical properties are fixed by the
manufacturing material and processes.

Note that the pulse oximeter readings do not depend upon the absolute
light intensity, rather upon the fluctuations in light intensity.
Characteristics such as thick skin or skin pigmentation will affect the
min and max proportionally, thus the ratio min/max does not
change. However, if too little light passes through, the pulse oximeter
will not display values. Pulse oximeters use two different wavelengths
of light (red and infrared), providing the ability to determine one
component of blood. The pulse oximeter is calibrated to closely
approximate functional oxygen saturation values. These values will
closely approximate laboratory instrument fractional saturation values
if the dysfunctional hemoglobin saturation levels are negligible.

In summary, because the pulse oximeter performs all computations
from the internal software and there are no critical parts to drift, no re­calibration is needed.

16

If the dysfunctional hemoglobin is carboxyhemoglobin or
methemoglobin, the difference between the oxygen saturation value
displayed by the pulse oximeter and the oxygen saturation values
determined by the laboratory instrument will be greater as the
dysfunctional hemoglobin levels rise approximately in accordance
with the following formulas, where:

Example 1

O2Hb = 96 O2Hb = 88
COHb = 0.5 COHb = 8
MetHb = 0.6 MetHb = 2
SpO2 = 97 SpO2 = 98
SaO2 = 97.07 SaO2 = 97.78

SpO2 = 950 determined and numerically

O2Hb = Fractional oxyhemoglobin

COHb =

MetHb =

SaO2 = Functional oxygen saturation in

displayed oxygen saturation in
percent

saturation in percent

Carboxyhemoglobin saturation
in percent
Methemoglobin saturation in
percent

percent

Example 2

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17

950 Averaging

For pulse rates below 112 BPM the averaging calculation is based on
a 4-beat exponential average for SpO2 (see below) and an 8-beat
sliding average for pulse rate. For pulse rates above 112 BPM the
averaging is doubled and then re-doubled above 225 BPM. The pulse
oximeter will not include questionable pulses in the average. Marginal
pulses may count less in the average than good pulses.

All averages are updated on a beat-by-beat basis. The display is
updated every 1 ½ seconds with the most recent value.

Also, if the pulse oximeter signal is “noisy” or missing, the display
will hold the last value for 10 seconds before showing dashes. With
the 4-beat exponential average, the effect of each measurement
gradually decreases beat by beat. Each measurement initially counts
for ¼ of the average. This weight is decreased by multiplying by ¾ on
each succeeding beat:

Beat Effect (weighting in average)

1 ¼ = 0.250
2 x ¾ = 0.1875
3 x ¾ = 0.1406
4 x ¾ = 0.1055
5 x ¾ = 0.0791

The SpO2 4-beat exponential average is fast enough to follow
physiological changes.

For the pulse rate sliding 8-beat average, each beat counts 1/8 for 8
beats and thereafter has no affect on the average.

18

Specifications

1. Oxygen Saturation
Range

2. Pulse Rate Range

3. Displays

a) Patient Indicators Tri-color perfusion light emitting diode (LED)
b) Digital Displays Two 3-digit 7-Segment LEDs

4. Measurement
Wavelengths

a) Red: 660 nanometers @ 3 mw nominal
b) Infrared: 910 nanometers @ 3 mw nominal

5. Accuracy

a) %SpO2 Accuracy
(+

1 S.D.)a

b) Rate Accuracy +

6. Temperature

a) Operating
b) Storage/

Transportation

7. Humidity

a) Operating 10 to 90% non-condensing
b) Storage/

Transportation

8. Power Requirements

9. Battery Life

a) Operating

b) Storage 9 months typical

12. Dimensions

13. Weight

Classifications per IEC 60601-1 / CSA601.1 / UL2601-1

Type of Protection Internally powered (on battery power)
Degree of Protection Type BF-Applied Part
Mode of Operation Continuous

0 to 100%

18 to 300 pulses per minute

70 to 100% +

3% + 1 digit

+32°F to +122°F (0° to +50°C)

-4°F to +122°F (-20° to +50°C)

10 to 95% non-condensing

2 AAA Batteries

Approximately 18 hours of continuous
operation

1.3 inch W x 1.3 inch H x 2.2 inch L
(3.3 cm x 3.3 cm x 5.7 cm)

2 ounces (60 grams), including 2 AAA
alkaline batteries

b

2 digits

c

English

a

Standard Deviation (S.D.) is a statistical measure; up to 32% of the readings

may fall outside these limits.

b

Using 2 AAA alkaline batteries; based on approximately 1,600 spot checks

calculated at 40 seconds per spot check.

c

Using 2 AAA alkaline batteries.

19

Parts and Accessories

Parts

Part Number Description

100-0337-00 950 Battery Door and Contact
100-0338-00 Gripping Insert
100-0339-00 950 External Spring
100-0340-00 Lanyard Cord and Lock (Black)

Accessories

The following accessories function with the Respironics 950:

• Model 960 Finger Phantom (pulse oximeter testing device)

For information regarding parts and accessories, contact your
local sales representative or distributor.

For the sales representative or distributor in your area contact
Respironics.

Technical Support

For technical support and before returning any equipment, call
Respironics:

Technical Support Telephone: [phone] (USA and Canada)
Technical Support Telephone: [phone] (International)

Customer Service Telephone: [phone] (USA and Canada)
Customer Service Fax: [phone] (USA and Canada)

www.respironics.com

20

Warranty

RESPIRONICS, INC. (RESPIRONICS) warrants to the purchaser that
the Model 950 (excluding batteries, lanyard and lanyard lock) will be
free from defects in material and/or workmanship for one year from
the date of delivery. During the warranty period, RESPIRONICS will
correct any defects in material or workmanship to conform to
specifications, free of charge. RESPIRONICS reserves the right to
replace the Model 950 with a comparable unit. Shipping costs are the
responsibility of the purchaser. Any replacement parts or units are
warranted for the remainder of the original warranty period. The
purchaser must notify RESPIRONICS of a defect within the
applicable warranty period, and return the Model 950 in question.
Proof of purchase may be required before any warranty consideration
by RESPIRONICS occurs. This warranty is not transferable.

Any sign of tampering with the Model 950, voids the warranty in
its entirety.

This warranty shall be the sole and exclusive remedy by the purchaser
thereunder for any units or accessories delivered to the purchaser that
are found to be defective in any manner, whether such remedies be in
contract, tort or by law.

DISCLAIMER AND EXCLUSIVITY OF WARRANTY:

THE EXPRESS WARRANTIES SET FORTH IN THIS MANUAL
ARE EXCLUSIVE AND NO OTHER WARRANTIES OF ANY
KIND, WHETHER STATUTORY, WRITTEN, ORAL, OR
IMPLIED INCLUDING WARRANTIES OF FITNESS FOR A
PARTICULAR PURPOSE OR MERCHANTABILITY SHALL
APPLY.

The purchaser agrees to pay a $100.00 (USD) service charge for a
warranty repair request on any Model 950 sent to RESPIRONICS that
is determined to be within specification.

Non-warranty work is charged at the minimum repair rate effective at
the time of the Model 950 return to RESPIRONICS. All repairs
include a complete functional test using factory test fixtures.

English

21

Troubleshooting Guide

Symptoms Possible Cause Possible Solution

Numeric displays
blinking at one second
intervals.

950 will not activate. Batteries incorrectly

Depleted batteries. Replace batteries. See

950 not attached to

950 turned off while on

Minus (-) sign in left
most digit of the
%SpO2 display.
Finger removal. Reinsert finger.
950 not functioning. Call RESPIRONICS

Unable to obtain green
perfusion.
Finger poorly perfused. Reposition 950 on

Finger not correctly

Possible interference

Batteries are low. Replace batteries

inserted.

patient.

finger.

Poor signal. Reposition finger.

Low patient pulse
strength.

positioned.

from:

immediately. See page

10.

Check batteries. See
page 9 and 10.

page 10.
Apply 950 to patient.
See page 11.
Remove 950 from
finger, then reinsert
finger.

Technical Support.

Reposition 950 on
finger.

finger.
Reposition 950 on
finger.
Reduce or eliminate
interference.

• arterial catheter

• blood pressure cuff

• electrosurgical

procedure

• infusion line

Circulation reduced

because of excess
pressure between 950
and hard surface after

inserting finger.
Excessive ambient light. Reduce ambient light.
Excessive patient

motion.
950 applied to polished

fingernail.

Allow 950 and finger
to rest comfortably on
surface.

Reduce patient motion.

Remove fingernail
polish.

22