2. Pulse Oximetry
– A portable device for the rapid noninvasive
measurement of arterial O2 saturation
– Assists in the diagnosis of hypoxia (lack of
oxygen)
3. Pulse Oximetry
There are many different makes, models, and styles of
pulse oximeters
• Some pulse oximeters have a screen which shows a
wave form, some also have an additional attachment
to monitor carbon dioxide levels in the blood
• The pulse oximeter will also give you a heart rate
reading as well
4. Oxygen saturation is an indicator of the percentage of
hemoglobin saturated with oxygen at the time of the
measurement. The reading, obtained through pulse
oximetry, uses a light sensor containing two sources of
light (red and infrared) that are absorbed by
hemoglobin and transmitted through tissues to a
photodetector. The amount of light transmitted through
the tissue is then converted to a digital value
representing the percentage of hemoglobin saturated
with oxygen
5. Pulse Oximetry
• Uses spectrophotometry based on the Beer-
Lambert law
• Differentiates oxy from deoxy Hb by the
differences in absorption of light at 660 nm and
940 nm
• Minimizes tissue interference by separating out
the pulsatile signal
• Estimates HR by measuring cyclic changes in light
transmission
• Estimates functional Hb by comparing amounts
of oxy and deoxy Hb
6. The accuracy of SpO2 measurements requires consideration
of a number of physiologic variables. Such patient variables
include the following:
• Hemoglobin level
• Arterial blood flow to the vascular bed
• Temperature of the digit or the area where
• the oximetrysensor is located
• Patient's oxygenation ability
• Percentage of inspired oxygen
• Evidence of ventilation-perfusion mismatch
• Amount of ambient light seen by the sensor
• Venous return at the probe location
7. Indications:
• Patients in respiratory distress
• All critically ill patients
• Patients requiring O2 concentrations of 40% or
greater
• Stable patients at risk from sudden deterioration
• Monitoring during procedures such as suctioning
8. indications
• hypoxemia
• During bronchoscopy
• 2.monitoring during anaesthesia
• 3.exercise testing
• 4.sleep studies – detect hypoxemia
10. How to Apply the Pulse
Oximeter
Step 1
– Body Substance Isolation
• Step 2
– Remove fingernail polish if it applies
• Step 3
– Apply pulse oximet
11.
12. Step 4
– Leave finger probe on for 15-30 (can take up
to 60) seconds to obtain an accurate reading
• Step 5
– Record time and reading
13.
14.
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16.
17. :Contraindications
Contraindications:
• Severe peripheral vascular disease
• Severe anemia (decreased Hemoglobin)
• Hypothermia A quality signal may be unobtainable in
10% of patients with a temperature less than 35.0
degrees Celsius A signal failure will occur at
temperatures less than 28.5 degrees Celsius
• Hypotension (Low b/p)
• Placement distal to a tourniquet, or blood pressure
cuff
19. • DEVICE LIMITATIONS/VALIDATION OF RESULTS:
1 Factors, agents, or situations that may affect readings, limit precision, or
limit the performance or application of a pulse oximeter include
7.1.1 motion artifact
7.1.2 abnormal hemoglobins (primarily carboxyhemoglobin [COHb] and met-
hemoglobin [metHb])
7.1.3 intravascular dyes
7.1.4 exposure of measuring probe to ambient light during measurement
7.1.5 low perfusion states
7.1.6 skin pigmentation
7.1.7 nail polish or nail coverings with finger probe
7.1.8 inability to detect saturations below 83% with the same degree of
accuracy and precision seen at higher saturations(
20. DEVICE LIMITATIONS/VALIDATION OF RESULTS
7.1.9 inability to quantitate the degree of
hyperoxemia present(
7.1.10 Hyperbilirubinemia has been shown not
to affect the accuracy of SpO2 readings.
21. HAZARDS/COMPLICATIONS:
Pulse oximetry is considered a safe procedure, but
because of device limitations, false-negative results
for hypoxemia and/or false-positive results for
normoxemia or hyperoxemia may lead to
inappropriate treatment of the patient.
In addition, tissue injury may occur at the measuring
site as a result of probe misuse (eg, pressure sores
from prolonged application or electrical shock and
burns from the substitution of incompatible probes
be-tween instruments).
22. INFECTION CONTROL:
No special precautions are necessary, but Universal
Precautions are recommended.
.1 If the device probe is intended for multiple patient use,
the probe should be cleaned between patient
applications according to manufacturer
recommendations.
.2 The external portion of the monitor should be cleaned
according to manufacturer's recommendations
whenever the device remains in a patient's room for
prolonged periods, when soiled, or when it has come
in contact with potentially transmissible organisms.
23. Advantages
• 1.noninvasive
• 2.continuous real time information
• 3.no calibration
• 4.rapid response time (5-7 sec)
• 5.minimal saturation error (1-2%) over range
of 60-90 %
24. SOURCES OF ERROR
• Sensitive to motion
• Sats below 85% have increased error
• Calibration is performed by company on
normal patients breathing various gas
mixtures, so cal is accurate only down to 80%
• Low perfusion state increases error
• Ambient light interferes with reading
• Delay in reading of about 12 seconds
25. SOURCES OF ERROR
• Skin pigmentation
– Darker color may make the reading more variable
due to optical shunting
– Dark nail polish has the same effect, especially
black, blue, and green…red is OK
– Hyperbilirubinemia has no effect
• Methylene blue and indigo carmine (dyes)
cause underestimation of the saturation
26. SOURCES OF ERROR
• Dysfunctional hemoglobin
– Carboxyhemoglobin leads to overestimation of
sats because it absorbs at 660 nm like oxyHb does
– MetHb can mask the true saturation because it
absorbs at both wavelengths used…sats are
overestimated
