19
calculated by the following method:
SpO2
= HbO2/ (HbO2 +Hb)×100%
HbO2 are the oxyhemoglobins (oxygenized hemoglobin), Hb are those
hemoglobins which release oxygen.
2. Principle of Measurement
Based on Lamber-Beer law, the light absorbance of a given substance
is directly proportional with its density or concentration. When the light
with certain wavelength emits on human tissue, the measured intensity
of light after absorption, reecting and attenuation in tissue can reect
the structure character of the tissue by which the light passes. Due to
that oxygenated hemoglobin (HbO2) and deoxygenated hemoglobin
(Hb) have different absorption character in the spectrum range from red
to infrared light (600nm~1000nm wavelength), by using these charac-
teristics,
SpO2
can be determined.
SpO2
measured by this oximeter is
the functional oxygen saturation - a percentage of the hemoglobin that
can transport oxygen.
In contrast, hemoximeters report fractional oxygen saturation - a per-
centage of all measured hemoglobin, including dysfunctional hemoglo-
bin, such as carboxyhemoglobin or metahemoglobin.
Clinical application of pulse oximeters:
SpO2
is an important physiologi-
cal parameter to reect the respiration and ventilation function, so
SpO2
monitoring used in treatment has become more popular. (For example,
such as monitoring patients with serious respiratory disease, patients
under anesthesia during operation and premature and neonatal infants)
The status of
SpO2
can be determined in timely manner by measure-
ment and will allow nding the hypoxemia patient earlier, thereby pre-
venting or reducing accidental death caused by hypoxia effectively.
3. Factors affecting SpO2 measuring accuracy
(interference reason)
• Intravascular dyes such as indocyanine green or methylene blue.
• Exposure to excessive illumination, such as surgical lamps, bilirubin
lamps, uorescent lights, infrared heating lamps, or direct sunlight.
• Vascular dyes or external used color-up product such as nail enamel
or color skin care.
• Excessive patient movement.
• Placement of a sensor on an extremity with a blood pressure cuff,
ENGLISH
To Next Page
Loading...
Need help?
General
