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Chapter13
SpO2 Monitoring
13.1
Definition of SpO2 Monitoring
The SpO
2
volume recording parameter is used to measure arterial SpO
2
, i.e., percentage of oxyhemoglobin.
For example, if there are 97% of hemoglobin molecules combining with oxygen out of the arterial red blood
cells, the blood will be described as SpO
2
97
％
, and the SpO
2
reading on the monitor will be 97
％
. SpO
2
values thus can show the percentage of oxygen-attached hemoglobin molecules (will form oxyhemoglobin),
meanwhile, SpO
2
volume recording parameters can also provide the PR signals and volume recording waves.
13.1.1
Principle for Measurement of SpO
2
Volume Recording Parameter
BOS (blood oxygen saturation) is measured and determined in the method of pulse oximetry, which is a
method of measuring and determining the oxyhemoglobin saturation continuously and without any hurt,
mainly used to measure and determine how many rays from the light source of the sensor penetrate the
patient‘s tissue (such as fingers or ears) and reach another receiver.
As for the wave length measurable by the sensor, generally the red LED is 660nm and the infrared LED,
940nm. The maximum selectable output power of LED is 4mW.
The number of penetrated rays rests with many factors where most are constant, but one of these factors
means the arterial flow changes through time because it is pulsant. The arterialized blood‘s BOS can be
obtained through measurement of absorbed rays during pulsation. A ―volume recording‖ waveform and PR
signal can be given through detection of pulsation.
―SpO2‖ value and ―Volume Recording‖ waveform can display on the main screen.
Warning
Where there is carboxyhemoglobin, ferrihemoglobin ordye dilution chemicals, SpO2 value will
have a deviation.
Warning
This type of monitor can automatically identify the oxygen sensor, however, owing to limits of
internal the hardware before delivery from factory, incorrect use of the oxygen sensor will lead to
wrong outcomes of parameters.
