What Is Spo2; How Does Pulse Oximetry Work - HP Codemaster 100 User Manual


Understanding Pulse Oximetry
What is SpO ?
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A blood-oxygen saturation reading indicates the percentage of hemoglobin
molecules in the arterial blood which are saturated with oxygen. The reading
is referred to as SpO . Readings vary from 0 to 100%. Normal readings in a
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healthy adult, however, range from 94% to 100%.

How Does Pulse Oximetry Work?

The pulse oximetry method used for measuring SpO uses LEDs (light
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emitting diodes) to transmit red and infrared light through suitable peripheral
areas of the body, typically the foot in neonates or the finger in adults. The
oxygen saturation is gauged by measuring the "redness" of the blood in the
arterial pulse.
A photodetector positioned opposite the light emitter compares light
absorption before and after pulsation to provide measurements that are
displayed on the monitor. If there is no pulse, measurements cannot be made.
See Figure 9-1.
Figure 9-1
Positioning of the Light Emitters and Photodetector
9-1
9-2