Rad-97
Chapter 1: Technology Overview
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24
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Masimo SET® DST
This figure is for conceptual purposes only.
General Description for Oxygen Saturation (SpO2)
Pulse oximetry is governed by the following principles:
1.
Oxyhemoglobin (oxygenated blood) and deoxyhemoglobin (non-oxygenated
blood) differ in their absorption of red and infrared light (spectrophotometry).
2.
The amount of arterial blood in tissue changes with your pulse
(photoplethysmography). Therefore, the amount of light absorbed by the varying
quantities of arterial blood changes as well.
Successful Monitoring for SpO2, PR and Pi
Stability of the SpO
2
readings may be a good indicator of signal validity. Although stability is
a relative term, experience will provide a good feeling for changes that are artifactual or
physiological and the speed, timing, and behavior of each.
The stability of the readings over time is affected by the averaging mode being used. The
longer the averaging time, the more stable the readings tend to become. This is due to a
dampened response as the signal is averaged over a longer period of time than during shorter
averaging times. However, longer averaging times delay the response of the oximeter and
reduce the measured variations of SpO
2
and pulse rate.
Functional Oxygen Saturation (SpO2)
The Rad-97 is calibrated to measure and display functional oxygen saturation (SpO
2
): the
amount of oxyhemoglobin expressed as a percentage of the hemoglobin that is available to
transport oxygen.
Note:
Dyshemoglobins are not capable of transporting oxygen, but are recognized as
oxygenated hemoglobins by conventional pulse oximetry.
