VM15 User Manual Masimo SpO2
Monitoring (Option)
130
Figure 20-3. Monitoring Setup – STD2
PRINCIPLE OF OPERATION
Pulse oximetry is governed by the following principles:
I. Oxyhemoglobin (oxygenated blood) and deoxyhemoglobin (non-oxygenated
blood) differ in their absorption of red and infrared light (spectrophotometry).
II. The amount of arterial blood in tissue changes with your pulse
(photoplethysography).
Therefore, the amount of light absorbed by the varying quantities of arterial blood changes
as well.
The VM15 Pulse Oximeter uses a two-wavelength pulsatile system to distinguish between
oxygenated and deoxygenated blood.
Signal data is obtained by passing red(rd)(660 nm wavelength) and infrared (ir)(905 nm
wavelength) light.
Through a vascular bed (for example a fingertip, a hand, a foot) and measuring changes in
light absorption during the pulsatile cycle.
This information may be useful to clinicians. The radiant power of the light is rated at 0.79mW
(max.).
See figure below. The VM15utilizes a sensor with red and infrared light-emitting diodes (LEDs)
that pass light through the site to a photodiode (photodetector).
The photodetector receives the light, converts it into an electronic signal and sends it to the
VM15 for calculation.
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