Revision C 250cx Series Maternal/Fetal Monitor 9-5
2036946-001
Maternal Pulse Oximetry Monitoring: MSpO2 Technology
Traditional pulse oximetry assumes that all pulsations in the light absorbance signal
are caused by oscillations in the arterial blood volume. This assumes that the blood
flow in the region of the sensor passes entirely through the capillary bed rather than
through any arterio-venous shunts.
Masimo’s principle of operation is that arterio-venous shunting is highly variable and that
fluctuating absorbance by venous blood is a major component of noise during the pulse.
The Masimo product decomposes red and infrared pulsatile absorbance into an arterial
signal plus a noise component and then calculates the ratio of the arterial signals minus the
noise.
The practitioner can adjust high and low alarm limits to a desired value, if required,
and then monitor the waveform, pulse rate and Sp0
2
value on the display. If an alarm
limit is reached, the information on the display helps to assess the condition of the
patient and aids in determining if any intervention is required.
Nellcor OxiMax
®
Due to a change in Nellcor technology, the SpO
2
parameter in the Corometrics
250cx Monitor is migrating from Nellcor 506 technology to Nellcor NELL-3
technology. To determine which Nellcor technology your monitor contains, refer to
the Service Lock screen.
To display the Service Lock:
1. Select the Setup softkey to display the General screen.
2. Select the Service softkey from the General Setup screen.
3. The Service Lock screen appears.
Nellcor uses pulse oximetry to measure functional oxygen saturation in the blood.
Pulse oximetry works by applying an OxiMax
®
sensor to a pulsating arteriolar
vascular bed, such as a finger or toe.
The OxiMax sensor contains a dual light source and a photodetector. Bone, tissue,
pigmentation, and venous vessels normally absorb a constant amount of light over
time. The arteriolar bed normally pulsates and absorbs variable amounts of light
during the pulsations. The ratio of light absorbed is translated into a measurement of
functional oxygen saturation (SpO
2
).
Exit
Service Lock
Enter Access Code
0 0 0 0
CPU VX.XX
DSP XX.XX
NIBP Pri 1.25 Sec.1.1
KeyPd 1.1
MSpO
2
NELLCOR NELL-3 V1.9.0.1 12/9/03
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