Patient Monitor User Manual Monitoring SpO
2
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•
a blood pressure cuff is inflated on the same extremity as the one with the sensor attached
•
there is arterial occlusion proximal to the sensor
•
low peripheral perfusion
NOTE:
1 To prevent interference from ambient light, ensure that the sensor is properly applied,
and cover the sensor site with opaque material.
2 Adjacent SpO
2
sensors may interfere with each other (eg, multiple SpO
2
measurements in the same patient). Be sure to cover the sensor with opaque
material to reduce cross-interference.
3 Move the sensor to a less active site, and keep the patient still, if possible.
4 For Nellcor SpO
2
module, the algorithm automatically extends the amount of data
required for measuring SpO
2
and PR depending on the measurement conditions.
During normal measurement conditions the averaging time is 6 to 7 seconds. During
conditions such as those caused by low perfusion, interference (e.g., external
interference such as ambient light or patient movement), or a combination of these,
the algorithm automatically extends the amount of data required beyond 7 seconds. If
the resulting dynamic averaging time exceeds 20 seconds, the screen will display
prompt message “SpO
2
Search Pulse” and SpO
2
and PR will continue to be updated
every second. As these conditions extend, the amount of data required continues to
increase. If the dynamic averaging time reaches 40 seconds, the screen will display
high-level alarm message “SpO
2
No Pulse” indicating a loss-of-pulse condition.
11.5 Assessing the Validity of a SpO
2
Reading
You can check the quality of the pleth wave and the stability of the SpO
2
values to assess whether
the sensor functions properly and whether the SpO
2
readings are valid. Always use these two
indications simultaneously to assess the validity of a SpO
2
reading.
Generally, the quality of the SpO
2
pleth wave reflects the quality of the light signals obtained by
the sensor. A wave of poor quality manifests a decline of the signal validity. On the other hand,
the stability of the SpO
2
values also reflects the signal quality. Different from varying SpO
2
readings caused by physiological factors, unstable SpO
2
readings are resulted from the sensor’s
receiving signals with interference. The problems mentioned above may be caused by patient
movement, wrong sensor placement or sensor malfunction. To obtain valid SpO
2
readings, try to
limit patient movement, check the placement of the sensor, measure another site or replace the
sensor.
NOTE:
1 The
SpO
2
accuracy has been validated in controlled human studies against arterial
blood sample reference measured with a CO-oximeter. SpO
2
measurements are
statistically distributed, only about two-thirds of the measurements can be expected
to fall within the specified accuracy compared to CO-oximeter measurements. The
volunteer population in the studies are composed of healthy men and women from
