Patient Monitor User Manual Monitoring SpO
2
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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.
10.5 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
age 19 to 37, with various skin pigmentations. Note that the study population was
healthy adults and not in the actual intended use population.
2 The pulse rate accuracy is obtained by comparison to the pulse rate generated with
an arterial oxygen simulator (also an electronic pulse simulator).
3 During monitoring, if the monitor's reading differs significantly from the patient's
physiological condition, it indicates that the signal may be disturbed, resulting in an
inaccurate reading. In this case, the artifact can disguise as a similar reading,
causing the monitor to fail to send an alarm. In order to ensure reliable monitoring, it
is necessary to regularly check whether the sensor is wearing properly and the signal
quality is good.
10.6 SpO
2
Alarm Delay
There is a delay between a physiological event at the measurement site and the corresponding
alarm at the monitor. This delay has two components:
1. The time between the occurrence of the physiological event and when this event is
represented by the displayed numerical values. This delay depends on the algorithmic
processing time and the sensitivity setting. The lower the sensitivity configured, the longer
the time needed until the numerical values reflect the physiological event.
2. The time between the displayed numerical values exceeding an alarm limit and the alarm
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