18 Monitoring SpO2
152
SpO2 Signal Quality Indicator
The SpO
2
numeric is displayed together with a signal quality indicator (if configured and enough space
is available) which gives an indication of the reliability of the displayed values.
The level to which the triangle is filled shows the quality of the signal; the indicator below shows a
medium signal quality, the signal quality is at a maximum when the triangle is completely filled.
Assessing a Suspicious SpO2 Reading
Traditionally, pulse rate from SpO
2
was compared with heart rate from ECG to confirm the validity of
the SpO
2
reading. With newer algorithms, such as FAST-SpO
2
, this is no longer a valid criteria because
the correct calculation of SpO
2
is not directly linked to the correct detection of each pulse.
When pulse rate is very low, or strong arrhythmia is present, the SpO
2
pulse rate may differ from the
heart rate calculated from ECG but this does not indicate an inaccurate SpO
2
value.
WARNING
With pulse oximetry, sensor movement, ambient light (especially strobe lights or flashing lights) or
electromagnetic interference can give unexpected intermittent readings when the sensor is not
attached. Especially bandage-type sensor designs are sensitive to minimal sensor movement that might
occur when the sensor is dangling.
Understanding SpO2 Alarms
This refers to SpO
2
specific alarms. See the Alarms chapter for general alarm information. SpO
2
offers
high and low limit alarms, and a high priority desat alarm. You cannot set the low alarm limit below the
desat alarm limit.
CAUTION
If you measure SpO
2
on a limb that has an inflated noninvasive blood pressure cuff, a non-pulsatile
SpO
2
INOP can occur. If the fetal monitor is configured to suppress this alarm there may be a delay of
up to 60 seconds in indicating a critical status, such as sudden pulse loss or hypoxia.
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