Radical Signal Extraction Pulse Oximeter Operator’s Manual
4-5
4
o p e r a t i o n
NUMERIC DISPLAY - SpO
2
Stability of the SpO
2
readings may be a good indicator of signal validity. Although stability
is a relative term, experience will provide a good feeling for changes that are artifactual
or physiological and the speed, timing, and behavior of each.The stability of the readings
over time is affected by the averaging mode being used. The longer the averaging time,
the more stable the readings tend to become. This is due to a dampened response as
the signal is averaged over a longer period of time than during shorter averaging times.
However, longer averaging times delay the response of the oximeter and reduce the
measured variations of SpO
2
and PR.
NUMERIC DISPLAY - PULSE RATE
The Pulse Rate displayed on the Radical may differ slightly from the heart rate displayed
on ECG monitors due to differences in averaging times.There may also be a discrepancy
between cardiac electrical activity and peripheral arterial pulsation. Significant
differences may indicate a problem with the signal quality due to physiological changes
in the patient or one of the instruments or application of the sensor or patient cable. The
pulsations from intra-aortic balloon support can be additive to the pulse rate displayed
on the pulse oximeter.
o p e r a t i o n
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Radical Signal Extraction Pulse Oximeter Operator’s Manual
4
SIGNAL IQ
The Radical display provides a visual indicator of the plethysmogram signal quality and
an alert when the displayed SpO
2
values are not based on adequate signal quality. The
signal quality indicator displayed on the Radical is called the Signal IQ.The Signal IQ can
be used to identify the occurrence of a patient's pulse and the associated signal quality
of the measurement.
With motion, the plethysmographic waveform is often distorted and may be obscured by
artifact. The Signal IQ, shown as a vertical line, coincides with the peak of an arterial
pulsation. Even with a plethysmographic waveform obscured by artifact, the Radical
locates the arterial pulsation. The pulse tone (when enabled) coincides with the vertical
line of the Signal IQ.
The height of the vertical line of the Signal IQ indicates the quality of the measured
signal. A high vertical bar indicates that the SpO
2
measurement is based on a good
quality signal. A small vertical bar indicates that the SpO
2
measurement is based on data
with low signal quality. When the signal quality is very low the accuracy of the SpO
2
measurement may be compromised, and a “Low Signal IQ” message is displayed in the
message area on the Radical display. When the "Low Signal IQ" message appears
proceed with caution and do the following:
■
Assess the patient.
■
Check the sensor and ensure proper sensor application. The sensor must be well
secured to the site for the Radical to maintain accurate readings. Also, misalignment
of the sensor's emitter and detector can result in smaller signals.
■
Determine if an extreme change in the patient's physiology and blood flow at the
monitoring site occurred, (e.g. an inflated blood pressure cuff, a squeezing motion,
sampling of an arterial blood specimen from the hand containing the pulse oximetry
sensor, severe hypotension, peripheral vasoconstriction in response to hypothermia,
medications, or a spell of Raynaud's syndrome.)
■
With neonates or infants, check that the peripheral blood flow to the sensor site is not
interrupted. Interruption, for example, may occur while lifting or crossing their legs,
during a diaper change.
After performing the above, if the "Low Signal IQ" message is displayed frequently or
continuously obtaining an arterial blood specimen for CO-Oximetry analysis may be
considered to verify the oxygen saturation value.
