User's Manual

4-12
Rad-87 Pulse CO-Oximeter Operator’s Manual
4
Numeric Display - PVI
The pleth variability index (PVI) is a measure of the dynamic changes in the perfusion index (PI)
that occur during the respiratory cycle. The calculation is accomplished by measuring changes
in PI over a time interval where one or more complete respiratory cycles have occurred. PVI is
displayed as a percentage (0-100%).
Low Perfusion
The Rad-87 indicates perfusion on a 10-bar LED indicator. The lower two segments of the
bar will turn red when the amplitude of the arterial pulsations is very low (low perfusion). It has
been suggested that at extremely low perfusion levels, pulse oximeters can measure peripheral
saturation, which may differ from central arterial saturation*. This “localized hypoxemia” may result
from the metabolic demands of other tissues extracting oxygen proximal to the monitoring site
under conditions of sustained peripheral hypoperfusion. (This may occur even with a pulse rate
that correlates with the ECG heart rate.)
CAUTION:
• If the Low Perfusion message is frequently displayed, find a better-perfused monitoring
site. In the interim, assess the patient and, if indicated, verify oxygenation status through
other means.
* Severinghaus JW, Spellman MJ. Pulse Oximeter Failure Thresholds in Hypotension and Vasoconstriction.
Anesthesiology 1990; 73:532-537
Signal Indication and Quality Indicator (SIQ)
The height of the Signal I.Q. Index indicates the quality of the measured signal. A high Signal I.Q. Index
indicates that the SpO
2
measurement is based on a good quality signal. A small Signal I.Q. Index
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. When the Signal I.Q. is low
the bar turns red and the parameter label flashes; 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 Rad-87 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 an episode 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 I.Q. message is displayed frequently or continuously
obtaining an arterial blood specimen for CO-Oximetry analysis may be considered to verify the
arterial oxygen saturation value.
Low SpCO SIQ and Low SpMet SIQ
When the signal quality for SpCO and/or SpMet is very low the accuracy of the SpCO and/or
SpMet measurement(s) may be compromised. In a low SpCO and/or low SpMet SIQ state, the
parameter label(s) will flash.
Operation