GE Medical Systems marquette Dash 2000, Operator'S Manual, Page: 208 / 272

11-6 Dash 2000 Patient Monitor Revision C
2005873-001
Signal and Data Validity
Signal Strength
Indicator
Quality of SPO2
Waveform
It is extremely important to determine that the probe is attached to the patient
correctly and the data is verifiable. To make this determination, three
indications from the monitor are of assistance—signal strength indicator, quality
of the SPO2 waveform, and the stability of the SPO2 values. It is critical to
observe all three indications simultaneously when ascertaining signal and data
validity.
The signal strength indicator is displayed within the SPO2 values window. This
indicator consists of 0, 1, 2, or 3 (strongest) asterisks depending on the
strength of the signal. Proper environmental conditions and probe attachment
will help to ensure a strong signal.
Under normal conditions, the SPO2 waveform corresponds to (but is not
proportional to) the arterial pressure waveform. The typical SPO2 waveform
indicates not only a good waveform, but helps the user find a probe placement
with the least noise spikes present. The figure below represents an SPO2
waveform of good quality.
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Good Quality SPO2 Waveform
If noise (artifact) is seen on the waveform because of poor probe placement,
the photodetector may not be flush with the tissue. Check that the probe is
secured and the tissue sample is not too thick. Pulse rate is determined from
the SPO2 waveform which can be disrupted by a cough or other hemodynamic
pressure disturbances. Motion at the probe site is indicated by noise spikes in
the normal waveform. (See the figure below.) It has been noted that letting the
patient view the SPO2 waveform enables them to assist in reducing motion
artifact.
116
SPO2 Waveform with Artifact