Case7 For Better SpO2 Monitoring - SQI, Signal Quality Index

The SpO2 value is often affected by the patient’s condition, artifacts created by external devices or by inappropriate attachment of probes, while monitoring continuously.
Nihon Kohden’s monitor has several features for better SpO2 measurement. Let us introduce one of the features here: SQI, Signal Quality Index.
For other three features, please see in each page. Pulse-amplitude Index, Sensitivity Mode, and Response.

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Signal Quality Index (SQI)

Nihon Kohden’s monitors display the quality of the pulse waveform signal, which is used to measure SpO2, by a bar graph. If the SQI bar graph displays 2 yellow bars or below, check for the patient’s physical movement and/or how a probe is attached.

SQI on the display


SQI Bar Graph Signal Quality

4 green bars4 green bars


3 green bars3 green bars

There may be some artifacts.

2 yellow bars

2 yellow bars 1

There may be significant artifacts. If this continues for a while, check the patient and probe attachment site.

1 red bar1 red bar 1

Very low.
Check the patient and probe attachment site.

0 bars0 bars

The signal cannot be detected.

1 If the SQI bar graph shows 1 or 2 bars, the “Low Quality Signal” message appears on the monitor.