Examples of the pulse oximeter signal
The following pictures show
samples of pulse oximeter signals. The signal obtained using the red wavelength
is shown in red. The signal from the infra red source is shown in blue.
At high SATs values the red pulseatile signal is
relatively small whilst the infra red pulseatile signal is relatively large. The
ratio of red over infra red is at its lowest.
As SATs values fall the red pulseatile signal
becomes relatively larger whilst the infra red pulseatile signal becomes
relatively smaller and the value of R increases. At SATs values reach the low
80s the pulsatile signals for the red and infra red are about the same size and
the value of R is about 1.
At SATs values fall below 80% the red
pulsatile signal becomes larger than the infra red pulsatile signal and the
value of R increases above 1.