BT-550 Operation manual
44
P/N : 550-ENG-OPM-EUR-R01
Bistos Co., Ltd.
2018.03
The above equations are combined and a noise reference (N’) is determined:
N’ = S(660) – S(905) x R
If there is no noise N’ = 0: then S(660) = S(905) x R which is the same relationship for the traditional
pulse oximeter.
The equation for the noise reference is based on the value of R, the value being sought to determine
the SpO
2
. The MS board software sweeps through possible values of R that corresponds to SpO
2
values
between 1% and 100% and generates an N’ value for each of these R-values. The S(660) and S(905)
signals are processed with each possible N’ noise reference through an adaptive correlation canceler
(ACC) which yields an output power for each possible value of R (i.e., each possible SpO
2
from 1% to
100%). The result is a Discrete Saturation Transform (DST™) plot of relative output power versus
possible SpO
2
value as shown in the following figure where R corresponds to SpO
2
= 97%:
The DST plot has two peaks: the peak corresponding to the higher saturation is selected as the SpO
2
value. This entire sequence is repeated once every two seconds on the most recent four seconds of
raw data. The MS board SpO
2
therefore corresponds to a running average of arterial hemoglobin
saturation that is updated every two seconds.
- Grounding
Connect the oximeter only to a three-wire, grounded, hospital-grade receptacle. The three-conductor
plug must be inserted into a properly wired three-wire receptacle; if a three-wire receptacle is not
available, a qualified electrician must install one in accordance with the governing electrical code.
WARNING
