GE TuffSat, Руководство пользователя и сервисное руководство

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TuffSat User’s Guide and Service Manual
1-4
The photodetector sends the electronic signal, which contains the light intensity
information, to the oximeter. The oximeter’s electronic circuitry processes the
electronic signal, calculates the SpO
2
and pulse rate values, and displays them on
the screen.
Calibration
Datex-Ohmeda pulse oximeters use two wavelength ranges, 650 nm to 670 nm and
930 nm to 950 nm, both with an average power of less than 1 mW. These
wavelengths are used to calculate the presence of oxyhemoglobin (O
2
Hb) and
reduced hemoglobin (HHb).
A CO-oximeter typically uses four or more wavelengths of light and calculates
reduced hemoglobin (HHb), oxyhemoglobin (O
2
Hb), carboxyhemoglobin (COHb), and
methemoglobin (MetHb).
Therefore, pulse oximetry readings and CO-oximetry readings will differ in
situations where a patient’s COHb or MetHb are increased. Increased patient COHb
leads to falsely increased SpO
2
in all pulse oximeters.
Assumptions
The calculation of SpO
2
assumes 1.6% carboxyhemoglobin (COHb), 0.4%
methemoglobin (MetHb), and no other pigments. These values are based on the
Datex-Ohmeda Pulse Oximeter Empirical Calibration Study. Appreciable variation
from these values will influence SpO
2
accuracy.
Methods
Two different methods of calibration are currently used by manufacturers of pulse
oximeters:
fractional and functional .
Important : The TuffSat pulse oximeter uses the functional calibration method. The
user cannot change the calibration method to fractional.
Functional saturation is represented mathematically as the percentage of
hemoglobin capable of carrying oxygen that is carrying oxygen.
Functional SpO
2
=
( )
x 100 =
( )
x 100
The functional calibration is obtained by multiplying the fractional SpO
2
by a value
of 1.02.
O2Hb
O2Hb + HHb
O2Hb
HbTOTAL – COHb – MetHb