TuffSat User's Guide and Service Manual
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
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
reduced hemoglobin (HHb).
A CO-oximeter typically uses four or more wavelengths of light and calculates
reduced hemoglobin (HHb), oxyhemoglobin (O
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
Assumptions
The calculation of SpO
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
Methods
Two different methods of calibration are currently used by manufacturers of pulse
oximeters: fractional and functional.
Functional saturation is represented mathematically as the percentage of
hemoglobin capable of carrying oxygen that is carrying oxygen.
Functional SpO
The functional calibration is obtained by multiplying the fractional SpO
of 1.02.
1-4
assumes 1.6% carboxyhemoglobin (COHb), 0.4%
2
Important: The TuffSat pulse oximeter uses the functional calibration method. The
user cannot change the calibration method to fractional.
(
=
2
Hb TOTAL – COHb – MetHb
and pulse rate values, and displays them on
2
Hb), carboxyhemoglobin (COHb), and
2
in all pulse oximeters.
2
accuracy.
2
O 2 Hb
)
x 100 =
Hb) and
2
O 2 Hb
(
)
x 100
O 2 Hb + HHb
by a value
2