Automatic Calibration - Nellcor OxiMax N-600X Operator's Manual

Principles of Operation

Automatic Calibration

172
Because oxyhemoglobin and deoxyhemoglobin differ in light
absorption, the amount of red and infrared light absorbed by blood is
related to hemoglobin oxygen saturation.
The monitor uses the pulsatile nature of arterial flow to identify the
oxygen saturation of arterial hemoglobin. During systole, a new pulse
of arterial blood enters the vascular bed, and blood volume and light
absorption increase. During diastole, blood volume and light
absorption reach their lowest point. The pulse oximeter bases its
SpO measurements on the difference between maximum and
2
minimum absorption (measurements at systole and diastole). By
doing so, it focuses on light absorption by pulsatile arterial blood,
eliminating the effects of nonpulsatile absorbers such as tissue, bone,
and venous blood.
Because light absorption by hemoglobin is wavelength dependent and
because the mean wavelength of LEDs varies, an oximeter must
know the mean wavelength of the O
accurately measure SpO
During monitoring, the instrument's software selects coefficients that
are appropriate for the wavelength of that individual O
red LED; these coefficients are then used to determine SpO
Additionally, to compensate for differences in tissue thickness, the
light intensity of the O
XI
Note: During certain automatic calibration functions, the N-600x
may briefly display a flat line on the plethysmographic waveform.
This is a normal operation and does not require any user intervention.
M sensor's red LED to
XI AX
.
2
M sensor's LEDs is adjusted automatically.
AX
N-600x Operator's Manual
M sensor's
XI AX
.
2