Parameter Menus Operations
2 - 32 0070-10-0666-01 Trio™ Operating Instructions
2.4.3 SpO
2
 Monitoring
Each of the following terms are associated with blood oxygenation: oxygen saturation, pulse 
oximetry, SpO
2
 and plethysmography.
Oxygen saturation in capillary blood is measured by a method called pulse oximetry. Pulse 
oximetry is a continuous and non-invasive measurement of oxyhemoglobin saturation (the 
amount of oxygen attached to the hemoglobin in red blood cells). SpO
2
 is the estimation of 
arterial oxygen saturation. This term is used interchangeably with SaO
2
. This value is 
displayed in the SpO
2
 parameter tile (FIGURE 2-31) along with the Pulse Rate and the Pulse 
Amplitude Indicator. The indicator provides a graphic depiction of the relative pulse volume.
When the Trio is equipped with Nellcor® OxiMax® SpO
2
, the SpO
2
 parameter tile 
displays a SatSeconds™ Indicator when the SatSeconds function is enabled as described in 
section 2.4.3.2.
FIGURE 2-31 SpO2 Parameter Tile
The corresponding plethysmogram is a waveform representation of the arterial oxygenation 
and pulse detection. The pleth waveform is automatically scaled and no adjustment can be 
made to its size. The SpO
2
 results are updated once every second.
Traditional pulse oximetry determines SpO
2
 by passing red and infrared light into a capillary 
bed and measuring changes in light absorption during the pulsatile cycle. Red and infrared 
light-emitting diodes (LEDs) in oximetry sensors serve as the light sources, a photodiode 
serves as the photo detector.
Traditional pulse oximetry assumes that all pulsations in the light absorbance signal are 
caused by oscillations in the arterial blood volume. This also assumes that the blood flow in 
the region of the sensor passes entirely through the capillary bed rather than through any 
arterio-venous shunts.
Pulse Rate
SpO
2
Pulse Amplitude Indicator
Alarm OFF Symbol
(SpO
2 
alarm high only)
SatSeconds Indicator
(Nellcor® only)
SatSeconds Setting
(Nellcor® only)
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