User's Manual

Pulse Oximetry Measurement
SpO2 Monitoring 9-5
Pulse Oximetry Measurement
The MX40 supports an SpO2 sensor connection using Fourier Artifact
Suppression Technology (FAST). The FAST algorithm overcomes many of
the issues associated with traditional pulse oximetry such as sensitivity to
patient movement and intense ambient light. The algorithm offers
improved motion artifact rejection as well as performance improvements
for patients with low perfusion. SpO2 can be measured continuously, where
a value is sent to the Information Center every second, or as a single,
individual Manual measurement. The Manual measurement will be
removed from the Information Center display after 1 hour.
The SpO2 parameter measures the arterial oxygen saturation, that is, the
percentage of oxygenated hemoglobin in relation to the total hemoglobin.
If, for example, a total of 97% of the hemoglobin molecules in the red blood
cells of the arterial blood combine with oxygen, then the blood has an
oxygen saturation of 97%. The SpO2 numeric that appears on the monitor
will read 97%. The SpO2 numeric indicates the percentage of hemoglobin
molecules which have combined with oxygen molecules to form
oxyhemoglobin.
 The oxygen saturation is measured using the pulse oximetry method.
This is a noninvasive method of measuring the arterial hemoglobin
oxygen saturation. It measures how much light, sent from light sources
on one side of the sensor, travels through patient tissue (such as a finger
or an ear), to a receiver on the other side of the sensor.
 The amount of light passing through depends on many factors, most of
which are constant, such as tissue or venous blood. However one of the
factors, the blood flow in the arterioles, varies with time because it is
pulsatile.
This measurement principle is used to derive the SpO2 measurement. The
numeric that is displayed is the oxygen saturation of the arterial blood - the
measurement of light absorption during a pulsation. Correct placement of
the sensor is essential for accurate measurements.
Note—Because pulse oximeter equipment measurements are statistically
distributed, only about two-thirds of pulse oximeter equipment
measurements can be expected to fall with ± Arms of the value measured
by a CO-oximeter.