General information on the use of pulse oximeters
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DefiMonitor XD 21324 / GB / K05
METRAX GmbH
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General information on the use of pulse oximeters
What is pulse oximetry?
A pulse oximeter measures the SpO
2
value (oxygen saturation) using optical measuring
procedures. With this procedure, light of different wavelengths is passed through tissue and
blood vessels.
The elements of the blood which are decisive for SpO
2
measurement are the oxygenated
haemoglobin and the deoxygenated haemoglobin, i.e. the components which play an
important role in supplying the organism with oxygen.
Body tissue and blood vessels are "x-rayed" with the help of transmitter and receiver elements
in an SpO
2
sensor. The amount of light which reaches the receiver side varies according to the
oxygen saturation of the blood. High-precision components and calibrated sensors allow very
accurate measurement of the SpO
2
value.
The normal attachment points for sensors are:
•
Fingertip
•
Toe
•
Earlobe
•
Heel
Why are different types of sensor used?
Different sensors must be used for different patients in order to ensure precise and reliable
measurement.
The following factors should be considered when selecting which type of sensor to use:
•
Weight of the patient
•
Degree of activity of the patient
•
Duration of measurement
•
Perfusion of extremities
•
Possible measurement point
•
Patient's condition
•
Sterile measurement necessary?
It stands to reason that no sensor will fulfil all these sometimes conflicting requirements. The
different types of SpO
2
sensor are designed for specific requirements.
As an example, take the DS-100 A or D-
YS sensor from NELLCOR®.
The DS-100 A is extremely quick and easy to use and has a sophisticated mechanism
allowing it to be fitted simply and easily on fingers of different sizes. The geometry of the
sensor makes it unsuitable for use on children. It is also not suitable for use on patients who
move around, a lot as the mechanism of the casing cannot prevent the sensor slipping off the
finger.