A&D TM-2564G Manuel d'instructions télécharger pdf (Page 61)

Causes of errors

In the pulse oximeter, adequate waveform implies

the reliability. Always check the plethysmograph or

bar graph for noises and disturbances. When

noises or disturbances occur, check the probe

connection or patient condition. The following are

the main causes of errors in arterial oxygen

saturation measurement.

Abnormal hemoglobin

Besides oxygenated hemoglobin and reduced hemoglobin, there are carboxyhemoglobin (COHb) and

methemoglobin (MetHb). They do not carry oxygen and are called abnormal hemoglobin. Normally,

carboxyhemoglobin is about 1%. Methemoglobin is abundant in neonates, but it decreases to a negligible

level as they grow. When abnormal hemoglobin has increased due to carbon dioxide poisoning or

methemoglobinemia, a measurement error occurs. For those suffering from these conditions,

2-wavelengh pulse oximeter can not be used.

Venous pulsations

When the sensor is secured tightly with tape, the venous pulsations may be also detected and the lower

arterial oxygen saturation is obtained.

Low perfusion

When peripheral circulation disorder exists, pulses enough to detect the arterial oxygen saturation can not

be obtained. Do not secure the sensor too tightly with tape or do not place the probe at the same location

for a long period of time.

A pulse oximeter does not require calibration. Check the performance using the optional checker

periodically.

Plethysmograph

Pulse bar graph

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A&D TM-2564G Manuel d'instructions Page 61