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Causes of errors
The pulse during blood pressure measurement is indicated in a graph,
which can be an objective indicator of the reliability in the measurement
accuracy. When noises occur due to irregular heart rhythm or physical
movements, the amplitude changes abnormally in the graph. When it
happens, blood pressure should be measured again, or be checked
using other methods. The following are the main causes of errors in
blood pressure measurement.
Cuff position
The cuff should be at the same level as the heart. Otherwise, a measurement error occurs. For example,
if the cuff is 10 cm lower than the heart level, the blood pressure measures 7 mmHg higher.
Cuff size
The cuff size should be adequate. Otherwise, a measurement error occurs. The small cuff yields high
blood pressure, regardless of the proper cuff pressure or normal artery. The large cuff yields low blood
pressure, especially for those who suffer from severe arteriosclerosis or have abnormal arterial valve. The
wrong cuff size is the main reason of the big difference that occurs between the results taken by invasive
blood pressure measurement and by oscillometric blood pressure measurement.
The cuff has the area labeled RANGE on it. When attached, the cuff inner end should be within the area
labeled RANGE. Using the indicator, select the proper cuff for the patient.
The accuracy of the blood pressure monitor is guaranteed using the pressure accuracy of the pressure
sensor, exhaust characteristics and measurement algorithm, as long as the proper cuff and hose are
used.
Check the pressure accuracy of the pressure sensor and exhaust characteristics periodically as specified
in "7-2 Calibration".
Pulse graph
