BT-740 Operation manual
83
P/N : 740-ENG-OPM-EUR-D03
Bistos Co., Ltd.
2018.05
11.3 Measurement limits
According to the patient's condition, the oscillometric method has some limitations. This
measurement is to look for the regular pulse waves generated by arterial pressure. If the
patient's condition makes this detection method difficult, the measured value becomes
unreliable, and pressure measurement time increases. The user should be aware that the
following conditions may interfere with measurement method, making the pressure
measurement unreliable or extend the time. In this case, the patient's condition does not
allow measurement.
Patient movement
If the patient is tacking or cramping, the measurement will be unreliable or even
impossible, as these may interfere with the detection of arterial pressure pulse, and
extend the pressure measurement time.
Arrhythmia
If the patient shows arrhythmia which results in irregular heartbeat, the measurement
will be unreliable and even cannot be done, and the pressure measurement time will be
extended.
Use of an artificial heart-lung machine
If a patient is connected to an artificial heart-lung machine, the measurement will be
impossible.
Pressure changes
If the arterial pressure pulse is being analyzed to obtain a measured value at a certain
time and the blood pressure of the patient changes rapidly, the measurement will be
unreliable or impossible.
Severe shock
If the patient is in severe shock or hypothermia, the pressure measurement will not be
reliable, because the decrease of blood flow to the periphery would cause decrease in
arterial pulsation.
Limit heart rate
If the heart rate is below 40bpm (beats / min) or above 240bpm (beats / min), the blood
pressure measurement is impossible.
Obese patients
A thick layer of fat around a limb blocks the arterial oscillation so that it cannot reach the
cuff. The accuracy is lower than normal.
Environmental Requirements
Measuring blood pressure should meet the environment range as follow:
