22
Non-Invasive Pressure Measurement Principles
Oscillometric method
The beat in the pulsation generated by the contraction of the heart is
captured as the pressure inside the cuff to measure the blood pressure.
If the cuff wrapped around the upper arm is pressurized suf¿ ciently, the
blood À ow stops, but the beat of the pulsation is present and the pressure
inside the cuff receives this and oscillates. Next, as the pressure inside
the cuff gradually decreases, the oscillation of the pressure within the
cuff gradually increases and reaches a peak. As the pressure within the
cuff decreases further, the oscillation decreases from its peak.
The pressure within the cuff and the relationship with the increase and
decrease of the oscillation within the cuff in this series of processes are
stored into memory, calculations are carried out, and the blood pressure
value is determined.
The pressure within the cuff when the oscillation increases drastically is
the systolic pressure and the pressure within the cuff when the oscillation
decreases drastically is the diastolic pressure. Also, the pressure within the
cuff when the oscillation peaks is taken as the average pulsation pressure.
The oscillometric method does not determine the blood pressure value
instantly like a microphone type automatic blood pressure gauge with the
auscultation method, but rather determines it from the series of change
curves as explained above. Therefore, it is not easily affected by external
noise, an electric scalpel or other electro surgical instruments.
To Next Page
Loading...
Need help?
General
