9
BPAro
ENG Revision A
Application, Safety Information
The blood pressure is measured by the oscillometric
method. The criteria for this method are the pressure
pulsations superimposed with every systole on the air
pressure in the cuff.
In order to measure the blood pressure, a blood pressure
cuff wrapped around the upper arm needs to be inflated and
subsequently deflated. The blood pressure is deter- mined
either during deflation of the cuff (deflation mea- surement
method) or, by using a novel and faster technology, already
during inflation of the cuff (inflation measurement
method).
The deflation measurement method is the most common
method used. With this technique, the cuff is inflated to a
pressure which must be clearly above the expected systolic
value. Including cuff inflation, the measurement typically
takes approx. 40 seconds. (See Fig. 1.1).
Fig. 1.1 Waveform representing the pressure in the cuff
during a measurement using the deflation mea-
surement method: systolic pressure at 125 mmHg,
diastolic pressure at 83 mmHg
The inflation measurement method is a novel method
based on the "Inflation Measurement Technology (IMT)"
developed by PAR Medizintechnik GmbH & Co. KG.
With this innovative technique, the cuff is inflated to a
pressure just above the expected systolic value. Once the
systolic value is determined, the cuff can immediately and
quickly be deflated. The measurement typically takes only
approx. 20 seconds. (See Fig. 1.2)
If disturbances occur during measurements with the in-
flation measurement method, which may be due to mo-
tion artifacts, for example, the ABPM device will
automatically switch to the deflation measurement
method and complete the blood pressure measurement.
Fig. 1.2 Waveform representing the pressure in the cuff
during a measurement using the inflation
measurement method: systolic pressure at 125
mmHg, diastolic pressure at 83 mmHg
With both methods, a pressure transducer measures the
cuff pressure as well as the superimposed pressure pulsa-
tions. During blood pressure measurements the cuff must
be at heart level. If this is not ensured, the hydrostatic
pressure of the liquid column in the blood vessels will lead
to incorrect results. (Each 10 cm difference result in a
pressure deviation of 8.0 mmHg.)
When the patient is sitting, lying or standing during
measurements the cuff is automatically at the correct level.
1.2
Functional Description
The ABPM devices accommodate the blood pressure
measuring system and a microprocessor for system control
and data processing.
A second microprocessor with a second pressure trans-
ducer and a second valve is provided for control of the
technical safety.
The devices are powered by two AA size batteries (either
rechargeable NiMH batteries or alkaline batteries).
