LE 5002 Non Invasive Blood Pressure Meter
USER MANUAL
21
8. OPERATING PRINCIPLE
Figure 13. Waveforms in a measurement. Up (pressure) and down (pulses).
Waveforms of Figure 13 have been obtained by connecting CUFF PRESSURE and
PULSE WAVE analog outputs to a data logger.
1.
As soon as the “START” button is pressed the air pump starts and pressure in
the sleeve starts to increase (see Figure 13). As of a certain pressure value, the
amplitude of the pulse wave starts to fall and will eventually reach zero (point
1
of the Figure 13). As of this time, and following another brief pressure increase,
the latter will start to fall, and the sleeve membrane will deflate. Point
1
is the
systolic pressure taken in
UP mode.
2.
The pressure value in the sleeve at the time when the blood pulses reappear
(point
2
) is equivalent to the systolic pressure in
DOWN mode.
3.
The pressure in the sleeve continues to fall until it reaches the value of diastolic
pressure, which is the pressure value corresponding to the instant when the pulse
wave recovers its initial value (point
3
). The air in the sleeve is immediately
released until pressure reaches zero, and the instrument is ready to take a new
measurement (point
4
).
It may be convenient, particularly when starting with this technique, to see the
analog display of the pulse to determine its quality.
Figure 14 shows a pulsation that is unsuitable for taking pressure: it is erratic and
unstable, indicating that the animal is still stressed.
Figure 15 shows a correct pulsation.