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RESP
The DPM4 patient monitor measures the RESP based on the impedance principle. While a man is
breathing, the action of the breast leads to impedance changes between RL and LL. Change the
high-frequency signal passing the RL and LL to amplitude-modulation high-frequency signal
(AM high-frequency signal), which is converted to the electric signal after being detected and
amplified and then sent to the A/D converter. The RESP module consists of the RESP circuit
board and coupling transformer. The circuit has several functions: vibration, coupling,
wave-detection, primary amplification and high-gain amplification.
2.4.3 NIBP
The NIBP is measured based on the pulse vibration principle. Inflate the cuff which is on the
forearm till the cuff pressure blocks the arterial blood, and then deflate the cuff according to a
specified algorithm. While the cuff pressure is decreasing, the arterial blood has pulses, which are
sensed by the pressure transducer in the cuff. Consequently, the pressure transducer, connected
with the windpipe of the cuff, generates a pulsation signal. Then, the pulsation signal is filtered
by a high-pass filter (about 1Hz), amplified, converted to the digital signal by the A/D converter,
and finally processed by the MCU. After that, the systolic pressure, diastolic pressure and mean
pressure can be obtained. For neonates, pediatric and adults, it is necessary to select the cuffs of a
proper size to avoid possible measurement errors. In the NIBP measurement, there is a protection
circuit used to protect patient from over-high pressure.
The NIBP measurement modes include:
1. Adult/pediatric/neonate mode: To be selected according to the build, weight and age of
the patient;
2. Manual/Auto/Continuous mode: The manual measurement is also called single
measurement; in this mode, only one measurement is done after being started. In the auto
measurement mode, the measurement can be done once within the selected period, with the
interval being 1, 2, 3, 4, 5, 10, 15, 30, 60, 90, 120, 180, 240 or 480 minutes. In the
continuous measurement mode, quick continuous measurement will be done within 5
minutes after being started; it detects the changes in blood pressure effectively.
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