Summary: | 碩士 === 中原大學 === 醫學工程研究所 === 97 === Hypertension, diabetes and stroke are the three major chronic
diseases of the people in Taiwan. In the clinical applications, the benefit
of invasive blood pressure measurement is that it can record the
continuous pressure pulse accurately. However, it can’t be used in routine
examination. Although the non-invasive blood pressure measurement can
be used at home and in routine examination, it causes discomfort during
measurement due to the high air pressure applied by the air pump.
Besides, it can not be easily carried around because of its size. For these
reasons, this study purposes to construct a novel blood pressure
measurement device without the air cuff. The proposed device measures
blood pressure through a mechanism that is made of silicon rubber. The
system consists of a 8051F321 to control the measurement flow and
perform necessary computation. Thus, the final result is a portable
real-time non-invasive blood pressure measurement system.
In this study, blood pressure readings were obtained using the new
system and bedside monitor (Spacelabs Medical, model 90367) from ten
young volunteers. The results of mean pressure, systolic pressure and
diastolic pressure from the new system were all higher than those from
bedside monitor. Including all measured blood pressure readings, the
correlation coefficient between these two system for mean, systolic and
diastolic pressures were 0.15, 0.18 and 0.29, respectively. Re-exam the
collected data, we found that when the speed of pressure application is
too fast or too slow or the obtained blood pressure waveform
characteristic did not coincide with typical oscillometric measurement,
large variations appear. However, after exclude the above mentioned
measurements, there is no significant improvement, the correlation
coefficients of mean, systolic and diastolic pressures were 0.16, 0.16 and
0.38, respectively.
Further examination, we identified one more factor that can
influence the measurement result that is, during the measurement, there
must included more than eight blood pressure pulses that conformed with
oscillometric blood pressure measurement characteristic. After
eliminating these recorded, the correlation coefficient increased to 0.71,
0.60 and 0.41 for diastolic pressure, mean pressure and systolic pressure,
respectively.
We can conclude from these results that the accuracy can be
improved effectively by defining the user regulation more precisely. The
above mentioned interference factors can be identified and eliminated by
the microprocessor to provide a reliable blood pressure measurement in
practical applications.
In this study, low accuracy is still troubling the current system. If the
accuracy can be improved by incorporating the foregoing findings, this
new system may replace the traditional devices in the future.
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