Development of the novel cuff-less blood pressure measurement device

• Main Authors: Yao-Lin Kao, 高耀臨
• Other Authors: Liang-Yu Shyu
• Format: Others
• Language: zh-TW
• Published: 2009
• Online Access: http://ndltd.ncl.edu.tw/handle/61779267871840670149

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.