二、與會心得
這個會議是醫學工程領域每年舉辦一次的大型會議，在這邊可以看到許多醫工相關領 域的論文發表，可以了解目前其他國家的研究現況。不過此次地點比較遠，花費也比較高。
不過因為以前並沒有到過中南美洲，所以也是一個不錯的經驗，可以大概了解當地的風土 民情。
三、考察參觀活動(無是項活動者略)
無。四、建議
未來到中南美洲開會可以停留多一點時間，比較不會太累。
五、攜回資料名稱及內容
1.
Final program and abstract book 一本，內容為每天議程時間表和論文摘要。2. 光碟一片
六、其他
Abstract— In this paper, we developed a wireless blood pressure monitoring system which provides a useful tool for users to measure and manage their daily blood pressure values.
This system includes an ARM-based blood pressure monitor with a ZigBee wireless transmission module and a PC-based management unit with graphic user interface and database. The wireless blood pressure monitor can measure the blood pressure and heart rate and then store and forward the measuring information to the management unit through the ZigBee wireless transmission. On the management unit, user can easy to see their blood pressure variation in the past using a line chart.
Accuracy of blood pressure measurement has been verified by a commercial blood pressure simulator and shown the bias of systolic blood pressure is ≤≤≤≤ 1 mmHg and the bias of diastolic blood pressure is ≤≤≤≤ 1.4 mmHg.
I. INTRODUCTION
YPERTENSION is a critical risk factor for cardiovascular morbidity and mortality in the general population and reduction of blood pressure (BP) with effective antihypertensive therapy significantly decreases cardiovascular morbidity and mortality [1]. Keeping observing BP is also a matter of concern for those who have hypertension, coronary heart disease, or other cardiovascular diseases [2]. BP measurement is also important for particular disease patients, such as hemodialysis patients [3]. Hence, in the daily life, BP measurement and management is very useful for handling health situation and plays a preventive function. Many researches point out that the importance of BP measurement and management for elder and hypertensions [4]. Elderly people usually have higher BP, prone to take sick, and the morbidity of BP disease is higher.
In patients with hypertension, BP measurement and management warn patients to take medicines and pay attention to diet, to get treatment effect.
In recent years, homecare is becoming an important topic.
Manuscript received April 23, 2010. This work was supported in part by a research grant from the National Science Council under Grant NSC 98-2218-E-011-007-.
Wun-Jin Li is with the Department of Electronic Engineering, National Taiwan University of Science and Technology, Taiwan. (email:
m9802111@mail.ntust.edu.tw).
Yuan-Long Luo is with the Department of Electronic Engineering, National Taiwan University of Science and Technology, Taiwan. (email:
m9802110@mail.ntust.edu.tw).
Yao-Shun Chang is with the Graduate Institute of Biomedical Engineering, National Taiwan University of Science and Technology, Taiwan. (email: yao_shun@hotmail.com).
Yuan-Hsiang Lin is with the Department of Electronic Engineering, National Taiwan University of Science and Technology, Taiwan.
(corresponding author to provide phone: +886-2-2730-3618; fax:
+886-2-2737-6424; e-mail: linyh@mail.ntust.edu.tw).
The market for automated BP measuring devices is growing rapidly. Home blood pressure measurement (HBPM) is becoming more and more popular [5]. The study of G. Bobrie and others [6] indicated that BP should systematically be measured at home in patients receiving treatment for hypertension. With the advances in technology and health awareness, many researchers use sensor and network technologies for home health monitoring system. In order to achieve monitoring of everywhere in home environment, J. H.
Shin and others [7] used the non-invasive sensor to implement a homecare monitoring system for ECG and PPG monitoring, whether sleeping on the bed, sitting on sofa, and even in toilet.
Physiological measurement using wireless transmission is becoming a trend. Y. Fang and others [8] used Bluetooth and GPRS technology to implement a real-time health information acquisition and alarm system. It is mainly used to detect the BP and pulse of the cardiovascular and cerebrovascular disease patient, send the monitoring data to the information analyzing center by the aid of Bluetooth and mobile communication device. Compared with infrared and Bluetooth technology, ZigBee doesn’t have the advantages of transmission speed and efficiency. But it has some advantages with low power consumption, low cost and small size. ZigBee wireless transmission is gradually used in home automation, home security and personal healthcare treatment.
Health monitoring system is also using ZigBee wireless data transmission [9]. We can see the future of ZigBee applications would be very promising.
Traditionally, we have to record the data by ourselves when the measurement is completed. However, automatically data recording with PC or Laptop when the measurement is completed would be more convenient and can save human resources in home environment. With connecting to database, patients can record the past measuring results. Therefore, in this study, we combined a wireless BP monitor and database on PC or Laptop to store the measuring results. Users or doctors can see the past records on the graphic user interface (GUI) anytime, and the interface can show the line chart to express the BP variation. So it can be faster to see the health situation is abnormal or not. Users use the BP monitor which connects to database through the ZigBee wireless transmission has advantage of portable; they can manage their health anytime, anywhere. In home environment, patients with poor action can also easy to record every measurement result through the ZigBee wireless transmission.
So it would provide a convenient health management environment at home.
A Wireless Blood Pressure Monitoring System for Personal Health Management
Wun-Jin Li, Yuan-Long Luo, Yao-Shun Chang, and Yuan-Hsiang Lin, Member, IEEE
H
32nd Annual International Conference of the IEEE EMBS Buenos Aires, Argentina, August 31 - September 4, 2010
978-1-4244-4124-2/10/$25.00 ©2010 IEEE 2196
II. METHODS A. System Architecture
The system architecture of this BP management system is shown in Fig. 1. The system is consisted of the wireless BP monitor and the management unit. The wireless BP monitor is based on an ARM-based platform, which integrates with the pressure sensor, analog circuits including amplifiers and filters, pump and valve, and the ZigBee wireless transmission module. Measuring results can be transmitted to the management unit via the ZigBee wireless network. On the management unit, BP values and related information such personal ID, measuring time and date, are recorded into database. Through the GUI developed on the management unit, it is easy to see the past measuring data and BP variation curves.
Fig. 1. System architecture of wireless blood pressure monitoring system.
1) Analog circuits: Pressure sensor receives the cuff pressure signal from the cuff. A High CMRR instrument amplifier is used to amplify this signal and then the pre-amplified signal goes through a 4-order high-pass filter and a 4-order low-pass filter. Finally, the AC signal (bloodstream oscillate signal) is obtained from the output of low-pass filter and DC signal (pressure value signal) is obtained from the output of instrument amplifier. AC signal and DC signal are both sent to ARM platform and ARM-based platform, which is made by STMicroelectronics Company. This platform integrates a microcontroller STM32F103ZET6, one 128×64 dot-matrix LCD, one joy stick, buttons, UARTs, and USB peripherals. The STM32F103ZET6 is a high density ARM 32-bit microcontroller based on the Cortex-M3 core, with 512 Kbytes of embedded Flash memory, 64 Kbytes of embedded SRAM and a rich set of on-chip peripherals, including 12-bit ADCs and DACs, GPIOs, UARTs and USB, et al..
Fig. 2 shows the user operating interfaces on the ARM platform, including LCD display, joy stick, start/stop button and four different color LEDs which are used for display the measurement status and result. From left to right, the LED colors are blue, red, yellow and green separately. The initial screen is shown on this display, including user ID and current time and date.
Fig. 2. User interfaces on the ARM platform.
On this platform, we use C language to implement a BP measurement program. The flow chart of software is shown in Fig. 3. Before starting measurement, user can select their ID by joy stick and then press a start/stop button to initiate the measurement procedure. First, the pump starts to inflate the cuff. When CPU detects the pressure value in the cuff is equal to or bigger than a threshold 1(variable). The pump stops inflating, and then deflates through deflation gate with reducing 3mmHg per second until the pressure value is smaller than a threshold 2 (variable). Finally, CPU controls the deflation gate to take a complete deflation. In this paper, we implemented a 101-tap FIR digital low-pass filter with cut-off frequency of 0.1Hz for reducing the noise of DC cuff pressure signal to prevent the detection error.
Fig. 3. Flow chart of software for the ARM platform.
After inflation and deflation measurement procedure, the systolic BP (SBP) and diastolic BP (DBP) are calculated according to the oscillometric method, and then the SBP, DBP, and heart rate (HR) will show on the LCD display.
Besides, we also used 4 LEDs with different color to indicate normal BP, prehypertension, stage 1 hypertension, and stage 2 hypertension respectively, according to BP classification [1]. TABLE I shows the relationship of BP classification and the LED colors. If the ZigBee network is connected, the user’s ID, SBP, DBP, HR and measuring time information will also be transmitted to the management unit immediately.
If the ZigBee network is not connected at this time, the data will be stored on the local memory until next connection is established. There are ten IDs are available for users to select.
TABLE I. BPCLASSIFICATION AND LEDCOLORS
BP Classification SBP(mm Hg) DBP(mm Hg) LED Colors
Normal <120 <80 Green
Prehypertension 120~139 80~89 Blue
Stage 1 hypertension 140~159 90~99 Yellow
Stage 2 hypertension ≥160 ≥100 Red
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3) ZigBee wireless transmission: In this paper, two ZigBee wireless transmission modules are used for the data transmission. This ZigBee module is based on a TI MSP430F1611 microcontroller and a UZ2400 low power 2.4 GHz transceiver made by Uniband Electronic Corporation.
UZ2400 is an IEEE802.15.4 compliant single-chip solution, integrates 2.4 GHz PHY, Baseband and MAC layer. UZ2400 is controlled by the MSP430F1611 MCU through the serial peripheral interface bus (SPI) to apply in this wireless application. One ZigBee module is connected to ARM platform and another one is connected to management unit (PC/Laptop), and both of them are using the standard UART interface. The baud rate is set to 230.4kb/s.
4) Management unit: The management unit is established on the PC or Laptop. An application program with GUI and MySQL database are implemented. This program is implemented by C# language. Through ZigBee wireless transmission module, the management unit can receive and record BP and HR values from the wireless BP monitor for every measurement. With this GUI, user can easy to trace their past measurement records. For long-term personal BP management, this management system can record every measurement result, and show a line chart to express the BP variation on a specific period, such as a week or a month. It is helpful to observe personal BP values variation. This BP measurement program lets user to store the data into the database and perform a BP management. Users and doctors are easily to know the BP statistics, and it can help to observe the treatment effects and save the treatment resources.
B. Blood Pressure Measurement and Calibration Methods BP calculation is finished on the ARM platform, which uses the digital data transformed from the DC and AC signals of cuff pressure. According to the oscillometric method, the peak-to-peak value for each AC pulse should be detected during the deflation. We developed a simple threshold-comparing method to perform peak detection. The DC cuff pressure value on the position that has maximum peak-to-peak (Pmax) AC pulse is defined as the mean BP (MBP). Fig. 4 shows the peak detection results for each AC pulse and the DC and AC waveforms of cuff pressure in once measurement.
A Fluke CuffLink non-invasive blood pressure (NIBP) simulator is used to verify and calibrate the measuring results in this paper. The CuffLink simulator offers a quick, reliable, and consistent way to evaluate the operation and performance of oscillometric NIBP signals. With user-programmable selections, the CuffLink will simulate the full range or normal, hypertensive, and hypotensive dynamic NIBP waveforms.
According to our test results, we got the SBP value is corresponding to the position that the peak-to-peak value of AC pulse is around 0.45 Pmax, and the DBP value is corresponding to the position that the peak-to-peak value of AC pulse is around 0.75 Pmax. Fig. 4 also demonstrates the detected results.
Fig. 4. DC and AC signals of cuff pressure and peak searching results.
III. RESULTS A. Wireless Blood Pressure Monitor
In Fig. 5, except the SBP, DBP and HR are shown on the LCD display of ARM platform. The green LED is also lighting to indicate normal BP. User is easier to understand their BP situation via the LED colors.
B. GUI on the Management Unit
Fig. 6 shows the GUI on the management unit. There are four main functions on this GUI:
1) Query: For user to perform database query. When they select one of IDs, they can see this ID’s past measuring information. For example, the table on the right hand side of Fig. 6. The information includes SBP, DBP, and HR for each measuring time. On the left hand side, the line charts for the SBP, DBP, and HR are also shown. The variation of these parameters can clear to display.
2) UART setting: For setting the UART communication protocol of the ZigBee wireless transmission module.
3) Data export: The data of database can be exported and saved as a text file format.
4) Data import: The data of database can be imported from a saved file.
C. Blood Pressure Measuring Results
TABLE II shows the measuring results. We measured four kinds of pressure values from CuffLink; each pressure value has been measured 5 times. The results show the bias of SBP is ≤ 1 mmHg, precision of SBP is ≤ 1.643 mmHg and the bias of DBP is ≤ 1.4 mmHg, precision of DBP is ≤ 1.788 mmHg.
The bias is the average of the differences between the CuffLink and our measuring results, and the precision is the standard deviation of the differences between CuffLink and our measuring results.
Fig. 5. Measuring results are shown on the LCD and LEDs.
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TABLE II. BPMEASURING RESULTS
In clinical test, there were 26 volunteers have been tested;
the range of age is from 21 to 50 years old. The SBP range is from 94 mmHg to 142 mmHg, and the DBP range is from 57 mmHg to 92 mmHg by auscultatory method. The results show the bias of SBP is ≤ 1.846 mmHg, precision of SBP is ≤ 3.085 mmHg and the bias of DBP is ≤ 0.077 mmHg, precision of DBP is ≤ 2.529 mmHg. The bias is the average of the differences between the auscultatory method and our measuring results, and the precision is the standard deviation of the differences between auscultatory method and our measuring results.
IV. DISCUSSION AND CONCLUSION
A wireless BP monitoring system was designed and implemented, including an ARM-based BP monitor with ZigBee transmission interface and a PC-based management unit with GUI and database. The accuracy of BP measurement was verified and calibrated by a CuffLink non-invasive BP simulator. This system provides users an easy-to-use interface and simple BP management environment. The ZigBee wireless interface provides a convenient and low-power consumption method for data transmission. These personal measuring information including SBP, DBP, HR, measuring time and date can be recorded on the database. Through the GUI on management unit, users can easy and clear to see their past BP variation.
The measurement information is also very useful for the medical staff to understand the situation of patient in the past.
Although a preliminary clinical test results have been done.
In order to get a more robust BP measurement method, we still need to verify in more cases, such as arrhythmia.
For use of ZigBee module, the ZigBee data transmission is only tested in a peer-to-peer environment. Now we are going to test them on a completely ZigBee wireless network and also working to connect the UZ2400 to ARM platform directly by SPI interface. Besides, we will also do more further research in comparison with Bluetooth and ZigBee.
ACKNOWLEDGMENT
The authors would like to thank professor Wen-Tzeng Huang and his students for their assistance in providing the ZigBee modules for this research.
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Fig. 6. Graphic user interface on the management unit.
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