An Internet-based blood pressure monitoring system for patients Ishak Bin Aris*, A A E Wagie*, Norman Bin Mariun* and A B E Jammal { *Department of Electrical and Electronic Engineering, University Putra Malaysia; { Faculty of Medicine and Health Sciences, University Putra Malaysia, Selangor, Malaysia Summary We developed a personal blood pressure monitoring system for patients with hypertension or hypotension. The system can be used to measure a patient’s blood pressure at home and to transmit the data automatically to a hospital database via the Internet. The accuracy of blood pressure readings using the system was assessed by comparison with readings from a standard digital sphygmomanometer in four subjects. The measurement error for the systolic readings was 1.7–2.7% and for the diastolic readings 2.7–3.2%. The system therefore appears to be a promising means of assessing blood pressure remotely. Introduction ............................................................................... Telemedicine enables the electronic transfer of medical data (e.g. images, sounds, text) by one of several means, such as the Internet, an intranet, satellite links or the telephone network. The Internet represents an almost ubiquitous communications system and recent advances in Web-browser technology have made it a major communications tool. For example, the World Wide Web can now be used as a telemedicine communications channel 1 . With it, a computer running standard, low-cost applications can send and receive medical information from almost anywhere in the world 2 . Hypertension and hypotension are common diseases in Malaysia, as elsewhere. If not treated, they predispose the patient to more serious conditions, such as heart disease and stroke. Regular blood pressure monitoring at home can be helpful in the management of these diseases. The data can be used to evaluate the patient’s condition and to indicate the need for treatment. Systolic blood pressure is the peak pressure while the heart is contracting. The diastolic reading represents the blood pressure when the heart is resting between beats. For example, 122/76 mmHg indicates that the systolic reading is 122 mmHg (162hPa) and the diastolic reading is 76mmHg (101hPa). A blood pressure reading of less than 140/90 is considered normal for adults, while anything above this is high 3,4 . A number of surgical (invasive) and non-surgical (non-invasive) methods can be used to measure blood pressure, with various degrees of accuracy and suitability for the clinical situation. The invasive catheterization technique is not suitable for measuring blood pressure generally 5 and non-invasive methods are normally preferred 4,6–9 . We have therefore developed an Internet-based blood pressure monitoring system for measuring patients’ blood pressure regularly at home. Methods ............................................................................... The system consisted of both hardware and software components. Blood pressure was measured with an automatic sphygmomanometer. An eight-bit serial interfacing card was developed to link the output of the blood pressure monitoring device with a PC. As shown in Fig 1, the hardware parts of the interfacing card included an analogue/digital (A/D) converter (ADC0804), a universal asynchronous receiver transmitter (CDP6402), a clock generator (74HC4060) Preliminary communication ..................................................................................................................................................... " Journal of Telemedicine and Telecare 2001; 7: 51–53 Accepted 24 September 2000 Correspondence: Dr Ishak Bin Aris, Department of Electrical and Electronic Engineering, Faculty of Engineering, University Putra Malaysia, 43400 Serdang, Selangor, Malaysia (Fax: +603 8948 8939; Email: ishak@eng.upm.edu.my)