Fusion Physiological Sensing System for Healthcare

Introduction

In the super-aging society, daily healthcare monitoring is well recognized as important for the early diagnosis and timely treatment of lifestyle-related diseases, especially for inpatients and/or outpatients living with the chronic disorders that require acute life support or chronic therapies. Moreover, medical care and rehabilitation efforts at home are also increasingly important. Some platforms and methods of information transfer (Continua Health Alliance, 2006) have been developed for daily healthcare monitoring, and there are commercially available devices for the home healthcare that are networked. However, the sensing techniques for obtaining physiological information are not focused. For example, cumbersome devices may obstruct continuous monitoring, and, consequently, useful data for checking health condition cannot be obtained, even if information and communications technology (ICT) such as the network technology or the platform mentioned above are used to the information transfer. Thus, in this paper, we have focused on new bioinstrumentation techniques and their applicability for the daily healthcare monitoring by fusion with the ICT.

First, non-invasive monitoring is necessary for daily healthcare and many commercially available devices, such as blood pressure (BP) monitors, electrocardiogram monitors, etc., are used conventionally as a medical use. However, the demands for new technologies with which to carry out the long-term and continuous monitoring of health conditions have been increasing. In particular, as contributions towards the development of the most desirable healthcare monitoring, two promising systems, ambulatory and non-conscious physiological measurement, have recently been developed through modern technological advances.

Regarding ambulatory physiological measurement, the Holter-type electrocardiogram (ECG) recorder (Holter, 1961) and the portable sphygmomanometer, called the ambulatory BP monitor (ABPM), which is based on the auscultation and/or the cuff-oscillometric method (Mauck, Smith, Geddes, & Bourland, 1980; Yamakoshi, K., 1991), are also widely used in clinical medicine to obtain continuous vital signs. However, the conventional methods can only measure intermittent BP. Moreover, modern microelectronics and mechanical technologies have enabled the production of more convenient devices capable of monitoring BP, ECG, respiration, etc. For example, some wearable instruments that monitor ECG or respiration using textile electrodes or woven sensors made of smart material with conductive and piezoresistive properties were reported (Bourdon, et al., 2005; Paradiso, Loriga, Taccini, Gemignani, & Ghelarducci, 2005; Rantanen, et al., 2002). Additionally, for ambulatory monitoring, we developed some systems capable of measuring BP both at a specified interval (Yamakoshi, K., Kawarada, Kamiya, Shimazu, & Ito, 1985) and on a beat-by-beat basis (Tanaka & Yamakoshi, K., 1996; Yamakoshi, K., 2004) using volume-oscillometric and volume-compensation methods, respectively (Yamakoshi, K., Shimazu, & Togawa, 1980; Yamakoshi, K., Shimazu, Shibata, & Kamiya, 1982). They can also combine these measurements of BP with other hemodynamic variables, including the cardiac output (CO), using electrical admittance methods (Ikarashi, Nogawa., Tanaka, & Yamakoshi, K., 2007; Ito, Yamakoshi, K., & Togawa, 1976; Yamakoshi, K., Nakagawara, & Tanaka, 1997). It is apparent that the concurrent acquisition of BP and CO data on a beat-by-beat basis enables the detailed analysis of hemodynamic responses and the autonomic regulation of the cardiovascular system in response to various kinds of daily activities.