___________________________________________ 0-7803-8560-8/04/$20.00©2004IEEE ANALYSIS OF BIOELECTRICAL TISSUE CONDUCTIVITY IN MALAYSIAN ADULTS Fatimah Ibrahim 1 , Wan Abu Bakar Wan Abas 1 , Mohd Nasir Taib 2 1 Department of Biomedical Engineering, Faculty of Engineering, University of Malaya, 50603 Kuala Lumpur, Malaysia. 2 Facuty of Electrical Engineering, Universiti Teknologi Mara, 40450 Shah Alam, Selangor, Malaysia. ABSTRACT This paper presents the bioelectrical tissue conductivity (BETC) analysis of Malaysian adults using bioelectrical impedance. A total of 142 subjects (91(64.1%) female and 51(35.9%) male) with no past medical history were studied. The BETC was measured using phase angle ( ), resistance (R), reactance (Xc) and body capacitance (BC). There is a significant difference (P<0.001) in the BETC mean values of the subjects. The mean phase angles measured were 7.4 0.8 and 6.3 0.6 with corresponding mean body capacitances of 818 158pF and 557 101pF for male and female, respectively. The results show that and BC mean values are higher in the male than the female. However, the female R (635 71.5 ) and Xc (69.9 8.4 ) were higher than the male R (504 63.4 ), and Xc (64.6 6.8 ), respectively. These results show that the BETC values in Malaysian adults are in agreement with the normal healthy subjects at large. Index Terms—Bioelectrical, tissue conductivity, Bioelectrical impedance, Malaysian 1. INTRODUCTION Measurement of body composition is important to assess the nutritional status in both normal individuals and hospital patients. Many techniques are currently available for estimating body composition, but all are indirect [1]. Recently, a new and non-invasive technique known as bioelectrical impedance analysis (BIA) has been used to estimate body composition in adult human [2-4] and also to assess changes in electrical tissue conductivity that indicates altered body composition. However, most of these studies have been carried out in the developed countries [4-6]. To date, no known literature describes the body composition and bioelectrical tissue conductivity (BETC) in Asian population including Malaysia. In this study, we focused on the BETC measurements (reactance (Xc), resistance (R), phase angle ( ), and body capacitance (BC)) in BIA for the adult’s Malaysian population. Hence, this paper will be the first attempt to describe the BETC reference values for the Malaysian adults, hence, which may also be useful as a guideline or reference for the general Asian population. 2. BIOELECTRICAL IMPEDANCE ANALYSIS Bioelectrical impedance analysis (BIA) is a technique to estimate body composition and measures the impedance or opposition to the flow of an electrical current through the body fluids [7-9]. The impedance of biological tissue comprises two components, the resistance (R) and the reactance (Xc). In the body, highly conductive lean tissue contains large amounts of water and conducting electrolytes, and represents a low resistance electrical pathway. Fat and bone, on the other hand, are poor conductors or high resistance electrical pathway with low amounts of fluid and conducting electrolytes. Reactance (Xc) is also known as capacitive reactance when describing biological tissues is the opposition to the instantaneous flow of electric current caused by capacitance [8-10]. Hence, the human body is a circuit of resistors and capacitors. Although the electrical circuit, which represents the body, is very complex, it can be reduced to the following model as shown in Fig. 1. Fig. 1: Equivalent Electrical circuit model of the human body. where, Ro = Fluid component of the body which is outside (extra cellular) the cells. R o R i C m 680