P1180 RXC GRAPH METHOD: BIA VECTOR IN THE FIRST YEAR OF LIFE

Abstract

Introduction: Bioelectrical impedance analysis (BIA) is a safe, non invasive, portable and inexpensive method which allows to evaluate nutritional state. Its evaluation is possible with BIA vector (BIVA), which is the resultant of two variables: R/H and Xc/H. They are obtained from direct measurements of resistance (R) and reactance (Xc) standardized by the infant’s length (calculated in metres). R and Xc are respectively hydration and cellular mass indicator. Aim: To evaluate R/H and Xc/H’s variations in the RXc Graph in the first year of life and to map out the BIA vector for each month. Methods: A longitudinal study was performed on 41 healty infants aged 0–12 months, seen in a pediatric out-patient department from May 2002 to September 2003. They have been evaluated for growth indexes such as weight, length, cranial circumference, BMI. Bioimpedance parameters (R and Xc) were estimated by a single frequency phase sensitive impedance analyser( Quantum BIA-101Q, Rjl System Akern; Firenze Italy), standardized by the infant’s lenght (R/H; Xc/H), once a month. The bioelectrical impedance vector analysis (BIVA, or BIA vector) has been plotted by bioimpedence values, for each month. Statistical analysis was performed using t-test. Results: We observed a progressive shortening and down-sloping of the impedance vector over successive measurements; all through the growing it leans to origin of the axis.Table 1: R/H - Xc/H in the first year of life (M ± DS)Conclusion: The trend rose from the 1° to the 12° month according to the data reported in literature for the following years until the puberal age. Furthermore the RXc graph could be an efficacious and immediate method for bioimpedance values interpretation in nutritional state evaluation.