VARIATIONS OF BODILY COMPOSITION BY BIOEL ECTRIC IMPEDANCEMETRY FOLLOWING MAJOR SURGERY

Body water variations are traditionally measured postoperatively by fl uid balance and body weight. Bioelectrical impedance assessment permit s the evaluation of body composition, i.e. lean body mass, body fat an d total body water. We compared the traditional method (body weight an d fluid balance) with bioelectrical impedance assessment while estimat ing body water. Body weight, fluid balance, resistance, reactance, lea n body mass, body fat, total body water, triceps skinfold and total pr otein blood level were measured prospectively (preop, and on days 1, 3 and 5 postop) in 30 patients admitted for major surgery (thoracic, ab dominal or vascular). The results suggest that body composition change d significantly with time (p < .05); in all 3 surgical groups. There w as a low correlation between total body water measured by bioelectrica l Impedance and fluid balance. Bioelectrical impedance assessment is s ensitive to body water changes but appears to overestimate these varia tions compared to the traditional method.