title: Bioelectrical impedance analysis for body composition: clinical evaluation in general surgical patients.
abstract: Body composition was measured in 112 surgical patients and eight normal subjects by bioelectrical impedance analysis (BIA), and the results compared with our standard five-compartment method utilizing in vivo neutron activation analysis and tritium dilution space to measure fat-free mass and total body water. In a population with a mean fat-free mass of 49.2 kg by the latter method, BIA underestimated fat-free mass by 1.3 kg, with a standard deviation (SD) of 4.0 kg. Total body water was overestimated by 0.5 liter, with SD of 0.47 liter, when compared to a mean tritium dilution space of 36.7 liter. Changes in total body water which occurred over a treatment period of at least 1 week were also measured by the two methods. The change as measured by isotopic dilution could be estimated from the change as measured by BIA with a standard error of 2.25 liter. Although the results suggest that BIA should not be used as a research tool, it is concluded that in clinical practice, when nutrient requirements are being estimated, fat-free mass measured by BIA may have a useful place.
authors.affiliation: University Department of Surgery, Auckland Hospital, New Zealand.
authors.forename: D
authors.initials: D
authors.lastname: Schroeder
authors.forename: P M
authors.initials: PM
authors.lastname: Christie
authors.forename: G L
authors.initials: GL
authors.lastname: Hill
mesh_terms: D000293:Adolescent; D000328:Adult; D000368:Aged; D000369:Aged, 80 and over; D001823:Body Composition; D015992:Body Mass Index; D003720:Densitometry / Q000295:instrumentation; D004553:Electric Conductivity; D005260:Female; D006801:Humans; D008297:Male; D008875:Middle Aged; D009751:Nutritional Requirements; D012984:Software; D013514:Surgical Procedures, Operative