Sartorio A, Malavolti M, Agosti F, Marinone P G, Caiti O, Battistini N, Bedogni G
Malattie Metaboliche III e Laboratorio di Endocrinologia Sperimentale, Istituto Auxologico Italiano IRCCS, Piancavallo, Italy.
Eur J Clin Nutr. 2005 Feb;59(2):155-60. doi: 10.1038/sj.ejcn.1602049.
To measure body water distribution and to evaluate the accuracy of eight-polar bioelectrical impedance analysis (BIA) for the assessment of total body water (TBW) and extracellular water (ECW) in severe obesity.
Cross-sectional study.
Obesity clinic.
In all, 75 women aged 18-66 y, 25 with body mass index (BMI) between 19.1 and 29.9 kg/m(2) (ie not obese), 25 with BMI between 30.0 and 39.9 kg/m(2) (ie class I and II obese), and 25 with BMI between 40.0 and 48.2 kg/m(2) (ie class III obese).
TBW and ECW were measured by (2)H(2)O and Br dilution. Body resistance (R) was obtained by summing the resistances of arms, trunk and legs as measured by eight-polar BIA (InBody 3.0, Biospace, Seoul, Korea). The resistance index at a frequency of x kHz (RI(x)) was calculated as height (2)/R(x).
ECW : TBW was similar in women with class III (46+/-3%, mean+/-s.d.) and class I-II obesity (45+/-3%) but higher than in nonobese women (39+/-3%, P<0.05). In a random subsample of 37 subjects, RI(500) explained 82% of TBW variance (P<0.0001) and cross-validation of the obtained algorithm in the remaining 38 subjects gave a percent root mean square error (RMSE%) of 5% and a pure error (PE) of 2.1 l. In the same subjects, RI(5) explained 87% of ECW variance (P<0.0001) and cross-validation of the obtained algorithm gave a RMSE% of 8% and a PE of 1.4 l. The contribution of weight and BMI to the prediction of TBW and ECW was nil or negligible on practical grounds.
ECW : TBW is similar in women with class I-II and class III obesity up to BMI values of 48.2 kg/m(2). Eight-polar BIA offers accurate estimates of TBW and ECW in women with a wide range of BMI (19.1-48.2 kg/m(2)) without the need of population-specific formulae.
测量身体水分分布，并评估八电极生物电阻抗分析（BIA）在评估重度肥胖患者总体水（TBW）和细胞外水（ECW）方面的准确性。
横断面研究。
肥胖诊所。
共75名年龄在18 - 66岁的女性，其中25名体重指数（BMI）在19.1至29.9 kg/m²之间（即不肥胖），25名BMI在30.0至39.9 kg/m²之间（即I级和II级肥胖），25名BMI在40.0至48.2 kg/m²之间（即III级肥胖）。
通过氘水（²H₂O）和溴稀释法测量TBW和ECW。通过将八电极BIA（InBody 3.0，韩国首尔百利达公司）测量的手臂、躯干和腿部电阻相加获得身体电阻（R）。以身高²/R(x)计算x kHz频率下的电阻指数（RI(x)）。
III级肥胖女性（46±3%，均值±标准差）和I - II级肥胖女性的ECW : TBW相似（45±3%），但高于非肥胖女性（39±3%，P<0.05）。在37名受试者的随机子样本中，RI(500)解释了TBW变异的82%（P<0.0001），在其余38名受试者中对所得算法进行交叉验证得到的均方根误差百分比（RMSE%）为5%，纯误差（PE）为2.1升。在同一组受试者中，RI(5)解释了ECW变异的87%（P<0.0001），对所得算法进行交叉验证得到的RMSE%为8%，PE为1.4升。基于实际情况，体重和BMI对TBW和ECW预测的贡献为零或可忽略不计。
BMI值高达48.2 kg/m²的I - II级和III级肥胖女性的ECW : TBW相似。八电极BIA能够准确估计BMI范围广泛（19.1 - 48.2 kg/m²）女性的TBW和ECW，无需特定人群公式。
