Division of Cardiology, Department of Internal Medicine, Medical Research Institute, Pusan National University Hospital, Busan, Korea.
Department of Thoracic and Cardiovascular Surgery, Medical Research Institute, Pusan National University Hospital, Busan, Korea.
J Korean Med Sci. 2019 Aug 5;34(30):e198. doi: 10.3346/jkms.2019.34.e198.
Accurate volume measurement is important in the management of patients with congestive heart failure or renal insufficiency. A bioimpedance analyser can estimate total body water in litres and has been widely used in clinical practice due to its non-invasiveness and ease of results interpretation. To change impedance data to volumetric data, bioimpedance analysers use equations derived from data from healthy subjects, which may not apply to patients with other conditions. Bioelectrical impedance vector analysis (BIVA) was developed to overcome the dependence on those equations by constructing vector plots using raw impedance data. BIVA requires normal reference plots for the proper interpretation of individual vectors. The aim of this study was to construct normal reference vector plots of bioelectrical impedance for Koreans.
Bioelectrical impedance measurements were collected from apparently healthy subjects screened according to a comprehensive physical examination and medical history performed by trained physicians. Reference vector contours were plotted on the RXc graph using the probability density function of the bivariate normal distribution. We further compared them with those of other ethnic groups.
A total of 242 healthy subjects aged 22 to 83 were recruited (137 men and 105 women) between December 2015 and November 2016. The centers of the tolerance ellipses were 306.3 Ω/m and 34.9 Ω/m for men and 425.6 Ω/m and 39.7 Ω/m for women. The ellipses were wider for women than for men. The confidence ellipses for Koreans were located between those for Americans and Spaniards without overlap for both genders.
This study presented gender-specific normal reference BIVA plots and corresponding tolerance and confidence ellipses on the RXc graph, which is important for the interpretation of BIA-reported volume status in patients with congestive heart failure or renal insufficiency. There were noticeable differences in reference ellipses with regard to gender and ethnic groups.
准确的容量测量在充血性心力衰竭或肾功能不全患者的管理中很重要。生物阻抗分析仪可以以升为单位估计总体水量，由于其非侵入性和易于解释结果，已在临床实践中广泛使用。为了将阻抗数据转换为体积数据，生物阻抗分析仪使用从健康受试者数据中得出的方程，这些方程可能不适用于患有其他疾病的患者。生物电阻抗矢量分析（BIVA）的开发是为了通过使用原始阻抗数据构建矢量图来克服对这些方程的依赖。BIVA 需要正常参考图来正确解释个体向量。本研究的目的是构建韩国人的生物电阻抗正常参考向量图。
根据受过训练的医生进行的全面体格检查和病史，对筛选出的明显健康受试者进行生物电阻抗测量。使用双变量正态分布的概率密度函数在 RXc 图上绘制参考矢量轮廓。我们进一步将其与其他种族群体进行比较。
2015 年 12 月至 2016 年 11 月期间，共招募了 242 名年龄在 22 至 83 岁的健康受试者（男性 137 名，女性 105 名）。男性的耐受椭圆中心为 306.3 Ω/m 和 34.9 Ω/m，女性为 425.6 Ω/m 和 39.7 Ω/m。女性的椭圆较宽。韩国人的置信椭圆位于男性和女性的美国人和西班牙人之间，没有重叠。
本研究提供了性别特异性的正常参考 BIVA 图以及 RXc 图上的相应耐受和置信椭圆，这对于解释充血性心力衰竭或肾功能不全患者 BIA 报告的容量状态非常重要。参考椭圆在性别和种族群体方面存在明显差异。
