Suzuki H, Rounds J D, Wilmore D W
Department of Surgery, Brigham and Women's Hospital, Harvard Medical School, Boston, Massachusetts 02115, USA.
J Surg Res. 1996 Sep;65(1):63-9. doi: 10.1006/jsre.1996.0344.
There is need for a rapid, noninvasive, inexpensive yet accurate bedside technique to measure body composition. Bioelectrical impedance analysis measures the resistance and conductance of a weak electrical current passed through the body. It has been suggested that multifrequency impedance analysis can determine the distribution of fluid between the extracellular and intracellular compartments.
The correlation between the resistance signals obtained from multifrequency bioelectrical impedance measurements and body composition was determined in normal rats ranging from 150 to 400 g in weight. Total body water, body fat, total body sodium, and total body potassium were measured using the carcass analysis technique, and extracellular water was derived from a dilutional marker using sodium bromide. Fat-free mass was calculated as the difference between body weight and body fat, and intracellular water was derived from total body water and extracellular water. Multifrequency bioelectrical impedance was measured at frequencies ranging from 3 to 300 kHz. Resistance at zero frequency and infinite frequency was calculated using the Cole and Cole equation.
Resistance index (i.e., length of the animal2/resistance) was highly correlated with all body compartments (r = 0.879-0.996) at all frequencies. There was also a high correlation among all compartments of the body (r = 0.971--0.999). Because of this high intercorrelation among the body compartments, a specific relationship between the multifrequency bioelectrical impedance signal and a specific compartment was not identified.
Resistance index at any frequency will be correlated with any body compartment in a normal population. The utility of this technique should be determined in situations where there is a disturbance in the relationship between various compartments of the body.
需要一种快速、无创、廉价且准确的床边技术来测量身体成分。生物电阻抗分析测量通过身体的微弱电流的电阻和电导。有人提出，多频阻抗分析可以确定细胞外和细胞内液之间的液体分布。
在体重150至400克的正常大鼠中，测定多频生物电阻抗测量获得的电阻信号与身体成分之间的相关性。使用胴体分析技术测量总体水、体脂、总钠和总钾，并使用溴化钠从稀释标记物中得出细胞外液。无脂体重计算为体重与体脂之间的差值，细胞内液由总体水和细胞外液得出。在3至300千赫的频率范围内测量多频生物电阻抗。使用科尔方程计算零频率和无限频率下的电阻。
在所有频率下，电阻指数（即动物长度的平方/电阻）与所有身体组成部分高度相关（r = 0.879 - 0.996）。身体所有组成部分之间也存在高度相关性（r = 0.971 - 0.999）。由于身体各组成部分之间的这种高度相互关联，未确定多频生物电阻抗信号与特定组成部分之间的特定关系。
在正常人群中，任何频率下的电阻指数都将与任何身体组成部分相关。该技术的实用性应在身体各组成部分之间的关系受到干扰的情况下确定。
