Preliminary Study On The Distribution Of Body Fluid By Using Biological Impedance Spectroscopy And Laser Doppler Technique

ObjectiveWhile there has been broad consensus within meridian studies of the lower impedance along the meridian and also the origin of this has been analyzed associating to higher content of interstitial fluid(IF), no further study has taken an insight into the differentiation of contribution made by lower impedance components, namely the intracellular fluid(ICF) and the extracellular fluid(ECF) of which 3/4 is IF and the rest 1/4 is blood. This leads to an uncertain knowledge of the essence of meridians. This study explored the resistance of ECF (Re) and the resistance of ICF(Ri) respectively and the blood perfusion(BP) on the anterior thigh section of the Stomach Meridian line(ST) and the nonmerdian line(NM) to achieve a better understanding of the biological essence of the lower impedance along meridians, thereby exploring the nature of the meridian.To test the validation of the bioimpedance spectroscopy measuring system designed by us, the changes of ECF and ICF were measured respectively during the body position alternations. Afterwards, Re and Ri along ST and NM were gauged by the system and the proportion of ECF along ST and NM were calculated. Finally, combining the difference percentages of BP of ST and NM, the difference percentages of IF of ST and NM could be estimated.Methods1. The bioimpedance spectroscopy techniqueThe bioimpedance spectroscopy measuring system is consisted of a Lock-in amplifier (7280 DSP, made in USA) with a sine signal of 1-100kHz frequency and 50μA output current and a oscillator which ensure a constant output. Two pairs of disposable ECG electrode linked to the constant current source serve as output electrodes and in between are the other pair of disposable ECG electrodes serving as detecting electrodes. The voltage(V) and phase angle(9) of the tested area could be measured under 13 set of frequencies by the bioimpedance spectroscopy measuring system. And then entered the data of V and 0 to the software of MATLABR2011a along with Cole-Cole curve fitting program and the Ri and Re could be get. Finally, ρi and ρe would be reached through the circumference of the calf.2. The Laser Doppler Blood Perfusion Imager techniqueA Laser Doppler Perfusion Imager (PeriScan PIM 2, Perimed Co. made in Sweden,) and LDP12.6 software was used. Parameters setting:NR scan mode, medium scanning precision, 64 x 64 sampling points,5cm× 5cm of the scanning range. The detector of the laser Doppler perfusion imager scanned target sites in dark state, and filed the result. Then calculated the mean blood perfusion of the interested area with LDP12.6 software.Experiment 1 Using the bioimpedance spectroscopy technique to observe the changes of intra-and-extra-cellular fluid during posture alternations15 subjects with average age of 27.93 ± 7.09 were recruited. The experiment was carried out at a constant temperature of 26 ± 1 ℃.Subjects lay supine on a height adjustable bed with their calf exposed for 1.5 hours (each position maintained 0.5 hour).The amplitude and phase angle of the calf were recorded at 30min of horizontal position(HP),20 min and 30 min of 11 ° head up tilt position(HUT),20 min and 30 min 11 °head down tilt position(HDT) under 13 sets of frequencies using multi-frequency bioimpedance techniques. Combining the cole-cole curve fit method and the circumference of the calf, we approximately worked out the resistivity of extracellular fluid (ρe) and intracellular fluid (ρi).Experiment 2 Using the bioimpedance spectroscopy technique to observe the distribution of intra-and-extra-cellular fluid on the Stomach meridian21 subjects with average age of 35.81 ± 11.49 were recruited. The experiment was carried out at a constant temperature of 26 ± 1 ℃.First we lined out the stomach meridian line (ST) and take 5cm from it according to the national standard of acupuncture points location of China. We marked the nonmeridian line (NM) on the venter musculi of the vastus lateralis muscle parallel to the stomach meridian and take 5cm from it(NM). After 30 minutes lying supine, the amplitude and phase angle under 13 sets of frequencies of ST and NM were measured. The computation methods were the same as the first experiment. We approximately worked out the resistivity of extracellular fluid (ρe) and intracellular fluid (ρi).Experiment 3 Blood perfusion measurement of Stomach Meridian by Laser Doppler Perfusion ImagerSubjects and the experimental requirements were the same as the experiment previous. A Laser Doppler Blood Perfusion Imager was used to record the blood perfusion (BP) of ST and NM on the anterior thigh.ResultsExperiment 1 Using the bioimpedance spectroscopy technique to observe the changes of intra-and-extra-cellular fluid during posture alternationsThe changes of the resistivity of the intra-and-extra-cellular fluid during the position alternations had a very significant difference. Since the volume of ECF and ICF are negatively proportional to their resistivity, the results could be formulated as follows:the ECF increased when turning from HP to HUT 20 min while the ECF decreased when turning from HUT to HDT 20 min and it reached its lowest level at HDT 30 min, which was less than that of HP. As for the ICF, it increased when turning from HP to HUT 30 min and decreased when turning from HUT to HDT 30 min, which was less than that of HP. With respect to time factor, the general variation tendency of ECF and ICF under were the Friedman test had a very significant difference(P<0.01).What’s more, the results showed that the variation of ICF lagged behind that of ECF within the position alternation.Experiment 2 Using the bioimpedance spectroscopy technique to observe the distribution of intra-and-extra-cellular fluid on the Stomach meridianThe mean(median±inter-quartile) ρe of ST and NM were 571.6±357.6Ωcm and 666.3±586.7Ωcm, which had a difference percentage of 17.89% and a very significant difference(P<0.01), i.e. there were more extracellular fluid on the Stomach Meridian line we tested than on the nonmeridian line. While the mean ρi of ST and the NM were 461.7±301.4Ωcm and 450.2±527.0Ωcm, which had no significant difference, i.e. there were no significant difference between the intracellular of Stomach Meridian line we tested and that of the nonmeridian.Experiment 3 Blood perfusion measurement of Stomach Meridian by Laser Doppler Perfusion ImagerThe mean BP of ST and NM were 0.471410.1947 and 0.428510.1768 (PU) with a difference percent of 9.1%, which had a very significant difference (P<0.01), i.e. there were more blood perfusion on the stomach meridian we tested than on the nonmeridian line.ConclusionThe Bioimpedance spectroscopy techniquewe used could measure the variation of the intra-and-extra-cellular fluid. This study initially proved that there were more extracellular fluid on the Stomach Meridian line we tested than on the nonmeridian line, while the difference of the intracellular were not significant, which meant there isn’t much difference on the cells as for meridians and it is the extracellular components that make a difference. What’s more, we used the laser doppler techniqueto find out that there was more blood perfusion on the stomach meridian we tested than on the nonmeridian, namely both the interstitial fluid and the blood perfusion were rich on the Stomach Meridian, which accorded well with the conception that meridians are the channel of Qi and blood as well as the classic description of the Stomach Meridian as both rich in Qi and blood and also supported the view of fluid channel of meridians hold by the school embodied by professor Xie Haoran and Zhang Weibo.