Impedance at ST36, ST19, ST21 and Ren12 while drinking chilled water

The experiment was intended to measure any change in impedance on key stomach-related acupoints that occur when the subject drank chilled water on an empty stomach.

To monitor the impedance, it was decided to use an intermittent signal, to rule out the possibility that a continuous signal applied on key acupoints affects the stomach function and so provides misleading results.

THE RESULTS
Most of the acupoints on the body are repeated in pairs, on the left and right. It is usually stated that both instances of these acupoints have the same effect. However, the left and right ST36 plots, show different activity. This pattern is often seen in this project’s experiments, which suggests that the left and right acupoint reflect different aspects of an organ’s function.

The impedance at both the left and right ST36 acupoints moves in contrary motion, suggesting that this pattern is a genuine reflection of the related organ’s function, rather than being artefact, which would produce similar motion in the impedance changes on two locations only 6mm apart.

Impedance of the right ST21 acupoint shows a sharp drop immediately after the start and end of the subject drinking the chilled water. Since samples were only taken once every 4s, there is not enough detail to show any response accurately. Nonetheless, there seems to be a clear response in this acupoint’s impedance. And again, the trend of the two traces moves in contrary motion, suggesting that the features are a genuine reflection of the related organ’s function, rather than being artefact.

The Ren12 plots move in contrary motion, but apart from this, there is not enough detail to be able to confidently identify any response in relation to the markers, except for a contrary motion feature at 160s, some 15s after the second marker.

The left ST19 acupoint registered a distinct drop in impedance after the first swallow, which is less evident in the +6mm location. But again, the 4s sample rate does not provide enough detail to make confident observations about the degree of the response, nor its delay after the first swallow. The right ST19 acupoint displayed a different response to the left; the right’s response was a gradual increase in the gradient between the acupoint and the +6mm location. Again, this follows the pattern of the left and right acupoint perhaps reflecting a different aspect of the related organ.

The results were comparable to those obtained when using a continuous signal, which suggests that using a continuous signal does not stimulate the acupoints unduly and hence provide misleading results, though this possibility should always be born in mind.

This experiment has been redesigned to use a continuous signal, sampled at the rate of 1000 samples per second, so that the responses can be captured in more detail. The subject also reported an ache centred on Ren12, which was induced by drinking the chilled water, and this will also be monitored in the follow-up experiment.

本实验旨在测量受试者空腹饮用冷水时，胃部相关关键穴位的阻抗变化情况。

为监测阻抗变化，本实验决定采用间歇式信号，以排除连续信号作用于关键穴位后影响胃部功能、进而导致结果出现误导性偏差的可能性。

实验结果
人体多数穴位均左右成对分布，传统观点认为此类穴位的左右两侧功效一致。然而本次实验中左右足三里（ST36）的信号曲线呈现出不同的活性表现。该现象在本项目的实验中并非首次出现，提示左右两侧穴位或许反映了对应脏器功能的不同侧面。

左右两侧足三里（ST36）的阻抗变化呈反向运动趋势，提示该模式确为对应脏器功能的真实反映，而非实验伪迹（artefact）——因为若为伪迹，相距仅6mm的两处位置的阻抗变化应当呈现相似趋势。

右侧梁门（ST21）的阻抗在受试者开始饮用冷水及饮用结束时均出现显著下降。由于采样间隔为每4秒一次，无法精准捕捉完整的响应细节，但该穴位阻抗的响应趋势仍较为明确。同样，两条信号曲线呈反向运动趋势，提示该特征确为对应脏器功能的真实反映，而非实验伪迹。

中脘（Ren12）的信号曲线呈反向运动趋势，除此之外，仅在160秒处（距第二个标记点约15秒）出现一处反向运动特征，并无足够细节可明确识别与其他实验标记相关的响应。

左侧胃经19穴（ST19）在首次吞咽后出现明显的阻抗下降，该变化在偏移6mm的对照位点上表现较弱。但受限于4秒的采样间隔，无法准确判断响应幅度及首次吞咽后的响应延迟。右侧ST19的响应模式与左侧存在差异：其阻抗与6mm对照位点间的梯度呈逐渐升高趋势。该现象同样提示左右两侧穴位或可反映对应脏器功能的不同侧面。

本次实验结果与采用连续信号所获结果相近，提示使用连续信号并不会过度刺激穴位并导致结果出现误导性偏差，但仍需始终警惕该可能性的存在。

本实验已重新设计，将采用采样率为1000样本/秒的连续信号进行数据采集，以更细致地捕捉响应细节。受试者报告称饮用冷水后出现以中脘（Ren12）为中心的痛感，该现象也将在后续实验中进行监测。