生物电阻抗方法测量液体胃排空的研究

Liquid gastric emptying measurement by an electrical bio-impedance technique

目的:为寻找方便、有效的无损伤胃排空测量手段,尝试建立一种生物电阻抗测量新方法以获取液体胃排空曲线,测量半排空时间。方法:研制了4电极法电阻抗胃排空测量系统,系统由正弦信号发生器、恒流源、电极、前置放大器、解调滤波电路、数据采集单元和上位PC机构成。进行了24例正常人液体胃排空实验,年龄20～21岁。上午空腹,试餐为37℃纯净水400mL,测量时间约30min。通过阻抗胃排空曲线计算半排空时间。受试者对实验均知情同意。结果:所有健康志愿者的阻抗胃排空曲线均显示饮水前基础阻抗稳定,在饮水400mL后阻抗急剧升高,然后先快速下降,再缓慢变化,趋近基础阻抗值。24例纯净水胃排空实验的半排空时间均值为(8.78±1.76)min。结论:胃阻抗法虽然受到胃液分泌、试验餐成分等多种因素的影响,但是选用对胃内影响较小、电导率低的非营养性液体可以获得阻抗信号和胃容积变化的对应关系。电阻抗法能实现液体胃排空信号的提取,为临床胃排空功能研究提供一种无创测量的新途径。

AIM： To seek a convenient effective non-invasive gastric emptying way, we develop a new approach based on bio-impedance technology to obtain the liquid gastric emptying curve and measure the half of gastric emptying time. METHODS： An impedance measurement system using four-electrode method has developed. The measurement system consists of sine signal generator, constant-source, electrodes, preamplifier, demodulation/filter circuit, data acquisition system and a computer. Twenty-four healthy volunteers （20 to 21 years old）, fasting breakfast, drunk 400 mL of pure water with 37 ℃. The human gastric emptying test lasted about 30 minutes. The half gastric emptying time （GET/2） was calculated by the gastric emptying curve of impedance. All subjects signed the informed consent. RESULTS： The base impedance was constancy in fasting for all volunteers. The amplitude of impedance was step up sharply after drinking 400 mL water, and then decreased quickly, at last slow-moving step down to the base impedance. The average of GET/2 was （8.78± 1.76） minutes in the experiments of 24 samples. CONCLUSION： The new approach based on bio-impedance technology is influenced by many factors such as gastric secretion, components of test meal. But the non-nutrient fluid that has low electric conductivity and has no impact on stomach can be employed to investigate the relationship between the emptying curve of impedance and gastric volume. The method can extract gastric emptying signal, accomplish gastric bio-impedance information and provide a non-invasive method to investigate gastric emptying function in clinic.