Mintchev M P, Bowes K L
Department of Surgery, University of Alberta, Edmonton, Canada.
Med Biol Eng Comput. 1998 Jan;36(1):7-10. doi: 10.1007/BF02522850.
The impact of the dimensions of the stomach on cutaneous recordings of gastric electrical activity (GEA) has not been adequately studied. The stomach was represented as a truncated conoid in a spherical coordinate system. The gastric electric field was modelled using a previously described methodology. Electrical potentials were calculated from sets of points simulating standard cutaneous recordings. The frequency of the signals was maintained at 3 cycles min-1 (period of repetition: 20 s), while the velocity of propagation of the depolarisation waves was reduced relative to the reduction in gastric dimensions. The signals were digitally contaminated with a random artificial artefact with a constant amplitude range of 0.2 mV, while the dimensions of the conoid (the circumferential radii and the length of the central axis) were decreased by factors of 1.5, two, four, six and eight. Simulated EGG signals were evaluated quantitatively. Simulated EGG records contaminated with random signals recorded from stomachs with decreasing dimensions exhibited non-linearly increasing standard deviations (p < 0.001). Randomly contaminated EGGs calculated from stomachs with dimensions reduced four, six and eight times were abnormal according to previously established quantitative criteria. Computer modelling indicated that gastric dimensions can significantly influence the validity of EGGs. These findings could be particularly important in a paediatric electrogastrography.
胃的尺寸对胃电活动（GEA）皮肤记录的影响尚未得到充分研究。在球坐标系中，胃被表示为一个截头圆锥体。采用先前描述的方法对胃电场进行建模。从模拟标准皮肤记录的点集计算电势。信号频率保持在3个周期/分钟（重复周期：20秒），而去极化波的传播速度相对于胃尺寸的减小而降低。信号被数字污染，加入幅度恒定在0.2mV的随机人为伪迹，同时圆锥体的尺寸（圆周半径和中心轴长度）分别减小1.5倍、2倍、4倍、6倍和8倍。对模拟的胃电图（EGG）信号进行定量评估。从尺寸不断减小的胃记录的、被随机信号污染的模拟EGG记录显示标准差呈非线性增加（p<0.001）。根据先前确立的定量标准，从尺寸减小4倍、6倍和8倍的胃计算出的随机污染EGG是异常的。计算机建模表明，胃的尺寸可显著影响EGG的有效性。这些发现可能在儿科胃电图检查中尤为重要。
