Development of the defecation pacemaker using artificial muscle

1.自然排便时结肠和肛门直肠的运动模式：(1)结肠巨大收缩向直肠的迁移(2)直肠舒缩顺序(3)肛门括约肌松弛在排便过程中起重要作用。结肠和肛门直肠对第一或第二骶神经电刺激的反应(1)结肠有向远端传播的收缩。(2)直肠松弛或收缩。(3)肛门内括约肌松弛。这些反应类似于自发排便时观察到的运动模式。智能凝胶作为人工肛门括约肌的可能性该智能凝胶是由丙烯酸甲酯和丙烯酸硬脂酯自由基聚合而成。在38ﾟC温度变化下，凝胶的力学性能呈现可逆的转变。在35ﾟC时，该凝胶的弹性和弹性分别很高和很低，但在40ﾟC时，它可以通过较低的力得到很高的伸长率。用这种凝胶制成直径2.0厘米、长2.0厘米的管状人工肛门括约肌。狗的结肠被拉了出来。结肠的巨大收缩推动排泄物，并扩大人工括约肌，使其在摄氏40度的温度下排出。当结肠排空时，括约肌恢复到原来的形状。在35ﾟC的温度下，收缩不能使凝胶变宽，内容物也不会被排出。这些发现提出了两种可能的系统来控制排便和保持可控性。(1)对于有中枢神经系统问题的患者，使用骶神经刺激器来诱导排便。(2)起搏系统，它可以检测到结肠的巨大收缩，并同时为丧失肛门直肠功能的患者加热凝胶。

1. Motility patterns of the colon and anorectum during spontaneous defecation.(1) Migration of giant contraction of the colon to the rectum (2) rectal relaxation-contraction sequence (3) anal sphincter relaxation play important roles during defecation.2. Responses of the colon and anorectum to the first or second sacral nerve electric stimulation(1) The colon shows contractions propagated distally. (2) The rectum isrelaxed or contracted. (3) The internal anal sphincter is relaxed. These responses are similar to the motility patterns observed during spontaneous defecation.3. Possibility of the intelligent gel as an artificial anal sphincter The intelligent gel is prepared by the radical polymerization of methylacrylate and stearylacrylate. It exhibits the reversible transition of mechanical properties by the change of temperature at 38ﾟC.While the modulus and elasticity of this gel is very high and low, respectively, at 35ﾟC, it can be extended highly by the low force at 40ﾟC.Namely the intelligent gel can show the similar mechanical behavior as the muscle. A tube shaped artificial anal sphincter 2.0 cm in diameter ; 2.0 cm long is made of the gel. The canine colon is pull through it. The giant contractions of the colon propel the fecal material and widen the artificial sphincter to evacuate it at a temperature 4OﾟC.The sphincter returns to the original shape when the colon is emptied. The contraction fails to widen the gel and the contents is not expelled at a temperature 35ﾟC.These findings suggest two possible systems to control defecation and to maintain continence.(1) The sacral nerve stimulator to induce defecation for the patients with central nervous system problems.(2) The pacemaker systems, which detect the giant contraction of the colon and heat the gel simultaneously for the patients who, loosed the function of the anorectum.