Biomechanical properties of the rectal wall were studied in 17 healthy adult volunteers (nine men and eight women). With impedance planimetry it is possible to obtain simultaneous measurements of pressure and rectal cross sectional area (CSA) during balloon inflations. Rectal distensions were done with an intraluminal balloon using specified pressures up to 40 cmH2O above baseline rectal pressure. Balloon inflation elicited a phase of rapid increase in rectal CSA followed by a phase of slow increase until a steady state was reached. Steady state occurred within 67 to 140 seconds with the shortest period at the highest distension pressures. Steady state rectal CSA values had a non-linear relation to increasing distension pressure. Rectal CSA values in women showed a tendency of being slightly higher than male values at all pressure steps with a significant difference at 3 and 5 cm H2O. Biomechanical parameters were calculated from rectal CSA pressure relations. Circumferential wall tension increased in a linear way. Rectal compliance decreased in a non-linear way with no further decline between 30 and 40 cmH2O. The pressure elastic modulus increased steeply until a distension pressure of 35 cmH2O with no further increase to 40 cmH2O. This suggests that rectal tone is reduced as the muscle fails to resist further distension at 35 cmH2O and higher pressures. Impedance planimetry offers new possibilities for investigation of anorectal physiology through the study of segmental biomechanical wall properties of the human rectum.
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机译：在17名健康的成年人志愿者（9名男性和8名女性）中研究了直肠壁的生物力学特性。利用阻抗平面测量法，可以在球囊充气期间同时获得压力和直肠横截面积（CSA）的测量值。使用管腔内球囊，使用比基线直肠压力高40 cmH2O的特定压力进行直肠扩张。球囊膨胀引起直肠CSA迅速增加，然后缓慢增加直至达到稳态。稳态在67至140秒内发生，在最高扩张压力下的时间最短。稳态直肠CSA值与扩张压力呈非线性关系。在所有压力阶跃中，女性的直肠CSA值均显示略高于男性的趋势，在3 cm和5 cm H2O时差异显着。由直肠CSA压力关系计算生物力学参数。周壁张力以线性方式增加。直肠顺应性以非线性方式下降，在30至40 cmH2O之间没有进一步下降。压力弹性模量急剧增加，直到35 cmH2O的膨胀压力，不再增加到40 cmH2O。这表明，由于肌肉无法抵抗在35 cmH2O和更高压力下的进一步扩张，直肠音调会降低。阻抗平面法通过研究人类直肠的节段生物力学壁特性，为肛肠生理学研究提供了新的可能性。
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