Kurbel Sven, Kurbel Beatrica, Vcev Aleksandar
Department of Physiology, Osijek Medical Faculty, J. Huttlera 4, 31000 Osijek, Croatia.
Med Hypotheses. 2006;67(2):235-9. doi: 10.1016/j.mehy.2006.01.057. Epub 2006 Mar 29.
All gases entrapped in closed body cavities are destined to be partially or completely absorbed. Intestinal gases often accumulate and cause flatulence. This paper proposes a simple concept of intestinal gas occurrence based on our knowledge on gas resorption in other body cavities. Compliance of intestinal and abdominal walls makes pressure in the liquid chyme bubbles near 760 mmHg. Intestinal gases are from three sources. Air can be swallowed, CO2 come from the gastric acid neutralisation and from intestinal bacterial colonies that also produce hydrogen and methane. In continuously mixed liquid chyme, the total pressure of blood gases is similar or lower than in the venous blood (<or=706), well below the bubble forming pressure (>or=760 mmHg). Some local production of bacterial gases with partial pressure of more than 90 mmHg is required, so the resulting small bowel bubbles would contain less than 20% of bacterial gases. If peristaltic mixing of chyme is prevented by an obstacle, local pressures of bacterial gases build up, form bubbles that fuse and finally make X-ray visible aeroliquid levels. Bacterial gases make almost 3/4 of the flatulence. Formation of bubbles destined to become flatulence might depend on altered rheological condition of the large bowel content, with local abundant production of bacterial gases near bacterial colonies. Gases are unable to diffuse rapidly through the dense liquid content and local accumulation allows formation of bubbles mainly of bacterial gases. Their pressure can be higher 760 mmHg, since they are stretching the thick content. Poor diffusion of gases keeps them almost free of blood gases and their entrance makes them bigger. As the content moves along the colon, the content is becoming more solid and gases are becoming entrapped in large bubbles. Some blood and bacterial gases are absorbed and exhaled, but the remaining quantity has no other escape except flatulence. Flatulence rich in bacterial gases might be the price for the large bowel water reabsorption. It seems that beside the peroral use of antibiotics active in the colon, little can be done to reduce flatulence.
封闭体腔内截留的所有气体都注定会被部分或完全吸收。肠道气体常常积聚并导致肠胃胀气。本文基于我们对其他体腔气体吸收的了解，提出了一个关于肠道气体产生的简单概念。肠壁和腹壁的顺应性使得液体食糜泡内的压力接近760毫米汞柱。肠道气体有三个来源。空气可被吞咽，二氧化碳来自胃酸中和以及肠道细菌菌落，这些细菌菌落还会产生氢气和甲烷。在持续混合的液体食糜中，血气的总压力与静脉血中的相似或更低（≤706），远低于气泡形成压力（≥760毫米汞柱）。需要一些局部产生的分压超过90毫米汞柱的细菌气体，因此产生的小肠气泡中细菌气体含量将少于20%。如果食糜的蠕动混合因障碍物而受阻，细菌气体的局部压力就会升高，形成气泡并融合，最终使X射线可见气液平面。细菌气体几乎占肠胃胀气的3/4。注定会导致肠胃胀气的气泡形成可能取决于大肠内容物流变学状况的改变，在细菌菌落附近局部大量产生细菌气体。气体无法迅速扩散通过浓稠的液体内容物，局部积聚使得主要由细菌气体形成气泡。它们的压力可能高于760毫米汞柱，因为它们在拉伸浓稠的内容物。气体的扩散不良使它们几乎不含血气，而血气的进入会使它们变大。随着内容物沿结肠移动，内容物变得更加固体化，气体被困在大气泡中。一些血液和细菌气体被吸收并呼出，但剩余的量除了通过肠胃胀气排出外没有其他出路。富含细菌气体的肠胃胀气可能是大肠重吸收水分的代价。似乎除了口服对结肠有活性的抗生素外，几乎没有什么办法可以减少肠胃胀气。
