How the formation of intestinal obstruction?

Autopsy

Simple complete mechanical intestinal obstruction occurred, over parts of the intestine obstruction expansion. Wall thinning, mucosal erosions and ulcers occur easily. Serous membrane can be torn, the entire wall can be due to blood supply and necrosis, intestinal obstruction most often isolated and empty the following collapses.

Expansion when the bowel paralytic ileus, bowel wall thinning.

Strangulated intestinal obstruction in the early, due to venous obstruction, veins and hair cells in blood vessels can occur bleeding, increased permeability, or even rupture or leakage of blood plasma. At this time intestines internal congestion and edema and purple. Then the arterial blood flow obstruction, thrombosis, intestinal ischemia and necrosis due to, intestinal bacteria and toxins can damage the intestinal wall into the abdominal cavity. Necrosis of the bowel was dark purple, and finally free to break.

Pathophysiology

Obstruction of the major pathophysiological changes as swelling, fluid and electrolyte loss and infection and toxaemia. The extent of these changes depending on the level of obstruction, intestinal obstruction, and whether the length of the blood supply to different obstacles.

(A) of the intestinal swelling

Mechanical intestinal obstruction, the obstruction of the intestine above the swelling due to fluid pneumatosis, bowel obstruction in the first reaction to the increased peristalsis, and strong peristalsis caused by colic. At this point the upper esophageal sphincter relaxation reflex occurred, the patient unconsciously when inhaling air swallowed a large number of gastrointestinal, the lumen 70% of product gas swallow air, mostly nitrogen, can not easily be gastrointestinal absorption, the remaining 30% of the product gas is the intestinal pH and bacteria in and produced by fermentation, or from the Notes to the lumen dispersion CO2, H2, CH4 and other gases. Normal adult gastrointestinal tract daily saliva secretion, gastric juice, bile, pancreatic juice and intestinal fluid of the total of about 8L, most were small intestinal absorption, in order to maintain fluid balance. Obstruction when a large number of liquids and gases to accumulate in the proximal intestinal obstruction expansion, while inflation could inhibit the intestinal mucosa to absorb moisture, and later to stimulate the increased secretion of the intestine that have piled up liquid, so that sexual increase intestinal swelling. In the simple obstruction, the pressure generally lower intestine, is often lower than first 8cmH2O.

However, with the obstruction time, the pressure within the intestine can be achieved even 18cmH2O. Obstruction of the intestine only an average pressure in the 25cmH2O. Obstruction of the intestine when the pressure in the 25cmH2O above average, even higher to 52cmH2O water column. Intestinal wall can increase the pressure within the venous return disorder, caused by bowel wall congestion and edema. Permeability. The pressure continues to increase intestinal blood flow could block the intestinal wall into the simple obstruction to strangulating intestinal obstruction. Intestinal swelling and even make a serious push up the diaphragm, affecting the patient's respiratory and circulatory functions.

(B) the loss of body fluids and electrolytes

Swelling can cause intestinal obstruction pregnant vomiting reflex. When high intestinal obstruction and vomiting frequently, large amounts of water and electrolytes are excreted. Such as pyloric or duodenal obstruction in the upper section, Ouchu excess stomach acid, is easy to produce dehydration and low-chloride potassium alkalosis. Such as obstruction in the duodenum or jejunum on the lower section of the severe loss of bicarbonate. Low intestinal obstruction, vomiting, although far less rare in high positions, but due to the decrease of intestinal absorption increased secretion of fluid volume, obstruction of the intestine in the plot to stay for more than a lot of liquid, sometimes as many as 5 ~ 10L, contains a large number of sodium bicarbonate. The liquid has not yet been eliminated from the body, but can not be closed in the intestine into the blood, equal to the loss of body fluids. In addition, the excessive expansion of influence of intestinal venous return, leading to bowel wall edema and plasma extravasation, in strangulated intestinal obstruction, the blood and plasma loss is particularly serious. Therefore, occurrence of dehydration in patients with multi-oliguria, azotemia and acidosis. Such as dehydration continued, further enrichment of blood, have resulted in hypotension and hemorrhagic shock. Loss of potassium and not into the diet can cause low potassium-induced intestinal paralysis, and then add to the development of intestinal obstruction.

(C) infection and toxaemia

Normal bowel movements so that forward movement of intestinal contents and updated regularly, so the small intestine is sterile, or only a very small number of bacteria. Simple mechanical obstruction of the small intestine, the intestinal bacteria and toxins are also vertical can not be a normal mucosal barrier, which is little risk. If the strangulated obstruction into the beginning of blood flow is blocked, the involved bowel wall blood and plasma exudation to further reduce blood volume, blood flow is blocked and then accelerated ischemic bowel necrosis . Strangulated section of intestine with a large number of bacteria in the liquid (such as Clostridium, Streptococcus, E. coli, etc.), blood and necrotic tissue, bacteria and toxins and the decomposition of blood and necrotic tissue is highly toxic product of both. This liquid through the broken wall into the abdominal cavity or perforation, may cause strong peritoneal irritation and infection, were peritoneal absorption of causing sepsis. Severe peritonitis and sepsis are major causes of death of patients caused intestinal obstruction.

In addition to these three main pathophysiological changes, the case of strangulating intestinal obstruction is often accompanied by intestinal wall and bleeding within the abdominal cavity and intestine, strangulated bowel loop longer, the greater the blood loss is also patients with intestinal obstruction caused the death of one of the reasons.