5.1 Estado del arte
5.1.2 Estado del arte internacional
Delayed and prolonged reactions to stimuli:
In the fasting state, the spike potentials of a normal patient and the patient with irritable bowel syndrome are about the same. After a meal the normal patient has a rapid increase in spike potentials reaching a peak at about 40 minutes and shortly after returning to a normal resting level. This is considered a normal gastrocolic reflex. In the patient with irritable bowel syndrome, there is a delay and then a steady rise of the spike potentials. They only reach about 60% of their peak levels at 40 minutes and do not reach their peak until 90 minutes. The IDS patient's response is delayed and prolonged to normal changes in the internal environment. This is not in the best interest of the patient's total health.
Decreased nerve threshold levels encouraging excessive reaction to stimuli that would otherwise be considered to be nonnal:
In a study demonstrating
this phenomenon, a balloon was placed in the rectosigmoid region of normal
patients and also in patients with IDS. Just placement of the balloon into that
region of the intestine caused immediate and delayed contractions in the patient
with irritable bowel syndrome. Then, with
60
cc of air in the balloon,55 %
of the patients with ms complained of pain while only6%
of the "normalpatients" had pain. Even with only
20
cc of air in the balloon,50%
of the patients with IBS still had pain.Apparently, excessive contractility of the bowel over a long period of time reduces the bowel's threshold to distension. As a result, even the usual amounts of intestinal gas cause the patient to have pain. The gut will remain overactive long after the stimulus is removed.
Intense emotional reactions: One of the most important factors determining
"intensity of reaction" in patients with IBS, is the emotional level at which they live their lives. Anxiety should trigger sympathetic over activity and therefore reduced bowel function and activity should be expected.2 Gillhorn at the University of Minnesota suggested that "the hypothalamus can tune against itself."3 By this he meant that once the initial panic has subsided, the sympathetic effect is overruled by excessive induction of parasympathetic stimuli. A hypothalamic tuning can be either parasympathetic or sympathetic in response and may extend to related viscera such as the small intestine or the urinary tract.
Abnormal contraction patterns of the intestines: IBS patients may have
"narrowing" of the intestines which produces diarrhea. This pattern is often found in the terminal small bowel and abnormal contractions in the cecum and ascending colon. They may have "segmentation" which is another abnormal pattern of contractions associated with the pain and flatulence of spastic
constipation. This latter type of contraction causes "functional obstruction." If narrowing and segmentation occur together, the result is abdominal pain with constipation and stool with excessive mucus--but no blood.
Excessive gas: Man normally produces
6-8
liters of gas in the intestine every day, so gas is not abnormal in the intestinal tract.The gas may be obtained from our external environment through swallowing air. This accounts mainly for the presence of nitrogen and oxygen. The gas produced in the normal bowel itself is the source of its carbon dioxide and hydrogen gas, but
30%
of patients also produce methane gas. This gas is apparently produced through the action of some intestinal bacteria that still remain unidentified. If it were possible to develop a practical way to identify the people who produce methane gas, they could be watched closely; because85 %
of these patients will develop cancer of the colon. People who develop cancer of the colon also produce methane gas in their colons.All of the gases mentioned up to this point are odorless. Offensive odors from intestinal gas indicates the presence of trace gases which contain sulfa or various
amine compounds and are more likely to be present when there is some bowel dysfunction.
Gas in the bowel can be absorbed if the partial pressures between the intestine and the gas in the capillary is appropriate, if the blood flow around the lumen is sufficient, and if the peristaltic activity is normal. Intestinal gas can be
absorbed, passed rectally, belched, or, in certain cases, excreted by the lungs.
A medical researcher has observed and reported that patients with excessive flatulence often have increased low back lordosis. He might be describing the somatic effects of viscerosomatic reflexes activated through visceral afferent nerves from the colon and small intestine to the somatic nerves in the
thoracolumbar area. The lordosis of the low back area might also be affecting the function of the intestine via a somatovisceral reflex.
Pain in the abdomen: Abdominal pain is a common complaint and results from a complex interplay of emotions, sensory factors and motor activity as well as neurologic and hormonal influences.
65 %
of the patients complain of pain below the umbilicus,10%
above the umbilicus:25 %
complain of pain above and below the umbilicus at the same time.The pain lasts for minutes in
30%,
hours in50%
and days in20%.
Though pain located in the upper right quadrant does not occur very often, it must be carefully distinguished from pain caused by gallbladder disease or cholelithiasis.If a gallbladder is removed unnecessarily in a patient with ms, the so-called
"gallbladder pain" will increase because there is an increase, and constant release, of cholecystokinin (CCK) into the intestine after cholecystectomy. This enzyme increases bowel spasms.
Abdominal pain is due to various mechanisms:
Distention pain
Distention pain is not produced by stretching in the bowel wall, but by an attempt to stretch the mesenteries and serosal covering of the bowel beyond its normal length. Mesenteric and serosal tissues do not stretch. Distention is therefore limited by the serosal and mesenteric circumference allowed by the intestine. Lymphatic edema or venous congestion of the mesenteric tissue of the gut wall would reduce the amount of gas tolerated before pain from mesenteric pull would occur.
Contraction pain