What is diarrhea?
Diarrhea is a condition in which a healthy person passes a formed stool of no more than 200-300 g once a day, with an increased number of bowel movements (>3/day), increased stool volume (>200 g/day), and thin stools (>85% water content). Diarrhea for more than 3-6 weeks or recurrent episodes is called chronic diarrhea.
In 2012 the World Gastroenterology Organization (WGO) published Global Guidelines: A Global Perspective on Acute Diarrhea in Adults and Children. The guidelines classify diarrheal episodes into three categories: acute diarrhea (manifested by 3 or more abnormal pasty or watery stools within 24 h of onset), dysentery (manifested by bloody stools visible to the naked eye), and persistent diarrhea (acute onset lasting more than 14 days).
The pathogenesis of diarrhea from the pathophysiological point of view has the following four mechanisms.
1, osmotic diarrhea osmotic diarrhea is due to the presence of a large amount of hypertonic food and drugs in the intestinal tract, and a large number of water molecules of body fluids entering the intestine in a hypertonic state.
Common causes are: malabsorption of carbohydrates, the use of light laxatives containing magnesium and sodium, the use of intestinal cleansers containing polyethylene glycol or drugs for constipation.
This type has two main characteristics: the diarrhea stops or is significantly reduced after 48 h of fasting; the osmotic pressure of the stool increases.
2, secretory diarrhea secretory diarrhea is caused by irritation of the intestinal mucosa resulting in excessive secretion of water and electrolytes or inhibition of absorption.
Common causes are.
(1) abnormal mediators activate intestinal cell membrane cAMP, intracellular cAMP content increases, is cytoplasmic calcium ion content increases, resulting in increased intestinal secretion, water, electrolyte loss. Mediators include bacterial enterotoxins, pathologically secreted gastrointestinal polypeptides from tumors, prostaglandins, pentraxin, etc.
(2) Endogenous or exogenous laxative substances, such as bile acids, fatty acids, certain laxatives, etc.
(3) Intestinal lymphatic drainage disorders, such as small intestinal lymphoma, intestinal tuberculosis, Crohn’s disease, etc.
(4) Secretory rectal or sigmoid villous adenoma.
(5) Congenital chloride diarrhea and congenital sodium diarrhea.
Characteristics of this type: daily stool volume exceeds 1L or even up to 10L; watery stool without pus and blood; plasma-fecal osmolality <50 mmol/L H2O; stool pH is mostly neutral or alkaline; diarrhea persists after 48 h of fasting, and stool volume is still greater than 500 ml/24 h.
3, Exudative diarrhea Exudative diarrhea is caused by massive exudation of intestinal mucosal integrity damaged by inflammation, ulceration and other lesions. In addition, malabsorption and accelerated motility play a large role in the pathogenesis.
It can be divided into infectious and non-infectious. The former has diverse pathogens, while the latter leads to mucosal necrosis. Exudative diseases can be autoimmune, inflammatory bowel disease, tumors, radiation, malnutrition, etc.
Characteristically, stools contain exudate and blood. The colon mostly has pus and blood stools. The lesion exudate, blood and stool are mixed together.
4, gastrointestinal motility disorders some drugs, diseases and gastrointestinal surgery can change the normal motor function of the intestine, promote intestinal peristalsis, so that the intestinal contents pass through the intestinal lumen too quickly and contact time with the mucosa is too short, thus affecting digestion and absorption resulting in diarrhea.
Causes of accelerated motility include: medications (e.g., gastrokinetics, propranolol, etc.); enteric neuropathy (e.g., diabetes); prokinetic hormones (e.g., thyroxine, growth hormone, etc.); gastrointestinal surgery.
Characteristically, the stool is without exudate, often accompanied by hyperactive bowel sounds, and abdominal pain may or may not be present.
Diarrhea often occurs due to a combination of these causes, and there are some diarrheas that are not yet fully explained by the above mechanisms.
The WGO 2012 global guidelines place more emphasis on acute diarrhea due to infectious factors such as E. coli, Campylobacter, Shigella, Vibrio cholerae, Salmonella, and viruses such as rotavirus, adenovirus, and clostridium, as well as rare parasitic infections such as Cryptosporidium microsporum, Giardia intestinalis, and amoeba.
In addition to the above pathogens, pathogens such as Aeromonas, Bacillus cereus, Clostridium perfringens, and Yersinia pestis were also mentioned in our 2013 expert consensus on the treatment of acute infectious diarrhea in adults.
Treatment of diarrhea Diarrhea is a clinical symptom and treatment should be directed to the etiology. Symptomatic and supportive treatment can be given according to its pathophysiological characteristics.
1. Infectious diarrhea needs to be treated according to the etiology The assessment of water, electrolyte and acid-base balance is an important component of the diagnosis of acute infectious diarrhea in adults, with the assessment of dehydration being particularly important. The degree of dehydration can be assessed based on dry skin and elasticity tests, the absence of tears or sunken eyes, pulse count, the presence of postural hypotension or hypotension, the degree of weight loss, and the state of consciousness.
Viral diarrheal disease is most often associated with dehydration and electrolyte disturbances, and those with vomiting may have hypochlorhydria and hypokalemic alkalosis. Severe dehydration may be accompanied by metabolic acidosis. Severe water testing can lead to renal injury.
Treatment of diarrhea with non-infectious factors lactose intolerance and celiac disease with wheat gum requires elimination of lactose and wheat gum components from food. Hyperosmolar diarrhea should be treated by stopping hyperosmolar foods and medications. Bile salt reabsorption disorders can be treated with bile acid adsorption with kaufenamide. For the treatment of bile acid deficiency-induced steatorrhea, medium-chain fats can be used instead of daily long-chain fats.
2. Symptomatic treatment includes correction of water and electrolyte disorders and acid-base balance caused by diarrhea. Nutritional support is given to malnutrition. For severe diarrhea, anti-diarrheal drugs can be given.
3, rehydration treatment patients with mild dehydration or patients without clinical evidence of dehydration can be treated with normal water or appropriate oral rehydration. Patients with watery diarrhea and those with clinical dehydration should be actively rehydrated. Oral rehydration salts should be given intermittently, in small amounts and several times, and should not be consumed in large amounts for a short period of time. The oral dose should be 1.5-2 times the sum of the cumulative loss plus the continued loss.
The WHO recommended rehydration formula is: sodium chloride 3.5 g, sodium citrate 2.9 g or sodium bicarbonate 2.5 g, potassium chloride 1.5 g, sucrose 40 g or glucose 20 g, and water to 1 L. The 2012 WGO Global Guidelines also give a recipe for homemade rehydration solution: 1 teaspoon of salt, 8 teaspoons of sugar, and 1 liter of drinking water or cooled water.
Other commonly used antidiarrheal medications are as follows.
1. astringent adsorption to protect the mucosa: montmorillonite, bismuth subcarbonate, medicinal charcoal, pectin, etc. have the effect of adsorbing intestinal toxins to protect intestinal mucosa. Montmorillonite adults 3.0 g / time, 3 / day, oral.
2. Probiotics: There is considerable evidence that live bacterial preparations can be used to treat diarrhea. Common adverse effects are gastrointestinal flatulence and mild discomfort. Immune deficiency and short bowel syndrome are contraindicated.
3. Inhibition of intestinal secretion: bismuth subsalicylate, enkephalinase inhibitors (such as abscisicadotril). The effect of abscisicadotril is on peripheral enkephalinase, which does not affect the central system, and has an effect on gastrointestinal motility and basal secretion. The commonly used dose is 100 mg tid orally before meals, and the treatment does not exceed 7 days.
4. Intestinal motility inhibitors: loperamide, benzopidine, compound camphor tincture, etc. Loperamide acts directly on the muscles of the intestinal wall to inhibit intestinal peristalsis and prolong the passage time of food. It should be avoided in patients with suspected inflammatory diarrhea or bloody diarrhea, such as fever or significant abdominal pain. Benzedrine is a synthetic pethidine derivative with effects similar to morphine, but without analgesic effect. It is contraindicated in intestinal obstruction, jaundice, pseudomembranous enterocolitis and enterotoxin-producing bacterial diarrhea. 20 mg daily for 10 days without improvement should be discontinued.