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Lecture 30 Flashcards

1
Q

What is the clinical definition of diarrhoea?

A

Someone has noticed a change in the frequency/consistency of their bowel habits.

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2
Q

What are the quantified definition of diarrhoea?

A

> 200g/day. The consistency is loose and the frequency has increased for the individual.

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3
Q

What does stool consistency depend on?

A

Water.

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4
Q

What is constipation?

A

Not enough water.

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5
Q

What is diarrhoea?

A

Too much water in the stool.

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6
Q

What is acute diarrhoea?

A

Diarrhoea lasts up to 14 days.

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7
Q

What is chronic diarrhoea?

A

Diarrhoea that lasts over 14 days.

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8
Q

What are the causes of acute diarrhoea?

A

Infection:

1) Bacteria.
2) Viral.
3) Parasitic.

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9
Q

What are the causes of chronic diarrhoea?

A

Many causes, can be grouped according to underlying mechanism:

1) Inflammatory.
2) Osmotic.
3) Secretory.
4) Fatty.

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10
Q

What is inflammatory diarrhoea?

A

Damaged epithelium of the colon, which will lead to an inflammatory exudate. Which will cause diarrhoea.

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11
Q

What is osmotic diarrhoea?

A

Osmotically active compound in the lumen of the gut, which draws fluid into the lumen, and causes excessive water to stay in the lumen.

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12
Q

What is secretory diarrhoea?

A

The colon is irritated by something, which will lead to stimulation of excessive fluid in the gut.

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13
Q

What is fatty diarrhoea?

A

Malabsorption of fat inn the gut.

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14
Q

What are the bacteria that cause bacterial acute diarrhoea?

A

Salmonella.

Campylobacter.

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15
Q

What are the viruses that causes viral acute diarrhoea?

A

Rotovirus.

Norovirus.

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16
Q

What does campylobacter cause?

A

Inflammatory diarrhoea.

It will causes mucosal inflammation, which will produce and exudate.

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17
Q

What does giardia cause?

A

Osmotic diarrhoea.
Cause damage to villi in SI, this will lead to carb malabsorption. The undigested carbs will act as an osmotically active compound. This will draw fluid in to the gut.

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18
Q

What does E.Coli cause?

A

Secretory diarrhoea.

It releases a toxin that irritates the colon, which will causes excessive fluid secretion.

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19
Q

What causes inflammatory diarrhoea?

A

1) Inflammatory bowel disease.
2) Diverticulitis.
3) Small intestinal bacterial overgrowth (bacteria causes direct inflammation of enterocytes).
4) Radiation colitis.
5) Ischaemic colitis.
6) Colon cancer.

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20
Q

What causes osmotic diarrhoea?

A

1) Carbohydrate malabsorption.
2) Coeliac disease.
3) Small intestinal bacterial overgrowth.
4) Laxative abuse.

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21
Q

What causes secretory diarrhoea?

A

1) Terminal ill resection.
2) Cholecystectomy.
3) Microscopic colitis.
4) Inflammatory bowel disease.
5) Diverticulitis.
6) Neuroendocrine tumours.
7) Small intestinal bacterial overgrowth.
8) Disordered motility.
9) Colon cancer.
10) Laxative abuse.

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22
Q

What causes fatty diarrhoea?

A

1) Pancreatic exocrine insufficiency.
2) bile acid malabsorption.
3) Small intestinal bacterial overgrowth.
4) Coeliac disease.
5) Short bowel syndrome.

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23
Q

What is small intestinal bacterial overgrowth?

A

It is excessive amounts of colonic bacteria in the small intestine.

24
Q

What are the symptoms for small intestinal bacterial overgrowth?

A

1) Bloating.
2) Flatulence.
3) Abdominal discomfort.
4) Diarrhoea.
5) Steatorrhoea.
6) Malabsorption.

25
Q

What causes small intestinal bacterial overgrowth?

A

1) Impaired motility.
2) Anatomic disorders.
3) Metabolic/systemic diseases.
4) Immune deficiency disorders.

26
Q

What is impaired motility in regards to small intestinal bacterial overgrowth?

A

The migrating motor complex is a mechanism of preventing small intestinal bacterial overgrowth by cleansing the small bowel of debris. Scleroderma, diabetes, opiate use (morphine) and radiation enteritis cause this mechanism to not work properly.

27
Q

What are anatomic disorders that lead to small intestinal bacterial overgrowth?

A

An anatomic disorder is stasis in the small intestine. Adhesions, strictures, diverticulum, and blind loops (e.g. post-surgical) can lead to SIBO.

28
Q

Describe the mechanism of SIBO affecting digestion (maldigestion)?

A

1) Bacteria deconjugates (breaks down) bile acids, leading to an impaired micellar formation and fat digestion.
2) Bacterial degradation of carbohydrates in the intestinal lumen occurs, this also produces osmotically active by-products.
3) Bacterial degradation of protein precursors in the intestinal lumen.

29
Q

Describe the mechanism of SIBO affecting absorption (malabsorption)?

A

The bacteria damages enterocytes by direct adherence, producing enterotoxins and enzymes.

30
Q

What are contents that are being malabsorbed due to SIBO?

A

1) Bile acids.
2) Fats.
3) Carbohydrates.
4) Proteins.
5) B12 - bacteria competes for B12.

31
Q

How does SIBO cause fatty diarrhoea?

A

There is deconjugation of bile acids - which will cause impaired micelle formation. This will cause impaired fat digestion and absorption.

32
Q

How does SIBO cause inflammatory diarrhoea?

A

Bacteria causes direct inflammation of enterocytes.

33
Q

How does SIBO cause osmotic diarrhoea?

A

Malabsorption of proteins, carbohydrates, fats and other osmotically active by-products of bacteria metabolism. Deconjugated bile acids inhibit carbohydrate transporters.

34
Q

How does SIBO cause secretory diarrhoea?

A

Unabsorbed food products and bile acids can stimulate secretory cells in the colon.

35
Q

Describe Case 1?

A
  • 35yo female.
  • Epigastric pain for the past 2 weeks. Gets better after eating food and worse at night.
  • Vomiting occurs 3 hours after food.
  • Presents with passing black bowel motions for 2 days.
36
Q

What is epigastric pain typical of?

A

Duodenal ulcer.

37
Q

What does black bowel motions mean?

A

Melaena. Blood is altered by acid (so it has been digested in the SI) so it suggests bleeding occurs in the upper GI tract.

38
Q

What does delayed vomiting suggest?

A

Pyloric obstruction.

39
Q

What are the treatment options for case 1?

A

1) Endoscopic balloon dilatation.

2) Gastro-jejunostomy (bilroth) and truncal vagotomy (uncommon these days).

40
Q

What occurs after she has had a bilroth surgical procedure?

A

1) Developed upper abdominal discomfort after meals. There is rapid gastric emptying of digested food particles into the small bowel. The high osmotic load draws large volume of fluid into the jejunum.
2) Diarrhoea. Osmotic diarrhoea.

N.B. Vagotomy leads to increased small bowel motility.

41
Q

What happens to the woman 10 years after the surgery?

A

1) Diarrhoea has gotten worse. 8-10 times/day with pain bleeding and mucus; urgency.
2) Colonoscopy. Continuous inflammation from rectum to transverse colon.
3) Ulcerative colitis.
4) Diarrhoea. Inflammatory exudate of fluid and electrolytes across damaged epithelium - inflammatory diarrhoea.
5) Fails to respond to medications - colectomy and ileostomy.

42
Q

What is an ileostomy?

A

The SI is taken to the surface of the skin. The contents are entered into a bag. Normally located in the mid portion of the abdomen, usually on the right. Patent empties several times a day.

43
Q

Describe what comes out of the ileostomy?

A

1) 0.6-1L fluid a day.
2) The consistency of the fluid is thick.
3) The colour is a dark green/brown colour (no bacteria).
4) There is no odour (no bacteria.
5) Content: similar electrolytes to plasma. Sodium loss 60-80mmol per day higher than normal state. Increased sodium re-absorption in kidneys.
6) High oral sodium intake usually enough.

44
Q

Describe case 1 after the ileostomy?

A

Initially she has had problems with high output from ileostomy - 2000mL/day. This is due to previous gastric surgery (no pylorus or vagus nerve or colon).

45
Q

How can you manage small bowel motility?

A

By decreasing small bowel motility with medication (e.g. anti-diarrhoea agents like loperamide) absorption can be increased.
This will reduce ileostomy output and sodium loss.

46
Q

Describe case 2?

A
  • 65yo female with Crohn’s disease.
  • Previous resection of 150cm of terminal ileum.
  • Since then, diarrhoea 3-4 times/day.
47
Q

What is Crohn’s disease?

A

Inflammatory condition that can occur at any part of the GI tract (but favours terminal ileum and colon). Chronic inflammation can occur, left untreated can causes fibrosis and narrowing (stricture).

48
Q

What happens if you resect the terminal ileum?

A

Removal of the terminal ileum will cause a loss of specialised receptors for B12/IF complex.

49
Q

How does bile salt malabsorption occur when you resect the terminal ileum?

A

There is reduced re-uptake of bile salts via the enterohepatic circulation. Bile acids are lost through faeces. Due to less bile acids, fat malabsorption occurs -> FATTY diarrhoea. Due to bile salts being in the colon, it will stimulate water and electrolyte secretion -> SECRETORY diarrhoea.

50
Q

What has happened to the patient since getting diarrhoea?

A

Was given cholestyramine (drug which binds bile acids). In the next few years:

  • Several further operations for small bowel crown’s disease (more ileum resected).
  • Remaining small bowel is 1m.
  • Severe diarrhoea with episodes of dehydration requiring hospital admissions (secondary to short bowel syndrome)..
51
Q

What is short bowel syndrome?

A

Not enough small intestine. Complication that follows small bowel surgery.

52
Q

What does short bowel syndrome cause?

A

Malabsorption of:

1) Vitamins, minerals.
2) Water, electrolytes.
3) Proteins, fats, carbohydrates.
4) Bile acids.

53
Q

What happens in people with small bowel syndrome who still have their colon intact and ileocaecal valve?

A

They do better than those who have had colon removed. Over time, the colon undergoes adaption and reabsorbs more water. The ileocaecal valve will act as a sphincter to reduce the amount of fluid to enter the colon. This will allow time for the colon to adjust to the increased fluid load.

54
Q

What are the adaptions that occur in short bowel syndrome?

A

1) Ileal adaption: hypertrophy of the villi in the SI.

2) Colon increases absorptive capacity.

55
Q

How do you manage short bowel syndrome?

A

1) Diet - diet not to high in osmotic compounds.
2) Anti-motility drugs - slow down motility of gut.
3) Acid suppressant medications.
4) Cholestryamine.
5) Total parenteral nutrition (TPN).

DS (32 decks)

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