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Flashcards in Nichols + ??? 3 Deck (75)
1

Constipation

-Infrequent BM <3/week for 12 months with straining/feeling of incomplete evacuation/hard stool at least 25% of time

2

Normal Colonic Motility

-motor function depends on contraction of circular layer of smooth muscle
-has 3 patterns of contractions

3

Short Duration Colonic Contractions

Stationary Motor Contractions
-Present over short areas of colon
-Causes mixing of fecal material and extraction of water
-Persists for <15 seconds

4

Long Duration Colonic Contraction

-may be stationary or propagate for short distances
-may travel in orad or aboral direction
-assists in mixing and local propulsion of feces
-migrates toward rectum in distal colon

5

Giant Migrating Complexes of Colon

-propagates aborally aver extended distances
-causes mass movement of feces
-normally occurs 1-2 times/day
-may be precipitated by colonic distention

6

Food Intake & Colonic Motility

-food causes increased segmental activity
-gastrocolic reflux-may be mediated by CCK
-response is proportional to caloric content of meal

7

Hormones & Colonic Motility

CCk causes increased frequency & amplitude of segmental contractions
PgF
PgE
Serotonin

8

PgF

stimulates longitudinal muscle contraction

9

PgE

inhibits circular muscle contraction

10

Serotonin

mediates intestinal peristalsis and secretion in GI tract as well as modulation of pain perception

11

Role of Serotonin

-serotonin (5-HT) is an important neurotransmitter in the brain-gut interaction (released by enterochromaffin cells)
-80% of total body 5-HT located in GI tract
-5-HT3 receptor antagonists have offered some help in alleviating pain in IBS and functional dyspepsia
-5-HT4 receptor agonists have a prokinetic effect in humans

12

Epidemiology of Constipation

-12-19% of people
-more common in individuals with little daily physical activity, low income, and poor education
-in patients 65 years of age, especially more in women

13

Constipation: Pediatric Etiology

95% functional
5% organic
-anatomic
-metabolic
-neuropathic
-drugs
-endocrine connective tissue D/O
-lead intoxication or botulism

14

Functional Constipation

-infants and pre-school
-2 weeks duration Pebble-like, hard stools

15

Functional Fecal Retention

-common cause of chronic constipation
-with fear and toilet refusal from infancy to 16 years old

16

Constipation: Elderly

-endocrine and metabolic disease
-neurologic disease
-psychological conditions
-structural abnormalities
-lifestyle
-iatrogenic (meds)

17

Constipation Diagnosis

-H&P/other medical conditions
-evaluate current meds
-rule out thyroid disorders or electrolytes problem
-colonoscopy or Barium Enema
-colon transit of markers
-anorectum manometry

18

Lab Data of Constipation

performed in patients with rectal bleeding, weight loss of >10lbs, a family history of colon cancer, IBD, anemia, positive fecal occult blood, short-term constipation
-CBC
-serum glucose, creatinine, calcium
-TSH

19

Malabsorption

-problem in GI lumen, Defects in epithelial absorptive surface, post-epithelum defect
-steatorrhea, carbs, proteins

20

Steatorrhea

greater than 5% of dietary fat intake

21

Patients with steatorrhea?

-weight loss
-stool characteristics
-osteomalacia
-easy bruising
-Fe deficiency anemia not due to blood loss
-adult dev. of lactase insufficiency
-gastric surgery, specially Billroth II

22

Steatorrhea Stool Characteristics?

-floats
-greasy
-stinks
-hard to flush
-oil droplets with minimal stools

23

Mechanisms causing diarrhea in steatorrhea?

-increase of osmotically active particles of mal-absorbed dietary constituents
-hydroxylation of 10-hydroxy-oleate which acts as cathartic
-fatty acids themselves impair fluid & electrolyte absorption

24

Diagnostic Studies with Steatorrhea?

-chemical fat balance, D-xylose absorption, secretin test, X-ray (flat plate of abdomen, CT scan, barium)
-hydrogen breath test, aspiration of duodenal content for giardia & quant

25

Stages of Malabsorption

1. Intraluminal Stage
2. Intestinal Stage
3. Lymphatic Transport Stage

26

What Causes the most Steatorrhea?

pancreatic insufficiency

27

Intraluminal Stage

-chronic pancreatitis
-Zollinger-Ellison Syndrome
-Post-gastrectomy
-cystic fibrosis
Solubilization: bile acid insufficiency
-cholestatic liver disease, terminal lleum resection, bacterial overgrowth in small intestine, reduced CCK released

28

Effects of Impaired Circulation of Bile Salts

-diarrhea and if severe steatorrhea
-increased proportion of the bile acids pols conjugated with glycine vs. taurine
-increased proportion of deoxycholate in bile
-a reduced bile salt pool size

29

Intestinal Stage

Epithelial cell surface digestion
-Disaccharidase Insufficiency
-Stasis Syndrome

30

Intestinal Stage: Intestinal Cell Dysfunction

-gluten sensitivity enteropathy
-stasis syndrome
-whipple's disease
-intestinal ischemia
-radiation enteritis
-tropical sprue
-genetic disorders such as cystinuria
-anderson's disease
-abetalipoproteinemia

31

Causes of Malabsorption of GSE

-Cells at surface of intestine are immature:
-intestine is in a secretory state (Na-Cl-water)
-conc. of bile salts above their CMC is reduced
-absorptive functions of mature enterocytes (disaccharidases, Fe, Ca) are reduced
-complex lipid synthesis is reduced
-Endocrine Cells that produce CCK are reduced
-absorptive area of intestine is greatly reduced

32

GSE Pathogenesis & Treatment

-inciting agent is gluten in a person with the right genetic background
-treatment: remove exposure to gluten foods
-clinical response to the gluten exclusion diet is mandatory to sustain a diagnosis of GSE
-If NO response: patient is exposed to hidden sources, patient has GSE plus pancreatic insufficiency or the stasis syndrome, patient has a cause of villous atrophy other than GSE

33

Diagnosis of GSE

IgA antibody ELSIA in detection of GSE

sen. 95-98%
spec. 94-95%

34

Unexplained Causes of Steatorrhea

-giardiasis
-adrenal insufficiency
-amyloid
-diabetes
-hyperthyroidism
-combined variable immunodeficiency

35

Lymphatic Transport Stage

-lymphatic duct obstruction: lymphoma, Whipple, Intestinal lymphangectasia, TB, carcinoid

36

Pathology: Celiac Sprue/Gluten Sensitive Enteropathy

villous blunting
CD8
-noninfectious cause

37

Viral Gastroenteritis

temporary dissacharidase deficiency

38

Whipple Disease

-rare intestinal, lymph node, cerebral, cardiac and joint infection with Tropheryma whippelii
-PAS stain-positive actinomycete
-late middle age white males

39

Radiography with Constipation

-plain films of abdomen: megacolon, impaction
-barium enema
-colon transit study (sitz marker)
-defecography

40

Sitzmarks

-different techniques
-Pt takes 1 capsule on day 0, check X-ray day5
-if over 80% of the marker are passed by day 5 than colon transit normal

41

Severe idiopathic chronic constipation

-mostly women
-complaints include infrequent defecation, excessive straining when defecating, or both

42

Sitz marker study

-Normal Colonic Transit
-Colonic inertia: with delayed passage of marker through proximal colon and no increase in motor activity after meals or with the administration of laxatives
-outlet delay: in which markers move normally through colon but stagnate in rectum (more common in pelvic floor dyssenergia)

43

Pelvic Floor Dyssynergia

Defecation Normally: involves relaxation of puborectalis and external anal sphincter muscles, together with increased intraabdominal pressure and inhibition of colonic segmenting activity

In Dyssynergic Defecation: ineffective defecation is associated with a failure to relax, or inappropriate contraction of, the puborectals and external anal sphincter muscles

44

Severe Idiopathic Constipation

-in one study frequency of the different abnormalities that can produce severe idiopathic chronic constipation
-slow transit constipation 11%
-dyssynergic defecation 13%
-combo 5%
-IBS 71%

45

Treatment of Constipation

Education: increase fluid & fiber intake
Laxatives
Lubiprostone: Cl channel activator
5HT4 agonists: Prucalopride
Bio-feedback
Surgery: sub-total colectomy with ileorectal anastomosis
Suppositories: glycerin or bisacodyl
Disimpaction: patients with fecal impaction

46

Fiber & Laxatives

Fiber: improve symptoms, bulk forming laxatives, Metamucil, methylcellulose, Ca poycarbopphil
Stool softners: docusate sodium
Osmotic Agents: polethylene glycol, lactulose
Stimulant Laxatives: bisacodyl, senna

47

Lubiprostone

-locally acting chloride channel activator that enhances chloride-rich intestinal fluid secretion (anticonstipation)

48

Misoprostol

prostaglandin analog

49

Prucalopride

5HT4 prokinetic agent
not in US

50

Hirschsprung Disease

-congenital disorder: obstipation from birth and colonic dilatation proximal to a spastic, non-relaxing and nonpropulsive segment of distal bowel MEGA COLON

51

Hirschsprung Disease: Pathogenesis

absence of ganglion cells in large bowel, functional obstruction and proximal dilatation

52

Hirschsprung Disease: Epidemiology

1:5000-8000
males>females 4:1
10% of cases in Down's Syndrome
most sporadic, few familial

53

Hirschsprung Disease: Heterogeneous defects in genes regulating

1. migration and survival of neuroblasts
2. neurogenesis
3. receptor tyrosine kinase activity

54

Hirschsprung Disease: Presentation

-failure to pass meconium
-obstructive constipation, occasional passage of stool
-bouts of diarrhea, abdominal distention

55

Physiological Definition of Diarrhea?

>200gm stool per day

56

Normal stool frequency?

3 bm a week to 3 bm per day

57

Fluid Input Into Gut?

Ingestion 2L
Saliva 1.5L
Gastric Secretions 2L
Bile 0.5L
Pancreatic Secretions 1.5L
Small Intestinal Secretions 1L

58

Function of Na+ in Fluid Absorption: Small Intestinal Villi

-Na+/glucose co-transporter
-Na+/H+ exhanger

59

Function of Na+ in Fluid Absorption: Large Intestinal Crypts

-epithelial Na+ channel (ENaC)

60

Increased Intraluminal Fluid: Pathophysiological Mechanisms

1. Decreased Absorption (osmotic)
-ingestion of unabsorbable solute
-osmotic draw of fluid into the gut lumen
2. Increased Secretion
-active secretion of electrolytes + fluid into lumen
-electrolytes comprise most stool osmolality
3. Inflammation
-mediators stimulate secretion
-epithelial barrier compromised by cell death

61

Causes of Osmotic Diarrhea

1. Non-absorbable carbohydrates
-lactose (milk, yougert, cheese)
-sorbitol, mannitol
-lactulose
2. Non-absorbable electrolytes (laxatives)
-Mg2+ compounds
-Golytely (PEG) prep for colonoscopy
-fleet phoshphosoda prep
3. Miscellaneous

62

Key to Secretory Diarrhea?

-excessive Cl- secretion into the gut

63

Osmotic VS Secretory

volume: moderate vs voluminous, watery
resolves w/fasting vs persists during fasting
much flatulence vs no flatulence
stool ph < 5.3 vs ph 6-7
osmolar gap > 125 vs <50

64

Causes of Secretory Diarrhea

1. Bacterial toxins (cholera, heat stable e.coli, yersinia)
2. Laxatives: senna, phenolphthalein, bisacodyl, ricinoleic acid (caster oil)
3. meds: cholinergics, prostaglandins
4. Chemical irritants: bile, arsenic, caffeine, ETOH
5. Neuroendocrine tumors: VIPoma, carcinoid, medullary carcinoma of thyroid

65

Acute Diarrhea

< 3 weeks
infectious
secretory or inflammatory
self-limited
supportive care (mostly)

66

Most common cause of Diarrhea in US?

-viral
-E. coli
-campylobacter (bloody)
-salmonella, shigella (bloody)
-giardia (bad water)
-cryptosporidium (aids)
-c. difficile (hospital)

67

Diarrhea cause in third world?

-viral
-campylobacter
-E. coli
-vibrio cholerae
-entameba histolytical
-salmonella, shigella
-cryptosporidium (infants)

68

Traveler's Diarrhea

20-60% of travelers to third world
Prophylaxis recommendations: cooked food only, bottled beverages, no ice, wash hands before meals, peptobismol
-if diarrhea: fluids, anti-diarrheals, ciprofloxacin if severe

69

Traveler's Diarrhea: most common cause

E. Coli (40%)

70

C. Difficile Colitis

Risk factors: abx use, extremes of age, hospitalization, institutionalization
Cause: Cytotoxins A & B
Diagnosis: pseudomembranous colitis on endoscopy, stool assay
Treatment: stop abx, metronidazole or vancomycin po, cholestyramine to bind toxins

71

Chronic Diarrhea

> 3 week duration
-infectious, immune-mediated, malabsorption
-osmotic, secretory (no mucosal injury)
-inflammatory (mucosal injury)
variable prognosis
-special interventions required

72

Clinical Features of Lactase Deficiency

1. osmotic diarrhea
2. flatulence
3. acidic stool pH

73

Irritable Bowel Syndrome

-common cause of chronic diarrhea in US
-disorder of motility & pain perception
-Diagnosis-abdominal pain, bloating, symptoms associated with bowel functions, no weight loss, bleeding, malnutrition, or anemia
Treatment: anti-cholinergic meds (diarrhea), 5-HT receptor antagonists (constipation), reassurance

74

Microscopic Colitis

2 Types
-Lymphocytic colitis
-Collagenous colitis
Chronic watery, non-bloody diarrhea in adults
Treat: bismuth, aminosalisylates, steroids

75

Behcet's Disease

generalized vasculitis
-oral & genital aphthous ulcers
-uveitis
-GI tract ulcers
-non-erosive arthritis
Treatment: immunosuppressives