Nichols + ??? 3 Flashcards
1
Q
Constipation
A
-Infrequent BM <3/week for 12 months with straining/feeling of incomplete evacuation/hard stool at least 25% of time
2
Q
Normal Colonic Motility
A
- motor function depends on contraction of circular layer of smooth muscle
- has 3 patterns of contractions
3
Q
Short Duration Colonic Contractions
A
Stationary Motor Contractions
- Present over short areas of colon
- Causes mixing of fecal material and extraction of water
- Persists for <15 seconds
4
Q
Long Duration Colonic Contraction
A
- 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
Q
Giant Migrating Complexes of Colon
A
- propagates aborally aver extended distances
- causes mass movement of feces
- normally occurs 1-2 times/day
- may be precipitated by colonic distention
6
Q
Food Intake & Colonic Motility
A
- food causes increased segmental activity
- gastrocolic reflux-may be mediated by CCK
- response is proportional to caloric content of meal
7
Q
Hormones & Colonic Motility
A
CCk causes increased frequency & amplitude of segmental contractions
PgF
PgE
Serotonin
8
Q
PgF
A
stimulates longitudinal muscle contraction
9
Q
PgE
A
inhibits circular muscle contraction
10
Q
Serotonin
A
mediates intestinal peristalsis and secretion in GI tract as well as modulation of pain perception
11
Q
Role of Serotonin
A
- 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
Q
Epidemiology of Constipation
A
- 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
Q
Constipation: Pediatric Etiology
A
95% functional 5% organic -anatomic -metabolic -neuropathic -drugs -endocrine connective tissue D/O -lead intoxication or botulism
14
Q
Functional Constipation
A
- infants and pre-school
- 2 weeks duration Pebble-like, hard stools
15
Q
Functional Fecal Retention
A
- common cause of chronic constipation
- with fear and toilet refusal from infancy to 16 years old
16
Q
Constipation: Elderly
A
- endocrine and metabolic disease
- neurologic disease
- psychological conditions
- structural abnormalities
- lifestyle
- iatrogenic (meds)
17
Q
Constipation Diagnosis
A
- 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
Q
Lab Data of Constipation
A
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
Q
Malabsorption
A
- problem in GI lumen, Defects in epithelial absorptive surface, post-epithelum defect
- steatorrhea, carbs, proteins
20
Q
Steatorrhea
A
greater than 5% of dietary fat intake
21
Q
Patients with steatorrhea?
A
- 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
Q
Steatorrhea Stool Characteristics?
A
- floats
- greasy
- stinks
- hard to flush
- oil droplets with minimal stools
23
Q
Mechanisms causing diarrhea in steatorrhea?
A
- 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
Q
Diagnostic Studies with Steatorrhea?
A
- 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
```
