Constipation and Irritable Bowel Syndrome

Question 1

Functions of the large intestine?

Answer 1

• mixing and dehydration of fecal material
• storage until evacuation is convenient
• salvaging of water, salt and some nutrients (fat soluable vitamins like vitamin K)

Question 2

Diagnosing Constipation?

Answer 2

Must include 2 or more of the following:

• straining during at least 25% of defecations
• lumpy or hard stools in at least 25% of defecations
• sensation of incomplete evacuation for at least 25% of defecations
• sensations of anorectal obstruction/ blockage for more than 25% of defecations
• manual manvers to facilitate at least 25% of defecations
• fewer than three

Question 3

functional bowel disorder characterized by symptoms of abdominal pain or discomfort and associated with disturbed defecation

Answer 3

Irritable bowel syndrome

Question 4

Associated Conditions with IBS

Answer 4

• fibromyalgia
• chronic fatigue syndrome (also known as systemic exertion intolerance disease)
• gastroesophageal reflux disease
• functional dyspepsia
• non-cardiac chest pain
• psychiatric disorders including major depression, anxiety, and somatization

Question 5

Diagnosis of IBS?

Answer 5

recurrent abdominal pain or discomfort on average 1 day/week in the last 3 months associated with two or more of the following

• related to defecation
• associated with a change in frequency of stool
• assoicated with a change in form (appearance) of stool

Question 6

what are the four subtypes of IBS?

Answer 6

• diarrhea predominant (IBS-D)
• constipation-predominant IBS
• mixed symtpom IBS
• IBS unclassified (meet criteria for IBS but not specifically a subtype

pts change subtypes, often starting in D & C and moving to M

Question 7

medications that can cause constipation?

Answer 7

narcotics, calcium channel blockers, antidepressants, antipsychotics, diuretics, anticonvulsants

Question 8

red flag symptoms for constipation

Answer 8

• fever
• weight loss
• blood in stools- particularly turning the toilet water red
• anemia
• family history of IBD or colon cancer
• abnormal physical findings
• abnormal blood work
• waking from sleep due to pain or needing to stool

Question 9

categories of constipation

Answer 9

severe idopathic chronic constipation

• Normal transit
• slow transit or colonic inertia
• outlet delay - transit throught the colon is normal but slows at the rectum

Dyssynergic defecation
megacolon

Question 10

• failure of relaxation or inappropriate contraction resulting in a narrowing of the anorectal angle and an increase in the pressures of the anal canal
• this can be conscious or an unconscious act

Answer 10

dyssynergic defecation

Question 11

• MOA: primarily works by absorbing water and increasing fecal mass which can lead to increase frequency and softer stools
• can be used alone or with other therapies
• side effect: gas and bloating
• contraindicated: if concerned for bowel obstruction
• Psyllium, Methylcellulose

Answer 11

Bulk forming laxatives

Question 12

• MOA: Primarily works by lowering the surface tension of stool so water can more easily enter the stool. thus stools are softer and easier for normal colon transit to move
• often used in combination with bulk forming laxative
• se: contact dermatitis have been reported, diarrhea and abdominal cramping
• contraindicated: if concerned for bowel obsruction, acute abdomen, appendicitis
• Docusate sodium

Answer 12

Surfactants (stool softners)

Question 13

• MOA: These medication increase water secretion which in turn increase stool frequency
• miralax, lactulose, Mg citrate
• caution, watch out for electrolyte and fluid disturbances in patients with renal and cardiac dysfunction. use caustion in elderly pts
• SE: nausea, bloating, gas, diarrhea, rectal irritation, watery stools
• polyethylene glycol, magnesium citrate, glycerin

Answer 13

Osmotic Agents

Question 14

• MOA: alters electrolyte transport through the intestinal mucosa which increases intestinal motility
• abuse of these medications can cause hypokalemia, protein losing enteropathy and salt overload
• no evidence that chronic use causes structural or functional impairment of the colon so long term use is fine
• SE: gastric or rectal irritation, melanosis coli (dark pigmentation), cramping, N/V
• contraindicated: acute abdomen, GI obstruction, or perforation, toxic megacolon
• bisacodyl 5mg, senna 8.6mg

Answer 14

stimulant laxatives

Question 15

• minimally absorbed peptide agnoist of the guanylate cylcase C-receptor
• MOA: stimulates intestinal fluid secretion and transit
• SE: diarrhea, abdominal pain and bloating
• contraindicated: pts less than 18, concern for obstruction

Answer 15

Linzess

Question 16

• MOA: increases intestinal fluid secretion and motility
• best reserved for patients with severe constipation in whom other approaches have been successful
• SE: nausea, diarrhea, headaceh
• caution/contraindicated: severe diarrhea, liver impairment, concern for obstruction

Answer 16

Chloride channel activator- Lubiprostone

Question 17

three general mechanisms of IBS

Answer 17

• Hypersensitivity- enhanced visceral perception and pain
• altered gut activity- motility and secretion are altered in IBS patients with triggers to alert the activities including eating, gut distention, inflammation, bacterial, psychosocial stress and other environemental stimuli
• dysregulation- of the brain-gut axis- suspected altered perception by the brain and the signals from the gut are possibly distorted

Question 18

risk factors for development of post infectious IBS

Answer 18

• female gender, younger age
• smoking
• prolonged fever
• severe diarrheal illness
• weight loss > 10lbs during diarrheal illness
• bloody diarrhea
• pre-existing anxiety or depression, history of stress
• treated with antibiotics
• sleep disturbance

Question 19

• Psychosocial factors of IBS

Answer 19

• there is a striking prevalence of psychiatric comobidity among IBS patients
• key life events that can influence IBS include abuse (emotional, sexual, or physical) stressful life events
• 80% of IBS pts also have- depression, somatization disorder, generalized anxiety, panic disorder, phobias

Question 20

• can reduce pain and bloating
• best if used intermittently
• MOA: act via anticholinergic or antimuscurinic properties causing selective inhibition of gastrointestinal smooth muscle which reduces intestinal motility and spasm
• se: xerostomia, dry eye, UA retention, constipation, sleepiness
• caution: elderly, CHF, CAD, renal/hepatic impairment, risk of obstruction, patient with glaucoma
• dicylomine, hyoscyamine

Answer 20

Antispasmodic agents

Question 21

• MOA: suspected effect on the enteric nervous system
• more effective than placebo at relieving global IBS symptoms
• SE: drowsiness, xerostomia, dizziness, constipation, blurred vision, palpation
• caution: withdrawal if stopped suddenly, elderly, GI/GU obstruction, urinary retention, glaucoma, pregnancy
• amitriptyline, nortriptyline

Answer 21

antidepressants

Question 22

• MOA: slow stool transit time and frequency by binding gut wall opioid receptors and inhibiting peristalsis
• no effect on abdominal discomfort or pain
• SE: constipation, nausea, abdominal crampin, dizziness, drowsiness
• contraindicated: abdominal pain w/out diarrhea, bloody diarrhea, UC less than 2 yrs old, pseudomembranous colitis

Answer 22

Loperamide and lomotil

Question 23

• MOA: antibiotic
• SE: nausea, elevated ALT
• caution/contraindicated- if pt has C.diff, child-pugh, possible fetal harm

Answer 23

rifaxamin (for IBS-D)

Question 24

Lifestyle contributions

Answer 24

• Smoking
• volume and timing of meals- do they have a job that hours keep changing, do they eat one large meal a day vs. small one
• menses: consider birth control to reduce the frequency of periods
• aerophagia- increase gas issues