1. 2 chronic constipation - an evidenced based approach robert a. baldor, md, faafp professor,...
TRANSCRIPT
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Chronic constipation - an evidenced based approach
Robert A. Baldor, MD, FAAFPProfessor, Family Medicine & Community
HealthUMass Medical School
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Learning Objectives
• by the end of the session, you will have a clear understanding of the basic pathophysiology related to chronic constipation
• …and develop an evidenced based approach for the primary care diagnosis and treatment of these chronic problems.
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Mrs Z.• A 34-year-old white female who complains
of constipation; she hasn’t discussed it in the past as “it’s embarrassing,” but states that she has been constipated her entire life and has tried a variety of OTC products without much relief.
• She further reports that she is very active, runs 4 days a week, that she always has a bottle of water with her and tries to eat salads regularly…..
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History
• Character of the problem– Consistency– Frequency– Straining, bloating– Diarrhea
• Medications
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Mrs. Z• Doesn’t have much discomfort, but has to strain
and has hard stools along with blood occasionally on TP – she tends to go about twice a week
• She will occasionally have diarrhea – but it seems related to something she had eaten
• Takes Tums for her ‘bones’
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Constipation No Clear Definition
A group of syndromes with similar findings
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Am College of Gastroenterology …
Unsatisfactory defecation, characterized by infrequent stools and/or difficult stool passage
Brandt 2005
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Pathophysiology…
• As food leaves stomach, gastroileal reflex relaxes the ileocecal valve and digested food (chyme) enters the colon
• Peristaltic contractions move chyme through the colon
• Na+ actively absorbed - water follows because of the generated osmotic gradient
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Normal Colonic Transit Time
• A meal reaches the ileo-cecal valve in 4 hours…the sigmoid colon 12hours later… then slows to the anus.
• Plastic pellets with a meal → 70% recovered in 3 days; remainder in a week!
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Defecation• Food distends the stomach, initiating the gastro-colic
reflex causing rectal contractions & a desire to go!• ‘Urge to defecate’ occurs as rectal pressures ↑• Defecation reflexes can be inhibited by voluntarily
contracting the external sphincter or facilitated by straining
• Pelvic floor/anal sphincter dysfunction interfere with normal defecation
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Most with primary constipation suffer from which one of the following?
1. Slow colonic transit time2. Pelvic floor/anal sphincter dysfunction3. Functional – normal transit time and
sphincter function
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Most with primary constipation suffer from which one of the following?
1. Slow colonic transit time2. Pelvic floor/anal sphincter dysfunction3. Functional – normal transit time and
sphincter function
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Secondary Constipation
• Endocrine dysfunction (DM, hypothyroid)• Metabolic disorder (↑ Ca,↓ K)• Mechanical (obstruction, rectocele)• Pregnancy• Neurologic disorders (Hirschsprung’s,
multiple sclerosis, spinal cord injuries)
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Medication Effect• Anti-cholinergic effects
– Antidepressants– Narcotics– Antipsychotics
• Calcium channel blockers• Antacids (calcium, aluminum)
Mrs. Z taking Tums (ca carbonate) for osteoporosis - ca phosphate (Posture) and ca citrate (Citracal) less constipating.
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IBS ? Rome III Criteria
• Symptoms at least 3 days/month of recurrent abdominal pain or discomfort associated with hard constipated stools interrupted by brief episodes of diarrhea …
Drossman Gastroenterology. 2006
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IBS Treatment
• Multiple RCTs with inconsistent results – best evidence for treating IBS-C:– Bulking agents– Psychotropic agents
DARE review 2001
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Red flags
1. Onset after age of 502. Hematochezia/melena3. Unintentional weight loss4. Anemia5. Neurological defects
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Physical Exam
• Digital rectal examination – Stool character– Pain, anal tone– Masses, fissures, hemorrhoids,
• Abdominal/gynecological exam– Masses, pain
• Neurological exam
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Treatment – Behavioral
• Toileting program to take advantage of natural reflexes
• Obey the urge – Gastro-colic– Defecation reflex
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Medications - Laxatives
• Bulking agents• Stool softeners• Osmotic agents• Stimulants• Lubricants• Other
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Bulking Agents at the Grocery Store…
• Vegetables• Fruits• Whole grain foods• Bran (hard outer layer of cereal grains)*
• Bloating and gas can be problematic– Gradually increase intake to 25 grams/day– Less fermentable fiber like wheat bran tends to be
better tolerated
* Limited evidence for effectiveness
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Food Serving Fiber (Gm)
All Bran® cereal 1/3 cup 10
Whole wheat bread 2 slices 4
Wheat bran muffin medium 3
Brown rice 1cup 3
Apple/Pear medium 4
Banana medium 3
Dried figs 5 8
Prune juice 1 cup 3
Sunflower seeds ¼ cup 3
Baked potato w/skin medium 4
Canned baked beans ½ cup 5
Chickpeas ½ cup 5
Lentils/ Kidney beans ½ cup 8
Corn ½ cup 2
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Bulking Agents at the Pharmacy…• Moderate evidence
– Psyllium (Metamucil 2.5gms fiber/dose)• Limited evidence
– Bran methycellulose (Citrucel 2gms fiber/dose)– Polycarbophil (Fibercon)
Fiber needs to be accompanied by adequate amounts of liquid to be useful - 8oz/2-3gms of added fiber!
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Stool Softeners – Limited Evidence
• Contain docusate (Colace), an anionic detergent with hydrophilic and hydrophobic ends that improves the ability of water to mix with and soften the stool
• Helpful to soften stools to make defecation easier (post-op, childbirth)
• Helpful for hemorrhoids or anal fissures• ↑ dose if no effect is seen after a week
– 40-400mg daily QD-QID
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Stimulants (Irritants)
• Irritate bowel, causing muscle contractions – often in combination with ducosate – work in 8-12 hrs (try qhs, increase to BID)
• Senna/ducosate (Senokot-S, Ex-lax - max 4/d)• Bisacodyl/ducosate (Dulcolax, Correctol- max
30mg/d)• Casanthranol/ducosate (Peri-colace – max 2/d)
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Stimulant Suppositories …
• Contain bisacodyl/ducosate (Dulcolax)• Glycerin suppositories also believed to
have their effect by irritating the rectum• Insertion of the suppository into the
rectum may itself stimulate a bowel movement
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Osmotic Laxatives• Polyethylene glycol - PEG (good evidence)
– 17 grams daily• Saccharines – lactulose (moderate evidence)
– flatulence, bloating, cramping – 15 - 120 ml qhs
• Sorbitol (effective as lactulose in elderly men*)– less bloating than lactulose– 15 - 120 ml qhs
• Magnesium salts (MOM)– avoid in renal insufficiency, best for acute treatment
* Lederle. ACP Journal Club, 1991.
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A Closer Look at Polyethylene Glycol - good evidence for use
• PEG: Large, chemically inert polymer, with substantial osmotic activity– Bowel flora unable to metabolize– Pulls water into colon to soften and increases
fecal bulk (takes 2-4 days to work)– First used in a balanced electrolyte solution for
colon cleansing (Golytely)– PEG 3350 (Miralax) or with electrolytes
(Movical)
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Lubricant Laxatives
• Contain mineral oil (15-45 ml/day)• Short-term use only
– Binds fat-soluble vitamins– May decrease absorption of some drugs
• Avoid lubricants in those at risk for aspiration (lipid pneumonia)
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Lubiprostone (Amitiza)• Selective Chloride channel activator
↑ secretion of Cl- ions into small bowel; Na+ and water follow, resulting in a softer, bulkier stool
• 24 mcgs BID• Nausea is common (32%) • Avoid use in pregnancy, breast-feeding
Methylnaltrexone (Relistor)
• Methyl group reduces lipidophilic properties of the opioid antagonist naltrexone - ↓ ability to cross blood-brain barrier
• Peripherally Acting Mu-Opioid Receptor (PAM-OR) antagonist
• Indicated for palliative care• For short-term use (< 4months)• Side effects - abdominal pain and flatulence
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Other, Non-FDA Approved Agents, Act to Decrease Transit Time
• Misoprostol (Cytotec 100-200mcg QID) – a prostaglandin increases colonic motility1
• Colchicine (0.6mg qd - tid)– neurogenic stimulation ↑ colonic motility 2
1.Roarty. Alimen pharm & Therapeutics. 19972. Verne. Am J. Gastroenterology. 2003, Frame J ABFP, 1998
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A Practical Approach…
R/O treatable secondary causes..Am Gastroenterological Assn (AGA) guidelines:
• CBC, Glucose, TSH, calcium, creatinine• Sigmoid/colonoscopy if red flags are present.
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Address Immediate Concerns
• Bloating/discomfort/straining – Osmotic agent like PEG
• Post-op, childbirth, hemorrhoids, fissures– Stool softener to make defecation easier
• Stimulants and suppositories acutely• Manual disimpaction as needed
then approach the chronic condition….
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Start with Lifestyle Changes …
• Exercise, increase fluids and fiber to 25 grams/day over a period of 6 weeks.* – Fiber must be accompanied by sufficient fluid– Initial approach – fruits and vegetables– Add commercial bulking agents
• Obey the ‘Urge’!• For children trial of rice vs cow’s milk
* Uncontrolled studies support fiber for normal transient constipation. Am J Gastroenterol. 1999; G Nutr 4/2010
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If No Improvement…
• Add osmotic laxative – adjust dose slowly until stools are soft – take several days to work– caution if CHF or renal insufficiency
• Add stimulant laxatives• Lubiprostone
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Trial of Other Agents…
• Misoprostol (Cytotec)• Colchicine
Refractory to empiric approach .…
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Pursue Diagnostic Evaluation• Colonoscopy if not indicated sooner ….• Barium enema for obstruction/megacolon• Radiopaque Sitz-Markers to measure transit time
– markers ingested, KUB in 5 days – retention >20% markers indicates slow transit– markers seen exclusively in distal colon/rectum
suggests pelvic floor dysfunction
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Referral to evaluate defecation….
• Balloon expulsion• Defecography using a barium paste.• Anorectal manometry with a rectal
catheter• Biofeedback with artificial silicon stool • Surgery rarely indicated
Enck. Dig Dis Sci. 1993
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Summary….• Constipation - unsatisfactory defecation, with
infrequent stools, difficult stool passage or both• Functional constipation (normal transit time and
sphincter function) seen most often• Work-up is necessary in the presence of red flags
– onset >50 yrs; hematochezia/melena; unintentional weight loss; anemia; neurological defects
• Best evidence for effectiveness is for osmotic agents
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Long-term Laxative Concerns…
• No evidence for addiction• No evidence for tolerance• No evidence for dependence• No evidence for harm from stimulant use,
melanosis coli may develop, but it is a benign condition
Muller-Lissner. Am J Gastroenterology. 2005
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The End!
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