Fast Fact and Concept #15: Constipation

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Title: Fast Fact and Concept #15: Constipation

Author(s): Hallenbeck, J.; Weissman, D.

This Fast Fact and Concept reviews the mechanism and causes of constipation along with key teachingp points. Suitable for ward rounds discussion or use at a teaching conference.

Educational Objective(s):
Know the common causes of constipation at end-of-life. Understand how to appropriately select drug therapy for constipation.
Constipation - it's not fun to have or to treat. As with other symptoms, rational therapy should be based on a sound understanding of underlying physiology.

Teaching Points!
Our goal in treating constipation is not to "cure" something, but to help the patient return to the best possible balance that will allow a normal bowel movement to be passed. Four major components affect the production of a normal BM: solid waste, water, motility and lubrication.

Solid Waste - Too much or too little is a problem. The intestine is most efficient pushing intermediate volumes. Patients on fiber-poor diets may improve if fiber, usually psyllium, is added. Note: In patients with minimal fluid intake or poor gut motility (e.g. the dying patient) additional fiber can worsen the situation, causing a 'soft impaction'.

Water Content - Stool water content depends on how much water we drink, our general hydration status, how much water is absorbed from and secreted into the intestine and how fast stool moves through the bowel. Any of these variables can be manipulated. It is easiest to limit absorption (and increase secretion into the gut) by adding osmotically active particles that retain water (e.g. Mg salts, or non-absorbable sugars: sorbitol and lactulose). Note: Magnesium and phosphorus salts are contraindicated in renal failure. Hyperosmolar solutions may worsen dehydration by drawing body water into the gut lumen. Sickly-sweet sorbitol and lactulose may be difficult to for patients to tolerate.

Motility - Patients with low-activity levels (bed-ridden, dying patients and patients with advanced neurodegenerative disorders) and use of certain drugs (see below) lead to motility problems. Senna preparations, which stimulate the myenteric plexus are generally favored. Senna tablets (or granules, liquid, or tea), starting with 1 tab QHS, may be gradually increased to 4 tabs BID if needed. Before increasing motility, evacuate existing, constipated stool with an enema or cramping can result.

Lubrication simply eases passage and minimizes pain that can interfere with excretion. Most commonly used is dioctyl sodium sulfosuccinate (DSS), which decreases stool surface tension much like soap. Usual dosage is 240 mg PO QD- BID. DSS also tastes like soap, so liquid DSS should never be given PO, but may be given to tube-fed patients. Note: DSS is commonly used in combination with senna in opioid-induced constipation, but is generally inadequate as a sole agent. Mineral oil can be used as an enema but should not be given PO, as pneumonitis can result if aspirated. Glycerin suppositories can provide lubrication and draw-in water due to osmotically active particles.

Medications that can cause/exacerbate constipation:
Opioids, Anticholinergics, Tricyclic antidepressants, Scopolomine, Oxybutinin, Promethazine, Diphenhydramine), Lithium, Verapamil, Bismuth, Iron, Aluminum, Calcium salts.

Fast Facts and Concepts are developed and distributed as part of the National Internal Medicine Residency End-of-Life Education project, funded by the Robert Wood Johnson Foundation.

Disclaimer Concerning Medical Information:
Health care providers should exercise their own independent clinical judgment. Accordingly, official prescribing information should be consulted before any product is used.

Contact: David E. Weissman, MD, FACP Palliative Care Program Director Medical College of Wisconsin (P) 414-805-4607 (F) 414-805-4608 [email protected]

Copyright Notice: Users are free to download and distribute Fast Facts for educational purposes only. Citation for referencing: Weissman, D. Fast Fact and Concepts #15: Constipation. June, 2000. End-of-Life Physician Education Resource Center www.eperc.mcw.edu.

Disclaimer: Fast Facts provide educational information, this information is not medical advice. Health care providers should exercise their own independent clinical judgment. Some Fast Fact information cites the use of a product in dosage, for an indication, or in a manner other than that recommended in the product labeling. Accordingly, the official prescribing information should be consulted before any such product is used.

Creation Date: 5/2000

Format: Handouts

Purpose: Instructional Aid, Teaching

Training: Fellows, 1st/2nd Year Medical Students, 3rd/4th Year Medical Students, PGY1 (Interns), PGY2-6, Physicians in Practice
Specialty: Anesthesiology, Emergency Medicine, Family Medicine, General Internal Medicine, Geriatrics, Hematology/Oncology, Neurology, OB/GYN, Ophthalmology, Pulmonary/Critical Care, Pediatrics, Psychiatry, Surgery
Non-Physician: Patients/Families, Nurses

ACGME Competencies: Medical Knowledge, Patient Care

Keyword(s): Gastrointestinal

The Fast Facts series is distributed for educational use only and does not constitute medical advice. For the most current version of Fast Facts visit the EPERC web site at www.eperc.mcw.edu. This mirror version is provided subject to copyright restrictions for educational use within the Inter-Instutional Collaborating Network on End-of-Life Care (IICN).