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Fast Fact and Concept #45: Medical Management of Bowel Obstruction

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Title: Fast Fact and Concept #45: Medical Management of Bowel Obstruction

Author(s): Charles von Gunten, MD PhD and J. Cameron Muir, MD

Malignant bowel obstruction is a common oncologic complication; most common in ovarian and colon cancer. Symptoms include abdominal pain, colicky and/or continuous, nausea and vomiting. Treatment options include surgical correction, placement of a venting gastrostomy tube, stent placement across the obstructed site or medical management. The need to rely solely on medical management is common, especially when the patient's functional status is poor and expected survival is short. In the past 10 years there has been significant advances in the medical management of this problem, so that virtually all patients can avoid dying with the traditional approach of intravenous fluids and nasogastric tubes ("drip and suck"). The cornerstone of treatment is drug therapy.

Major Drugs
Opioids and anti-emetics (usually dopamine antagonists, e.g. haloperidol) can be administered (IV or SQ) to relieve pain and nausea. Antimuscarinic/anticholinergic drugs (e.g. atropine, scopolamine) are used to manage colicky pain due to smooth muscle spasm and bowel wall distension. In the US, scopolamine can be administered by parenteral (10 ?g/hr sc/iv continuous infusion) or transdermal routes (10ug/hr). Scopolamine is only available as the hydrobromide salt, which penetrates the CNS with the attendant potential for significant side effects, notably delirium. An alternative agent is glycopyrrolate, a quaternary ammonium antimuscarinic with similar clinical effects to scopolamine, but without the CNS side-effects (0.2-0.4 mg sc q 2-4h).

A recent advance is to use somatostatin analogs, which lack the adverse effects of antimuscarinic agents. Somatostatin inhibits secretion of GH, TSH, ACTH and prolactin and decreases the release of gastrin, CCK, insulin, glucagon, gastric acid and pancreatic enzymes. It also inhibits neurotransmission in peripheral nerves of the GI tract leading to decreased peristalsis and a decrease in splanchnic blood flow. Octreotide (Sandostatin) is administered as a SQ injection (starting at 50-100 mcg q 8 hours) or as continuous IV or SC infusion, beginning at 10-20 mcg/hr. The drug is titrated every 24 hours until nausea, vomiting, and abdominal pain are controlled.

Minor Drugs
Prokinetic drugs (e.g. metoclopramide) may be beneficial if there is a partial obstruction. However, if there is total obstruction prokinetic agents should be discontinued as they may exacerbate symptoms. Corticosteroids have been recommended to decrease the inflammatory response and resultant edema, as well as relieve nausea, through both central and peripheral antiemetic effects.

Care Plan
The goal of medical management is to decrease pain, nausea and secretions into the bowel so to eliminate the need for an NG tube and IV hydration. During the medication titration phase, IV fluids should be restricted to 50 cc/hr. When NG output is less than 100cc/day, the NG tube can be clamped for 12 hours and then removed. Once out, patients are instructed that they may drink and even eat, although, vomiting may occur (note: if a venting gastrostomy tube is already in place, oral intake can be normal without fear of vomiting). Supplemental parenteral hydration is only indicated if a) patients remain dehydrated despite oral intake and b) use of hydration to extend life is consistent with the patients' goals.

References:
Baines, MJ. The pathophysiology and management of malignant intestinal obstruction. In Doyle, D, Hanks, GWC, MacDonald, N, eds. Oxford Textbook of Palliative Medicine, Oxford University Press, Oxford, 1998; 526-534.
Riley, J., Fallon, MT., Octreotide in terminal malignant obstruction of the gastrointestinal tract. European Journal of Palliative Care, 1(1): 23-25, 1994.

Copyright Notice: Users are free to download and distribute Fast Facts for educational purposes only. Citation for referencing: von Gunten C and Muir, JC Fast Facts and Concepts #45: Medical Management of Bowel Obstruction July, 2001. End-of-Life Physician Education Resource Center www.eperc.mcw.edu.

Fast Facts and Concepts was originally developed as an end-of-life teaching tool by Eric Warm, MD, U. Cincinnati, Department of Medicine. See: Warm, E. Improving EOL care--internal medicine curriculum project. J Pall Med 1999; 2: 339-340.

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: 7/2001

Format: Handouts

Purpose: Instructional Aid, Self-Study Guide, Teaching

Audience(s)
Training: Fellows, 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: Nurses

ACGME Competencies: Medical Knowledge, Patient Care

Keyword(s): Addiction, Cancer, Chronic non-malignant pain, Controlled substance regulations, Gastrointestinal, Interventional procedures, Pain, Pain assessment, Pain treatment


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