Medical Management of Bowel Obstruction
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 mg/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.

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Edward E. Rylander, M.D.
Diplomat American Board of Family Practice.
Diplomat American Board of Palliative Medicine.