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.
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.
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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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