Symptomatic Relief
Standard antiemetics can be used for symptom relief. The more expensive 5-HT3 antagonists (e.g., ondansetron) have not been proved to be of greater benefit than the less expensive antiemetic agents. Some patients have significant pain; if pain is associated with gut dilatation, decompression may be needed (see below). In the absence of dilatation, narcotics should be avoided, because these agents may aggravate the motility disorder. Parenteral ketorolac may be useful during acute exacerbations of pain.
Antibacterial Therapy
Bacterial overgrowth must be suppressed in infected patients with pseudo-obstruction. A common practice is to use a different antibiotic for 7 to 10 days each month to avoid development of bacterial resistance, although no trials have been performed to study this approach. Typical antibiotics used are doxycycline (100 mg b.i.d.), metronidazole (500 mg t.i.d.), ciprofloxacin (500 mg b.i.d.), or double-strength trimethoprim-sulfamethoxazole (two tablets b.i.d.). These measures usually result in significant symptomatic relief in those patients with diarrhea and steatorrhea.
Decompression
Decompression is rarely necessary in patients with chronic intestinal pseudo-obstruction and should be restricted to patients with severe motility disorders who are being cared for at tertiary care centers. Venting enterostomy creates a means to relieve abdominal distention and bloating and has been shown to significantly reduce the frequency of nasogastric intubations or hospi-talizations for acute exacerbations in patients with severe intestinal pseudo-obstruction that require central parenteral nutrition.40 Access to the small intestine may also provide a way to deliver nutrients by the enteral route. Enteral tubes are available that facilitate both aspiration and feeding with the same apparatus.
Electrical Stimulation and Gastric Pacing
Electrical stimulation and gastric pacing is an evolving treatment option for patients who do not respond to standard medical therapy51; however, the evidence for efficacy of electrical stimulation is controversial, and the mechanism for relieving symptoms is unknown.
Surgical Treatment
Surgical treatment should be considered whenever the motili-ty disorder is localized to a portion of the gut that can be resected. In clinical practice, the two most common surgical therapies are (1) colectomy and ileoproctostomy for intractable symptoms associated with slow-transit constipation, colonic inertia, or pseudo-obstruction and (2) completion gastrectomy for patients with stasis syndrome after gastric surgery.40 The role of small bowel transplantation in patients with pseudo-obstruction is unclear. Successful transplants have been performed in children with pseudo-obstruction,52 but the experience in adults is limited.52
Prognosis
The prognosis depends on the severity of the case. Patients with suspected postviral gastroparesis appear to have a good overall prognosis, with restoration of nutrition and reduction of symptoms within 2 years. On the other hand, patients with myo-pathic and dilated bowel have persistent symptoms, are more prone to develop bacterial overgrowth, and usually require long-term parenteral nutrition, which carries inherent morbidity. Between these extremes are patients with mild to moderately severe motility disorders who have recurrent or chronic symptoms. These patients can usually be managed as outpatients with dietary supplementation to maintain nutrition (including liquid formula supplements) and medications (e.g., prokinetics or antiemetics) and decompression to relieve symptoms.
Dumping Syndrome and Accelerated Gastric Emptying
Rapid gastric emptying results from impaired relaxation of the stomach upon ingestion of food. Postprandial intragastric pressure is relatively high and results in active propulsion of liquid foods from the stomach. A high caloric (usually carbohydrate) content of the liquid phase of the meal evokes a rapid insulin response with secondary hypoglycemia. These patients may also have impaired antral contractility and gastric stasis of solids, which may paradoxically result in a clinical picture of both gastroparesis (for solids) and dumping (for liquids). Typically, these conditions follow truncal vagotomy and gastric drainage procedures; with the use of more selective vagotomies in the treatment of peptic ulceration, it is likely that the prevalence of these problems may decrease. The most useful means of assessment is a dual-phase (solid and liquid) radioisotopic gastric emptying test.
Management of dumping53 includes patient education (particularly regarding the avoidance of high-nutrient liquid drinks) and, possibly, the addition of guar gum or pectin to retard liquid emptying. If these measures are ineffective, pharmacologic approaches, such as use of subcutaneous oc-treotide (50 to 100 mg) 15 minutes before meals, decreases many of the vasomotor symptoms and also retards gastric emptying and small bowel transit, thereby relieving associated hypoglycemia and diarrhea.
Rapid-Transit Dysmotilities of the Small Bowel
Rapid transit through the small bowel is a minor component of IBS in some patients.4 However, it is a major component of other diseases and results in a significant loss of fluid and osmotical-ly active solutes that overwhelm colonic capacitance and reab-sorptive capacity and result in severe diarrhea. Examples include postvagotomy diarrhea, short bowel syndrome, diabetic diarrhea, and carcinoid diarrhea.56 These disturbances of small bowel transit can best be identified by use of scintigraphy or, if scintigra-phy is not available, by use of the lactulose-hydrogen breath test.
The objectives of treatment are restoration of hydration and nutrition and retardation of small bowel transit. Dietary interventions include avoidance of hyperosmolar drinks (e.g., virtually all soft drinks), use of iso-osmolar or hypo-osmolar rehydra-tion solutions, and reduction of the fat content in the diet to around 50 g a day to avoid delivery of unabsorbed fat to the colon (where their metabolites are cathartic). Correction of nutritional deficiencies (commonly, calcium, magnesium, potassium, and water- and fat-soluble vitamins) is often required.
Pharmacotherapy should be delivered in a stepwise fashion. First, an opioid agent in high dosage (e.g., loperamide, 4 mg) is given one-half hour before each meal and at bedtime to suppress the small bowel transit and colonic response to feeding. Next, verapamil (40 mg b.i.d.) or clonidine (0.1 to 0.2 mg orally or by patch) should be given, and if these are ineffective or produce unacceptable side effects (usually hypotension), subcutaneous octreotide, starting at 50 |ig before meals, should be prescribed.54 Patients with less than 1 m of residual small bowel may be unable to sustain fluid and electrolyte homeostasis without par-enteral support. However, it is almost invariably possible to maintain patients with more than 1 m of residual small bowel with oral nutrition, pharmacotherapy, and supplements.
