DESCRIPTION

Whole-bowel irrigation (WBI) is a method to clear the gut by mechanical displacement of foreign substances.

FORMS AND USES

• WBI is used in gastrointestinal decontamination when the agent involved is not absorbed by activated charcoal or is in a form that may persist in the gastrointestinal tract (e.g., extended-release formulations).
• WBI is also used routinely for bowel evacuation in preparation for surgical and endoscopic procedures and in the treatment of constipation.
• WBI is performed by orally administering polyethylene-glycol-based bowel evacuation solutions, including Golytely and Colyte.
  • These products are mixtures of polyethylene glycols with molecular weights of 3,000 to 3,700 daltons and electrolytes (sodium sulfate, sodium bicarbonate, sodium chloride, or potassium chloride).
  • They are supplied as powders, to be mixed with water so that the final solution is 280 mOsm/kg, the same osmolarity as human plasma.

MECHANISM OF ACTION

• WBI involves the administration of a polyethylene-glycol-based solution to push intestinal contents through the gastrointestinal tract before they can be absorbed.
• WBI acts by mechanically displacing the bowel contents, which is thought to make it particularly appropriate for the treatment of drug bezoars or concretions.
• Because the solutions are isoosmolar, they do not induce the fluid and electrolyte shifts seen in patients treated with multiple doses of cathartics.

DRUG AND DISEASE INTERACTIONS

The absorption of therapeutic drugs probably is decreased during the course of WBI treatment.

PREGNANCY AND LACTATION

• Polyethylene glycol solutions are not absorbed from the gastrointestinal tract and are considered safe in pregnancy.
• US FDA Pregnancy Category C. The drug exerts animal teratogenic or embryocidal effects, but there are no controlled studies in women, or no studies are available in either animals or women.

Section Outline:

• DESCRIPTION
• FORMS AND USES
• MECHANISM OF ACTION
• DRUG AND DISEASE INTERACTIONS
• PREGNANCY AND LACTATION

• Precise recommendations for WBI have not yet emerged.
• Typical uses of WBI in gastrointestinal decontamination include:
  • Substances that are not well adsorbed to activated charcoal (e.g., iron, lithium, and lead)
  • Drugs that are designed for sustained or delayed release (many antidysrhythmic drugs, lithium, and theophylline); for example, in the case of an increasing theophylline level despite appropriate gastrointestinal decontamination
  • Substances that form bezoars or concretions (salicylate, carbamazepine, or enteric-coated medications, etc.); for example, in the case of an increasing salicylate level despite appropriate gastrointestinal decontamination
  • A history of ingestion of drug packets (body stuffers or body packers)
  • Heavy metals (lead, arsenic, or mercury); for example, presence of radioopaque objects on abdominal radiographs
  • Cases of ingestion of foreign bodies with potential toxic effects (batteries or lead objects); for example, presence of radioopacities on abdominal radiographs

CONTRAINDICATIONS

• Ileus or mechanical bowel obstruction will lead to recurrent vomiting.
• WBI may increase intraabdominal contamination if perforation exists.
• Unprotected airway may allow pulmonary aspiration.

ADVERSE EFFECTS

• Diarrhea, bloating, nausea, vomiting, and anal discomfort secondary to diarrhea are all common; the rate of fluid ingestion can be decreased.
• Persistent emesis may make administration of polyethylene glycol solution difficult, especially in patients who have received ipecac or ingested drugs that cause emesis.
  • Aggressive use of antiemetic agents may be necessary.
  • Suggested combination regimens in adults include metoclopramide 0.5 to 1.0 mg/kg, diphenhydramine 25 to 50 mg, and prochlorperazine 10 mg or droperidol 2.5 mg intravenously; ondansetron 8 mg intravenously infused over 15 minutes is an alternative. Suggested regimens in children include diphenhydramine 1 mg/kg, maximum of 5 mg/kg/day; meto-clopromide (dose is the same as adults); prochlorperazine should not be used in children; droperidol should not be used in children; ondansetron 0.15 mg/kg for three doses is an alternative (should not be used in children under 4 years of age).
• Pulmonary aspiration of pure polyethylene glycol solution is relatively nontoxic; however, if the aspirate is contaminated with stomach contents, infection and diffuse pulmonary injury may occur.

Section Outline:

• CONTRAINDICATIONS
• ADVERSE EFFECTS

ADULTS AND ADOLESCENTS

• The initial dose is 2 L/h for 1 hour followed by 1 to 2 L/h; typical adult dose is 4 to 5 L ingested over 2 to 4 hours.
• Solution may be administered orally or by continuous infusion through a nasogastric tube.
• Administration should continue until rectal effluent becomes clear.
• For radioopaque substances or foreign bodies, abdominal radiographs may be useful in demonstrating disappearance of toxicant.

CHILDREN

• The initial dose is 20 ml/kg/h followed by 10 to 20 ml/kg/h, up to 1 L/h.
• Solution should be administered orally or by continuous infusion through nasogastric tube.
• Administration should continue until rectal effluent becomes clear.
• For radioopaque substances or foreign bodies, abdominal radiographs may be useful in demonstrating disappearance of toxicant.

Section Outline:

• ADULTS AND ADOLESCENTS
• CHILDREN

• Patients with CNS depression, seizures, or other compromise in protecting airway require endotracheal intubation prior to WBI.
• Patients with partial ileus secondary to drug effects (anticholinergic, opioid, etc.) may not tolerate the large volume of fluid.
• Children may be less tolerant of the large volumes of fluid required.
• WBI may be difficult to administer in an uncooperative patient.
• WBI does not enhance elimination of toxicants that have already been absorbed; it should be administered early to maximize efficacy.
• Polyethylene glycol solutions decrease the adsorptive capacity of activated charcoal for some substances; administering a second dose of activated charcoal to patients receiving WBI should be considered.

Howland MA. Whole-bowel irrigation. In: Goldfrank LR, Flomenbaum NE, Lewin NS, et al., eds. Goldfrank's toxicologic emergencies. 6th ed. Norwalk, CT: Appleton & Lange, 1998.

Author: Katherine M. Hurlbut

Reviewer: Richard C. Dart