EP's sometimes have difficulty deciding when to administer whole bowel irrigation and how to implement it. With what common toxins/overdoses would you recommend whole bowel irrigation? How should it be performed?

by
Lewis S. Nelson, MD
Director, Fellowship in Medical Toxicology
New York City Poison Control Center
New York University School of Medicine
Attending Physician, Emergency Medicine
NYU Medical Center/Bellevue Hospital Center

Whole bowel irrigation refers to the mechanical cleansing of the
entire gastrointestinal tract by the instillation of large volumes of an
isotonic fluid. Early attempts with Ringer's lactate or normal saline
produced significant peripheral edema in addition to electrolyte
abnormalities.

With the advent of polyethylene glycol (PEG) solutions this problem
seems to have been overcome. Commercially available as Colyte or
Golytely, these solutions contain a 3500 molecular weight polyethylene glycol molecule in a balanced salt solution. Thus they are isotonic (and don't cause large fluid or electrolyte shifts).

Whole bowel irrigation produces a rapid catharsis, clearing most
matter from the GI tract in hours. It has been used safely in small
children, and appears to be effective both in experimental overdose models and in actual poisoned patients. It should be stated that there are no truly conclusive studies on the beneficial effects of WBI. Although most ancillary evidence supports its utility, no well designed, controlled, prospective trials have been, or will likely ever be, performed for this purpose. However, conceptually, and based on this regimen's use for other purposes, as well its long history of safe use, we routinely recommend this method of gastrointestinal decontamination for patients who ingest either agents contained in a sustained release formulation or those not well adsorbed to charcoal (iron, lead, lithium, zinc). Note that WBI does not replace activated charcoal, but rather complements it.

Indications:
1. Substances with a prolonged absorption phase - like sustained release preparations or drug concretions (drug bezoars).
2. Rising drug levels despite gastric emptying and the use of activated charcoal (suggesting SR products or gastrointestinal drug bezoar)
3. Gastrointestinal drug smuggling (body packers, or body stuffers are a rare form of an SR product)
4. The ingestion of a potentially toxic amount of a substance not well adsorbed to activated charcoal.

Contraindications:
1. Bowel obstruction or perforation (absolute)
2. Absent bowel sounds (relative)

Dose:
1. Adults - 2 liters per hour (minimally)
2. Children - 500 mL per hour
3. The WBI solution containing PEG is given orally or via a nasogastric tube; NG tube may be preferable given the large volumes of required.
Therapy is continued until the patient's rectal effluent is clear, which
should be 4-6 hours if done properly.

Complications
1. Vomiting or bloating frequently occurs.
2. Rectal irritation.

Adjuncts
1. Antiemetics (e.g. metoclopramide) are often required

Why not whole bowel irrigate everybody? In pills lacking a sustained release formulation, the WBI fluid may solubilize drug and increase its systemic absorption. Furthermore, in a number of situations, WBI solution may occupy activated charcoal's binding sites; this means that the addition of WBI solution can liberate toxin from charcoal, potentially increasing toxicity and it may interfere with charcoal's overall efficacy. It is also labor intensive and messy.

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