Whole Bowel Irrigation (Lavage)

GENERAL

A technique that uses large volumes of an iso-osmolar solution (polyethylene glycol, PEG-ELS) that is not absorbed. It has been shown the most efficient means of gastrointestinal decontamination in some circumstances. It may be more efficient for virtually all poisonings (though direct comparisons have been made for only a few drugs) but because of the amount of labour associated with the technique it is largely limited to some specific poisonings for which activated charcoal alone is not satisfactory.

INDICATIONS

Medications not absorbed by charcoal (e.g. iron and lithium)
Sustained release preparations (e.g. theophylline and verapamil)
Other toxins that form pharmacobezoars (e.g. salicylates)

see also controlled release drugs in overdose.

MECHANISM OF ACTION

It physically flushes tablets from the gastrointestinal tract. It also increases the clearance of drugs by interrupting enterohepatic circulation. The other putative mechanism is by 'gastrointestinal dialysis'. Lipid soluble drugs of relatively low molecular weight are able to move from the gut capillaries back into the lumen (if there is a diffusion gradient) and be flushed through (which maintains the gradient).

DOSE

15 mL/kg per hour of polyethylene glycol (colonic lavage solution, GoLytely). If tolerated increase to 25 mL/kg/hr.

ADMINISTRATION

Oral or by nasogastric tube
If the patient agrees to drink the solution, they should be reassessed after 15 minutes to determine their compliance, Most patients require nasogastric tubes

Some patients may require an antiemetic if they are vomiting. Initially the fluid rate may be turned down until the vomiting is controlled.
Metoclopramide 10 mg IV or IM, repeated as necessary, is an appropriate choice, as it does not have the cardiac and sedative effects of the phenothiazines. Ondansetron, tropisetron, dolasetron etc. are effective second line antiemetics in this situation.

The end point of administration of polyethylene glycol is to have a clear rectal effluent which usually occurs after 4 - 5 litres of fluid (2-4 hours). Tablets will often be noted in the effluent

REFERENCES

Buckley NA, Dawson AH, Reith DA. Controlled release drugs in overdose. Clinical considerations.Drug Safety 1995;12:73-84.
Tenenbein M. Whole bowel irrigation for toxic ingestions. Journal of Toxicology - Clinical Toxicology 1985;23:177-184.
Tenenbein M. Whole bowel irrigation as a gastrointestinal decontamination procedure after acute poisoning. Medical Toxicology & Adverse Drug Experience 1988;3:77-84.
Tenenbein M. Position statement: whole bowel irrigation. American Academy of Clinical Toxicology; European Association of Poisons Centres and Clinical Toxicologists. J Toxicol Clin Toxicol 1997;35(7):753-62