Whole-bowel irrigation (WBI) is a procedure intended to prevent the absorption of poisons by removing them from the gastrointestinal tract. It consists of the rapid enteral administration of large amounts of the special irrigation fluid polyethylene glycol electrolyte lavage solution (PEGELS) over several hours (1). It is routinely used in patients of all ages as a colonoscopy preparative procedure. It differs from the other gastrointestinal decontamination procedures, syrup of ipecac–induced emesis, gastric lavage, and single-dose activated charcoal administration in that it has the potential to decontaminate the intestines as well as the stomach. Although WBI has been shown to decrease the bioavailability of selected ingestants to a greater extent than these other procedures, it should be restricted to specific indications because it is both labor intensive and time consuming.

Prevention of absorption is a cardinal tenet of treating the acute overdose patient. The traditional approach was to use either ipecac-induced emesis or gastric lavage as the primary intervention, followed by activated charcoal as an adjunctive procedure. However, opinion has shifted to charcoal monotherapy (2,3,4,5), and current practice reflects this change.

Situations arise, however, when charcoal would be expected to be of limited benefit. These include ingestion of substances not adsorbed by charcoal (iron being the most important) and presentation of a patient several hours after the ingestion of delayed release pharmaceuticals. These drugs can persist for prolonged periods within the intestines and thus beyond the reach of ipecac, gastric lavage, and charcoal.

Drug absorption depends on such factors as dissolution of the pharmaceutical, ionization state (the ionized form of a drug is less well absorbed), location of the substance within the gastrointestinal tract (more surface area and blood flow to the proximal small intestine), and transit time for the toxin through the gastrointestinal tract. Most toxins are absorbed in the proximal small intestine. The rationale for using WBI is to hasten the transit of poison past the area of absorption and thus decrease its bioavailability (1).

Human bioavailability studies in volunteers receiving WBI have consistently shown decreases in drug absorption of 67% to 73% (6,7,8). This exceeds the performance of syrup of ipecac, gastric lavage, or a single dose of activated charcoal when performed at comparable times after ingestion. Only 3,500 molecular weight polyethylene glycol electrolyte solution should be used for WBI, because it was specifically designed to prevent fluid or electrolyte flux across the gastrointestinal epithelium (9).

The indications for using WBI are the ingestion of substances not adsorbed by charcoal and the ingestion of delayed release pharmaceuticals (Table 127.1) (10). These types of pharmaceuticals can persist within the gut for many hours beyond the reach of the other decontaminating procedures. Of the toxins not adsorbed by activated charcoal, iron is most commonly ingested, and it has been shown to be removed by WBI (11). WBI should also be considered for the treatment of lithium (8), lead (12), and zinc (13) overdoses. Ingestion of very large amounts of toxic substances and delayed presentation after ingestion are potential indications (1); however, these specific situations are difficult to identify in the clinical setting. WBI is also of potential benefit for illicit drug body stuffers and packers (14). While this is an unlikely presentation in the pediatric age group, such cases have been reported (15).