Chapter 5: Techniques Used to Prevent Gastrointestinal Absorption

INTRODUCTION

Gastrointestinal (GI) decontamination is a highly controversial issue in medical toxicology. It can play an essential role in the initial phase of management of orally poisoned patients and frequently is the only treatment available other than routine supportive care. Unfortunately, as is true in most areas of medical toxicology, rigorous studies that demonstrate the effects of GI decontamination on clinically meaningful endpoints are difficult to find. The heterogeneity of poisoned patients demands that very large randomized studies be performed because patients who present to an emergency department (ED) typically have both unreliable histories and low-risk exposures (Chaps. 4 and 130). These factors, as well as other significant sources of bias, are often hidden in inclusion and exclusion criteria of even the best available studies. Numerous determinants contribute to the difficulties in designing and completing studies that provide sound evidence for or against a particular therapeutic option. Incontrovertible endpoints, such as complication-specific mortality, also demand exceptionally large studies because the overall morbidity and mortality of poisoned patients are quite low (Chap. 130). Whereas other endpoints, such as the length of stay in the hospital or intensive care unit (ICU), change in xenobiotic concentration, the rate of secondary complications, such as seizures or QT interval prolongation, and the need for specific treatments requiring expensive antidotes, must all be considered, these surrogate markers are not adequately rigorous and are inadequately precise measures of morbidity. In the science of decontamination investigators are also faced with the dilemma that randomizing half of a group of potentially ill patients to no decontamination is a significant ethical concern. Acetaminophen is often used both as the xenobiotic of choice in volunteer studies^{64,124,141,237,373} and in the evaluation of actually poisoned patients.⁷⁸ However, despite its widespread use as a model, the applicability of the management approach for APAP poisoning to other ingestions is limited. It is our recommendation that decontamination should rarely be omitted unless a minimally toxic exposure has occurred.

As might be suspected, no available study provides adequate guidance for the management of a patient who has definitely ingested an unknown xenobiotic at an unknown time. Fortunately, in most cases, there is some component of the history or clinical presentation, such as vital signs, physical examination, or focused diagnostic studies such as an electrocardiogram (ECG) and anion gap, that offers insight into the nature of the ingested xenobiotic (Chap. 3).

For many, the ongoing controversy or debate on GI decontamination culminated in 1997 with the publication of the position statements on activated charcoal (AC), orogastric lavage, syrup of ipecac–induced emesis, and whole-bowel irrigation (WBI) from the American Academy of Clinical Toxicology (AACT) and the European Association of Poisons Centres and Clinical Toxicologists (EAPCCT),^{66,186,331,351,352} and evolved toward sequentially lesser aggressive approaches after subsequent revisions.^33,67,186...