10: Principles and Techniques Applied to Enhance Elimination

INTRODUCTION

Enhancing the elimination of a xenobiotic from a poisoned patient is a logical step after techniques to inhibit absorption such as orogastric lavage, activated charcoal, or whole-bowel irrigation have been considered. Table 10–1 lists methods that might be used to enhance elimination. Some of these techniques are described in more detail in chapters that deal with specific xenobiotics. In this chapter, hemodialysis, hemoperfusion, and hemofiltration are considered extracorporeal treatments because xenobiotic removal occurs in a blood circuit outside the body. Currently, these methods are used infrequently because most poisonings are not amenable to removal by these methods. In addition, because these elimination techniques have associated adverse effects and complications, the risk-benefit analysis suggests a benefit in a relatively small proportion of patients.

EPIDEMIOLOGY

Although undoubtedly an underestimate of true use, enhancement of elimination was used relatively infrequently in a cohort of approximately 2.4 million patients reported by the American Association of Poison Control Centers (AAPCC) National Poison Data System (NPDS) in 2011 (Chap. 136).¹² Alkalinization of the urine was reportedly used 10,843 times, multiple-dose activated charcoal (MDAC) 1904 times, hemodialysis 2323 times, and hemoperfusion 14 times. As in the past, there continue to be many instances of the use of extracorporeal treatments that we consider inappropriate, such as in the treatment of overdoses of cyclic antidepressants (CAs).¹²

Although data reporting remains important in comparing the most recent data with past reports (Table 10–2), there is a continued increase in the reported use of hemodialysis, paralleling a decline in reports of charcoal hemoperfusion (Chap. 136). Lithium and ethylene glycol were the most common xenobiotics for which hemodialysis was used between 1985 and 2005. Possible reasons for the decline in use of charcoal and resin hemoperfusion are described in the section Hemoperfusion below. Peritoneal dialysis (PD), a slower modality that should have little or no role in any poisoning, is no longer separately reported (Chap. 136). “Other extracorporeal procedures” in past AAPCC reports may include continuous modalities (discussed below in the section Continuous Hemofiltration and Hemodiafiltration), plasmapheresis, and PD.