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Because of modern medical approaches mortality from poisoning is low. However, severe poisoning in certain groups of patients is associated with a high mortality: poisons with toxic metabolites (eg, methanol, ethylene glycol, and acetaminophen), poisons inducing metabolic changes (eg, salicylates), and poisons that produce deep coma (eg, phenobarbital). This chapter will discuss the role of forced diuresis and modern dialysis techniques used to treat poisoning, and will give the clinician guidance in the appropriate use of these treatments applied to drug or chemical intoxication. We will use real case reports to illustrate these points.
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The cumulative American Association of Poison Control Center (AAPCC) database now contains 33.8 million human poison exposures. During 2003, 2,395,582 human exposures were reported by 64 participating poison centers, reflecting an increase of 0.7% compared to the 2002 AAPCC report, and an increase of 10.5% over the exposures reported in 2000. Although the majority of cases were managed at home, in 2003, 525,710 cases required treatment in a health care setting and 1106 patients died; 134,619 patients were treated with single dose activated charcoal, 7875 were treated by alkalinization, 1509 received hemodialysis, and 27 received hemoperfusion.
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One method of removing toxins from the body is the administration of multiple doses of activated charcoal. Charcoal given acutely decreases the absorption of toxins from the gastrointestinal tract, but has also been recommended in repeated doses in the hope of trapping toxic substances from the enterohepatic recirculation. However, although there is some experimental evidence that this mode of therapy can decrease the half-life of many xenobiotics, there are only a few toxic substances for which multidose charcoal administration has been shown to be effective. According to the American Academy of Clinical Toxicology, these include carbamazepine, dapsone, phenobarbital, quinine, and theophylline. One recent study in volunteers suggests that repeated doses of superactivated charcoal may have some detoxification benefit up to 3 hours after acetaminophen ingestion. However, two other volunteer studies conclude that multidose activated charcoal may not be effective more than 1 hour after acetaminophen overdose. Multidose activated charcoal has also been reported to reduce death and serious arrhythmias in yellow oleander poisoning (Table 59–1).
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Many substances are eliminated by the kidneys if they are filtered and not reabsorbed or if they are actively secreted by the tubules into the urine. Filtration occurs freely for smaller molecules (<5000 Da) that are not highly bound to plasma proteins such as albumin. Phenobarbital is such a substance. For such substances to be excreted effectively, they must remain largely in the tubular fluid as they traverse the nephron.
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If a substance is cleared by filtration and kidney function ...