According to data from the American Association of Poison Control Centers' Toxic Exposure Surveillance System, there were an estimated 2.3 million human poisonings in 1994.1 Sixty-eight percent of these exposures occurred in the pediatric age group (<20 years) with 54% of all reported poisonings occurring in children younger than 5 years of age. The majority of these poisonings were insignificant and did not require emergency department evaluation. As one examines poisoning trends over the past 11 years of American Association of Poison Control Centers' data, the most striking change has been the change in management of toxic ingestions (Table 1). For example, over the past 9 years, the use of ipecac, long considered the foundation of poison management in most childhood ingestions, fell from 13% of exposures to 3%. Concomitantly, administration of activated charcoal increased in prevalence from 4% to 6.8%.
This dramatic shift in decontamination trends reflects the changes that have occurred in the recommended management of the poisoned patient. These new recommendations have resulted from the proliferation of studies that have reevaluated the relative contribution made by each of the three components of gastrointestinal decontamination: gastric evacuation, activated charcoal administration, and catharsis. Each of these three interventions has been reexamined in both clinical and laboratory settings, in patients with actual overdoses and under experimental conditions. Collectively, the data they have produced require a modification in the management of the poisoned child, especially management provided in the emergency department.
This article briefly discusses current methods of gastrointestinal decontamination and the efficacy of specific decontamination measures. A recommended approach to the immediate management of the poisoned child or young adult abo is provided.
The purpose of gastric evacuation is to remove toxin from the stomach before it travels beyond the pylorus into the small bowel where most absorption occurs. Gastric evacuation can be accomplished by either induced emesis or gastric lavage. While many agents have been used to induce vomiting - including dilute detergent, hydrogen peroxide, and salt water - syrup of ipecac is the sole approved emetic in current use. Decades of use have proven ipecac to be safe and effective for the poisoned patient. The dose of ipecac administered is age dependent: patients 6 to 12 months of age should receive 10 mL; those 1 to 12 years, 15 mL; and those older than 12 years of age, 30 mL. The dose may be repeated once in children older than 1 year if emesis has not occurred within 15 to 20 minutes.
The general indication for syrup of ipecac is a significant ingestion of toxin in an awake, alert patient with an intact gag reflex. Contraindications to induced emesis are ingestion of corrosives, absence of protective airway reflexes, coma, or seizures. Because syrup of ipecac may cause protracted vomiting (mean duration: 2 hours; range: up to 12 hours), it is relatively contraindicated for ingestions that may result in seizures or depressed mental status. It also is contraindicated in children who have ingested hydrocarbons when the risk of aspiration of the hydrocarbon outweighs the benefit of gastric evacuation.
Syrup of ipecac can be used in children as young as 6 months of age.2 Uncommon complications include protracted emesis, lethargy, and aspiration of gastric contents; Mallory-Weiss tears and pneumomediastinum also have been reported. As mentioned, ipecac use continues to decrease, in part reflecting the growing list of medications for which its use is relatively contraindicated.
Syrup of ipecac is an effective emetic resulting in vomiting in 88% of patients within 30 minutes when given at recommended doses.3 However, although it effectively induces emesis, ipecac may not significantly decrease the amount of toxin absorbed. For example, the amount of ingested substance removed by induced emesis is correlated with the interval between ingestion and emesis; even a delay of 30 minutes can result in a lack of a significant reduction in absorption of ingested substances.4 Therefore, although ipecac may be useful when administered at home immediately after an ingestion has occurred, the typical delay in presentation to an emergency department (>1 hour in children and >3 hours in adolescents and young adults according to epidemiological data) decreases its utility. Finally, syrup of ipecac can cause protracted vomiting that precludes the administration of activated charcoal. One study found that use of syrup of ipecac delayed administration of activated charcoal on average by 2.2 hours.5
Gastric lavage is the alternative to induced emesis for gastric evacuation. In performing gastric lavage, a large-bore tube is placed in the stomach via an orogastric rather than a nasogastric route. "Sump" or double lumen tubes cannot be used for gastric evacuation unless the ingested product is a liquid. (If the toxin is a liquid such as ethylene glycol, the stomach can be evacuated via a small nasogastric tube; there is no need for gastric lavage.)
Gastric lavage must be performed properly in order to reduce complications. In the child who does not have an adequate gag reflex, the airway must be protected by elective endotracheal intubation before lavage is begun. An orogastric tube with the largest bore possible should then be passed. At least a 36French tube should be used in an adult and a 16- to 28-French tube in a child.
Tube placement is confirmed by aspiration of gastric contents or air insufflation with a stethoscope placed over the stomach. Ideally, the child then is placed in the Trendelenburg left lateral decubitus position. Normal saline is introduced in 50- to 100mL aliquote in the young patient and in 1 50- to 200mL aliquote in the older patient. Fluid is withdrawn either by aspiration with a large syringe or by gravity drainage. Lavage should be continued until the effluent is clear. If activated charcoal is to be administered, it should be infused at the completion of lavage. The tube then is removed. Complete physical restraint is often necessary to perform lavage in the pediatric patient. Otherwise, the same principles of lavage apply regardless of age.
Indications for gastric lavage include obtundation, need for urgent removal of a substance due to an anticipated rapid deterioration in the patient's clinical status (eg, camphor or tricyclic antidepressants), or the ingestion of a substance known to form concretions. Contraindications to gastric lavage include caustic, and most hydrocarbon ingestions, or a history of esophageal surgery.
Gastric lavage has a 3% complication rate in adult populations. The most common complication is aspiration of gastric contents, although perforation of the esophagus or stomach and propulsion of toxins beyond the pylorus - thereby potentially speeding absorption - also have been reported.6
The efficiency of gastric lavage in decontamination has been studied using a variety of overdose paradigms that have yielded conflicting results. Using an ampicillin overdose model, Tenenbein et al7 found that gastric lavage did not significantly reduce drug absorption. Similarly, Young et al8 found that only 30% of a radioactive label placed in capsules was recovered when volunteers underwent gastric lavage until clear. Gastric lavage was proved by endoscopy to leave residual pill fragments in the stomach of 88% of self-poisoned patients.9 These and other studies indicate that, like induced emesis, gastric lavage has relatively poor efficacy at removing ingested toxins. This is particularly true if gastric lavage is performed more than 1 hour postingestion (the "golden hour" of toxicology). In general, both methods of gastric emptying remove no more than 35% of ingested substances.
Activated charcoal is the residue following destructive distillation of various organic materials. It is processed so that the granule size has interstices, thereby increasing its absorptive surface area. Activated charcoal typically has a surface area of 900 to 1000 mp 2/g; "super-activated" charcoals have a surface area two to three times greater. A 50-g dose of activated charcoal has a surface area approximately equal to 10 football fields.
The absorptive capacity of activated charcoal has been appreciated since the 1800s. A dramatic display of its ability to absorb poisons occurred in 1830 when a French pharmacist drank a lethal dose of strychnine mixed with charcoal and developed no signs of toxicity.10 Activated charcoal adsorbs most compounds with the exception of hydrocarbons, corrosives, alcohols, and metals or minerals such as lithium, iron, or lead. An activated charcoal-to-toxin ratio 10:1 or greater is considered ideal in producing maximum adsorption.
Activated charcoal may be used alone or following gastric evacuation. It is generally administered as a slurry with cathartic. Many commercial preparations of activated charcoal are premixed with a cathartic. If not premixed, charcoal may be reconstituted with either sterile water or a cathartic. The dose of activated charcoal is 1 g/kg. The maximum dose generally is 60 g, although single doses as large as 200 g have been administered. There is no minimum dose. Despite attempts to make charcoal more palatable by adding flavors such as chocolate, children frequently refuse to drink it. In this situation, a 12- to 14-French nasogastric tube is placed and the charcoal administered via the tube. A single dose of activated charcoal has virtually no side effects.
Bowel Transit Times for Activated Charcoal Administered Alone and With Cathartics*
In recent years, the trend in gastric decontamination has been away from gastric evacuation and toward the use of activated charcoal alone. A growing body of research has shown activated charcoal as a sole decontamination measure to be superior to gastric evacuation.
Several clinical studies of self-poisoned patients have been conducted to determine the impact of activated charcoal with or without prior gastric emptying on clinical outcomes. Kulig et al5 published the first of these studies in 1985. Nearly 600 patients presenting to an emergency department were randomized on the basis of odd/even day of presentation to receive either activated charcoal alone or gastric evacuation followed by activated charcoal. Only the subgroup of patients who presented with obtundation and had gastric lavage performed within 1 hour of ingestion had a significant improvement in level of intoxication compared with the group who received activated charcoal alone.5
In a separate study, 808 poisoned patients were randomized to receive activated charcoal following induced emesis, activated charcoal following lavage, activated charcoal alone, or observation without decontamination.11 This study showed that symptomatic patients who underwent gastric evacuation prior to activated charcoal had a higher rate of admission to the intensive care unit and of aspiration pneumonia than those receiving activated charcoal alone. A study that evaluated the use of activated charcoal alone versus activated charcoal and gastric evacuation in patients with tricyclic antidepressant overdose found no intergroup differences in clinical outcome.12 These studies reinforce that activated charcoal is the single most important component of decontamination with the other components conferring little or no benefit in most cases of poisoning.
Cathartics (or purgatives) were first used in poisoning management as agents that would enhance the expulsion of toxins before systemic absorption could occur. Their use preceded the widespread use of activated charcoal. Since the advent of charcoal, catharsis has been thought to offer the advantage of facilitating the expulsion of a toxin-charcoal complex in the event that drug desorption from charcoal occurs.13
Cathartics are typically categorized by their primary mechanism of action. Common categories include osmotic cathartics - subcategorized as saline (magnesium sulfate or citrate) or saccharides (sorbitol) - and stimulant cathartics (castor oil or Phenolphthalein). The cathartics most commonly used in the treatment of toxic ingestions are magnesium citrate and sorbitol.
The cathartics have a wide range of efficacy in producing catharsis. In a study examining the ability of varying cathartics to produce stooling when administered with activated charcoal, time to stooling ranged from 24 hours (for activated charcoal and water only) to 77 minutes after administration of sorbitol (Table 2).14 By this measure of effect, therefore, sorbitol is a superior cathartic. However, recent studies have redefined the efficacy of cathartics by their ability to improve clinical outcome or reduce serum concentrations of toxin; newer data have failed to identify consistent benefit from cathartics. Analogous to the efficacy of ipecac not being correlated with its ability to produce vomiting, the efficacy of cathartics cannot be equated with their ability to produce charcoal stools.
While cathartics are generally safe, they have been associated with clinical toxicity. For magnesium-containing cathartics, their repeated administration (often done in conjunction with repetitive administration of activated charcoal) has led to hypermagnesemia, manifested by hypotonia, altered mental status, and in severe cases, respiratory failure.15,16 Sorbitol also has produced toxicity after its repeated administration. In both children and adults, pooling of fluid within the gastrointestinal tract, excessive fluid losses in stool, and severe dehydration (particularly hypernatremic dehydration) with cardiovascular instability have occurred.17 Children younger than 2 years may be particularly susceptible to this adverse effect. Sorbitol is also emetogenic, resulting in vomiting of administered activated charcoal.
Despite these potential toxicities, cathartics provide the potential benefit of expelling toxins in rapid fashion with little to no clinical toxicity when used as prescribed. Therefore, their use is still recommended (although the administration of activated charcoal in water is an acceptable alternative). Sorbitol should be used cautiously in young children because of its recognized ability to produce excessive fluid losses. The recommended dose of magnesium citrate in children is 4 to 8 cc/kg (maximum 300 mL).18 Sorbitol is administered in a dose of 2 cc/kg of 70% sorbitol (1 to 2 g/kg). Repetitive doses of sorbitol should never be administered.
Whole-bowel irrigation, a modified version of catharsis that has received greater attention in recent years, is the process of administering an electrolytebalanced solution in large volumes until a clear rectal effluent is produced. This treatment stems from the "bowel preparation" that patients undergo prior to bowel radiography or surgery. The polyethylene glycol solution used for whole-bowel irrigation is the same product used for these surgical/radiographic procedures. In poisoning management, patients drink (or are administered via nasogastric tube) 2 to 50 L of solution at an average rate of 0.5 to 1.5 L/hour for adolescents and 20 to 40 mL/kg per hour in young children. As much as 44 L have been administered to children without untoward effect.19,20
Whole-bowel irrigation has proven efficacy in two types of intoxication. First, with those toxins that are poorly adsorbed by activated charcoal (eg, iron or lithium), gastric evacuation and catharsis are the only two components of gastrointestinal decontamination available.21,22 In these cases, whole-bowel irrigation has proven to produce prompt expulsion of whole tablets before they can be absorbed. A second potential role for whole-bowel irrigation is the management of children and adolescents with ingestions of sustained-release medications. In these cases, in which there can be substantial delay of drug absorption due to pharmaceutical characteristics (eg, slow dissolution), whole-bowel irrigation can be used to accelerate expulsion of these agents.23
No toxicity from the polyethylene glycol solution has been identified. Also, it does not diminish the efficacy of activated charcoal. However, the process of whole-bowel irrigation can be problematic; in clinical practice, patients must sit on the commode during administration, away from an optimally monitored setting, or soil their bed repeatedly because they develop copious stooling.
RECOMMENDED APPROACH TO DECONTAMINATION
Management of the poisoned child is a clinical challenge that does not lend itself to simple algorithms. However, there are three factors that can help the practitioner determine what modalities should be used to decontaminate most poisoned patients:
* the seriousness of the ingestion,
* the category of the substance ingested (ie, corrosive, hydrocarbon, metal, or an alcohol), and
* the time since ingestion.
The Figure gives a recommended approach to emergency department management of a poisoned child using these three factors. Clearly, although this algorithm may be useful in the majority of poisonings, there are a number of exceptions. For example, although it is generally recommended that a child who ingests a hydrocarbon be observed without any decontamination (due to concern of aspiration), if a child ingests a large quantity of an aliphatic hydrocarbon or a hydrocarbon with a toxic additive such as pesticide, then lavage is recommended.
The most important and often the most difficult judgment to make is determining the seriousness of the ingestion. The severity of the ingestion depends on both the substance as well as the quantity ingested. For example, ingestion of children's chewable multivitamins with iron is rarely serious as it is nearly impossible for a child to ingest 60 mg/kg of iron. In contrast, ingestion of adult strength ferrous sulfate tablets can be serious. An ingestion is severe if it may result in life- threatening complications; an ingestion is of moderate seriousness if it can result in significant cardiovascular compromise. Some of the most common life-threatening ingestions include: tricyclic antidepressants, monoamine oxidase inhibitors, calcium channel antagonists, beta blockers, iron, and hydrocarbons. It is impossible to provide an inclusive list of life-threatening ingestions. Therefore, if the practitioner has any question about seriousness of the ingestion, it is recommended that a regional poison center be consulted.
A critical branch point is the substance category; categories include hydrocarbons, corrosives, alcohols, metals/minerals, and substances with delayed absorption. Activated charcoal does not absorb hydrocarbons, corrosives, metals/minerals, or alcohols, and there is no utility in administering activated charcoal to patients with these ingestions unless there are suspected co-ingestants. In cases of corrosive and most hydrocarbon ingestions, the child should not undergo lavage because of the high likelihood of potential complications (eg, perforation or aspiration). Patients who have ingested alcohols such as methanol or ethylene glycol do not need lavage. Rather, the alcohol should be evacuated from the stomach via a small bore nasogastric tube if the patient presents within I hour of the ingestion; decontamination is unlikely to be effective if the patient presents more than 1 hour after ingestion.
There are a number of substances that have delayed absorption either because they are sustainedrelease preparations (sustained-release theophylline), decrease gastric motility due to anticholinergic properties (tricyclic antidepressants), or have a tendency to form concretions (carisoprodol, meprobamate, and enteric-coated aspirin). In these types of ingestions, lavage should still be considered even if the patient presents after 1 hour of ingestion. Finally, metals and minerals such as iron or lithium that do not absorb to activated charcoal can only be removed by lavage or whole-bowel irrigation.
In the child or adolescent with a significant toxic ingestion, the cornerstone of treatment remains early gastrointestinal decontamination. Gastrointestinal decontamination can be life-saving when provided rapidly, efficiently, and appropriately. Scientific investigations continue to demonstrate a minor role for gastric evacuation and catharsis, placing activated charcoal as the single most important and, in many cases, the only decontamination necessary after a toxic ingestion. Moreover, due to the relative ineffectiveness of ipecac and the growing list of relative contraindications, emergency health-care providers must abandon ipecac and gain the necessary expertise to administer activated charcoal in the young child and perform gastric lavage if indicated.
1 . Litovitz TL, Felberg L. Soloway RA. Fold M, Geller R. 1994 annual repon of the American Association of Poison Control Centers' Toxic Exposure Surveillance System. AmJ Emerg Med. In press.
2. Litovitz, TL, Klein-Schwartz W, Odera GM, Matyunas NJ, Wiley S, Gorman RL. Ipecac administration in children younger than 1 year of age. Pediatrics. 1985;76:761-764.
3. Robertson WO. Syrup of ipecac - a slow or fast emetic? Am ) Dis Child. 1962;103:58-61.
4. Neuvonen PJ, Vartiainen M, Tokola O. Comparison of activated charcoal and ipecac syrup in prevention of drug absorption. Eur J Clin Pharmacol. 1983;24:557562.
5. Kulig K, Bar-Ot D, Cantril SV, Rosen P, Rumack BH. Management of acutely poisoned patients without gastric emptying. Arm Emerg Med. 1985;14:562-567.
6. Matthew H, Mackintosh TR Tompsett SL, Cameron JC. Gastric aspiration and lavage in acute poisoning. Br Med J. 1966;1:1333-1337.
7. Tenenbein M, Cohen S, Sitar DS. Efficacy of ipecac-induced emesis, orogastric lavage, and activated charcoal for acute drug overdose. Ann Emerg Med. 1987;16:838-841.
8. Young WF Jr, Bivcns HG. Evaluation of gastric emptying using radionuclides: gastric lavage versus ipecac-induced emesis. Ann Emerg Med. 1993;22:1423-1427.
9. Saetta J, Quinton DN. Residual gastric content after gasttic lavage and Ipecacuanha- induced emesis in self-poisoned patients: an endoscopic study. Royal Society of Medicine. 1991;84:35-38.
10. Anderson H. Experimental studies on the pharmacology of activated charcoal. 1: absorption power of charcoal in aqueous solutions. Acta Pharmacologia et !oncologia. 1946;2:69-78.
11. Merrigian KS, Woodard M, Hedges JR, Roberts JR, Stuebmg R, Rashkin MC. Prospective evaluation of gastric emptying in the self-poisoned patient. Am J Emerg Med. 1990;8:479-483.
12. Bosse GM, Barefoot JA, Pfeifer MP, Rodgers GC Comparison of three methods of gut decontamination in tricyclic antidepressant overdose. J Emerg Med. 1995;13:203-209.
13. Shannon M, Fish SS. Lovejoy FL Cathartics and laxarives - do they still have a place in management of the poisoned patient! Medical lexicology. 1986;1:247-252.
14. Krenzelok EP. Gastrointestinal transit times of cathartics used with activated charcoal. Clin Pharm. 1985;4:446-448.
15. Garrelts JC, Watson WA1 Holloway KD, Sweet DE. Magnesium toxicity secondary to catharsis during management of theophylline poisoning. Am J Emerg Med. 1989;7:34-37.
16. Smilltstein MJ, Smollaste SC. Kulig KW, Rumack BH. Severe hypermagnesemia due to multiple-dose cathartic therapy. West J Med. 1988;198:208-211.
17. Farley TA. Severe hypematremic dehydration after use of an activated charcoalsorbitol suspension. J Pediotr. 1986;109:719-722.
18. Sue YJ, Woolf A, Shannon M. Efficacy of magnesium cirrate cathartic in pediatric toxic ingestions. Ann Emerg Med. 1994;24:709-712.
19. Tenenbein M, Cohen S, Sitar DS. Whole bowel irrigation as a decontamination procedure after acute drug overdose. Arcli Intern Med. 1987;147:905-907.
20. Kaczorowski J, Wax P. Whole bowel irrigation with 44 liters of polyethylene glycol in a pediatric iron OD. Vet Human Toxicol 1994:36:340.
21. Tenenbein M. Whole bowel irrigation in iron poisoning. J Pediotr. 1987;111:142145.
22. Smith SW, Ling LJ, Halstenson CE. Whole-bowel irrigation as a treatment for acute lithium overdose. Ann Emerg Med. 1991;20:536-539.
23. Kirshenbaum LA, Mathews SC, Sitar DS1 Tenenbein M. Whole-bowel irrigation versus activated charcoal in sorbitol for the ingestion of modified release pharmaceuticals. CIm Pharmacol Ther. 1989;46:264-271.
Bowel Transit Times for Activated Charcoal Administered Alone and With Cathartics*