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February 2005
From HealthPartners Medical Group & Clinics
Emergency Medicine Department (Toxicology Section)


Management Strategies in Overdoses: The ABCDEs of Toxicology
The number and variety of drugs and toxins that can be ingested in an overdose is large. Although the ABCs (Airway, Breathing, and Circulation) of emergency medicine stabilization are well known to most clinicians, the ABCDEs (Antidote, Basics, Charcoal, Decontamination and Enhanced elimination) of toxicology are often less familiar. The initial management of overdose using the ABCDEs of toxicology is discussed below. Early consultation with your regional poison center (1-800-222-1222 this is a universal number throughout the United States and will be routed to your regional poison center) or your local toxicologist is often an important additional step in the management of the overdose patient.

Antidote
If you know the drug or toxin that has been ingested and its antidote, administer the antidote as soon as possible. Selected drugs/toxins encountered in an overdose situation and their antidotes are summarized below:

Table I: Antidotes for Common Overdose Drugs/Toxins

Drug/Toxin

Acetaminophen, Carbon tetrachloride Antidote: N-Acetylcysteine
Anticholinergics Antidote: Physostigmine
Benzodiazepines Antidote: Flumazenil
Beta blockers Antidote: Glucagon
Calcium channel blockers Antidote: Calcium
Carbon monoxide, Cyanide, Hydrogen sulfide Antidote: Oxygen
Ethylene glycol, Methanol Antidote: Ethanol, Fomepizole
Digoxin, Cardiac glycoside plants (foxflove, oleander) Antidote: Fab Fragments (DigiFab, Digibind)
Hydrofluoric acid, Fluorides, Oxalates Antidote: Calcium
Iron Antidote: Deferoxamine
Isoniazid (INH) Antidote: Pyridoxine
Lead (FDA approval), Arsenic, Mercury Antidote: Dimercaptosuccinic acid (DMSA)
Narcotics/Opiates Antidote: Naloxone (1)
Organophosphates Antidote: Atropine, Pralidoxime
Tricyclic antidepressants Antidote: Sodium bicarbonate


Basics
Make sure that the ABCs of emergency medicine stabilization have been implemented. The management of a potentially serious overdose should always include the initiation of the Emergency Medicine Safety Net (i.e., oxygen, intravenous access, and ECG monitor).

Charcoal
Activated charcoal is beneficial for the management of potentially toxic ingestions due to a number of drugs/toxins including phenobarbital, theophylline, quinine, dapsone, aspirin, tricyclic antidepressants, and carbamazepine. The usual dose is 50-100 grams for adults or 1 gm/kg in children. Charcoal is usually administered as an aqueous suspension (2) and is most beneficial if given within 60 minutes following a potentially toxic ingestion of a drug/toxin that is adsorbed to charcoal. Multiple doses (initial dose followed by half doses every 2-4 hours up to a total of 3-4 doses) may be given for overdose due to aspirin, enteric coated or sustained release preparations, tricyclic antidepressants, theophylline, and phenobarbital. Remember that activated charcoal does not adsorb metals (iron, lithium, potassium) very well and should not be used in caustic and hydrocarbon ingestions.

Decontamination
Decontamination procedures such as gastric lavage/irrigation are often recommended if done within 60 minutes of a potentially lethal ingestion (gastric lavage has not been shown to change the course or outcome of an ingestion if performed more than 60 minutes post-ingestion). Remember that gastric lavage (3) is not a benign procedure and may increase morbidity (e.g., esophageal injuries and aspiration). Placing the patient on their left side with their head down may help prevent aspiration and improve the yield of the procedure. Endotracheal intubation may be necessary in obtunded patients.

Ipecac syrup and other cathartics have not been shown to be of benefit in the management of overdose (4) and their use in the emergency department should be abandoned. If ipecac is used, it is usually given at home very early following an ingestion at the direction of the Poison Center.


Enhanced elimination
Hemodialysis, hemoperfusion, whole bowel irrigation (WBI) (5), and manipulation of urine and/or blood pH, and other adjunct therapeutic modalities may be useful in certain toxic situations by enhancing the elimination of the drug/toxin. Drug overdoses that can be managed by hemodialysis include salicylates, theophylline, methanol, meprobamate, metoprolol, barbiturates (especially long-acting), lithium, ethylene glycol (antifreeze), and valproate.

(1) Naloxone can be given intravenously, intramuscularly, endotracheally, subcutaneously, or intralingually. The initial dose for patients with respiratory depression is 2 mg. The dose may be repeated every 2 minutes up to a total of 10 mg. In narcotic-dependent patients (due to concern about withdrawal symptoms) or those with non-life threatening symptoms, the initial dose is 0.1 mg, doubled every two minutes up to a total of 10 mg. Large doses may be needed for synthetic narcotics.

(2) Activated charcoal usually comes pre-mixed in an aqueous solution or with sorbitol. Activated charcoal pellets are available and one container can be mixed with 4 oz of water for a 25 gm dose.

(3) Gastric lavage is contraindicated following the ingestion of corrosives and most hydrocarbons. A 34- to 40- French tube is used for adults. In adults, warm tap water in 300 mL aliquots is used until the returns are clear. Saline should be used in pediatric or geriatric patients.


(4) Ipecac was granted over-the-counter status for home treatment of poisonings in 1965. In 1985, the American Academy of Pediatrics recommended that ipecac be discussed with and given to parents at the 6-month infant visit as part of anticipatory guidance. Since that time, a number of concerns have been raised regarding ipecac. These include administration without the advice of a health care professional or Poison Center; variable success for removal of a substance from the stomach even if administered immediately following the ingestion; failure to improve outcomes or reduce the use of emergency services; potential adverse effects including persistent vomiting, lethargy, and diarrhea; and potential abuse by bulimics or use as an agent for Munchhausens syndrome by proxy. At least in part because of these concerns, Poison Centers rarely (0.7% of contacts in 2001) recommend ipecac for the treatment of home poisonings any longer. In June 2003, an Advisory Committee recommended that the FDA rescind ipecacs over-the-counter status and make it available only by prescription. Ipecac may still be available in many households and the American Academy of Pediatrics recommends that providers advise parents to safely dispose of ipecac currently in their homes.

(5) Whole bowel irrigation may be beneficial in patients who have ingested substances not well absorbed by activated charcoal and/or are not amenable to gastric lavage including iron, lithium, slow-release potassium, and packets or vials containing cocaine or other drugs. Polyethylene glycol solutions such as Golytely or Colyte are administered orally or via nasogastric tube at a rate of 2 L per hour in adults or 0.5 L per hour in children until the rectal effluent is clear.

References
American Academy of Clinical Toxicology; European Association of Poisons Centres and Clinical Toxicologists. Position Paper: Ipecac Syrup. J Toxicol Clin Toxicol 2004; 42 (2): 33-34.

American Academy of Clinical Toxicology; European Association of Poisons Centres and Clinical Toxicologists. Position Statement: Single-Dose Activated Charcoal. J Toxicol Clin Toxicol 1997; 35 (7): 721-741.

American Academy of Clinical Toxicology; European Association of Poisons Centres and Clinical Toxicologists. Position Paper: Whole Bowel Irrigation. J Toxicol Clin Toxicol 2004; 42 (6): 843-854.

Bond GR. Home Syrup of Ipecac Use Does Not Reduce Emergency Department Use or Improve Outcome. Pediatrics 2003; 112: 1061-1064.

Committee on Injury, Violence, and Poison Prevention of the American Academy of Pediatrics. Policy Statement: Poison Treatment in the Home. Pediatrics 2003; 112: 1182-1185.

Larsen LC, Cummings DM. Oral Poisonings: Guidelines for Initial Evaluation and Treatment. American Family Physician 1998; 57: 85-92.

Shannon M. The Demise of Ipecac (commentary). Pediatrics 2003; 112: 1180-1181.


Questions
If you have questions relating to this Pearl of the Month, please email your questions to IME Pearl .

Questions will be forwarded to the HealthPartners Emergency Medicine Department (Toxicology Section) and feedback and feedback will be posted at
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Register now to attend the Toxicology conference, to be held October 14-15 at theHoliday Inn Metrodome, Minneapolis. And don't miss the 19th Annual Family Medicine Today Conference, March 10-11, 2005, at the Holiday Inn East, in St. Paul. View our web site at ime.healthpartners.com for all the current conference listings: Institute for Medical Education (IME)

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Last modified: February 14, 2005
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