Chapter 30 Toxicologic Emergencies

Randal Bryan Badillo, Kimberly Hovseth, Scott Schaffer

According to the 2009 Annual Report of the American Association of Poison Control Centers’ National Poison Data System, approximately 2.5 million cases of human exposure to poisons were reported in that year.¹ The five substances most frequently involved in all human exposures were analgesics; cosmetics/personal care products; household cleaning substances; sedatives/hypnotics/antipsychotics; and foreign bodies/toys/miscellaneous. The five most common exposures in children ages 5 years and under were cosmetics/personal care products; analgesics; household cleaning substances; foreign bodies/toys/miscellaneous; and topical preparations.¹

Exposures can be occupational, environmental, recreational, or therapeutic. Toxic exposures occur through inhalation, ingestion, injection, or contact with skin and mucous membranes. Most poisonings are unintentional, relatively mild, and do not require emergency services. Treatment in a health care facility is required for about 24% of those who contact a poison control center, approximately half of whom are treated and released.¹ Only about 16% of these patients are admitted to a critical care unit.¹

The field of toxicology, the science of poisons and their effects on living organisms, is evolving rapidly, and practices routinely change as better interventions are identified. Because it is difficult for individual practitioners to keep current, poison control centers located throughout the United States have assumed a vital role in the identification and management of toxic emergencies. Poison control center experts help clinicians to assess patients and can suggest current management practices. These centers have access to POISINDEX and other toxicology databases that are updated regularly. Poison center contact should be made by an emergency department clinician for each poisoned patient. This not only allows poison control centers to be of assistance to emergency departments, but also helps them to track patients and gather demographic and statistical information on poisonings.

Nationwide Poison Control Center phone number: 1-800-222-1222

Because most patients with a poison exposure will have no significant problems, it is important to be able to recognize those at greatest risk for serious complications and death. Consider persons in the following categories as “red flag” patients:

• Age: The older the patient, the more likely the patient is to die from ingestion.

• Pharmaceuticals: Pharmaceutical agents are generally more toxic than plants, household chemicals, and recreational drugs.

• Polypharmacy: Patients exposed to multiple substances are at increased risk for death.

• Intentional poisonings: Persons who intentionally expose themselves to toxic substances are considerably more likely to sustain adverse events than are those with unintentional exposures.

• Altered mental status or other severe symptoms on presentation: Patients who are significantly compromised upon arrival to the emergency department are more likely to have a poor outcome.

General Priorities for Poisoned Patients

Give basic and advanced supportive care (physiological and psychological) as needed. Support the patient’s airway, breathing, and circulation; airway protection is critical in patients with an altered mental status. Specifically:

• Administer supplemental oxygen as needed.

• Establish intravenous access and infuse lactated Ringer solution or normal saline solution.

• Give naloxone (Narcan) 0.4 to 2 mg intravenously, endotracheally, intramuscularly, subcutaneously, intraosseously, or sublingually if the patient has a potential opioid exposure.

• Check blood glucose level and infuse dextrose 50% at 50 mL (25 g) intravenously as needed to maintain normoglycemia.

• Administer 50 to 100 mg thiamine intravenously to adult patients with suspected chronic alcohol abuse.

• Initiate continuous cardiac monitoring and obtain 12-lead electrocardiograms as indicated.

• Monitor urinary output.

• Draw arterial blood gases as indicated.

• Perform serial monitoring of electrolyte levels, vital signs, and respiratory, cardiac, and neurologic status.

• Obtain an exposure history:

• To what substance or substances was the patient exposed?

• When did the exposure occur? Is this an acute or chronic exposure?

• What was the route of exposure?

• Are there currently any signs or symptoms of poisoning?

• How much of the substance is involved?

• Was the exposure intentional or unintentional?

• Does the patient have a history of previous toxic exposures?

• What treatment was rendered before arrival of emergency medical services?

• How old is the patient?

• What is the patient’s medical history (especially cardiac, hepatic, psychiatric, and renal disorders)?

• Are any psychological, social, or environmental risk factors involved?

• Administer the appropriate antidote (if one is available).

• Provide education to patients, families, and significant others to prevent future incidents.

Identifying the Poison

Toxidromes

A toxidrome is a set of toxic symptoms caused by a particular class of medication or type of poison. In the patient with an unknown poisoning, early recognition of a toxidrome will enable emergency personnel to rapidly initiate appropriate treatment. Table 30-1 summarizes common toxidromes that can aid in identification of the poison. Table 30-2 lists some other diagnostic clues for identifying unknown toxins.

TABLE 30-1 TOXIDROMES

TABLE 30-2 DIAGNOSTIC CLUES IN UNKNOWN EXPOSURES

CLUE OR SYMPTOM	POSSIBLE AGENT OR CAUSE
Metabolic acidosis	MUDPILES mnemonic: Methanol, Uremia, Diabetic ketoacidosis, Paraldehyde, Isoniazid/Iron, Lactic acidosis, Ethanol/Ethylene glycol, Salicylates/Sympathomimetics
Radiopaque medications	CHIPE mnemonic: Chloral hydrate, Heavy metals, Iron, Phenothiazines, Enteric-coated tablets
Breath Odors
Alcohol	Ethanol, chloral hydrate, phenols
Acetone	Acetone, salicylates, isopropyl alcohol, diabetic ketoacidosis
Bitter almond	Cyanide
Coal gas	Carbon monoxide
Garlic	Arsenic, phosphorus, organophosphates
Nonspecific	Consider inhalant abuse
Oil of wintergreen	Methylsalicylates
Urine Color
Red	Hematuria, hemoglobinuria, myoglobinuria, pyrvinium, phenytoin, phenothiazines, mercury, lead, anthocyanin (food pigment found in beets and blackberries)
Brown-black	Hemoglobin pigments, melanin, methyldopa, cascara, rhubarb, methocarbamol
Blue or blue-green	Amitriptyline, methylene blue, triamterene, Clorets gum, Pseudomonas
Brown or red-brown	Porphyria, urobilinogen, nitrofurantoin, furazolidone, metronidazole, aloe, seaweed
Orange	Rifampin, phenazopyridine, sulfasalazine

Data from Dart, R. D. (Ed.). (2000). The 5-minute toxicology consult. Philadelphia, PA: Lippincott Williams & Wilkins.

Anticholinergic Toxidrome

• Includes antihistamines, tricyclic antidepressants, cyclobenzaprine, Parkinson’s disease medications, antispasmodics, mydriatics, and certain plants (e.g., jimsonweed)

• Signs and symptoms include the following:

• Increased blood pressure, heart rate, and temperature

• Mydriasis, decreased bowel sounds, dry mucous membranes, flushing, urinary retention, agitation, delirium, and hallucinations

• A helpful memory aid is HOT as a hare (hyperthermia), RED as a beet (flushing), DRY as a bone, BLIND as a bat (mydriasis), MAD as a hatter (delirium, hallucinations)

Cholinergic Toxidrome

• Includes organophosphates and carbamate insecticides, physostigmine, pilocarpine, and nicotine

• Combination of muscarinic and nicotinic effects (Table 30-3)

TABLE 30-3 MUSCARINIC AND NICOTINIC EFFECTS OF CHOLINERGIC TOXIDROMES

MUSCARINIC EFFECTS (DUMBELS MNEMONIC)	NICOTINIC EFFECTS
Diarrhea, diaphoresis	Tachycardia
Urination	Hypertension
Miosis	Fasciculations
Bradycardia, bronchorrhea	Paralysis
Emesis	Mydriasis
Lacrimation
Salivation

Therapeutic Interventions for Poisonings and Overdoses

Gastrointestinal Decontamination

Decontamination of the digestive system can be done in several ways, including by induced emesis, administration of activated charcoal or multiple-dose activated charcoal, gastric lavage, cathartics, and whole-bowel irrigation (WBI). Hemodialysis and charcoal hemoperfusion are also used in some severe poisonings.

Induced Emesis

Although once a mainstay of care, the role of syrup of ipecac in the management of the poisoned patient has significantly decreased in recent years. Routine use of syrup of ipecac is no longer recommended.² Some of the serious side effects of ipecac include:

• Risk of aspiration

• Inducing vomiting may lead to increased intracranial pressure

• Increases risk for hemorrhagic bleeding and profound fluid and electrolyte disorders

Syrup of ipecac is only marginally effective at emptying the stomach, and its use is associated with numerous contraindications and complications. Emesis can delay charcoal administration significantly. However, there are rare circumstances under which ipecac may be considered appropriate,² and as a result, the drug is still available over the counter and at hospitals throughout the United States.

Activated Charcoal

Recently, some research has indicated that the use of activated charcoal alone is equivalent or even superior to other poisoning treatment modalities and combinations. However, no well-controlled studies have documented significant improvement in patient outcome.³

Given by mouth or gastric tube, activated charcoal has the advantage of being minimally invasive, relatively easy to administer, and safe for both children and adults. Activated charcoal absorbs and binds most commonly ingested substances. Specific contraindications to use of activated charcoal include the following:⁴

• Ingestion of a corrosive agent or hydrocarbons.

• Decreased or absent bowel sounds (relative contraindication).

• Toxins not bound by charcoal, such as iron, lead, and lithium.

Substances Not Absorbed by Activated Charcoal

• Caustics

• Heavy metals (lead, zinc, mercury)

Recommendations for the administration of activated charcoal are as follows:

• In rare cases where syrup of ipecac has been administered, activated charcoal should not be administered until induced emesis has subsided (usually 60 to 90 minutes after the patient last vomited).

• Alert, cooperative patients can drink activated charcoal through a straw.

• Activated charcoal is gritty but not particularly unpleasant tasting. Flavoring (e.g., cherry or chocolate syrup) makes the charcoal more palatable and does not decrease its effectiveness.

• Small, intermittent doses may reduce vomiting.

• Shake the activated charcoal mixture (slurry) thoroughly to eliminate clumping.

• More dilute slurries are easier to drink or pass through a gastric tube, particularly tiny pediatric tubes.

• In patients with an altered mental status, aggressively protect the airway (endotracheal intubation) before administration of activated charcoal. Visualization of the epiglottis is difficult after activated charcoal has been vomited. Aggressive suctioning of aspirated charcoal appears to improve patient outcome.

• A standard-sized Salem sump tube is adequate for activated charcoal instillation.

• Securely anchor gastric tubes to prevent retraction from the stomach to the esophagus.

• Reconfirm appropriate gastric tube placement immediately before administration of activated charcoal.

Multiple-Dose Activated Charcoal

Multiple-dose (“multidose” or “repeated dose”) activated charcoal may be considered for poisonings involving extended-release medications, carbamazepine, dapsone, quinine, theophylline, and medications that may form bezoars or concretions (e.g., enteric-coated tablets). Multiple-dose activated charcoal commonly is used for other substances as well.

Indications for Multiple-Dose Activated Charcoal ⁵

Evidence-Based	Frequently Used
• Carbamazepine	• Digoxin
• Dapsone	• Phenytoin
• Phenobarbital	• Salicylates
• Quinine	• Sustained-release preparations
• Theophylline	• Tricyclic antidepressants

Dosing for Multiple-Dose Activated Charcoal

• Administer 0.5 g/kg (25 to 50 g in adults) every 4 to 6 hours for up to 12 to 24 hours.⁵

• Seek consultation with the poison center for pediatric patients.

• Use aqueous formulation, without sorbitol, to prevent fluid loss and electrolyte disturbances.

Cathartics

Cathartics—such as magnesium sulfate, magnesium citrate, or sorbitol—have long been added to activated charcoal to enhance gastrointestinal elimination of poisons. However, overuse of cathartics causes diarrhea, nausea and vomiting, abdominal pain, increased magnesium levels, electrolyte imbalances, and hypovolemia.⁷ Cathartics should not be given if bowel sounds are absent. Never administer cathartics to children under 1 year of age; cases of fatal diarrhea have been reported in this population.⁴

Whole-Bowel Irrigation

Whole-bowel irrigation involves the use of an electrolyte solution (GoLYTELY, CoLyte) administered orally or by gastric tube. Caution must be taken in the pediatric population, and WBI for pediatric patients should be guided by a poison center clinician. WBI produces a rapid catharsis, eliminating most matter from the gastrointestinal tract within a few hours. It most commonly is given following ingestion of an agent that is not well adsorbed by activated charcoal, such as enteric- or sustained-release products, iron, lead, lithium, or zinc. Adverse effects of WBI include nausea, vomiting, and severe cramping as well as increased risk of electrolyte imbalance. It is contraindicated in cases of preexisting gastrointestinal pathology or in patients with increased risk of ileus or obstruction. Swallowed button batteries and cocaine-filled condoms or other packets of illicit drugs can also be removed by WBI.⁴

Hemodialysis and Charcoal Hemoperfusion

Hemodialysis is indicated for certain serious poisonings associated with severe metabolic acidosis, electrolyte abnormalities, or renal failure. Peritoneal dialysis also can be used for short-term treatment. Early consultation with the local poison center can help determine when hemodialysis or charcoal hemoperfusion may be appropriate.

Poisons That Respond to Hemodialysis ^4,⁷

• Acetaminophen	• Paraldehyde
• Alcohols	• Phenacetin
• Amphetamine	• Phenytoin
• Antibiotics	• Potassium
• Arsenic	• Quinidine
• Chloral hydrate	• Quinine
• Ergotamine	• Salicylate
• Ethylene glycol	• Strychnine
• Isoniazid	• Sulfonamide
• Meprobamate	• Theophylline
• Methanol	• Valproic acid