Toxic Ingestion

Definition and Recognition

Exposure to toxic substances occurs commonly, as evidenced by the 3.1 million calls received by poison control centers in 2013. Such calls typically involved an acute (88%), unintentional (80%), oral (79%) exposure to a single toxin (89%) by a child (57%) at a private residence (91%). Although almost 70% of such cases in 2013 were managed outside the health care system, toxic ingestions still resulted in 601,642 physician visits, 228,230 hospital admissions, 99,117 critical care admissions, and 2113 deaths. These data are even more impressive given that poison control center information likely underestimates the true incidence of both toxic exposure and adverse poisoning outcomes due to underreporting. Drug classes associated with the largest number of deaths in 2013 (in descending order of frequency) were analgesics, stimulant/street drugs (heroin, methamphetamine, and cocaine), cardiovascular drugs, antidepressants, and sedatives/hypnotics/antipsychotics.

Risk Assessment

Most poisoning ingestions tend to follow one of two general patterns. Children (<12 years of age) usually take small quantities of a single toxin unintentionally and seldom manifest significant morbidity or mortality. In contrast, adolescents and adults typically ingest larger amounts of multiple toxins intentionally and suffer higher rates of morbidity and mortality.

Large series of mixed adult overdoses suggest that the coingestion of ethanol occurs in approximately 50% of cases, and alcohol significantly confounds the initial clinical assessment in a similar percentage of trauma patients. Ethanol-related motor vehicle accidents in the United States during 2013 caused nearly one-third (31%) of all traffic-related deaths and resulted in an associated cost of over $59 billion. To complicate things, drugs other than alcohol are reportedly involved in approximately 18% of motor vehicle driver deaths.

The clinician should therefore maintain a high index of suspicion that adolescent and adult trauma victims have some form of acute intoxication and should evaluate the patient for evidence of substance abuse during the initial history, physical examination, and diagnostic workup. Important historical data include the specific toxin or toxins, quantity taken, ingestion time, signs and symptoms since ingestion, past medical and psychiatric history (including suicidal intent), current medications, allergies, and trauma (accidental, incidental, or self-inflicted). Because the history can often be unreliable or incomplete in acute poisoning situations, supplemental data from other sources (e.g., public safety personnel, family, medical records, area pharmacies, local poison control centers, state narcotic databases) may be helpful in diagnosing toxic exposures. A rapid, systematic, and thorough physical examination is mandatory, given the vague history that often surrounds poisoning and trauma scenarios. Barrier precautions should be exercised where appropriate to prevent self-intoxication (such as cutaneous exposure to organophosphate insecticides). The assessment should initially focus on the ABCs (airway, breathing, and circulation), with aggressive intervention to stabilize any abnormalities discovered. Additional assessment considerations are as follows:

• Gag reflex. This has implications for airway protection and possible aspiration in overdose patients, but contributes little to clinician assessment and the Glasgow Coma Scale regarding the possible need for intubation.

• Core temperature disturbances. Multiple etiologies may be involved, including toxic (salicylates, stimulants), environmental, and/or infectious causes.

• Neurologic examination abnormalities. Detection of central nervous system dysfunction (such as confusion, coma, or delirium) should prompt the clinician to pursue additional diagnostic imaging such as CT or magnetic resonance imaging to evaluate for other potential causes such as cervical spinal cord injury, ischemic stroke, or intracranial hemorrhage.

• Incidental trauma and stigmata of substance abuse. The patient should be examined for puncture wounds, needle tracks, and nasal septal perforation.

• Constellation of signs and symptoms (“toxidromes”). The ingestion of certain toxins may present as characteristic toxidromes typically involving abnormal vital signs, altered mental status, pupillary changes, and a variety of miscellaneous effects that can be attributed to the known pharmacologic properties of the particular drug class. Examples of specific toxidromes are provided in Table 80.1 .

  TABLE 80.1

  Common Toxidromes

  Data from Hoffman RS, Howland MA, Lewin NA, et al., editors: Goldfrank’s toxicologic emergencies, 10th ed. New York, McGraw-Hill, 2015; and Levine M, Brooks DE, Truitt CA, et al.: Toxicology in the ICU: part 1: general overview and approach to treatment. Chest 140:795-806, 2011.

  Syndrome	Common Clinical Signs	Potential Toxic Agents
  Anticholinergic	Tachycardia, fever, dry skin, urinary retention, ileus, mydriasis, delirium, seizures	Antihistamines, phenothiazines, tricyclic antidepressants, antipsychotics, atropine, scopolamine, jimsonweed, amantadine, antiparkinson drugs, Amanita mushrooms, baclofen
  Cholinergic	Bradycardia, diaphoresis, urinary or fecal incontinence, emesis, miosis, central nervous system depression, weakness, fasciculations, wheezing	Organophosphate and carbamate insecticides, physostigmine, pyridostigmine, edrophonium, certain mushrooms
  Sympathomimetic (stimulants)	Tachycardia (bradycardia with pure α-agonist), hypertension, mydriasis, diaphoresis, piloerection, fever, delusions, paranoid ideation, restlessness, agitation	Cocaine, amphetamines, over-the-counter decongestants (pseudoephedrine, phenylpropanolamine, phenylephrine)
  Narcotic	Mental status depression, hypoventilation, miosis, ileus, hypotension, bradycardia	Opioids
  Sedative-hypnotic	Confusion, slurred speech, mental status depression, respiratory depression, ataxia, hypothermia	Benzodiazepines, barbiturates, ethanol, antipsychotics, anticonvulsants
  Serotonin	Fever, diaphoresis, flushing, diarrhea, hyperreflexia, tremor, myoclonus, trismus	Selective serotonin reuptake inhibitors, trazodone, clomipramine, meperidine, methadone, dextromethorphan, linezolid, tramadol, others.
  Hallucinogenic	Hallucinations, psychosis, paranoid ideation, panic, fever, mydriasis	Cocaine, amphetamines, cannabinoids, phencyclidine (PCP), lysergic acid diethylamide (LSD), antihistamines
  Extrapyramidal	Tremor, rigidity, opisthotonos, torticollis, choreoathetosis, trismus, hyperreflexia	Typical and atypical antipsychotics

Laboratory evaluation should be based on the suspected ingestion (i.e., drug levels, blood alcohol level) and should include consideration of acetaminophen and salicylate levels in overdose situations. Urine drug screens may occasionally provide diagnostic clues about possible ingestions, although results are typically not available in a timely manner, and the substances detected will vary between institutions.

Concomitant trauma and poisoning may confound the accurate assessment of each individual entity, as exemplified by the case synopsis. Normal blood pressure and pulse pressure in the presence of anemia, tachycardia, and metabolic acidosis likely reflects hypovolemic shock that is partially masked by amphetamine-associated vasoconstriction.