Toxicology Part 1: Approach to Ingestions

Shauna Jain

Introduction

Young children are at risk for accidental poisonings
Adolescents have higher morbidity and mortality because large amounts ingested and maybe multiple ingestants particularly in suicide attempts
Acetaminophen is the most common ingestion
Tricyclic antidepressants are the most common fatal ingestion

Table 55.1 Epidemiology

Children < 6 years ingest substances in small quantities. Most commonly ingest:

Cleaning products
Analgesics (acetaminophen most common)
Personal care products/cosmetics
Cough and cold preparations
Plants
Topical agents
Pesticides, hydrocarbons

Children > 6 years ingest toxins commonly involved in fatalities:

Analgesics
Antidepressants
Cleaning products
Hydrocarbons and pesticides
Minerals (iron most common fatal ingestion)

Toxins associated with adolescent fatalities:

Analgesics
Antidepressants
Sedatives, hypnotics, psychotics
Street drugs (especially stimulants)
Cardiac medications
Toxic alcohols

Approach to a Toxic Ingestion

ABCDs of toxicology:
- Stabilize: Airway, Breathing, Circulation, Disability/dextrose
- Consider: Decontamination/elimination/antidote
Complete history including amount and timing of ingestion, possibility of co-ingestants and significant past medical history
Key physical exam findings: vitals and evidence of toxidrome (level of consciousness, pupils, skin, bowel/bladder abnormalities)
Key laboratory tests: glucose, electrolytes, anion gap, osmolar gap, CBC, ECG, U/A, toxicology screen, drug level
Call poison control, consult Poisindex^® or toxicologist for advice

The Toxicologic Exam

Toxidromes

May not be helpful in the face of multiple ingestions
All signs and symptoms may not be present in every toxidrome
Considerable overlap of all toxidromes

Table 55.2 Toxidromes

Sympathomimetics	Fight or flight response Hypertension, tachycardia, tachypnea, hyperthermia, diaphoresis, mydriasis, altered mental status Risks: rhabdomyolysis, myocardial infarction, stroke Management: benzodiazepines, cooling Toxins: cocaine, PCP, XTC, amphetamines
Anticholinergics	Similar to sympathomimetic toxidrome except skin is dry Tachycardia, hyperthermia, dry, hot flushed skin, mydriasis, altered mental status, urine and stool retention Hot as a hare, dry as a bone, red as a beet, blind as a bat, mad as a hatter, plugged as a pig Risks: arrhythmias, seizures, rhabdomyolysis Toxins: TCA, jimsonweed, antihistamines, phenothiazines Treatment: NaHCO₃ for TCA
Cholinergics	Secretions from all sites Clinical findings include: SLUDGE Salivation, small pupils, Lacrimation, Urination, Diarrhea, diaphoresis, GI cramps, Emesis And the B‘s: Bradycardia, Bronchorrhea, Bronchoconstriction Toxin: organophosphate Management: ○ Protective clothing ○ Decontaminate patient ○ Supportive treatment ○ Atropine, pralidoxime
Opioids	Depression of pulse, blood pressure, respiratory drive, miosis Cause of death is respiratory arrest, risk of pulmonary edema Treatment: naloxone, supportive care Toxins: morphine, codeine
Sedatives	Depression of blood pressure, pulse, respiratory rate Benzodiazepine clinical picture is of depressed mental status with normal vital signs Treatment: supportive, flumazenil in some benzodiazepine cases but increased risk of seizures; contraindicated in multidrug ingestion

Table 55.3 Clues to the Toxins

Pupils and toxins	Miosis
		Cholinergics, clonidine
		Opiates, organophosphates
		Phenothiazines, pilocarpine
		Sedative-hypnotics
	Mydriasis
		Antihistamines
		Anticholinergics
		Antidepressants
		Sympathomimetics
Skin findings and toxins	Diaphoresis (SOAP)
Skin findings and toxins		Sympathomimetics
		Organophosphates
		ASA
		PCP
	Red skin: carbon monoxide
	Blue skin: methemoglobinemia
Bradycardia/hypotension and toxins	Antihypertensives:
Bradycardia/hypotension and toxins		β-blockers and Ca channel blockers
		Digoxin, narcotics
Seizures and toxins	(OTIS CAMPBELL)
	Organophosphates
	Tricyclic antidepressants
	Isoniazid
	Sympathomimetics
	Camphor
	Amphetamines
	Methylxanthines
	PCP, phenol, propanolol
	Benzodiazepine withdrawal
	Ethanol withdrawal
	Lithium
	Lidocaine, lead, lindane