Toxicology Emergencies CDEM

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Toxicologic Emergencies

Emergency Medicine Clerkship Lecture Series Primary Authors: Michael Levine, MD, Susan E. Farrell, MD Reviewer: Michael Beeson, MD

EPIDEMIOLOGY

In 2004, more than 2.4 million toxic exposures reported to U.S. Poison Control Centers

1183 deaths

Over half of poisonings occur in children under 5 years of age

EVALUATION OF THE POISONED PATIENT

History Physical Exam

Vital signs Pupil exam Skin findings Mental status Search for a toxidrome

MANAGEMENT OF THE POISONED PATIENT

A-B-C-D-Es: ACLS measures as appropriate IV, O2, cardiac monitoring, ECG Determine blood glucose in all intoxicated patients. (Empiric dextrose administration is indicated for all

patients with altered mental status if bedside glucose determination is not available)

Thiamine and naloxone empirically as indicated Decontamination Enhanced elimination Antidotal therapy Supportive care

HISTORY

Name and amount of agent(s) Type of agent (immediate release, sustained release) Time of ingestion/exposure Route of ingestion/exposure Any co-ingestants (including prescription, OTCs, recreational drugs, herbals, chemicals, metals) Reason for ingestion/exposure (e.g. accident, suicide attempt, therapeutic misuse, occupational) Search exposure environment for pill bottles, drug paraphernalia, suicide note, chemical containers

PHYSICAL EXAM: VITAL SIGNS

Assess and manage the A-B-Cs: Blood pressure Heart rate Respiratory rate

Tachypnea: Salicylates Bradypnea: Opioids Hyperpnea: Salicylates Shallow respirations: Opioids Hyperthermia: Serotonin syndrome, NMS, malignant hyperthermia, anti-cholinergic toxidromes, salicylates Hypothermia: Narcotic or sedative-hypnotic agents

Respiratory depth

Temperature

PHYSICAL EXAM: PUPILS

Size

Large: Anticholinergic or sympathomimetic toxidrome Small: Cholinergic toxidrome Pinpoint: Opioid toxidrome

Nystagmus: Check for horizontal,vertical, or rotatory (ethanol, phenytoin,ketamine, PCP)

PHYSICAL EXAM: SKIN

Temperature:

Hyperpyrexia: Anticholinergic or sympathomimetic toxidromes, salicylates Dry: Anticholinergic toxidrome Moist: Cholinergic, sympathomimetic

Moisture:

Color: Cyanosis, pallor, erythema

PHYSICAL EXAM: OVERALL EXAM

Physiologic stimulation: Everything is up: Elevated temperature, HR, BP, RR, agitated mental status Sympathomimetics, anticholinergics, central hallucinogens, some drug withdrawal states Physiologic depression: Everything is down: Depressed temperature, HR, BP, RR, lethargy/coma Sympatholytics, cholinergics, opioids, sedative-hypnotics Mixed effects: Polysubstance overdose, metabolic poisons (hypoglycemic agents, salicylates, toxic alcohols)

TOXIDROMES

Anticholinergic Cholinergic Opioid Sympathomimetic Serotonin syndrome Sympatholytic Sedative-hypnotic

TOXIDROMES: ANTICHOLINERGIC

VS: Hyperthermia, tachycardia, elevated BP CNS: Agitation, delirium, psychomotor activity, hallucinations, mumbling speech, unresponsive Pupils: Mydriasis (minimally reactive to light) Skin: Dry, warm, and flushed GI/GU: Diminished BS, ileus, urinary retention Examples: Atropine, antihistamines, CADs, cyclobenzaprine, phenothiazines, Datura spp. Remember: Dry as a bone, Red as a beet, Blind as a bat, Mad as a hatter, and hotter than hell

TOXIDROMES: CHOLINERGIC

VS: Bradycardia, high or low BP, tachypnea or bradypnea CNS: Agitation, confusion, seizures, coma Pupils: Miosis, eye pain, lacrimation Skin: Diaphoresis GI/GU: Salivation, vomiting, diarrhea, incontinence Musculoskeletal: muscle fasciculations, weakness, paralysis Examples: Organophosphate and carbamate insecticides, nerve agents, cholinesterase inhibitors (physostigmine, edrophonium), nicotine Remember: SLUDGE Salivation, Lacrimation, Urinary incontinence, diarrhea, Gastrointestinal emesis

TOXIDROMES: OPIOID

VS: Hypothermia, bradycardia, normal or low BP, bradypnea CNS: Lethargy, coma Pupils: Miosis (exceptions: meperidine, DXM) Skin: Cool, pale or moist, evidence of recent or remote needle injection possible Misc: Hyporeflexia, pulmonary edema, seizures (meperidine and propoxyphene), ventricular dysrhythmias (propoxyphene) Examples: Morphine and the synthetic opioids; (Note: clonidine can look like an opioid)

TOXIDROMES: SEDATIVE-HYPNOTIC

VS: Hypothermia, normal or bradycardic HR, hypotension, bradypnea CNS: Drowsiness, dysarthria, ataxia, lethargy, coma Pupils: Midsize or miosis, nystagmus Misc: Hyporeflexia; (possible breath odors) Examples: Alcohols, benzodiazepines, barbiturates, zolpidem, chloral hydrate, ethchlorvynol

TOXIDROMES: SEROTONIN SYNDROME

VS: Hyperthermia, tachycardia, hypertension, tachypnea CNS: Confusion, agitation, lethargy, coma Pupils: Mydriasis Skin: Diaphoretic, flushed Neuromuscular: Hyperreflexia, tremor, clonus, rigidity Examples: Combinations that increase 5-HT stimulation (MAOIs, SSRIs, NSRIs, meperidine, L-tryptophan, dextromethorphan, trazadone, linezolid)

TOXIDROMES: SYMPATHOLYTICS

VS: Bradycardia, hypotension, bradypnea, hypopnea CNS: Normal, lethargy, coma, seizures Pupils: Mid size to miotic Examples: Alpha1-adrenergic antagonists, beta-adrenergic antagonists, alpha2-adrenergic agonists, calcium channel blockers

TOXIDROMES: SYMPATHOMIMETICS

VS: Hyperthermia, tachycardia, hypertension, tachypnea, hyperpnea CNS: Enhanced alertness, agitation, delirium, seizures, coma Pupils: Mydriasis Skin: Diaphoretic, hot Neuromuscular: Hyperreflexia Examples: Cocaine, phencyclidine, phenylethylamines (amphetamines)

SEIZURE-INDUCING DRUGSOTIS CAMPBELL

O Organophosphates T TCAs I Insulin, Isoniazid (INH) S Sympathomimetics, salicylates, sulfonylureas C Cocaine, camphor, carbamazepine, carbamates, CO A Amphetamines, amantadine M Methylxanthines, meperidine, mushrooms (Gyromitra species) P Phenothiazines, propoxyphene, phencyclidine B Benzodiazepine/sedative-hypnotic withdrawal E Ethanol withdrawal L Lidocaine, lead L Lithium, Lindane (hexachlorocyclohexane)

DECONTAMINATION

Activated charcoal: 1g/kgThe primary means of GI decontamination, IF it is warranted. Some agents for which AC has reduced adsorptive capacity: metals (lead, iron), lithium, pesticides, hydrocarbons, alcohols, caustics, solvents Contraindications: bowel obstruction/perforation, unprotected airway, caustics and most hydrocarbons Whole bowel irrigation: PEG sol 1 2 l/h (adults); 500ml/h (ped) Indications: toxic foreign bodies (e.g. body packers), sustained release products, lithium and metals Contraindications: as for charcoal Gastric lavage: Indications: patients with life threatening ingestions (especially if no adequate antidote available) presenting within 1 hour of ingestion Contraindications: corrosive ingestions, hydrocarbons Syrup of ipecac: not recommended

ENHANCED ELIMINATION

Methods to increase the clearance of a substance from the body: Multiple dose activated charcoal: phenobarbital, theophylline, carbamazepine, dapsone, quinine Urinary alkalinization: salicylates Hemodialysis: Substance characteristics: water-soluble, low molecular weight ( 100 Creatinine > 3.4 Grade III or IV encephalopathy Lactate > 3.5mmol/L

TOXICOLOGY CASE 2

A 20 year old male presents via EMS after his neighbor found him unresponsive. The patient is comatose The neighbor developed a headache and nausea after spending 10 minutes in the patients house It is winter, and the patient had been using a camp stove for heat

TOXICOLOGY CASE 2 (contd)

VS: T: 98.9F, HR: 110 bpm, RR: 6, BP: 150/100 mmHg, SaO2: 99%. Moans to painful stimuli with no focal neurologic deficits Pupils 4mm, sluggishly reactive Skin notable for central cyanosis Blood glucose: 90mg/dL ECG: Sinus tachycardia, normal intervals,no evidence of acute ischemia Labs include: COHb: 60%

CO TOXICITY

17,115 cases of CO exposure reported to US Poison Control Centers in 2004 CO is a colorless, odorless, non-irritating gas Sources of CO exposure include: Smoke Car exhaust Propane powered vehicles or engines Hibachi grills and kerosene heaters Methylene chloride

CO TOXICITY

CO combines with Hgb to form carboxyhemoglobin (COHb) COHb has 240 X the affinity for O2 CO + Hgb shifts the O2 dissociation curve to the left: oxygen delivery to tissues is reduced CO can cause hypotension via CO-induced cGMP production and increased NO production CO can inhibit electron transport which limits ATP production CO is associated with microvascular damage and inflammation in the CNS

CLINICAL EFFECTS OF COCOHb% 70%

Signs/SymptomsNone or mild HA Slight HA, dyspnea on vigorous exertion Throbbing headache, dyspnea with moderate exertion Severe HA, irritability, fatigue, dim vision Tachycardia, confusion, lethargy, syncope Coma, seizures, death Rapidly fatal

CO TOXICITY

CO poisoning is frequently misdiagnosed: symptoms are nonspecific Need a high index of suspicion Consider CO poisoning: Multiple patients with similar complaints, especially from the same household Vague, flu like symptoms without fever or lymphadenopathy Winter, environmental history and exposures Uncommon presentation of syncope Normal COHb levels 0-5% in non-smokers up to 10% in smokers > 1ppd

PULSE OXIMETRY

Noninvasive measure of functional hemoglobin oxygen saturation Does not measure hemoglobin species that cannot carry oxygen

MetHb COHb

Co-oximeter measures fractional hemoglobin oxygen saturation

PULSE OXIMETRY GAPSevere CO poisoning Significant dyshemoglobinemia results in a divergence between functional and fractional hemoglobin oxyg