Poisoning

1. As part of well-child care, discuss preventing and treating poisoning with parents (e.g., “child-proofing”, poison control number).
2. In intentional poisonings (overdose) think about multi-toxin ingestion.
3. When assessing a patient with a potentially toxic ingestion, take a careful history about the timing and nature of the ingestion.
4. When assessing a patient with a potential poisoning, do a focused physical examination to look for the signs of toxidromes.
5. When assessing a patient exposed (contact or ingestion) to a substance, clarify the consequences of the exposure (e.g., don’t assume it is non-toxic, call poison control).
6. When managing a toxic ingestion, utilize poison control protocols that are current.
7. When managing a patient with a poisoning,
   1. Assess ABC's,
   2. Manage ABC's,
   3. Regularly reassess the patient’s ABC’s (i.e., do not focus on antidotes and decontamination while ignoring the effect of the poisoning on the patient).

General Overview

• ABC, Oxygen (consider intubation), Mental status
  • Vitals q5 mins
  • Temperature, glucose
  • IV access
• Cardiac monitor, EKG
• On Exam: Pupil size, Skin temperature/moisture, Neuro (r/o CNS event)
  • Rule out head/body injury (C-spine)
• DON'T forget in Universal Antidotes in altered mental status: Dextrose, Oxygen, Naloxone (Narcan), Thiamine
  • Dextrose can be given 50mL of D50W, if no IV access can give Glucagon 1mg IM
  • Oxygen, 100% O2 in carbon monoxide poisoning
  • Naloxone in life-threatening is 2mg initially up to 10mg, or if non-life-threatening 0.1mg initially doubled every two minutes up to 10mg
    • Caution with naloxone in multi-drug poisonings or opioid addiction (unmasking other symptoms)
  • Thiamine (B1) given 100mg IV/IM/PO with 25g dextrose (50mL of D50W) to prevent Wernicke's encephalopathy
    • Suspect thiamine deficiency in malnutrition (alcoholics, anorexics, hyperemesis of pregnancy)
• *CALL POISON CONTROL*

History

• Patient often unreliable – use collateral sources (paramedics, police, family, friends, pharmacist)
  • Who - patient's age, weight, PMH (alcoholism, renal or hepatic disease)
  • What - name, dosage of medications (including OTC) or substances, coingestants, amount
  • When
  • Where - Injection or ingestion
  • Why - intentional vs unintentional
• Commonly ingested nontoxic substances
  • Personal care products: Soap, shampoo, lipstick, lotion, perfume (low alcohol), eye makeup, toothpaste, deodarant
  • Household items: Thermometers (glass potentially harmful), pen ink, crayons, chalk, candles, pencils/erasers, laundry detergent, fabric softener, bleach

Suspect Overdose in altered mental status, dysrhythmia, trauma, bizarre presentation

GI Decontamination

• Activated charcoal within 1h-2h
  • Most effective gastric decontamination
    • Contraindications: Nontoxic ingestion, poisons not bound by AC (Caustic acids and alkalis, alcohols, lithium, heavy metals), high risk of aspiration
  • Dose: 1 to 2g/kg
    • Multiple dosing q2-6h effective in phenobarbital, phenytoin, carbamazepine, salicylates, digitalis, theophylline and dapsone
• Whole bowel irrigation
  • Indications: Toxic foreign bodies (drugs packets), sustain release drugs, or toxic materials not bound by AC
  • Contraindications: Mechanical obstruction, ileus, perforation
• Gastric lavage within 1h with AC after
  • Indications: Highly toxic substances or large ingestions, substances not adsorbed by activated charcoal (lithium, iron, lead, methanol) and potential jeopardized airway (altered mental status)
  • Contraindications: Ingestion of corrosives, hydrocarbons, depressed gag reflexes who are not intubated, clinically insignificant ingestions
    • Complications: Aspiration, perforation of esophagus/bronchus
• No longer recommended: Syrup of Ipecac, Cathartics, Dilution

Investigations

Labs

• CBC, electrolytes, glucose
• Hepatic and renal function
  • High creatinine with normal BUN consider isopropyl alcohol or DKA
• Urinalysis
• Serum osmolarity
  • Osmolar gap = Measured - (2 x [Na⁺] + [glucose] + [urea]) > 10
    • Methanol
    • Ethylene glycol
    • Sorbitol
    • Polyethylene glycol (IV lorazepam)
    • Propylene glycol (IV lorazepam, diazepam and phenytoin)
    • Glycine (TURP syndrome)
    • Maltose (IV IG – Intragram)
• VBG + lactate
  • AGMA ([Na⁺] – [Cl⁻] – [HCO₃⁻]>12)
    • Methanol
    • Uremia
    • DKA
    • Paraldehyde
    • Iron, Ibuprofen, INH
    • Lactate
    • Ethylene glycol
    • Salicylates
• Quantitative drug serum levels: Acetaminophen, Salicylates, Ethanol
  • Other: Digoxin, iron, lithium, theophylline, anticonvulsants, methanol, ethylene glycol
• Qualitative urine drug screen
• Pregnancy test

Other

• EKG
  • QRS, QTc
• CXR for aspiration, or medications (salicylates, narcotics, sedative-hypnotics) for pulmonary edema

Supportive Care

• Hypotension - IV fluids or pressors (norepinephrine)
• Hypertension - Benzodiazepines in agitated, or CCB (avoid BB alone for unopposed alpha-adrenergic stimulation and vasoconstriction)
• Ventricular tachycardia - Sodium bicarbonate in TCA and magnesium sulfate in Digoxin (with Digibind)
• Bradyarrhythmnia - Atropine/Pacing
  • Consider calcium, glucagon, high dose insulin in CCB or BB intoxication
• Seizure - Benzodiazepines (Barbiturates if needed), avoid phenytoin
  • Consider glucose for hypoglycemic agents
  • Pyridoxine for isoniazid toxicity
• Agitation - Benzodiazepines, Haldol
  • Consider Physostigmine for anticholinergic
• Hyperthermia - Ice water immersion or cooling (especially in sympathomimetic, serotonin syndrome or neuroleptic malignant syndrome)
• Hemodialysis
  • Salicylates, ethylene glycol, methanol, lithium, acidosis or hyperkalemia
• Observe in Emergency Department for 6 hours, if severe consult ICU

Clinical syndromes (Consider antidotes once STABLE)

• Excitation (high HR, BP, RR, T)
  • Anticholinergic, sympathomimetic, hallucinogenic, drug withdrawal
    • Treat with benzodiazepines and supportive care
• Depression
  • Ethanol, sedative-hypnotic, opiates, cholinergic (parasympathomimetic), sympatholytics, toxic alcohol (methanol, ethylene glycol)
• Mixed
  • Polydrug or metabolic (hypoglycemic, salicylate, cyanide), antiarrhythmic, or multiple drugs with multiple mechanisms of action (TCA)

Acetaminophen (Tylenol)

• Toxic above 150mg/kg (7.5-10g for an adult)
• Clinical manifestations:
  • 0.5-24h: Asymptomatic (possible nausea, vomiting, diarrhea)
  • 24-72h: RUQ pain (hepatic injury)
• Investigations:
  • Initial and more importantly >4h Acetaminophen Level evaluate on Rumack-Matthew normogram
  • ALT and INR (if ALT abnormal)
• Treatment:
  • Activated Charcoal 50g within 2h (up to 4h) of ingestion unless contraindicated (unable to protect airway)
  • N-acetylcysteine (NAC, Mucomyst)
    • If known time of ingestion, and above treatment line as per normogram
    • Time of ingestion not known or >24h, or chronic ingestion, treat if any acetaminophen concentration or abnormal AST/ALT
    • First dose, if serum level not available until >8h post-ingestion
      • Continue NAC if serum acetaminophen >10mcg/mL or elevated AST/ALT
    • ANY signs of liver injury (preferable to start NAC prior to elevated ALT)

Salicylate (Aspirin)

• Fatal above 10g in adults, 3g in children
• Clinical manifestations:
  • Tinnitus, tachypnea, vertigo, vomiting, diarrhea
  • Respiratory alkalosis initially, mixed, then metabolic acidosis
• Investigations:
  • Serum salicylate levels >40mg/dL (2.9mmol/L) possible toxicity
    • Measure q2h until decreasing, below 40mg/dL, asymptomatic and normal respiratory effort
  • Blood gas
• Treatment:
  • AVOID intubation (risk of neurotoxicity in acid pH from apnea)
  • Consider multi-dose activated charcoal in enteric-coated (50g q4h)
  • Alkalinization (serum and urine) with IV sodium bicarbonate (3 amps NaHCO3 in 1L D5W at maintenance rate x 2 )
    • Target urine pH >7.5 (repeat q1h)
  • Monitor for hypokalemia
  • Glucose especially if altered mental status
  • Early nephrology for possible dialysis

Methanol, ethylene glycol

• Clinical Manifestations:
  • Profound metabolic acidosis (HCO3<8mEq/L) and osmolal gap (>25mOsm), status epilepticus, shock, ischemic bowel
    • Visual blurring, scotoma, blindness -> Methanol
    • Flank pain, hematuria -> Ethylene glycol
• Investigations
  • Blood gas
  • Electrolytes (anion gap), serum osmolality, ethanol (determine osmolal gap), calcium (ethylene-glycol associated hypoglycemia)
  • Methanol, ethylene glycol and isopropranol
  • Urinalysis (oxalate crystals)
• Treat:
  • Fomepazole (alcohol dehydrogenase inhibition) or ethanol
  • Sodium bicarbonate
  • Hemodialysis in severe toxicity

Benzodiazepine poisoning

• Rarely toxic, rule out coingestant
• Risk of propylene glycol poisoning if receiving large IV BZDs (used as a diluent)
• Investigation:
  • Urine BZD identifies metabolites of 1,4-BZD (oxazepam), may not detect clonazepam, lorazepam, midazolam, alprazolam
• Treatment:
  • Intubate if needed
  • Consider avoid Flumazenil given risk of seizures in chronic benzodiazepine use
  • Avoid GI decontamination (risk of aspiration) unless airway protected and coingestant treatable by charcoal

Beta blocker

• Treatment (if severe can give all below simultaneously)
  1. Airway
  2. NS IV bolus with atropine 1mg IV (up to 3 doses)
  3. Glucagon 5mg IV bolus (may be repeated)
  4. Calcium chloride (central venous access)
  5. Vasopressor (eg. epinephrine)
  6. IV high-dose insulin and glucose
  7. IV lipid emulsion

Opioids

• Clinical manifestatios
  • Respiratory depression
  • Miotic pupils (coingestants may make pupils normal/large)
• Treatment:
  • Naloxone (Narcan) titrated to RR>12 (not until normal LOC)
    • Consider very small doses 0.04mg IV (or IO/IM/SC) q1min
    • In cardiorespiratory arrest, no evidence of benefit, may consider 2mg IV (or IO/IM/SC) q1min
      • If overshoot, manage withdrawal symptoms expectantly (not with opioids)
    • If no effect after 5-10mg consider other diagnoses

Other

• Antipsychotics (acute dystonic reaction) -> Benztropine, diphenhydramine
• Anticholinergic -> Physostigmine salicylate (Antilirium)
• BB -> Glucagon
• CCB -> Calcium
• Cholinergic -> Atropine, Pralidoxime
• Digoxin -> Digoxin immune Fab (Ovine, Digibind)
  • Consider MgSO4 to stabilize if delay in digoxin antibodies
• Iron -> Deferoxamine (Desferal)
• TCA (Cardiotoxicity, convulsion, coma)-> Sodium Bicarbonate 1-2mEq/kg

Well-child care

• Keep items locked and out of reach/sight
• Keep in original containers (safety lids)
• Don’t take medications in view of children
• Don't refer to medicine as “candy”