Category: Toxicology

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Salicylate toxicity is the great toxicologic mimicker!!!

Step 1: When to Suspect Salicylate Overdose

• Signs of CNS stimulation
  • Tachypnea
  • Hyperthermia
  • Altered mental status
• Signs of GI irritation
  • Nausea/Vomiting
  • Abdominal pain
• Common “mimicker”
  • Sepsis
  • Acute abdomen

Step 2: Testing Plan

• Electrolyte panel
  • Anion gap metabolic acidosis
    • Sodium – Chloride – Bicarb
      • Normal anion gap (AG) is <10
      • Caused by salicylic acid and lactic acid
• Blood gas
  • Mixed respiratory ALKALOSIS and metabolic ACIDOSIS

Step 3: Obtain Serum Salicylate Level

Step 4: Treatment Plan

• Mild salicylate toxicity
  • Alkalinize urine with sodium bicarbonate (NaHCO3) drip
• Severe salicylate toxicity
  • Dialysis

Additional Reading

• Salicylate Poisoning (LITFL)

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Acetaminophen is the most important overdose in toxicology

Step 1: Check a Serum Acetaminophen Level

• Common situations where testing is ordered
  • Suicidal ideation
  • Severe depression
  • Overdose

Step 2: Consult the Rumack-Matthew nomogram

• Only works for acute/single ingestions of acetaminophen
• Loses reliability if patient is on drugs that affect bowel motility
• If the time of ingestion is KNOWN
  • Measure acetaminophen level 4 hours post-ingestion
  • Plot on nomogram and treat if above line
• If time of ingestion is UNKNOWN
  • Determine earliest possible time of ingestion
  • Plot on nomogram and treat if above line

Step 3: Order hepatic labs (LFTs)

• AST
• ALT
• Alk Phos
• PTT/PT/INR

Step 4: Identify Phase of Toxicity

• Phase 1/Day 1
  • High acetaminophen levels
  • Normal LFTs
  • Minimal symptoms
• Phase 2/Day 2
  • Acetaminophen level starts decreasing
  • LFTs level starts increasing
  • Mild GI symptoms develop
    • Abdominal pain
    • Nausea/vomiting
• Phase 3/Day 3
  • Acetaminophen levels are normalized
  • LFTs are peaking
• Phase 4
  • Recovery

Step 5: Give N-Acetylcysteine (NAC)

• If patient meets criteria on Rumack-Matthew nomogram
• If patient is in phase 1, 2, or 3

Additional Reading

• Acetaminophen Overdose and NAC Dosing (MDCalc)

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Poison Control Hotline: 1-800-222-1222

Step 1: Evaluate the Airway

• General principles
  • “If they can’t speak, they can’t control their airway”
  • “If GCS is <8, intubate”
• In the real world, it’s a clinical judgement call

Step 2: Toxicology History

• What did they take?
• How much did they take?
• Why did they take it?
• When did they take it?

Step 3: Toxicology Exam

• Vital signs
• Pupils
• Skin

Step 4: Medication List

• Make note of all bottles with patient
• Make EXTRA note if any pills seem to be missing
• Bonus points if you bring your attending a med list

Step 5: Common Toxicology Tests

• Assessing for damage
  • Electrolytes
  • Liver function test
  • EKG
  • Pregnancy
• Assessing for co-ingestion
  • Serum acetaminophen
  • Serum salicylate
  • Serum alcohol
  • Urine drug screen

The “Big 5” Toxidromes

• Anticholinergic
  • Increased vitals
  • Big pupils
  • Dry skin
  • Treatment – Physostigmine (rarely given)
• Cholinergic
  • Decreased vitals
  • Small pupils
  • Moist skin
  • Treatment – Atropine
• Opioid
  • Decreased vitals
  • Small pupils
  • Dry skin
  • Treatment – Naloxone
• Sedative/Hypnotic
  • Decreased vitals
  • Normal pupils
  • Dry skin
  • Treatment – Flumazenil (rarely given)
• Sympathomimetics
  • Increased vitals
  • Big pupils
  • Moist skin
  • Treatment – Benzodiazepines

Additional Reading

• NBME Shelf Review – Ophthalmology and Toxicology (EM Clerkship)
• Toxidromes (Admin EM)