☠️ Lecture 21 — Poisoning Conference
Approach · Decontamination · Enhanced Elimination · Toxidromes · APAP/Salicylates · Opioids/TCA/CO · Toxic Alcohols · Antidotes
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Poisoning & Antidotes — Active Recall Drill Close notes. Fill from memory. Check against the answer key (opens in new window). High-yield focus: 4 classic toxidromes, decontamination/enhanced-elimination mnemonics (LAME Ca, SLIME, CPSA), APAP NAPQI pathway, TCA NaHCO₃, opioid triad, CO co-oximetry, toxic alcohols + fomepizole, and the antidote master table.
Epidemiology & Top Killers (NPDS)
Primary U.S. Source of Poisoning Epidemiology Data
Approx % of NPDS Exposures in Children ≤5 yrs
Mnemonic — Top 4 NPDS Killers ("SOAP")
S
O
A
P
Why Most Childhood Exposures Are Low Fatality but Most Adult Deaths Are High Fatality
Focused History — "WARS" Framework
Mnemonic — "WARS" for Poisoning History
W
A
R
S
2 Additional Critical History Items Beyond WARS
1.
2.
U.S. Poison Control Hotline Number + When to Call
Why Patient Weight + Age Matter for Risk Assessment
Alert Presentations — When to Suspect a Toxin
Red-Flag CategoryExamples to List (≥2 each)
🧠 Neurological
❤️ Cardiovascular
⚗️ Metabolic
👶 Pediatric / Multi-Family
Classic Alert Scenarios → "Think Of"
ScenarioLikely Toxin
Flu-like illness in winter, no fever, multiple family members + pets ill
Think: incomplete combustion → carboxyhemoglobin.
Young healthy adult with unexplained wide-complex arrhythmia
Think: Na-channel blockade + anticholinergic features.
Child AMS after visiting grandparents
Think: ingested a cardiac med (digoxin/CCB/β-blocker).
Anion-gap metabolic acidosis + visual changes
Think: toxic alcohol → formic acid.
Profound miosis + respiratory depression + AMS
Think: classic narcotic triad.
New seizures in adult on TB-prophylaxis drug
Think: B6 depletion → ↓ GABA.
Elevated LFTs, RUQ pain, 48–72h after a "minor" overdose
Think: NAPQI → centrilobular necrosis.
Universal Labs in Significant Poisoning
TestWhy?
BMP
LFTs + PT/INR
APAP level
Think: silent killer — always in intentional OD.
Salicylate level
Think: co-ingestion screen — always in intentional OD.
EKG
ABG with co-oximetry
Urine drug screen (UDS)
🚩 TRAP — UDS LIMITATIONS
Targeted Labs & Osmol Gap
Osmol Gap — Formula + Cutoff + What It Suggests
EKG Findings → Toxin Mapping (4)
1.
2.
3.
4.
External Decontamination
Exposure RouteAction / Key Detail
👁️ Ocular
🫁 Inhalation
🖐️ Skin/Dermal
GI Decontamination — Activated Charcoal
Activated Charcoal — Standard Adult Dose + Time Window
Why Time Window Matters (MOA in 1 line)
Single-Dose Charcoal Contraindications (≥3)
1.
2.
3.
Status of Ipecac in Modern Practice
Mnemonic — Toxins NOT Adsorbed by Activated Charcoal ("LAME Ca")
"LAME Ca" — 5 Categories Charcoal Misses
L
A
M
E
Ca
Whole-Bowel Irrigation (WBI) — 4 Indications
1.
2.
3.
4.
🚩 TRAP — CAUSTIC INGESTION (NaOH, ACID)
🛑 HARD TRAP — HYDROCARBONS
Enhanced Elimination — Urinary Alkalinization
2 Drugs Removed by Urinary Alkalinization + Target Urine pH
Mechanism (Ion Trapping) — 4 Steps
1.
↓
2.
↓
3.
↓
4.
Mnemonic — Hemodialysis-Removable Toxins ("SLIME")
"SLIME" — 5 Toxins Removed by HD
S
L
I
M
E
Properties That Make a Toxin "Dialyzable" (4)
1.
2.
3.
4.
Multi-Dose Activated Charcoal (MDAC) — "CPSA"
"CPSA" — 4 Indications for MDAC
C
P
S
A
MDAC Mechanism of Action ("Gut Dialysis")
🛑 HARD TRAP — DIGOXIN & HEMODIALYSIS
Anticholinergic Toxidrome — "Hot, Dry, Red, Mad"
Mnemonic — 4 "Hatter Signs" (Hot/Dry/Red/Mad)
H
D
R
M
Mnemonic — "Can't ___, Can't ___, Can't ___, Can't ___" (4 peripheral signs)
1.
2.
3.
4.
Causative Agents (≥4 categories)
Antidote + 1 Critical Contraindication
Cholinergic Toxidrome — SLUDGE / DUMBELS
"SLUDGE" — Muscarinic Effects (6)
S
L
U
D
G
E
"DUMBELS" — Adds Life-Threatening Features (7)
D
U
M
B
E
L
S
Nicotinic Effects (4)
1.
2.
3.
4.
Causative Agents — 2 Drug Classes + Plant Source
Treatment — 2 Antidotes + Endpoint
1.
↓
2.
↓
3.
Why Pralidoxime Timing Is Critical ("Aging")
Sympathomimetic Toxidrome
5 Hallmark Signs
1.
2.
3.
4.
5.
Causative Agents (≥3)
Treatment — 1st-Line + What to AVOID in Cocaine OD + Why
Sympathomimetic vs Anticholinergic — KEY Discriminator (2 Findings)
1.
2.
Opioid (Narcotic) Toxidrome — Classic Triad
Classic Opioid Triad (3)
1.
2.
3.
Antidote + Why Repeat Dosing or Infusion May Be Needed
Side-by-Side Toxidrome Comparison
FeatureAnticholinergicCholinergicSympathomimeticOpioid
Pupils
HR
Temp
Skin
Bowel sounds
Mental status
Respiration
Antidote
APAP (Acetaminophen) — 4-Phase Course
PhaseTimeFeatures
I
II
III
IV
APAP Toxic Metabolite Pathway (Mechanism Chain)
1.
↓
2.
↓
3.
↓
4.
Risk-Stratification Tool + Antidote + Time Window
NAC Mechanism (2 actions)
1.
2.
Why "Looks Fine in the ED" Is the Wrong Reason to Skip Treatment
Salicylate (ASA) Poisoning
Early Signs (≥3)
1.
2.
3.
Classic Acid-Base Pattern (Mixed Disorder)
Mechanism of Hyperthermia + Late Acidosis
1.
↓
2.
↓
3.
Treatment — 1st-Line Enhanced Elimination + When to Dialyze
Iron Poisoning — 5-Phase Course
PhaseTimeWhat Happens
1 — GI
2 — "Quiet"
3 — Systemic
4 — Hepatic
5 — Late/Scarring
Iron Antidote + Mechanism
Key Lab Test + Optimal Timing Post-Ingestion
🚩 TRAP — IRON PHASE 2 "APPARENT RECOVERY"
Opioid Overdose
Receptor Target + Mechanism of Death
Opioids Particularly Tricky for Naloxone Reversal (≥2)
1.
2.
TCA (Tricyclic Antidepressant) Overdose — 3 Receptor Effects
Receptor Effect 1 → EKG Finding
Receptor Effect 2 → Hemodynamic Finding
Receptor Effect 3 → Peripheral Findings
Why TCA Also Causes Seizures (4th mechanism)
Antidote + Mechanism + Target Serum pH
1.
↓
2.
↓
3.
2 Drugs to AVOID in TCA OD + Why
1.
2.
Carbon Monoxide (CO) Poisoning
CO Mechanism — 2 Pathways of O₂ Deprivation
1.
↓
2.
↓
3.
Diagnostic Test — Why Standard SpO₂ Fails
SeverityCOHb %Symptoms
Mild
Think: "flu without ___"
Moderate
Severe
Treatment — Tier 1 vs Tier 2 (HBO Indications)
Why Cherry-Red Skin Is NOT a Reliable Sign
🛑 HARD TRAP — CO + PREGNANCY
Toxic Alcohols — Methanol vs Ethylene Glycol
FeatureMethanolEthylene Glycol
Source
Toxic Metabolite
Hallmark End-Organ Injury
Urine Finding
Latent Period
Both Show Which 2 Lab Gaps?
1.
2.
1st-Line Antidote + Mechanism + Backup if Unavailable
Antidote Master Table
ToxinAntidoteMechanism (1 line)
Acetaminophen (APAP)
Think: replenishes ___; conjugates NAPQI.
Opioids
Benzodiazepines
Think: GABA-A competitive antagonist — use with caution.
Beta-Blockers
Think: bypass blocked β-receptor → ↑ cAMP via different GPCR.
Calcium Channel Blockers
Digoxin
Think: antibody fragments bind free dig + pull from tissue.
Organophosphates
Think: antimuscarinic + reactivates AChE before "aging".
Methanol / Ethylene Glycol
Carbon Monoxide
Cyanide
Think: B12 precursor binds CN⁻ → cyanocobalamin (urine).
Iron
Lead — mild/moderate
Think: oral DMSA (succimer); outpatient.
Lead — severe / encephalopathy
Think: 2-drug IV regimen; avoid 1 in peanut allergy.
Methemoglobinemia
Think: dye that donates electrons via NADPH → reduces Fe³⁺ → Fe²⁺.
Warfarin
Heparin
Isoniazid (INH)
Think: B6 → restores GABA synthesis (gram for gram).
TCA
Sulfonylureas (refractory hypoglycemia)
Delayed Toxicity — "Looks Fine ≠ Safe"
ToxinOnset of ToxicityCritical Action
APAP
Hydrofluoric acid
Think: hypocalcemia → arrhythmia; topical/IV calcium gluconate.
Ethylene glycol
Methanol
Iron
Sulfonylureas
Think: serial glucose 12–24h; octreotide for refractory.
SR / XR formulations
Think: extended-release → delayed peak; consider WBI.
Rapid Toxicity — Treat in Minutes
ToxinOnsetHallmark Presentation + Antidote
Isoniazid (INH)
Think: refractory seizures → pyridoxine.
TCA
Cyanide
Think: cytochrome oxidase block; lactic acidosis; hydroxocobalamin.
Organophosphates
Supportive Care Cornerstones
Why Supportive Care Is the Cornerstone of Most Poisonings
Indications to Intubate (≥3)
1.
2.
3.
First-Line Anticonvulsant in Toxic Seizures
Mandatory Step Before Discharge for ALL Intentional ODs
🛑 HARD TRAP — FLUMAZENIL CONTRAINDICATIONS

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