Poisoning Flashcards
(16 cards)
Poisoning Type
Clinical Summary
Iron Poisoning
Toxin: Elemental iron (often from prenatal vitamins or iron tablets)
Mechanism: Direct corrosive effect on GI tract and mitochondrial dysfunction causing metabolic acidosis
Stages:
1. GI phase (0–6 hrs): Vomiting, diarrhea, hematemesis
2. Latent phase (6–24 hrs): Clinical improvement
3. Shock/metabolic acidosis (12–24 hrs)
4. Hepatotoxicity (2–3 days)
5. GI scarring (weeks later)
Diagnosis: Serum iron level at 4–6 hrs post-ingestion, anion gap metabolic acidosis, abdominal X-ray (radiopaque pills)
Management: IV fluids, IV deferoxamine (antidote), supportive care, whole bowel irrigation in severe cases
Acetaminophen (Paracetamol) Poisoning
Toxin: N-acetyl-p-benzoquinone imine (NAPQI, toxic metabolite)
Mechanism: Hepatocellular injury due to glutathione depletion
Clinical Features: Asymptomatic in early stages; then nausea, vomiting, RUQ pain, jaundice, hepatic failure
Diagnosis: Serum acetaminophen level (Rumack-Matthew nomogram), LFTs, INR, metabolic acidosis
Management: N-acetylcysteine (NAC) as antidote, supportive care, monitor LFTs
Organophosphate Poisoning
Toxin: Organophosphates (pesticides)
Mechanism: Inhibition of acetylcholinesterase → cholinergic excess
Clinical Features: DUMBBELS: Diarrhea, Urination, Miosis, Bradycardia, Bronchorrhea, Emesis, Lacrimation, Salivation
Diagnosis: Clinical + decreased RBC cholinesterase or plasma pseudocholinesterase levels
Management: Atropine (symptom control), pralidoxime (reactivates AChE), airway support, decontamination
Salicylate Poisoning
Toxin: Aspirin (acetylsalicylic acid)
Mechanism: Uncouples oxidative phosphorylation → metabolic acidosis and respiratory alkalosis
Clinical Features: Tinnitus, vomiting, tachypnea, metabolic acidosis, altered mental status
Diagnosis: Salicylate level, ABG (mixed acidosis/alkalosis), anion gap metabolic acidosis
Management: Activated charcoal (if early), sodium bicarbonate (alkalinize urine), hemodialysis if severe
Hydrocarbon Poisoning
Toxin: Kerosene, gasoline, mineral oil, turpentine
Mechanism: Aspiration → chemical pneumonitis
Clinical Features: Cough, choking, tachypnea, cyanosis, fever, CNS depression
Diagnosis: CXR (may lag 6–12 hrs), ABG, clinical exam
Management: Supportive care (oxygen, fluids), avoid gastric lavage/charcoal due to aspiration risk
Lead Poisoning
Toxin: Lead (from paint, dust, soil, pipes)
Mechanism: Inhibits heme synthesis enzymes (ALA dehydratase, ferrochelatase); interferes with neuronal development
Clinical Features: Irritability, abdominal pain, anemia, developmental delay, encephalopathy, wrist/foot drop
Diagnosis: Blood lead level, basophilic stippling on peripheral smear, abdominal X-ray (radiopaque chips)
Management: Remove exposure, chelation with DMSA (succimer), EDTA or BAL in severe cases
Methanol Poisoning
Toxin: Methanol (found in windshield fluid, antifreeze)
Mechanism: Metabolized to formic acid → optic nerve toxicity and metabolic acidosis
Clinical Features: Visual blurring, snowfield vision, headache, vomiting, seizures, coma
Diagnosis: High anion gap metabolic acidosis, elevated osmolar gap, serum methanol level
Management: Fomepizole or ethanol, folinic acid, hemodialysis if severe
Carbon Monoxide (CO) Poisoning
Toxin: Carbon monoxide
Mechanism: Binds hemoglobin with high affinity → tissue hypoxia
Clinical Features: Headache, dizziness, cherry-red lips, confusion, coma
Diagnosis: Elevated carboxyhemoglobin level, pulse oximetry often falsely normal
Management: 100% oxygen, hyperbaric oxygen in severe cases
Tricyclic Antidepressant (TCA) Overdose
Toxin: Amitriptyline, nortriptyline
Mechanism: Sodium channel blockade, anticholinergic effects
Clinical Features: CNS depression, seizures, wide QRS, tachycardia, anticholinergic symptoms
Diagnosis: ECG (QRS > 100 ms), metabolic acidosis
Management: Sodium bicarbonate (cardioprotection), activated charcoal, supportive care
Beta-Blocker Overdose
Toxin: Propranolol, atenolol, etc.
Mechanism: Beta-adrenergic blockade → bradycardia, hypotension, hypoglycemia
Clinical Features: Bradycardia, hypotension, hypoglycemia, seizures (especially with propranolol)
Diagnosis: Clinical, ECG, blood glucose
Management: IV fluids, atropine, high-dose glucagon, vasopressors, intralipid emulsion in refractory cases
Calcium Channel Blocker Overdose
Toxin: Verapamil, diltiazem, amlodipine
Mechanism: Inhibits L-type calcium channels → cardiac depression, vasodilation
Clinical Features: Hypotension, bradycardia, AV block, hyperglycemia
Diagnosis: ECG abnormalities, hyperglycemia out of proportion to illness
Management: IV calcium gluconate/chloride, high-dose insulin euglycemia therapy, vasopressors, intralipid emulsion
Opioid Overdose
Toxin: Morphine, codeine, fentanyl, heroin
Mechanism: μ-receptor agonism → CNS and respiratory depression
Clinical Features: Miosis (pinpoint pupils), bradypnea, coma, hypotonia
Diagnosis: Clinical, consider urine drug screen
Management: Naloxone (antidote), airway support, repeat dosing may be necessary
Benzodiazepine Overdose
Toxin: Diazepam, lorazepam, alprazolam
Mechanism: Enhances GABA-A receptor activity
Clinical Features: CNS depression, drowsiness, confusion, normal vitals usually
Diagnosis: Clinical + tox screen (if available)
Management: Supportive care, flumazenil (with caution – can precipitate seizures)
Isoniazid (INH) Toxicity
Toxin: Isoniazid (anti-TB drug)
Mechanism: Inhibits pyridoxine-dependent enzymes → neurotoxicity
Clinical Features: Seizures (refractory), metabolic acidosis, coma
Diagnosis: Clinical, anion gap metabolic acidosis, history of TB treatment
Management: IV pyridoxine (antidote, gram-for-gram replacement), benzodiazepines for seizures
Digoxin Toxicity
Toxin: Digoxin (cardiac glycoside)
Mechanism: Inhibits Na⁺/K⁺ ATPase → increased intracellular calcium
Clinical Features: Nausea, vomiting, visual disturbances (yellow vision), arrhythmias (heart block, VT)
Diagnosis: Serum digoxin level, ECG (scooped ST, bradyarrhythmias)
Management: Digoxin-specific antibody fragments (Digibind), correct electrolytes, supportive care
