Toxicology and Overdose Management - NREMT Paramedic Level
- Which antidote is used for methemoglobinemia with hypoxia and chocolate-brown blood?
- Methylene blue. Methylene blue acts as an electron donor, accelerating methemoglobin reduction to functional hemoglobin via enzymatic pathways.
- What medication reactivates acetylcholinesterase in organophosphate poisoning if given early?
- Pralidoxime (2-PAM). Pralidoxime regenerates acetylcholinesterase by removing the bound organophosphate, restoring normal enzyme function when given timely.
- What is the primary therapeutic goal of naloxone administration in overdose?
- Restore adequate ventilation, not full arousal. Naloxone competitively antagonizes opioid receptors to reverse life-threatening respiratory depression without needing complete consciousness.
- Which antidote treats carbon monoxide poisoning and what is the key initial therapy?
- No antidote; give 100% oxygen and consider hyperbaric oxygen. High-flow oxygen displaces CO from hemoglobin, accelerating elimination; hyperbaric therapy enhances this in severe cases, as no specific antidote exists.
- Which ECG finding is most characteristic of tricyclic antidepressant toxicity?
- Widened QRS complex. TCAs block sodium channels, delaying ventricular depolarization and prolonging the QRS duration on ECG.
- Identify the antidote for ethylene glycol or methanol poisoning that blocks toxic metabolite formation.
- Fomepizole. Fomepizole inhibits alcohol dehydrogenase, preventing conversion of these alcohols into their toxic acidic metabolites.
- Which toxidrome is classically associated with bradycardia, miosis, bronchorrhea, and diaphoresis?
- Cholinergic toxidrome (organophosphates/carbamates). Inhibition of acetylcholinesterase leads to acetylcholine excess, causing parasympathetic overstimulation with these hallmark symptoms.
- Which antidote is used for significant beta-blocker overdose with bradycardia and hypotension?
- Glucagon. Glucagon stimulates cardiac adenylate cyclase independently of beta receptors, increasing heart rate and contractility.
- Which toxidrome is most consistent with hallucinations, hypertension, tachycardia, and vertical nystagmus?
- Dissociative (PCP/ketamine) toxidrome. Dissociative agents disrupt glutamate signaling, inducing perceptual dissociation with sympathetic activation and specific nystagmus patterns.
- Which initial priorities should guide care for any suspected poisoning or overdose patient?
- Scene safety/BSI, ABCs, oxygen/ventilation, circulation, then tox-specific care. This protocol prioritizes provider protection and stabilization of vital functions before addressing the specific toxic exposure.
- Which antidote is indicated for acetaminophen overdose to prevent hepatic injury?
- N-acetylcysteine (NAC). NAC replenishes glutathione, enabling detoxification of the hepatotoxic metabolite NAPQI produced in acetaminophen overdose.
- Which intervention is contraindicated in caustic acid or alkali ingestion?
- Inducing vomiting or neutralization attempts. These actions risk re-exposure of tissues to corrosives or generate heat/exothermic reactions, potentially worsening mucosal injury.
- What is the first-line medication class for agitation, seizures, or hyperadrenergic toxicity from stimulants?
- Benzodiazepines. Benzodiazepines enhance GABAergic transmission, effectively managing sympathetic overstimulation and associated complications.
- Which toxidrome presents with hyperthermia, mydriasis, dry skin, urinary retention, and delirium?
- Anticholinergic toxidrome. Muscarinic receptor blockade inhibits parasympathetic responses, leading to sympathetic dominance and altered mental status.
- What clinical triad most strongly suggests opioid toxidrome?
- CNS depression, respiratory depression, and miosis. Opioid receptor activation suppresses central nervous system activity, reduces respiratory drive, and constricts pupils via parasympathetic effects.
- What is the most reliable field assessment for carbon monoxide exposure severity?
- Carboxyhemoglobin level by CO-oximetry (not standard pulse oximetry). CO-oximetry specifically quantifies carboxyhemoglobin, providing accurate severity assessment unlike standard oximetry which is unreliable in CO poisoning.
- Which core supportive treatment is prioritized for severe hyperthermia from toxicologic causes?
- Rapid active cooling plus benzodiazepines and supportive airway/ventilation. Active cooling mitigates heat-induced organ damage, while benzodiazepines control contributing factors like agitation, with ventilatory support as required.
- Which toxidrome is suggested by CNS depression with normal vital signs and nystagmus?
- Sedative-hypnotic toxidrome. Sedative-hypnotics potentiate GABA-mediated inhibition, causing central depression without marked autonomic instability, often with ocular signs.
- What is the antidotal therapy for tricyclic antidepressant toxicity with wide QRS or hypotension?
- Sodium bicarbonate. Bicarbonate alkalinizes serum and provides sodium, reducing TCA affinity for sodium channels and stabilizing cardiac membranes.
- What is the preferred prehospital decontamination method for liquid chemical exposure on skin?
- Remove clothing and irrigate skin with copious water. Immediate removal of contaminants and dilution with water minimize chemical absorption and tissue damage in prehospital settings.
- What is the most important immediate intervention for opioid overdose with hypoventilation?
- Ventilate with BVM and oxygen; support airway before or with naloxone. Respiratory failure is the primary life threat in opioid overdose, requiring immediate ventilatory support to maintain oxygenation.
- Which antidote is indicated for cyanide poisoning with severe hypoxia and cardiovascular collapse?
- Hydroxocobalamin. Hydroxocobalamin binds cyanide to form non-toxic cyanocobalamin, rapidly restoring cellular respiration in acute poisoning.
- Which medication is the antidote for calcium channel blocker overdose with hypotension and bradycardia?
- Calcium (e.g., calcium chloride or calcium gluconate). Administering calcium overcomes channel blockade by increasing extracellular calcium gradient, improving cardiac conduction and contraction.
- What is the antidote for organophosphate nerve agent poisoning that reverses muscarinic effects?
- Atropine. Atropine competitively blocks muscarinic receptors, counteracting the excessive cholinergic activity from organophosphate exposure.
- Which toxidrome is most consistent with diaphoresis, mydriasis, tachycardia, agitation, and seizures?
- Sympathomimetic toxidrome. Sympathomimetic agents enhance catecholamine effects, resulting in hyperstimulation of the sympathetic nervous system.