What is the approach to diagnosing and managing toxicological cases, including decontamination methods, common household poisonings, and the use of antidotes for substances like organophosphorus, paracetamol, and salicylate?

General Approach to Toxicological Cases

The management of poisoned patients must begin with immediate stabilization, toxidrome recognition, decontamination when appropriate, and timely administration of specific antidotes, with early consultation with a poison center (1-800-222-1222) for complex cases. 1

Initial Assessment and Stabilization

Primary Assessment

• Secure airway, breathing, and circulation (ABC)
• Administer oxygen, naloxone, glucose, and thiamine in patients with altered mental status
• Monitor vital signs continuously
• Obtain IV access

Secondary Assessment

• Identify the toxidrome (constellation of signs/symptoms suggesting specific toxin exposure)
• Collect collateral information about exposure (substance, time, amount, intent)
• Perform targeted laboratory tests:
  • Basic metabolic panel, complete blood count
  • Acetaminophen and salicylate levels (universal screening recommended for all suspected overdoses) 2
  • Specific toxin levels when indicated
  • ECG for conduction abnormalities
  • Arterial blood gas for acid-base disturbances

Common Toxidromes

Toxidrome	Clinical Features	Common Causes
Anticholinergic	Hyperthermia, dry skin/mucous membranes, mydriasis, tachycardia, urinary retention, delirium	Antihistamines, antipsychotics, tricyclic antidepressants
Cholinergic	Salivation, lacrimation, urination, defecation, GI upset, emesis, bronchorrhea, miosis	Organophosphates, carbamates, nerve agents
Opioid	Respiratory depression, miosis, CNS depression	Heroin, fentanyl, prescription opioids
Sedative-hypnotic	CNS depression, respiratory depression, hypotension	Benzodiazepines, barbiturates, alcohol
Sympathomimetic	Hyperthermia, diaphoresis, mydriasis, tachycardia, hypertension, agitation	Cocaine, amphetamines, MDMA
Serotonin syndrome	Hyperthermia, hyperreflexia, clonus, agitation	SSRIs, MAOIs, dextromethorphan

Decontamination Methods

Gastrointestinal Decontamination

1. Activated charcoal:

   • Most effective within 1 hour of ingestion
   • Dose: 1 g/kg (50-100g for adults)
   • Contraindications: Unprotected airway, caustics/corrosives ingestion, hydrocarbons 3

2. Whole bowel irrigation:

   • Useful for sustained-release medications, iron, lithium, lead
   • Polyethylene glycol solution at 1-2 L/hour until rectal effluent is clear

3. Gastric lavage:

   • Limited role in modern toxicology
   • Consider only for life-threatening ingestions within 1 hour
   • Contraindicated in caustic ingestions and hydrocarbons

Dermal Decontamination

• Remove all contaminated clothing
• Wash skin thoroughly with soap and water
• Pay special attention with organophosphates, corrosives 1

Management of Specific Poisonings

Organophosphorus Poisoning

1. Recognition:

   • Muscarinic effects: SLUDGEM (Salivation, Lacrimation, Urination, Defecation, GI upset, Emesis, Miosis)
   • Nicotinic effects: Muscle fasciculations, weakness, paralysis
   • CNS effects: Anxiety, seizures, respiratory depression 4

2. Safety measures:

   • Use appropriate PPE (respiratory protection, gloves, gowns) before approaching patient
   • Decontaminate outside healthcare facility to prevent secondary exposure 4

3. Treatment:

   • Atropine: 2-4 mg IV initially, double dose every 5 minutes until secretions dry
   • Pralidoxime (2-PAM): 1-2 g IV over 15-30 minutes, may repeat after 1 hour
   • Benzodiazepines for seizures 5

Paracetamol (Acetaminophen) Poisoning

1. Assessment:

   • Obtain level at ≥4 hours post-ingestion
   • Plot on Rumack-Matthew nomogram
   • Consider point-of-care testing for early detection 6

2. Treatment:

   • N-acetylcysteine (NAC): 150 mg/kg IV over 1 hour, then 50 mg/kg over 4 hours, then 100 mg/kg over 16 hours
   • Continue NAC if levels remain elevated or liver injury develops

Salicylate Poisoning

1. Assessment:

   • Obtain salicylate level
   • Check arterial blood gas for metabolic acidosis
   • Monitor for altered mental status, hyperthermia, tachypnea

2. Treatment:

   • Urinary alkalinization: IV sodium bicarbonate to maintain urine pH >7.5
   • Hemodialysis for severe cases (level >100 mg/dL, altered mental status, renal failure)

Opioid Poisoning

1. Recognition:

   • Respiratory depression, miosis, CNS depression

2. Treatment:

   • Naloxone: Start with 0.04-0.4 mg IV/IM/IN, titrate up to 2 mg if needed
   • Higher doses may be required for synthetic opioids
   • Caution: May precipitate withdrawal in opioid-dependent individuals 1

When to Refer to Poison Center

Immediate poison center consultation (1-800-222-1222) is mandatory in the following situations:

1. Unknown toxin with significant symptoms
2. Multiple ingestions or substances
3. Need for specific antidotes not available at facility
4. Pediatric exposures with significant symptoms
5. Pregnant patients with toxic exposures
6. Need for extracorporeal removal (hemodialysis, hemoperfusion)
7. Unusual toxins or envenomations (exotic snakes, plants)
8. Carbon monoxide or cyanide poisoning
9. Organophosphate poisoning requiring pralidoxime 1

Medicolegal Considerations

1. Documentation requirements:

   • Detailed history of exposure (substance, amount, time, intent)
   • Physical examination findings
   • Laboratory and diagnostic test results
   • Treatment provided and patient response
   • Consultations obtained (poison center, toxicology)

2. Mandatory reporting:

   • Child abuse/neglect cases
   • Suicide attempts in minors
   • Criminal poisonings
   • Public health threats (food poisoning outbreaks)

3. Chain of custody:

   • Preserve evidence (containers, pills, bodily fluids)
   • Document handling of specimens for forensic testing
   • Photograph relevant findings when appropriate

Role of Sodium Bicarbonate in Toxicology

1. Urinary alkalinization:

   • Enhances elimination of weak acids (salicylates, phenobarbital)
   • Target urine pH >7.5

2. Treatment of wide QRS dysrhythmias:

   • Sodium channel blockers (tricyclic antidepressants, local anesthetics)
   • Bolus 1-2 mEq/kg, then infusion to maintain pH 7.45-7.55

3. Metabolic acidosis correction:

   • Methanol, ethylene glycol poisoning
   • Severe salicylate toxicity

Common Household Poisonings

1. Cleaning products:

   • Alkaline agents cause more severe esophageal injuries than acidic agents
   • Immediate dilution with water (small amounts only)
   • Avoid induced emesis
   • Endoscopy for symptomatic caustic ingestions 7

2. Hydrocarbons:

   • Aspiration risk is primary concern
   • Supportive care, oxygen, close respiratory monitoring
   • Charcoal generally not indicated

3. Medications:

   • Secure all medications, especially in homes with children
   • Keep poison center number readily available
   • Utilize child-resistant packaging

Key Pitfalls to Avoid

1. Failing to recognize toxidromes - Use systematic approach to identify constellation of symptoms

2. Delaying decontamination - Most effective within first hour of exposure

3. Inducing emesis - No longer recommended due to aspiration risk and availability of better alternatives

4. Administering flumazenil to chronic benzodiazepine users - May precipitate seizures

5. Using succinylcholine in organophosphate poisoning - May cause prolonged paralysis 4

6. Overlooking acetaminophen or salicylate in mixed overdoses - Universal screening recommended 2

7. Neglecting rescuer safety - Always use appropriate PPE, especially with organophosphates, cyanide, and corrosives 1