What is the appropriate initial assessment and management for a patient with suspected herbicide poisoning?

Herbicide Poisoning: Initial Assessment and Management

Immediate Life-Threatening Actions

For any patient with suspected herbicide poisoning exhibiting life-threatening signs (altered mental status, seizures, respiratory distress, vomiting), immediately activate emergency medical services while simultaneously beginning resuscitation—do not delay for toxin identification. 1, 2

Primary Survey and Stabilization

• Airway, breathing, and circulation take absolute priority over any toxin-specific interventions, as supportive care is the primary determinant of survival in all poisoning cases 1, 3
• Secure the airway immediately if the patient shows CNS depression, loss of protective reflexes, or respiratory compromise 3, 4
• Provide bag-mask ventilation or proceed to endotracheal intubation for respiratory depression 3, 5
• Establish IV access and correct hemodynamic instability before pursuing specific antidote therapy 4

Early Expert Consultation

• Contact the Poison Control Center (1-800-222-1222 in the US) immediately to provide the product name, time of exposure, and clinical presentation 1, 2, 3
• Request urgent consultation with a medical toxicologist for potentially life-threatening exposures to prevent deterioration to cardiac arrest 1, 3

Decontamination Procedures

Dermal Exposure

• Remove all contaminated clothing while protecting yourself from secondary exposure—healthcare workers must wear appropriate personal protective equipment (gloves, gowns, eye protection) as herbicide residues can cause severe secondary poisoning 1, 2
• Brush off any powdered chemical with a gloved hand or cloth before washing 1, 2, 4
• Irrigate affected skin immediately with copious amounts of water and soap for at least 15 minutes (Class I, LOE B) 1, 2

Eye Exposure

• Flush eyes immediately with copious amounts of water for at least 15 minutes (Class I, LOE C) unless a specific antidote is available 1, 2

Ingestion

• Do NOT administer anything by mouth (water, milk, or activated charcoal) unless specifically directed by poison control, as there is insufficient evidence of benefit and risk of emesis with aspiration (Class III, LOE C) 1, 4
• Do NOT induce vomiting with ipecac—this is contraindicated in poisoning management 1, 4
• Gastric lavage may be considered only if presentation occurs within 60 minutes of ingestion, though evidence for benefit is limited 6, 7
• Activated charcoal is contraindicated for caustic substances, metals, and hydrocarbons 1, 3

Herbicide-Specific Considerations

Organophosphate Herbicides (if cholinergic toxidrome present)

The "all faucets on" cholinergic syndrome suggests organophosphate exposure 7:

• Administer atropine immediately for severe poisoning with bronchospasm, bronchorrhea, seizures, or significant bradycardia (Class I, LOE A) 1, 5
• Initial atropine dose should be doubled every 5 minutes until full atropinization is achieved (clear chest auscultation, heart rate >80/min, systolic BP >80 mmHg) 1
• Early endotracheal intubation is recommended for life-threatening organophosphate poisoning (Class I, LOE B-NR) 1
• Administer benzodiazepines (diazepam first-line or midazolam) to treat seizures and agitation (Class I, LOE C-LD) 1, 5
• Pralidoxime (2 g loading dose over 20 minutes followed by 0.5 g/hour infusion) is reasonable for organophosphate poisoning (Class IIa, LOE A), though should not be withheld when the specific poison class is unknown 1, 3

Paraquat and Diquat (Dipyridyl Herbicides)

• Paraquat is the most toxic herbicide and any exposure requires immediate evaluation even days after ingestion 8
• Pulmonary fibrosis is the hallmark of paraquat toxicity; deteriorating pulmonary status indicates grave prognosis 6, 8
• No proven antidote exists—treatment is entirely supportive with consideration of Fuller's earth, bentonite, or hemoperfusion in severe cases 6
• Novel approaches with N-acetylcysteine, vitamin C, vitamin E may be considered in consultation with toxicology 6

Chlorophenoxy Herbicides (2,4-D, MCPA)

• These cause dose-dependent cell membrane damage and uncoupling of oxidative phosphorylation 9
• Clinical features include gastrointestinal hemorrhage, hypotension, neurotoxicity (coma, hyperreflexia, seizures), respiratory failure, rhabdomyolysis, and metabolic acidosis 9
• Alkaline diuresis or hemodialysis should be considered in all seriously poisoned patients to enhance herbicide elimination 9

Glyphosate

• Commonly causes gastrointestinal corrosive effects, acid-base imbalance, pulmonary edema, shock, and arrhythmias 6
• Long-term complications include multi-organ failure (pulmonary fibrosis, renal failure, hepatic failure) 6
• Treatment is entirely supportive with consideration of hemodialysis or hemoperfusion for renal failure 6

Critical Monitoring Parameters

• Continuously monitor vital signs, as stable parameters can deteriorate rapidly in poisoning situations 3
• Assess for metabolic derangements (acidosis, electrolyte abnormalities) requiring immediate correction 4
• Monitor for respiratory muscle weakness even in alert patients, as hypoventilation may develop from neuromuscular effects rather than CNS depression 9
• Check creatine kinase for rhabdomyolysis and monitor renal function 9

Common Pitfalls to Avoid

• Never delay supportive care or EMS activation while awaiting specific herbicide identification 3, 4
• Do not use neuromuscular blockers metabolized by cholinesterase (succinylcholine, mivacurium) in organophosphate or carbamate poisoning (Class III, LOE C-LD) 1
• Do not waste time attempting to remove water from the airway with abdominal thrusts—water does not act as an obstructive foreign body 1
• Avoid administering activated charcoal in late presentations (>1-2 hours), as absorption is complete and this delays definitive care 4, 7