What is the appropriate emergency management for suspected cypermethrin (synthetic pyrethroid) poisoning?

Emergency Management of Cypermethrin (Synthetic Pyrethroid) Poisoning

For suspected cypermethrin poisoning, immediately contact Poison Control (1-800-222-1222 in the US) while initiating supportive care, as treatment is primarily symptomatic with no specific antidote available.

Immediate Priorities and Stabilization

Activate Emergency Response

• Contact Poison Control Center immediately for specialized toxicological consultation, as most clinicians encounter pyrethroid poisoning infrequently and expert guidance is essential 1
• Activate EMS if the patient exhibits life-threatening signs including altered mental status, seizures, respiratory difficulty, coma, or convulsions 2, 3
• Establish and maintain vital functions with standard life support measures, including CPR if cardiorespiratory arrest occurs 1, 4

Route-Specific Decontamination

Dermal Exposure:

• Remove all contaminated clothing and jewelry immediately to prevent continued absorption, taking care to avoid self-contamination 2, 1
• Perform thorough dermal decontamination with soap and copious amounts of water, as this is an essential component of treatment 5
• The skin is the primary route of occupational pyrethroid absorption 3

Eye Exposure:

• Flush eyes immediately with copious amounts of tepid water for at least 15 minutes 1

Ingestion:

• Do NOT administer anything by mouth (water, milk, or activated charcoal) unless specifically directed by Poison Control, as this may cause emesis and aspiration without proven clinical benefit 2, 1
• Do NOT induce vomiting or administer ipecac, as this is contraindicated and provides no clinical benefit while potentially causing harm 2
• Consider activated charcoal by small-bore nasogastric tube only if advised by Poison Control 1

Clinical Presentation and Monitoring

Expected Symptoms by Route

Dermal Exposure:

• Paraesthesiae (tingling/burning sensations) are the primary adverse effect, most commonly affecting the face 3
• Symptoms are exacerbated by heat, sunlight, scratching, sweating, or water application 3
• Paraesthesiae typically resolve within 12-24 hours 3

Ingestion (Acute Oral Intoxication):

• Immediate symptoms (within minutes): Sore throat, nausea, vomiting, abdominal pain, mouth ulceration, increased secretions, dysphagia 3
• Systemic effects (4-48 hours post-exposure): Dizziness, headache, fatigue, palpitations, chest tightness, blurred vision 3
• Life-threatening features: Coma, convulsions, prolonged bradycardia 3, 6, 5

Cardiovascular Monitoring

• Monitor for bradycardia, which can be prolonged and severe in cypermethrin poisoning 6
• Assess for tachycardia, altered peripheral pulse volume, cool peripheries, and prolonged capillary refill time (≥2 seconds) 2
• Monitor for signs of shock including hypotension and altered consciousness 2

Neurological Assessment

• Cypermethrin is a type II pyrethroid that acts by delaying closure of voltage-sensitive sodium channels and decreasing chloride currents 3, 6
• At high concentrations, it can act on GABA-gated chloride channels, potentially causing seizures 3
• Severe poisonings can present as an organophosphate-like toxidrome, creating a diagnostic conundrum 5

Specific Treatment Interventions

Symptomatic Management

For Bradycardia:

• Administer low-dose atropine sulphate for symptomatic bradycardia 6, 5
• Critical caveat: Avoid high-dose atropine commonly used for organophosphate poisoning, as cypermethrin poisoning may mimic organophosphate toxicity but does not require the same aggressive atropine dosing 5

For Paraesthesiae:

• Topical application of dl-alpha tocopherol acetate (vitamin E) may reduce severity, though symptoms usually resolve spontaneously in 12-24 hours 3

For Seizures/Coma:

• Provide mechanical ventilation if needed 5
• Implement standard seizure management protocols 3

Supportive Care

• Most patients recover within 6 days with supportive treatment alone 3
• Monitor for multi-organ toxicity requiring intensive supportive care 2
• Ensure adequate fluid management, as patients may develop dehydration from vomiting and diarrhea 2

Critical Pitfalls to Avoid

1. Do not delay EMS activation while attempting home interventions 4
2. Do not assume this is organophosphate poisoning based on initial presentation—severe pyrethroid poisoning can mimic organophosphate toxicity but requires different management, particularly regarding atropine dosing 5
3. Do not administer high-dose atropine reflexively; use low doses only if symptomatic bradycardia is present 5
4. Do not attempt dilution with water or milk for ingestions—this is not evidence-based and may worsen outcomes by causing vomiting and aspiration 2, 1
5. Do not overlook dermal decontamination, as skin absorption is the primary occupational exposure route 3, 5

Prognosis and Recovery

• Despite extensive worldwide use, relatively few severe pyrethroid poisonings occur, with less than ten deaths reported from ingestion or occupational exposure 3
• Pyrethroids are approximately 2,250 times more toxic to insects than mammals due to increased sodium channel sensitivity in insects, smaller body size, lower body temperature, and mammals' poor dermal absorption with rapid metabolism to non-toxic metabolites 3
• Most patients make full recovery with supportive care and symptomatic treatment 5