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Chemical Weapons Poisoning, Emergency Medicine

Basics

Description

- CNS: - Headache - Mental status changes - Seizures

- Pulmonary: - Dyspnea - Noncardiogenic pulmonary edema - Cyanosis uncommon

- Head, eyes, ears, nose, and throat (HEENT): - Airway occlusion from sloughing of debris - Laryngospasm, sore throat, sinusitis - Eye pain, photophobia, lacrimation, blurred vision, blepharospasm, periorbital edema, conjunctival edema, corneal ulceration

- Pulmonary: - Bronchospasm, tracheobronchitis - Respiratory failure - Hacking cough

- Lacrimators and riot control agents (tear gases): - HEENT: - Eye pain - Lacrimation - Blepharospasm - Temporary blindness

- Dermatologic: - Skin irritation - Papulovesicular dermatitis (tear gas) - Superficial burns

- HEENT: - Miosis - Hypersecretion by salivary, sweat, lacrimal, and bronchial glands

- CNS: - Irritability, nervousness - Giddiness - Fatigue, lethargy, depression - Ataxia, convulsions, coma

- GI: - Nausea, vomiting, diarrhea - Crampy abdominal pains - Urinary and fecal incontinence

- Musculoskeletal: - Fasciculations, skeletal muscle twitching - Weakness - Flaccid paralysis

- Incapacitating agents (BZ): - Anticholinergic (antimuscarinic) toxidrome: - Hot as a hare - Dry as a bone - Red as a beet - Blind as a bat - Mad as a hatter - Hypertension - Tachycardia - Hyperpyrexia - Urinary retention - Decreased bowel sounds

- Arterial blood gases: - Cyanide: - Decreased atrioventricular (AV) oxygen saturation gap - Lactic acidemia with high anion gap metabolic acidosis - Arterialization of venous blood - Cyanide levels cannot be performed in clinically relevant timeframe.

- Protection for health care workers: - Level A or B personal protective suit - Chemical-resistant suit - Heavy rubber gloves and boots, neoprene gloves

- Blister agents: - Supportive care - Standard burn management - Atropine to relieve eye pain - Monitor fluids, electrolytes, complete blood chemistry. - Monitor CBC for nadir. - Supportive care for sepsis, anemia, hemorrhage - Granulocyte colony-stimulating factor (G-CSF) for neutropenia

- Choking agents, lacrimators, riot control agents: - Supportive care, bronchodilators - Eye irrigation - CXR and careful monitoring for respiratory complications - Phosgenes require monitoring for delayed pulmonary edema for 24 hr

- Nerve agents: - Supportive care: - 100% oxygen - Frequent airway suctioning

- Incapacitating agents (BZ): - Supportive care - Aggressive IV fluid hydration - Benzodiazepines for agitation and increased muscular activity - Consider physostigmine in consultation with a poison center.

Chemical agents that affect CNS, pulmonary, cardiovascular, dermal, ocular, or GI systems when exposed to victims

Etiology

  • Blood agents: Cyanide:Inhibition of cellular respiration by binding to ferric ion in cytochrome oxidase a-a3 and uncoupling oxidative phosphorylation
  • Blister agents: Sulfur mustard, nitrogen mustard, lewisite, phosgene oxime:Alkylation and cross-linking of purine bases of DNA and amino acids resulting in change in structure of nucleic acid, proteins, and cellular membranes
  • Lacrimators and riot control agents: 1-chloroacetophenone (CN; Mace), o-chlorobenzylidene malononitrile (CS), oleoresin capsaicin-pepper spray (OC), chloropicrin, adamsite (DM):Mucous membrane irritators
  • Pulmonary irritants (choking agents):High water solubility: Ammonia:Mucous membrane irritation of eyes and upper airwayIntermediate water solubility: Chlorine:Forms hydrochloric acid, hydrochlorous acids, which form free radicals causing upper airway and pulmonary irritationLow water solubility: Phosgene:Mild irritant effects initially, then delayed pulmonary edema as late as 24 hrDirect pulmonary damage after hydrolysis in lungs to hydrochloric acid
  • Nerve agents:Anticholinesterase inhibitors-causes cholinergic overstimulation at muscarinic, nicotinic, and CNS sites
  • Incapacitating agents: 3-quinuclidinyl benzilate (BZ):Anticholinergic (antimuscarinic)

Diagnosis

Signs and Symptoms

History

Multiple victims, house fire, known exposure (agent determines history findings)

Physical Exam

  • Blood agents (cyanide and cyanogens):Vital signs:Tachypnea and hyperpnea (early); respiratory depression (late)Hypertension and tachycardia (early); hypotension and bradycardia (late)Death within seconds to minutesCNS:HeadacheMental status changesSeizuresPulmonary:DyspneaNoncardiogenic pulmonary edemaCyanosis uncommonGI:Odor of bitter almonds (sometimes)Burning in mouth and throatNausea, vomiting
  • Blister agents (mustards, lewisite):General:Dermatologic:Skin erythema, edema, pruritus can appear 2-24 hr after exposure.Necrosis and vesiculation appear 2-18 hr after exposure.Head, eyes, ears, nose, and throat (HEENT):Airway occlusion from sloughing of debrisLaryngospasm, sore throat, sinusitisEye pain, photophobia, lacrimation, blurred vision, blepharospasm, periorbital edema, conjunctival edema, corneal ulcerationPulmonary:Bronchospasm, tracheobronchitisRespiratory failureHacking coughGI:Hematologic:
  • Lacrimators and riot control agents (tear gases):HEENT:Eye painLacrimationBlepharospasmTemporary blindnessDermatologic:Skin irritationPapulovesicular dermatitis (tear gas)Superficial burnsPulmonary:CoughChest tightnessDry throatSensation of suffocationPulmonary edema when exposed to high concentrations without ventilation
  • Pulmonary irritants (choking agents):HEENT:Eye pain, lacrimation, blepharospasmTemporary blindnessDermatologic:Skin irritation, dry throat, nasal irritationPulmonary:Shortness of breath, cough, bronchospasmChest painPulmonary edema as late as 24 hr from exposure (phosgene)
  • Nerve agents (sarin, tabun, soman, VX):SLUDGEBAM syndrome:SalivationLacrimationUrinationDefecationGI crampsEmesisBronchorrhea, bronchoconstriction, bradycardia (most life threatening)Abdominal upsetMiosisHEENT:MiosisHypersecretion by salivary, sweat, lacrimal, and bronchial glandsCNS:Irritability, nervousnessGiddinessFatigue, lethargy, depressionAtaxia, convulsions, comaPulmonary:BronchoconstrictionBronchorrheaGI:Nausea, vomiting, diarrheaCrampy abdominal painsUrinary and fecal incontinenceMusculoskeletal:Fasciculations, skeletal muscle twitchingWeaknessFlaccid paralysis
  • Incapacitating agents (BZ):Anticholinergic (antimuscarinic) toxidrome:Hot as a hareDry as a boneRed as a beetBlind as a batMad as a hatterHypertensionTachycardiaHyperpyrexiaUrinary retentionDecreased bowel sounds

Essential Workup

  • History and symptoms key to type of agent exposure
  • Physical exam:Cyanide (bitter almonds, comatose, hypotensive, metabolic acidosis)Mustard (faint, sweet odor of mustard or garlic, blisters, sloughing of skin, dyspnea)Check for SLUDGEBAM syndrome.Lacrimators (eye irritation, lacrimation, blepharospasm)Choking agents (dyspnea, bronchospasm)

Diagnosis Tests & Interpretation

Lab

  • Arterial blood gases:Cyanide:Decreased atrioventricular (AV) oxygen saturation gapLactic acidemia with high anion gap metabolic acidosisArterialization of venous bloodCyanide levels cannot be performed in clinically relevant timeframe.
  • CBC:Leukopenia, thrombocytopenia, anemia with significant mustard exposure
  • Electrolytes, BUN, creatinine, glucose
  • Urinalysis
  • Creatine phosphokinase (CPK)
  • Lactate for cyanide
  • Erythrocyte cholinesterase activity for nerve agents

Imaging

CXR for pulmonary edema

Differential Diagnosis

  • Asthma/COPD
  • Stevens-Johnson syndrome
  • Toxic epidermal necrolysis
  • Pemphigus vulgaris
  • Scalded skin syndrome
  • Organophosphate or carbamate pesticide poisoning
  • Botulism
  • Radiation poisoning
  • CHF
  • Anaphylactoid reaction

Treatment

Pre-Hospital

  • Avoid contamination of environment and clinicians:Use level A or level B personal protective equipment.Decontamination:Dermal wet decontamination primarily for nerve and blistering agentsDry decontamination (removal of clothing and jewelry) for other agents
  • Administer atropine even if patient is tachycardic because condition may result from hypoxia.

Initial Stabilization/Therapy

  • ABCs
  • Patient decontamination:Brush off powder from chemical.Irrigate skin and eyes with copious amounts of water or saline.Remove and dispose of clothing in double bags.
  • Protection for health care workers:Level A or B personal protective suitChemical-resistant suitHeavy rubber gloves and boots, neoprene gloves
  • Administer oxygen, place on cardiac monitor, and measure pulse oximetry.
  • Establish IV access with 0.9% NS.

Ed Treatment/Procedures

  • Decontamination: Reduce secondary exposure
  • Blood agents:High flow 100% NRB oxygenBenzodiazepines for seizuresHydroxocobalamin (1st line)Cyanide antidote kit (2nd line), may be repeated.
  • Blister agents:Supportive careStandard burn managementAtropine to relieve eye painMonitor fluids, electrolytes, complete blood chemistry.Monitor CBC for nadir.Supportive care for sepsis, anemia, hemorrhageGranulocyte colony-stimulating factor (G-CSF) for neutropenia
  • Choking agents, lacrimators, riot control agents:Supportive care, bronchodilatorsEye irrigationCXR and careful monitoring for respiratory complicationsPhosgenes require monitoring for delayed pulmonary edema for 24 hr
  • Nerve agents:Supportive care:100% oxygenFrequent airway suctioningAtropine 2 mg IV q5min until reversal of bronchorrhea, bronchoconstriction, and hypoxemia:Antagonizes muscarinic effects and some CNS but no effect on skeletal muscle weakness or respiratory failurePupillary response and heart rate are not useful measures of adequate atropinization.Stop atropine after patient regains consciousness and spontaneous ventilation (may need for periodic relapses); give as much as it takes to reverse respiratory compromise.Pralidoxime chloride (2-PAM or Protopam):Regenerates cholinesterase by reversing phosphorylation (unless aging has occurred)Reduces abnormal skeletal muscle movements, improves skeletal muscle weakness, and reverses flaccid paralysisMay repeat 1st dose or start on continuous infusionIf improvement from 1st dose, repeat 60-90 min later.Diazepam: Administer for seizures.
  • Incapacitating agents (BZ):Supportive careAggressive IV fluid hydrationBenzodiazepines for agitation and increased muscular activityConsider physostigmine in consultation with a poison center.

Medication

  • Albuterol using nebulizer: 2.5 mg in 2.5 mL NS (peds: 0.1-0.15 mg/kg/dose)
  • Atropine: 2 mg IM or IV (5-6 mg in severely poisoned adults; peds: 0.02-0.08 mg/kg), then q5-10min titrate to clinical effect
  • Cyanide antidote kit:Inhale amyl nitrite ampule for 30 sec qmin until sodium nitrite given.Sodium nitrite: 10 mL of 3% solution or 300 mg IV over 3-5 min (peds: 0.15-0.33 mL/kg):Monitor methemoglobin levels to keep <30%.Sodium thiosulfate: 50 mL IV of 25% solution or 12.5 g (peds: 1.65 mL/kg)
  • Diazepam: 5-10 mg IV over 3-5 min (peds: 0.2-0.4 mg/kg up to 10 mg over 2-3 min)
  • Hydroxocobalamin: 5 g IV
  • Pralidoxime chloride (2-PAM, Protopam): 1-2 g IV over 20-30 min or 600 mg IM (diluted with water or saline to concentration of 300 mg/mL) given with 1st 3 atropine doses (peds: 25-50 mg/kg/dose IV), repeat in 2 hr if muscle weakness has not been relieved, and in 4-6-hr intervals if necessary. Continuous infusion of 500 mg/h has been used for organophosphate poisoning

Follow-Up

Disposition

Admission Criteria

  • ICU admission for symptomatic patients with significant exposure
  • Hospital admission to monitor for developing complications for blister, choking, lacrimating agents, incapacitating agents

Discharge Criteria

Riot control exposures:

  • Observe in ED for 6 hr and discharge if symptoms resolve.

Pearls and Pitfalls

Must perform adequate decontamination

Additional Reading

  • Davis K, Aspera G. Exposure to liquid sulfur mustard. Ann Emerg Med. 2001;37:653-656.
  • Keyes DC. Chemical warfare agents. In: Dart RC, Caravati EM, McGuigan MA, et al., eds. Medical Toxicology. 3rd ed. Philadelphia, PA: Lippincott Williams & Wilkins; 2004:1777-1794.

Codes

ICD9

  • 987.5 Toxic effect of lacrimogenic gas
  • 987.7 Toxic effect of hydrocyanic acid gas
  • 987.9 Toxic effect of unspecified gas, fume, or vapor
  • 987.6 Toxic effect of chlorine gas
  • 987.8 Toxic effect of other specified gases, fumes, or vapors

ICD10

  • T57.3X4A Toxic effect of hydrogen cyanide, undetermined, init encntr
  • T59.3X4A Toxic effect of lacrimogenic gas, undetermined, initial encounter
  • T59.94XA Toxic effect of unsp gases, fumes and vapors, undet, init
  • T59.4X4A Toxic effect of chlorine gas, undetermined, initial encounter
  • T59.894A Toxic effect of gases, fumes and vapors, undetermined, init

SNOMED

  • 243054000 Injury due to poison gas weapon (disorder)
  • 243055004 Poisoning due to irritant gas
  • 66207005 Toxic effect of cyanide (disorder)
  • 243057007 Poisoning due to vesicant gas (disorder)
  • 243056003 Poisoning due to crowd control gas (disorder)
  • 243059005 Poisoning due to nerve gas (finding)