Rosen & Barkin's 5-Minute Emergency Medicine Consult (150 page)

• 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 airway
      
  • Intermediate water solubility: Chlorine:
    
    • Forms hydrochloric acid, hydrochlorous acids, which form free radicals causing upper airway and pulmonary irritation
      
  • Low water solubility: Phosgene:
    
    • Mild irritant effects initially, then delayed pulmonary edema as late as 24 hr
      
    • Direct 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

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

• 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 minutes
      
  • CNS:
    
    • Headache
      
    • Mental status changes
      
    • Seizures
      
  • Pulmonary:
    
    • Dyspnea
      
    • Noncardiogenic pulmonary edema
      
    • Cyanosis uncommon
      
  • GI:
    
    • Odor of bitter almonds (sometimes)
      
    • Burning in mouth and throat
      
    • Nausea, vomiting
      
• Blister agents (mustards, lewisite):
  
  • General:
    
    • Mortality, 2–4%
      
  • 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 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
      
  • GI:
    
    • Nausea, vomiting
      
  • Hematologic:
    
    • Leukopenia
      
• Lacrimators and riot control agents (tear gases):
  
  • HEENT:
    
    • Eye pain
      
    • Lacrimation
      
    • Blepharospasm
      
    • Temporary blindness
      
  • Dermatologic:
    
    • Skin irritation
      
    • Papulovesicular dermatitis (tear gas)
      
    • Superficial burns
      
  • Pulmonary:
    
    • Cough
      
    • Chest tightness
      
    • Dry throat
      
    • Sensation of suffocation
      
    • Pulmonary edema when exposed to high concentrations without ventilation
      
• Pulmonary irritants (choking agents):
  
  • HEENT:
    
    • Eye pain, lacrimation, blepharospasm
      
    • Temporary blindness
      
  • Dermatologic:
    
    • Skin irritation, dry throat, nasal irritation
      
  • Pulmonary:
    
    • Shortness of breath, cough, bronchospasm
      
    • Chest pain
      
    • Pulmonary edema as late as 24 hr from exposure (phosgene)
      
• Nerve agents (sarin, tabun, soman, VX):
  
  • SLUDGEBAM
    syndrome:
    
    • S
      alivation
      
    • L
      acrimation
      
    • U
      rination
      
    • D
      efecation
      
    • G
      I cramps
      
    • E
      mesis
      
    • Bronchorrhea, bronchoconstriction, bradycardia (most life threatening)
      
    • A
      bdominal upset
      
    • M
      iosis
      
  • HEENT:
    
    • Miosis
      
    • Hypersecretion by salivary, sweat, lacrimal, and bronchial glands
      
  • CNS:
    
    • Irritability, nervousness
      
    • Giddiness
      
    • Fatigue, lethargy, depression
      
    • Ataxia, convulsions, coma
      
  • Pulmonary:
    
    • Bronchoconstriction
      
    • Bronchorrhea
      
  • 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
      

• 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)
    

• 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.
      
• 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
  

CXR for pulmonary edema

• 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

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

• 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 suit
    
  • Chemical-resistant suit
    
  • Heavy rubber gloves and boots, neoprene gloves
    
• Administer oxygen, place on cardiac monitor, and measure pulse oximetry.
  
• Establish IV access with 0.9% NS.
  

• Decontamination: Reduce secondary exposure
  
• Blood agents:
  
  • High flow 100% NRB oxygen
    
  • Benzodiazepines for seizures
    
  • Hydroxocobalamin (1st line)
    
  • Cyanide antidote kit (2nd line), may be repeated.
    
• 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
      
  • Atropine 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 failure
      
    • Pupillary 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 paralysis
      
    • May repeat 1st dose or start on continuous infusion
      
    • If improvement from 1st dose, repeat 60–90 min later.
      
  • Diazepam: Administer for seizures.
    
• Incapacitating agents (BZ):
  
  • Supportive care
    
  • Aggressive IV fluid hydration
    
  • Benzodiazepines for agitation and increased muscular activity
    
  • Consider physostigmine in consultation with a poison center.