Cyanide

Aka: Cyanide, Hydrogen cyanide, Hydrocyanic acid, Cyanogen chloride

1. Mechanism
   1. Site of action
      1. Absorbed effect (Hydrogen cyanide, Cyanogen chloride)
         1. Binds ferric ions in mitochondrial cytochromes
         2. Cell unable to perform aerobic metabolism
      2. Local respiratory effects (Cyanogen chloride)
         1. Pulmonary Intoxicant (Chlorine type effect)
   2. State
      1. Temperature below 78 F: Liquid and Vapor
      2. Temperature above 78 F: Gas
   3. Route of exposure
      1. Inhalation
      2. Percutaneous
      3. Ingestion
2. Sources
   1. Weapon or intentional toxin
   2. Tobacco smoking (0.4 mcg/ml)
   3. Foods: Fruits, seeds and pits
      1. Cherries, peaches, almonds, lima beans
      2. Cassava plant roots (staple in some parts of world)
   4. Structure fires
      1. Especially plastics (acrylonitrile)
   5. Industrial use Hydrogen cyanide (300,000 tons)
   6. Nitroprusside metabolite
3. Agents
   1. Hydrogen cyanide (Hydrocyanic acid, AC)
   2. Cyanogen chloride (CK)
4. Symptoms of Low level Cyanide Vapor exposure
   1. Intense eye, nose and airway irritation
   2. Increased Rate and depth of breathing
   3. Dizziness
   4. Nausea and Vomiting
   5. Headache
5. Signs of High Cyanide Vapor exposure
   1. Immediate
      1. Diaphoretic
      2. Pupils normal or large
      3. Hypertension and Tachycardia
   2. Effects at time 15 Seconds
      1. Transient increased Breathing Rate, depth
   3. Effects at time 30 Seconds:
      1. Seizure
   4. Effects at time 2 to 4 Minutes
      1. Respiratory arrest from central apnea
   5. Effects at time: 4 to 8 Minutes
      1. Terminal Hypotension
      2. Bradyarrhythmia
      3. Cardiac Arrest
   6. Effects at time 6 to 8 Minutes
      1. Death
6. Labs
   1. Blood Cyanide effects
      1. Mild effects: 0.5-1.0 mcg/ml
      2. Lethal effects: >2.5 mcg/ml
   2. Arterial Blood Gas
      1. Metabolic Acidosis with high Anion Gap
      2. Serum Lactic Acid high
7. Differential Diagnosis
   1. Nerve agent
      1. Miosis
      2. Increased Rhinorrhea and oral secretions
   2. Hydrogen sulfide
      1. Rotten egg odor
   3. Carbon Monoxide Poisoning
      1. Pink, healthy looking skin with Hypoxia
8. Detection
   1. Odor
      1. Bitter almonds (Only detectable by 50% of people)
   2. Detection Kits
      1. Hydrogen cyanide (AC)
         1. M256A1 (7.0 mg/m3)
         2. M272 (20.0 mg/m3)
         3. ICAD (250 mg/m3)
         4. M18A2 (8.0 mg/m3)
         5. M90 (30 mg/m3)
      2. Cyanogen chloride (CK)
         1. MINICAMS (130 ppbv)
         2. Draeger (0.25-5 ppm)
         3. M93A1 Fox (46 mg/m3)
9. Management
   1. Decontamination
      1. Vapor: None
      2. Liquid: Wash skin with soap and water
      3. Minimal risk of off-gassing
   2. Antidote (2 Step Process)
      1. First: Sodium Nitrite to form Methemoglobin
         1. Adults: 10 ml IV (1 ampule of Pasadena kit)
         2. Pediatric: 0.33 ml/kg of 3% solution IV over 10 min
         3. Alternative: Amyl Nitrate crushed and inhaled
         4. Contraindicated in carbon monoxide (e.g. fire)
      2. Next: Sodium thiosulfate to act as sulfur donor
         1. Adult: 50 ml (1 large bottle in Pasadena kit)
         2. Pediatric: 1.65 ml/kg IV of 25% standard solution
   3. Supportive care
      1. Oxygen
      2. Correct acidosis
10. Prevention
    1. Activated Charcoal in chemical protective mask
       1. Absorbs Cyanide and provides full protection
11. Triage
    1. Immediate
       1. Presentation within minutes of exposure
       2. Seizures or recent apnea with circulation intact
    2. Minimal
       1. Mild effects and out of exposure
    3. Delayed
       1. Recovering from mild effects or successful therapy
    4. Expectant
       1. Apnea and circulatory failure
    5. Course
       1. Observe survivors for 24-48 hours after exposure
12. References
    1. Medical Response to Chemical Warfare and Terrorism
       1. US Army Medical Research Institute Chemical Defense
       2. Video-Teleconference: 4/20/00 to 4/22/99
       3. Video-Teleconference: 12/5/00 to 12/7/00
       4. Text: 3rd Edition, December 1998