Cyanides

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Cyanides
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Cyanides

• Discoverer Karl Wilhelm Sheele died from its
  vapors
• Commercial and home use
• Found in some fruit seeds
• Accidental poisonings from apricot kernels

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Cyanides-Overview

• HCN and CK
• Highly volatile
• Easily dispersed as aerosols
• Readily soluble and stable in water
• Major route of toxicity is inhalation
• Aroma of bitter almonds or marzipan
• CK has cumulative effect on victims

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Cyanides-Toxicity

• Inhibits oxidizing enzymes containing ferric
  iron, mainly cytochrome oxidase
• Interferes with aerobic respiration
• Lactic acid accumulates and cells die from a
  histotoxic anoxia
• Alters calcium metabolism

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Cyanides-Toxicity

• Hydrogen Cyanide (HCN)
• 60 mgmin/m3 - No serious symptoms
• 200 mgmin/m3 - Fatal after 10 minutes
• Above 2,500 mgmin/m3 - death within a minute

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Cyanides-Toxicity

• Cyanogen Chloride (CK)
• Pulmonary irritant like phosgene
• 2.5 mgmin/m3 - irritation after 10 minutes
• 5 mgmin/m3 - intolerable at 10 minutes
• 400 mgmin/m3 - fatal after 10 minutes

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Protective Equipment

• Chemical protective clothing required
• Respirator filters containing silver oxide offer
  effective protection
• Change filter immediately after exposure

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Detection

• Several analytical detecting methods are
  available
• Main method of laboratory detection is gas
  chromatography/mass-spectrometry

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Decontamination

• First priority remove victims from area
• Skin wash well with soap and water
• Eyes flush well with water or saline
• Decontamination of clothing or equipment is
  unnecessary

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Signs and Symptoms

• Diagnosis
• History
• Abrupt onset of symptoms
• Bitter almond odor on the breath
• Mild HCN cases
• Headache
• Vertigo
• Nausea

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Signs and Symptoms

• Low HCN concentrations
• Apprehension, dyspnea, headache, vertigo and a
  metallic taste are seen initially
• Convulsions and coma may follow and can last for
  hours or days

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Signs and Symptoms

• Low HCN concentrations
• Prolonged coma, residual CNS damage may be seen
• Irrationality, altered reflexes, unsteady gait
• Nerve deafness also possible

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Signs and Symptoms

• High concentrations
• Throat constriction, giddiness, confusion,
  decreased vision, vice-like gripping of the
  temples, and pain in the back of neck and chest
• If unconsciousness follows, further exposure can
  be fatal within 2-3 minutes

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Signs and Symptoms

• Lower but still lethal concentrations
• Immediate, progressive sense of warmth, visible
  flushing
• Prostration ensues
• Nausea, vomiting, headache, dyspnea and chest
  tightness
• Unconsciousness asphyxia will follow

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Signs and Symptoms

• Very high concentrations
• Main initial symptom hyperventilation
• Loss of consciousness, convulsions, and loss of
  corneal reflex
• Death by cardiac and/or respiratory arrest

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Signs and Symptoms

• Effects are slower to develop to lethal amounts
  via ingestion or skin exposure
• Victim can survive 15-30 minutes
• Antidote could be given

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Signs and Symptoms

• CK exposure produces symptoms of cyanide
  poisoning and lung irritants
• Eye exposure
• Lacrimation and blepharospasm
• Respiratory exposure
• Irritation of the nose and throat, cough,
  dyspnea, and chest tightness

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Signs and Symptoms

• Exposuresgt50 mgmin/m3 produce pulmonary edema,
  followed by collapse, coma and death
• Liquid CK can cause 2º and 3º skin burns

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Laboratory/Diagnostics

• Useful lab findings include
• High anion gap metabolic acidosis
• Elevated lactate, methemoglobin, and urinary
  thiocyanate levels

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Laboratory/Diagnostics

• EKG
• Atrial fibrillation
• Ectopic ventricular beats
• Abnormal QRS waves with the T wave originating
  high on the R wave

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Treatment

• Victims asymptomatic after several minutes
  require no oxygen or antidotes
• Administer supportive care, oxygen and antidotes
• Acute effects (convulsions, dyspnea)
• Acute exposure (unconscious but breathing)

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Treatment

• Treat irritation effects of CK
• Wash eyes with a weak boric acid solution
• Apply soothing lotions/compresses
• Assess and treat burns as you would thermal burns
• Control hypoxia with O2 supplementation
• Consider early use of IPPB, PEEP or intubation

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Treatment

• For ingestions
• Initiate gastric lavage with water
• 15000 solution of potassium permanganate if
  available
• Antidotes dissociate the cyanide ion from
  cytochrome oxidase

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Treatment

• Goal create methemoglobin, which binds to
  cyanide to form cyanmethemoglobin
• Sodium nitrite
• Amyl nitrite
• 4-dimethylaminophenol-hydrochloride (DMAP)

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Treatment

• Other antidotes
• Cobalt in the forms of dicobalt edetate or
  hydroxocobalamin also combines with cyanide ions
• Hydroxocobalamin
• Dicobalt edetate

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Treatment

• Therapies are life saving not curative
• Follow these antidotes with sodium thiosulfate to
  aid the clearance of cyanide as non-toxic
  thiocyanate

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Long-Term Medical Sequelae

• Low doses no long-term problems
• At near lethal doses lower intellect,
  confusion, loss of concentration and Parkinsonism

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Long-Term Medical Sequelae

• Chronic poisoning ataxic neuropathy
• No specific data on developmental and
  reproductive effects, mutagenicity or
  carcinogenicity

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Environmental Sequelae

• HCN is highly volatile, removed from the
  environment in less than an hour
• CK is less persistent

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Summary

• Hydrogen cyanide (HCN) and cyanogen chloride (CK)
• Cyanide gases
• Military and terrorist potential
• Inhalation main route of exposure
• Decontamination is possible with soap and water
  but must be done immediately

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Summary

• Cyanide inhibits aerobic respiration at the
  cellular level
• Symptoms are immediate
• Supportive care and antidotes are required