Cyanide (CN) Flashcards
Sources of Cyanide
Common:
Smoke inhalation burning of natural substances (wool, silk, cotton, paper) or synthetic substances (plastics, other polymers)
Others
- Industrial (metal trades, mining, electroplating, jewelry manufacturing, x-ray film recovery)
- Laboratories
- Cyanogens : sodium nitroprusside
- Natural sources (e.g apricot and many other plants)
Forms of Cyanide
- Gaseous: hydrogen cyanide (HCN)
- Salts
•Routes:
- parenteral,
- inhalation,
- ingestion,
- dermal
•Manner:
- suicidal
- accidental
- mass disasters e.g. Terrorism
Mechanism of toxicity
- Cyanide is a cellular poison that virtually affects all body tissues
- Mainly inactivation of cytochrome oxidase →shift of cellular metabolism from aerobic to anaerobic +inhibiting cellular respiration (histotoxic anoxia)
- Cyanide is also a potent neurotoxin →neurodegeneration
Clinical picture
Acute toxicity
reflect rapid dysfunction of oxygen-sensitive organs
CNS: Headache, dizziness, convulsions, and coma.
Cardiac effects:
↓HR + ↑BP →↓BP + reflex ↑HR → ↓HR +↓BP (terminal)
Pulmonary effects
centrally-mediated tachypnea →bradypnea.
Cardiogenic/ Non-cardiogenic pulmonary edema (acute lung injury)
GIT effects
ingestion of inorganic cyanide and cyanogen corrosive nature hemorrhagic gastritis
Others Odor of bitter almonds, Cherry-red skin coloration, Fundoscopic examination revealed red –colored veins due to poor oxygen extraction,
Delayed neurologic sequelae
•
- Develop over weeks or months in survivors of severe poisoning
- Parkinsonian symptoms :
- Dystonia
- Rigidity
- Dysarthria
- Bradykinesia
•These symptoms may progress or resolve
Investigations of Cyanide Poisoning
•
1.Arterial blood gases (ABG)
- Blockade of aerobic metabolism. →→metabolic acidosis (elevated lactate)
- Oxygen saturation altered only when respiratory failure occurs.
- Elevated venous oxygen saturation
- Cyanide determination in the blood: It is not usually rapidly available.
- ECG and cardiac monitoring
- Cardiac enzymes
- Chest x-ray
- CT brain and MRI
Treatment
1.1st aid :
- Focus attention to airway patency, ventilation and oxygenation 100% oxygen.
- Do not give mouth-to-mouth resuscitation without a barrier.
- Be sure to assess for other causes in cases of altered mental status e.g. trauma /medical /combined
- Decontamination: according route of exposure + protection of rescuer
- Inhalation: remove from site
- Skin: washing
- Gastrointestinal : GL+ AC - Cyanide antidote:
• Amyl & sodium Nitrites + thiosulfate ± hydroxycobalamin (cyanide kit)
- Specific treatment of complications
Cyanide Antidote Kit
1.Nitrites + Thiosulfate
Hb (Fe2+) →Nitrites metHb
metHb→(Cyanide from cytochrome oxidase)cyanometHb cyanometHb →(Thiosulfate@Rhodanase E) thiocyanate+ sulfite
thiocyanate→┴(renal excretion) urine
2.Hydroxycobolamine
•Hydroxycobalamin +cyanide →→ cyanocobalamin (non-toxic)
Steps & Precautions
- Break a pearl of amyl nitrite under the nose of the victim then,
- Immediately adminster I.V. Sodium nitrite
- Monitoring Blood pressure: To avoid potentially fatal hemodynamic instability
- Measure level of methemoglobin: Methemoglobinemia, Never > 10% to avoid compromising oxygen carrying capacity
- Followed by IV sodium thiosulphate
- Hydroxycobalamin ( Vit B12)
