Toxic Gases (Cyanide)

Question 1

Cyanide Sources:

Answer 1

natural sources
Cherry green unripe guava, seeds of bitter almond : they contain amygdalin, which is converted to cyanide in the small intestine by bacteria

Occupational
Fires, metal refining, mining, jewelry manufacturers, x-ray film recovery

Iatrogenic
nitroprusside administration (when exposed to the light, it is converted to cyanide) is store in drak container

Question 2

Cyanide pathophysiology:

Answer 2

• Reversibly bind to a number of proteins and enzymes with a metallic component: hemoglobin, myoglobin, catalase, and the the cytochrome system 3 in the mitochondria.
• Decrease cellular respiration by blocking the reduction of oxygen to water.
• CNS and the myocardium (main targets)

Question 3

The main differences bt cyanide and CO in toxicity

Answer 3

• Carbon monoxide has a stronger affinity to hemoglobin, while cyanide has a stronger affinity to cytochrome
• Cyanide has a distinctive odor (that’s why poisoning with it is rare).
• Cyanide is metabolized by rhodanese and converted to non toxic metabolites

Question 4

Talk about Cyanide Metabolism:

Answer 4

Metabolized by rhodanese (sulfurtramsferase), which catalyzes its combination with sulfur to form thiocyanate water soluble and excreted in the urine.

Question 5

Wtire short notes about hydrogen cyanide:

Answer 5

Colorless gas with a faint, bitter almond-like odor.
It may be converted to a non-toxic compound by its combination with hydroxocobalamin (vit-B12a), which produces cyanocobalamin (Vit-B12).

Question 6

Sodium cyanide and potassium cyanide:

Answer 6

They are both white solids, with a bitter almond like odor in damp air.

Question 7

Common clinical manifestations of cyanide toxicity:

Answer 7

Weakness, asthenia, loss of energy, and pain throughout the body.

Question 8

CNS symptoms:
(Cyanide)

Answer 8

Headache, dizziness, weakness, confusion, and N&V. these followed by confusion, agitation, convulsions, paralysis, and coma.

Question 9

Cardiac manifestations of cyanide toxicity:

Answer 9

Chest pain may be due to myocardial ischemia or pulmonary disease.
Palpitation and dizziness due to tachyarrhythmias and bradyarrhythmias have been reported.

Question 10

Repiratory and GIT manifestations of cyanide toxicity:

Answer 10

Shortness of breath, cough, and difficulty breathing.
N&V due to stimulation of the CNS vomiting center and the direct irritant effects of cyanide compounds on the GI tract.

Question 11

Skin and fundoscopy findings in cyanide toxicity:

Answer 11

cherry red appearance due to ⬆⬆ Hb saturation in venous blood because of the inability to utilize O2 - fundoscopy show the same color.

Question 12

Treatment of cyanide toxicity:

Answer 12

Supportive therapy
Decontamination : gastric lavage or induction of emesis (ingestion), move him from the place of smell (inhalation)
Antidotes therapy: Hydroxocobalamin is the antidote of choice , especially in coexisting CO poisoning.

Question 13

Cyanide antidote kit:

Answer 13

Also called Nithiodote
Amyl nitrite (inhalation)
Sodium nitrite (infusion)
Sodium thiosulfate (infusion)
Note: They must be given in the same order

Question 14

Cyanide antidote kit administration:

Answer 14

1. Amyl nitrite (inhalation) & sodium nitrite (infusion): they form methemoglobinemia > cyanide binds to it and doesn bind to normal hemoglobin > free ferric iron in mitochondria > restore cellular respiration.
2. Thiosulfate (infusion): cyanomethemoglobin …. thiocyanate.

Question 15

Post mortem appearance (External):

Answer 15

• Odor of bitter almonds
• Brick red color of skin and mucous membranes
• Cyanosis of extremities
• Froth at mouth and nostrils

Question 16

Post mortem appearance (Internal):

Answer 16

• Hemorrhagic gastritis
• Pulmonary and cerebral edema
• Disseminated petechiae in the brain, meninges, pleura, lungs, and pericardium.