The Effects of Cyanide in the Tissue

By definition cyanide is a chemical compound that contains a cyano functional group. It occurs both naturally and as a byproduct of various manufacturing processes. Cyanide is a lethal substance that has been used as an agent of chemical warfare, in the execution of prisoners and in many cases of suicide including mass suicides. It has a number of variants, all extremely toxic, and exists in gaseous, liquid and solid states, the latter as a white crystalline powder. Cyanide exposure can occur via absorption through the skin, by ingestion or by inhalation. The body can tolerate very low doses of cyanide, but acute exposure to larger amounts can be fatal within a few minutes.

General Systemic Effects

• When cyanide enters the body, whether through the skin, the respiratory system or the digestive system, its immediate effect is to render inactive an enzyme called cytochrome oxidase. This enzyme is required for the effective delivery of oxygen to the various tissues of the body. Its inactivity prevents oxygenation of cells, thus depriving the cells and the body of oxygen, which leads quickly to death.

Blood

• Effects of cyanide on the blood apparent in laboratory analysis include an elevated concentration of blood cyanide. This is the only effect that is specific to cyanide. A higher than normal oxygen content in venous blood as compared to arterial blood is also observable. This demonstrates the failure of red blood cells to extract oxygen from respiration. The blood also has a low pH indicating an acid state.

Skin and Mucous Membranes

• Observable effects of cyanide poisoning on the skin begin with clamminess, followed by a bright cherry red appearance, particularly in the face and neck. As the poisoning progresses, the lips, face and extremities take on a bluish color, known as cyanosis, though this is not actually as pronounced as in some other types of poisoning, such as various nerve agents. The mouth and nose remain relatively dry with few secretions. Pupils of the eyes are either normal or slightly dilated, and veins and arteries of the eyes have a bright red appearance.

Organs

• A high concentration of lactic acid is observed in bodily tissues due to the entire metabolism changing from an oxygen-rich, or aerobic, state to an oxygen-deprived, or anaerobic, state, resulting in the production of lactic acid. This results in a condition of general metabolic acidosis evidenced by the combination of a low pH with a high anion gap, or AG. The AG reflects the ratio between negative ions, or anions, in the blood compared to positive ions, or cations. It is most commonly measured by subtracting the total concentration of bicarbonate and chloride (anions) from the total concentration of sodium and potassium (cations). A high AG means there are significantly more cations than anions, often noted specifically by a very low level of bicarbonate.