It does not reduce O2 carrying capacity but inhibits O2 mediated electron chain transfer
Cyanide poisoning involves Na thiosulfate and not bicarbonate.
Cyanide has a high affinity for metals like cobalt and trivalent iron, and for sulfane compounds such as sodium thiosulfate which contains a sulfur-to-sulfur bond. In large doses, cyanide quickly binds with iron in cytochrome a3, preventing electron transport in the cytochrome. This stops oxidative phosphorylation and adenosine triphosphate (ATP) production. As a result, intracellular oxygen utilization ceases. Cells are then forced into anaerobic metabolism, creating lactic acid and leading to acid-base imbalances and metabolic acidosis.
In small doses, cyanide can be metabolized into thiocyanate with the assistance of the hepatic enzyme, rhodanese. Thiocyanate is then excreted in urine. A small amount of cyanide can also be converted to carbon dioxide which leaves the body through exhalation. Some cyanide can react with hydroxycobalamin to form vitamin B12. Most cyanide leaves the body within one day.