Methaemoglobin forming compounds should be used cautiously in patients suffering from concurrent carbon monoxide poisoning or hypoxia. This is accomplished by giving sodium thiosulphate. It is generally agreed that binding the cyanide ions is the first priority of treatment but that thiosulphate must be provided to permit conversion of the cyanide ions to thiocyanate. Drugs That Bind Cyanide Ions. Compounds Producing Methaemoglobin.
Amyl nitrite is useful only in a closed positive pressure respiratory system.
Crushing the ampoule around the face or even inside the facepiece of the respirator is inadequate. It should not be used with concurrent oxygen administration due to the risk of explosion. Treatment with amyl nitrite should be followed by sodium thiosulphate. The sodium nitrite is given to produce methaemoglobin, thus sequestering the cyanide on the methaemoglobin. The cyanide is then removed from the body as thiocyanate after administration of sodium thiosulphate.