OpenAnesthesia and the APSF: Achieving Safe and Quality Anesthesia Care with Education Innovation

After nitroprusside enters red blood cells, electron transfer occurs and the compound dissolves into 5 cyanide ions and a nitroso group. The cyanide ions can undergo 3 different reactions: forming cyanmethemoglobin; binding with thiosulfate; or interacting directly with cytochrome oxidase. The inactivation of cytochrome oxidase is responsible for the uncoupling of mitochondrial oxidative phosphorylation and shift from aerobic to anaerobic metabolism. This causes production of lactic acid and the symptoms of cyanide toxicity including metabolic acidosis, arrhythmias, tachycardia, hypertension, neurologic dysfunction (confusion) and increased mixed venous oxygen content. One other key sign of cyanide toxicity is tachyphylaxis or the resistance to the effects of nitroprusside to reduce blood pressure.