Chemical Asphyxiants - Cyanides and Hydrogen Sulfides

화학적 질식제 -청화물과 황화수소를 중심으로

Cyanides and hydrogen sulfide ($H_2S$) are major chemical asphyxiants. They have common mechanism of action which inhibit cellular respiration and induce histotoxic hypoxia. They do not generate ATP, and all processes dependent on ATP are stopped. No extraction of $O_2$ from blood decreases AV $O_2$ differences, and the shift to anaerobic glycolysis brings about lactic acidosis with high anion gap. The mainstay of the treatment is rapid treatment with appropriate use of antidotes. However, there are several differences between cyanides and $H_2S$. First, $H_2S$ is not metabolized by enzymes such as thiosulfate. Thus thiosulfate does not play any role in treatment of $H_2S$. Second, $H_2S$ is a more potent inhibitor of cytochrome aa3 than cyanide. Third, $H_2S$ induces more divergent neurologic sequele than cyanide. Finally, $H_2S$ is not absorbed via skin.