Methylmercaptan Poisoning: Usefulness Of Monitoring Jugular Venous Oxygenation

Abstract

A 47-year-old man admitted for a confused state and severe metabolic acidosis shortly after exposure to methylmercaptan. To treat methylmercaptan-induced cytotoxic hypoxia and resultant confusion status, mechanical ventilation was performed to maintain an adequate oxygen supply to organs, especially to the brain. Sodium nitrite (3%, total 40ml), which caused methemoglobinemia (maximally 22%), was given intravenously to remove methylmercaptan from the cytochrome oxidase complex. Oxygen content in arterial blood was maintained at over 15ml/dl throughout the time course in our intensive care unit. Jugular venous oxyhemoglobin (Hbo2) decreased to 60%; Sjvo2 (oxygen saturation in the jugular venous blood) was maintained at over 75%. His level of consciousness improved on the next day. The treatment for methylmercaptan poisoning is similar to that for hydrogen sulfide poisoning. Excessive sodium nitrite treatment might cause hypoxic hypoxia due to induced methemoglobinemia. Jugular venous Hbo2 may indicate the adequate degree of induced methemoglobinemia at a point of the balance between oxygen delivery and consumption in the brain.