Systemic asphyxiants poisoning

A 20-year-old healthy and apparently eupnoic man was admitted into our hospital because of a strong headache; we noticed tachycardia, tachypnea and decreased O2 saturation. A methemoglobin level of 29,5% was determined in the arterial blood. Some time before, a very old tank of ink had accidentally spilled over his working suit. The toxic agent was identified as aniline, a systemic asphyxiant that is well absorbed through the skin, causing systemic toxicity. The effects of skin absorption can be delayed for several hours. Most adverse health effects of aniline are due to the formation of methemoglobinemia, a disorder characterized by a form of hemoglobin that does not bind oxygen and impairs oxygen transport capacity. When its concentration is elevated in red blood cells a functional anemia and tissue hypoxia may occur. Organs with high oxygen demands (i.e. CNS, cardiovascular system, etc.) are usually the first to show toxic effects. The severity of methemoglobinemia symptoms is related to the amount of methemoglobin present in blood and range from a bluish discoloration of the skin and mucous membrane to weakness, seizures, difficulty in breathing, dysrhythmias, acidosis, cardiac or neurologic ischemia. Treatment is determined by symptoms. The first step of therapy is to remove patient from the source of exposure and ensure adequate skin and eye decontamination. It is necessary to ensure adequate ventilation with 100% O2, too. Methylene blue is the first-line antidotal agent.