title: Methemoglobinemia induced by automobile exhaust fumes.
abstract: Although methemoglobinemia is an uncommon disorder, it should always be considered in the differential diagnosis of cyanosis. Major causes of acquired methemoglobinemia are nitrates, aniline, and analgesics, though rare cases have been reported to have been caused by automobile exhaust fumes. A 24-year-old man had inhaled a large amount of automobile exhaust fumes, intending to commit suicide. He had become unconscious, with dilated pupils and symptoms of cyanosis. Arterial hemoglobin oxygen saturation (Sp(O2)) was 86%, with a methemoglobin level of 44.3% and a carboxyhemoglobin level of 0%, while electrolytes, blood urea nitrogen, creatine, and glucose measurement results were normal. He was treated with methylene blue 250 mg (approximately 4 mg/kg) through a nasogastric tube. Four hours after the treatment, because the methemoglobin level was slightly above normal (2.2%), we added 180 mg of methylene blue. The results of final arterial blood gas analysis were a methemoglobin level of 0.4% and a carboxyhemoglobin level of 0.8%. He recovered uneventfully and returned home by himself the next day. To summarize, we successfully treated, with methylene blue given through a nasogastric tube, a young man who had developed severe methemoglobinemia from inhaling automobile exhaust fumes.
authors.affiliation: Critical Care Medical Center, Hiroshima Prefectural Hospital, 1-5-54 Ujina-Kanda, Minami-ku, Hiroshima, 734-8530, Japan.
authors.forename: Hidemichi
authors.initials: H
authors.lastname: Suyama
authors.forename: Shingo
authors.initials: S
authors.lastname: Morikawa
authors.forename: Shoko
authors.initials: S
authors.lastname: Noma-Tanaka
authors.forename: Hiroshi
authors.initials: H
authors.lastname: Adachi
authors.forename: Yasunobu
authors.initials: Y
authors.lastname: Kawano
authors.forename: Kotaro
authors.initials: K
authors.lastname: Kaneko
authors.forename: Shin
authors.initials: S
authors.lastname: Ishihara
mesh_terms: D000328:Adult; D002263:Carboxyhemoglobin / Q000032:analysis; D004791:Enzyme Inhibitors / Q000627:therapeutic use; D006801:Humans; D007441:Intubation, Gastrointestinal; D008297:Male; D008706:Methemoglobin / Q000032:analysis; D008708:Methemoglobinemia / Q000097:blood / Q000188:drug therapy / Q000209:etiology*; D008751:Methylene Blue / Q000627:therapeutic use; D013406:Suicide, Attempted; D001335:Vehicle Emissions / Q000506:poisoning*
chemical_list: D004791:Enzyme Inhibitors; D001335:Vehicle Emissions; D008706:Methemoglobin; D002263:Carboxyhemoglobin; D008751:Methylene Blue