title: Prophylactic methylene blue in a patient with congenital methemoglobinemia.
abstract: OBJECTIVE
  To report the beneficial effect of prophylactic methylene blue administration before induction of anesthesia in a patient with congenital methemoglobinemia.
  
  
  METHODS
  A 26-yr-old male patient known to have congenital methemoglobinemia was scheduled for turbinectomy under general anesthesia. The patient was clinically cyanotic with a pulse oximetry of 91%. Arterial blood gas analysis showed a partial pressure of oxygen (PaO(2)) of 81.3 mmHg associated with a fractional oxyhemoglobin of 80.7%, and a methemoglobin fraction of 0.159. Preoperative iv administration of 1 mg.kg(-1) of methylene blue resulted, within five minutes, in a decrease of methemoglobin fraction down to 0.05 associated with an increase of the fractional oxyhemoglobin saturation up to 94.7%. After two hours, the methemoglobin fraction decreased to 0.01 and the fractional oxyhemoglobin concentration increased to 97.7%. Induction of anesthesia as well as intraoperative and postoperative course were uneventful without any episode of hypoxemia. Postoperatively, the methemoglobin fractions remained low for 24 hr, to be followed by a gradual increase up to 0.02 on the second day to reach 0.094 on the fifth day.
  
  
  CONCLUSIONS
  The prophylactic preoperative methylene blue administration in a patient with congenital methemoglobinemia significantly decreased the methemoglobin level and increased the fractional oxygen saturation with a consequent increase of the safety margin against perioperative hypoxemia.
authors.affiliation: Department of Anesthesiology, American University of Beirut, P.O. Box: 11-0236, Beirut 1107-2020, Lebanon. abaraka@aub.edu.lb
authors.forename: Anis S
authors.initials: AS
authors.lastname: Baraka
authors.forename: Chakib M
authors.initials: CM
authors.lastname: Ayoub
authors.forename: Vanda
authors.initials: V
authors.lastname: Yazbeck-Karam
authors.forename: Roland N
authors.initials: RN
authors.lastname: Kaddoum
authors.forename: Frederic J
authors.initials: FJ
authors.lastname: Gerges
authors.forename: Ussama M
authors.initials: UM
authors.lastname: Hadi
authors.forename: Carla M
authors.initials: CM
authors.lastname: Dagher
mesh_terms: D000328:Adult; D006801:Humans; D000860:Hypoxia / Q000517:prevention & control; D008297:Male; D008706:Methemoglobin / Q000032:analysis; D008708:Methemoglobinemia / Q000097:blood / Q000151:congenital*; D008751:Methylene Blue / Q000627:therapeutic use*; D010100:Oxygen / Q000097:blood
chemical_list: D008706:Methemoglobin; D010100:Oxygen; D008751:Methylene Blue