title: Venous air embolism: an unusual complication of atlantoaxial arthrodesis: case report.
abstract: METHODS
  A unique case of a patient with intraoperative venous air embolism (VAE) during atlantoaxial arthrodesis has been discussed.
  
  
  OBJECTIVE
  To describe an uncommon complication of atlantoaxial arthrodesis, VAE.
  
  
  BACKGROUND
  Although several techniques for atlantoaxial arthrodesis have proven effective, lateral mass or pedicle screw constructs have been shown to have superior strength with acceptable morbidity. Placement of lateral mass or pedicle screws into the C1 or C2 vertebrae requires consideration of relevant local anatomy, including vascular and nervous structures. We present a rare complication of surgery in this anatomic distribution, VAE. To the authors' knowledge, there has been no similar report described.
  
  
  METHODS
  A previously healthy 38-year-old man was found to have os odontoideum with atlantoaxial instability; arthrodesis was thus planned, with C1 lateral mass and C2 pedicle screws. Intraoperatively, during dissection of the C1-C2 joint capsule, the patient experienced a precipitous drop in blood pressure, end-tidal CO2, and oxygen saturation. Shortly thereafter, the patient was noted to be asystolic.
  
  
  RESULTS
  With suspicion for air embolus, the surgical field was flooded with irrigant, the incision closed with haste, and the patient rolled to the supine position. Cardiopulmonary resuscitation was initiated with return of pulse within minutes. A transesophageal echocardiogram was performed approximately 15 minutes after the onset of suspected air embolus, revealing increased atrial pressures consistent with VAE. Following echocardiogram, the patient was returned to prone position for completion of arthrodesis. Remaining surgery and arousal were uneventful.
  
  
  CONCLUSIONS
  This is the first report of intraoperative VAE occurring with atlantoaxial arthrodesis. Enlarged venous anastomoses present at the atlantoaxial junction should be taken into consideration during surgical dissection, and the potential danger of VAE with atlantoaxial arthrodesis should be understood. With aggressive intraoperative treatment, this patient suffered no long-term complications.
authors.affiliation: Department of Neurosurgery, University of Vermont College of Medicine, Burlington, VT, USA.
authors.forename: Travis M
authors.initials: TM
authors.lastname: Dumont
authors.forename: David W
authors.initials: DW
authors.lastname: Stockwell
authors.forename: Michael A
authors.initials: MA
authors.lastname: Horgan
mesh_terms: D000328:Adult; D001174:Arthrodesis / Q000009:adverse effects* / Q000295:instrumentation / Q000379:methods; D001268:Atlanto-Axial Joint / Q000098:blood supply* / Q000601:surgery*; D004618:Embolism, Air / Q000209:etiology* / Q000517:prevention & control; D006801:Humans; D007431:Intraoperative Complications / Q000209:etiology* / Q000517:prevention & control / Q000601:surgery; D007593:Joint Instability / Q000503:physiopathology / Q000601:surgery; D008297:Male; D016684:Prone Position / Q000502:physiology; D016683:Supine Position / Q000502:physiology; D014680:Veins / Q000601:surgery*