title: A transesophageal echocardiography examination clarifies the cause of cardiovascular collapse during scoliosis surgery in a child.
abstract: OBJECTIVE
  The prone position is required for posterior spinal fusion surgery and may be associated with cardiovascular changes, including a decrease in venous return and cardiac index. We report a case of a patient who developed cardiovascular collapse, increased central venous pressure (CVP), and massive bleeding during posterior spinal fusion surgery. A transesophageal echocardiography examination (TEE) documented a right ventricular outflow tract (RVOT) obstruction associated with the use of transverse bolsters.
  
  
  METHODS
  We describe a case of a healthy 14-yr-old male with idiopathic scoliosis who developed severe intraoperative cardiovascular instability and massive bleeding. The surgery was suspended, and the patient was transferred to the intensive care unit. The patient subsequently underwent TEE in the supine and prone positions. The echocardiogram appeared normal in the supine position; however, in the prone position with transverse bolsters, we identified a significant decrease in the diameter of the RVOT that worsened with pressure applied against the thoracic spine. The central venous pressure increased from 10-24 mmHg simultaneously. We found appreciably less impact to the RVOT, RV size and flow, and CVP (10 to 14 mmHg) using longitudinal bolsters both with and without pressure to the back. This position was recommended for the patient's reoperation, which was uneventful.
  
  
  CONCLUSIONS
  A TEE confirmed a RVOT obstruction in the prone position that was associated, in this case, with the use of transverse bolsters. The RVOT obstruction was explained by the chest deformity, compliant chest cage, bolstering, and pressure applied to the patient's back by the surgeon. This positional RVOT obstruction may explain the increase in the CVP and the secondary massive bleeding during the first operation. The TEE was useful to diagnose the patient's condition and to guide his positioning for the second operation.
authors.affiliation: Department of Anesthesiology, Children's Hospital of Eastern Ontario, University of Ottawa, 401 Smyth Road, Ottawa, ON K1H 8L1, Canada. vneira@cheo.on.ca
authors.forename: Victor M
authors.initials: VM
authors.lastname: Neira
authors.forename: Letizia
authors.initials: L
authors.lastname: Gardin
authors.forename: Gail
authors.initials: G
authors.lastname: Ryan
authors.forename: James
authors.initials: J
authors.lastname: Jarvis
authors.forename: Debashis
authors.initials: D
authors.lastname: Roy
authors.forename: William
authors.initials: W
authors.lastname: Splinter
mesh_terms: D000293:Adolescent; D002318:Cardiovascular Diseases / Q000175:diagnosis / Q000209:etiology* / Q000473:pathology; D002496:Central Venous Pressure; D017548:Echocardiography, Transesophageal / Q000379:methods*; D006470:Hemorrhage / Q000175:diagnosis / Q000209:etiology; D006801:Humans; D008297:Male; D016684:Prone Position; D012086:Reoperation; D012600:Scoliosis / Q000601:surgery*; D016683:Supine Position; D014694:Ventricular Outflow Obstruction / Q000175:diagnosis / Q000209:etiology