title: Optimal Placement of Cerebral Oximeter Monitors to Avoid the Frontal Sinus as Determined by Computed Tomography.
abstract: OBJECTIVE
  To determine the optimal location to place cerebral oximeter optodes to avoid the frontal sinus, using the orbit of the skull as a landmark.
  
  
  METHODS
  Retrospective observational study.
  
  
  METHODS
  Academic hospital.
  
  
  METHODS
  Fifty adult patients with previously acquired computed tomography angiography scans of the head.
  
  
  METHODS
  The distance between the superior orbit of the skull and the most superior edge of the frontal sinus was measured using imaging software.
  
  
  RESULTS
  The mean (SD) frontal sinus height was 16.4 (7.2) mm. There was a nonsignificant trend toward larger frontal sinus height in men compared with women (p = 0.12). Age, height, and body surface area did not correlate with frontal sinus height. Head circumference was positively correlated (r = 0.32; p = 0.03) to frontal sinus height, with a low level of predictability based on linear regression (R(2) = 0.10; p = 0.02).
  
  
  CONCLUSIONS
  Placing cerebral oximeter optodes>3 cm from the superior rim of the orbit will avoid the frontal sinus in>98% of patients. Predicting the frontal sinus height based on common patient variables is difficult. Additional studies are required to evaluate the recommended height in pediatric populations and patients of various ethnic backgrounds. The clinical relevance of avoiding the frontal sinus also needs to be further elucidated.
authors.affiliation: Department of Anesthesia, University of Calgary, Foothills Medical Centre, Calgary, Alberta, Canada. Electronic address: alex.gregory@albertahealthservices.ca.
authors.forename: Alexander J
authors.initials: AJ
authors.lastname: Gregory
authors.affiliation: Department of Diagnostic Imaging, University of Calgary, Foothills Medical Centre, Calgary, Alberta, Canada.
authors.forename: Muhammed A
authors.initials: MA
authors.lastname: Hatem
authors.affiliation: Departments of Anesthesia and Perioperative Medicine and Surgery, University of Manitoba, Winnipeg, Manitoba, Canada.
authors.forename: Kevin
authors.initials: K
authors.lastname: Yee
authors.affiliation: Departments of Anesthesia and Perioperative Medicine and Surgery, University of Manitoba, Winnipeg, Manitoba, Canada.
authors.forename: Hilary P
authors.initials: HP
authors.lastname: Grocott
mesh_terms: D005626:Frontal Sinus / Q000000981:diagnostic imaging* / Q000378:metabolism*; D006801:Humans; D010092:Oximetry / Q000379:methods* / Q000592:standards; D012189:Retrospective Studies; D014057:Tomography, X-Ray Computed / Q000379:methods* / Q000592:standards
keywords: cerebral oximetry; computed tomography; frontal sinus; near-infrared spectroscopy; signal interference