title: Cerebral arterial oxygen saturation measurements using a fiber-optic pulse oximeter.
abstract: BACKGROUND
  A pilot investigation was undertaken to assess the performance of a novel fiber-optic cerebral pulse oximetry system. A fiber-optic probe designed to pass through the lumen of a cranial bolt of the type used to make intracranial pressure measurements was used to obtain optical reflectance signals directly from brain tissue.
  
  
  METHODS
  Short-duration measurements were made in six patients undergoing neurosurgery. These were followed by a longer duration measurement in a patient recovering from an intracerebral hematoma. Estimations of cerebral arterial oxygen saturation derived from a frequency domain-based algorithm are compared with simultaneous pulse oximetry (SpO2) and hemoximeter (SaO2) blood samples.
  
  
  RESULTS
  The short-duration measurements showed that reliable photoplethysmographic signals could be obtained from the brain tissue. In the long-duration study, the mean (±SD) difference between cerebral oxygen saturation (ScaO2) and finger SpO2 (in saturation units) was -7.47(±3.4)%. The mean (±SD) difference between ScaO2 and blood SaO2 was -7.37(±2.8)%.
  
  
  CONCLUSIONS
  This pilot study demonstrated that arterial oxygen saturation may be estimated from brain tissue via a fiber-optic pulse oximeter used in conjunction with a cranial bolt. Further studies are needed to confirm the clinical utility of the technique.
authors.affiliation: School of Engineering and Mathematical Sciences, City University, London EC1V 0HB, UK. justin.phillips.1@city.ac.uk
authors.forename: J P
authors.initials: JP
authors.lastname: Phillips
authors.forename: R M
authors.initials: RM
authors.lastname: Langford
authors.forename: S H
authors.initials: SH
authors.lastname: Chang
authors.forename: K
authors.initials: K
authors.lastname: Maney
authors.forename: P A
authors.initials: PA
authors.lastname: Kyriacou
authors.forename: D P
authors.initials: DP
authors.lastname: Jones
mesh_terms: D000368:Aged; D001930:Brain Injuries / Q000503:physiopathology; D020202:Cerebral Hemorrhage, Traumatic / Q000097:blood / Q000175:diagnosis / Q000503:physiopathology; D004867:Equipment Design; D005260:Female; D005336:Fiber Optic Technology; D015600:Glasgow Coma Scale; D006801:Humans; D008991:Monitoring, Physiologic; D009493:Neurosurgery / Q000379:methods; D010092:Oximetry / Q000295:instrumentation / Q000379:methods*; D010100:Oxygen / Q000097:blood*; D010865:Pilot Projects; D020521:Stroke / Q000503:physiopathology
chemical_list: D010100:Oxygen
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