title: Increased FiO2 improves intrathecal oxygenation during thoracic aortic cross-clamping in pigs.
abstract: OBJECTIVE
  To investigate the effect of 100% oxygen ventilation on cerebrospinal fluid (CSF) oxygenation in 11 pigs during thoracic aortic cross-clamping.
  
  
  METHODS
  An aorto-aortic shunt was used for control of central hemodynamics and study of hypoperfusion by exsanguination. CSF PO2, PCO2 and pH were continuously monitored before and during clamping. The changes in hemodynamic parameters and intrathecal gas tensions in response to variations in proximal mean aortic pressure and fraction of inspired oxygen (FiO2) were recorded.
  
  
  RESULTS
  Baseline CSF PO2 decreased from 4.8 +/- 1.9 to 2.6 +/- 2.2 kPa following aortic occlusion. Increasing FiO2 to 1.0 resulted in a significant increase in CSF PO2 to 4.1 +/- 3.0 with a return to 2.7 +/- 2.1 kPa after reducing FiO2 to 0.4 again. The same variations in FiO2 did not induce any significant changes in CSF PO2 during hypotension.
  
  
  CONCLUSIONS
  Increased FiO2 during experimental thoracic aortic cross-clamping with stable proximal arterial pressure helps to maintain CSF PO2, whereas severe hypotension could not be compensated for by hyperoxemia.
authors.affiliation: Department of Anesthesiology, University Hospital, Uppsala, Sweden. lennart.christiansson@anestesi.uu.se
authors.forename: L
authors.initials: L
authors.lastname: Christiansson
authors.forename: A T
authors.initials: AT
authors.lastname: Ulus
authors.forename: A
authors.initials: A
authors.lastname: Hellberg
authors.forename: D
authors.initials: D
authors.lastname: Bergqvist
authors.forename: L
authors.initials: L
authors.lastname: Wiklund
authors.forename: S
authors.initials: S
authors.lastname: Karacagil
mesh_terms: D000818:Animals; D001013:Aorta, Thoracic; D003250:Constriction; D004195:Disease Models, Animal; D005260:Female; D006439:Hemodynamics; D008297:Male; D010100:Oxygen / Q000134:cerebrospinal fluid*; D013552:Swine; D014656:Vascular Surgical Procedures / Q000295:instrumentation / Q000379:methods*
chemical_list: D010100:Oxygen