title: A novel technique for monitoring of fast variations in brain oxygen tension using an uncoated fluorescence quenching probe (Foxy AL-300).
abstract: BACKGROUND
  A novel uncoated fluorescence quenching probe allows fast measurement of oxygen tension in vessels and tissue. The present study reports the first use of the technology for dual measurements of arterial (paO(2)) and brain tissue oxygen tension (ptiO(2)) during hypoxic challenge in a pig model.
  
  
  METHODS
  Eight pigs were anesthetized using fentanyl and propofol. Fluorescence quenching pO(2) probes (Foxy AL-300, Ocean Optics, Dunedin, FL) were placed in the ascending aorta (Foxy-paO(2)) and subcortically at 14 mm in brain tissue (Foxy-ptiO(2)). As reference, a clark-type electrode probe (Licox-ptiO(2)) was placed into brain tissue close to the Foxy probe (Licox, Integra Neurosciences, Plainsboro, NJ). Measurements were taken at baseline (FiO(2) 1.0), during episodes of apnea, and during recovery (FiO(2) 1.0).
  
  
  METHODS
  descriptive results.
  
  
  RESULTS
  Individual Foxy-paO(2), Foxy-ptiO(2), and Licox-ptiO(2) courses were related to episodes of apnea. The response time of the Foxy measurements was 10 Hz. Baseline values at FiO(2) 1.0 were Foxy-paO(2) 520±120 mm Hg, Foxy-ptiO(2) 62±24 mm Hg, and Licox-ptiO(2) 55±29 mm Hg; apnea values were Foxy-paO(2) 64±10 mm Hg, Foxy-ptiO(2) 37±12 mm Hg, and Licox-ptiO(2) 31±16 mm Hg; recovery values at FiO(2) 1.0 were Foxy-paO(2) 478±98 mm Hg, Foxy-ptiO(2) 78±26 mm Hg, and Licox-ptiO(2) 62±32 mm Hg.
  
  
  CONCLUSIONS
  The present study demonstrates the feasibility of pO(2) measurements in macrocirculation and cerebral microcirculation using a novel uncoated fluorescence quenching probe. The technology allows for real-time investigation of pO(2) changes at a temporal resolution of 0.05 to 10 Hz.
authors: Department of Anesthesiology, Intensive Care Medicine and Pain Therapy, Medical University Vienna, Vienna, Austria. ulrich.klein@meduniwien.ac.at
authors: Klaus Ulrich
authors: KU
authors: Klein
authors: Stefan
authors: S
authors: Boehme
authors: Erik Kristopher
authors: EK
authors: Hartmann
authors: Marc
authors: M
authors: Szczyrba
authors: Matthias
authors: M
authors: David
authors: Klaus
authors: K
authors: Markstaller
authors: Kristin
authors: K
authors: Engelhard
mesh_terms: D000771:Anesthesia, Intravenous; D018686:Anesthetics, Intravenous; D000818:Animals; D001049:Apnea / Q000097:blood / Q000378:metabolism; D001784:Blood Gas Analysis; D002138:Calibration; D002560:Cerebrovascular Circulation / Q000187:drug effects / Q000502:physiology; D005283:Fentanyl; D005456:Fluorescent Dyes; D016343:Monitoring, Intraoperative / Q000379:methods*; D010092:Oximetry / Q000379:methods*; D010100:Oxygen / Q000097:blood; D010101:Oxygen Consumption / Q000502:physiology*; D011048:Polarography; D015742:Propofol; D013552:Swine
chemical_list: D018686:Anesthetics, Intravenous; D005456:Fluorescent Dyes; D010100:Oxygen; D005283:Fentanyl; D015742:Propofol