title: Transcutaneous pO2 imaging during tourniquet-induced forearm ischemia using planar optical oxygen sensors.
abstract: BACKGROUND
  Oxygen-dependent quenching of luminescence using transparent planar sensor foils was shown to overcome the limitations of the polarographic electrode technique in an animal model. This method was then transferred to a clinical setting to measure the transcutaneous pO(2) (p(tc)O(2)).
  
  
  METHODS
  In six healthy subjects, a cuff on the upper arm was occluded up to 20 mmHg above systolic pressure and released after 8 min. P(tc)O(2) was measured at the lower arm every 30 s before, during, and up to 20 min after cuff occlusion (40 degrees C applied skin temperature) using luminescence lifetime imaging (LLI) of platinum(II)-octaethyl-porphyrin immobilized in a polystyrene matrix. For validation, the polarographic Clark electrode technique was applied in close proximity, and measurements were conducted simultaneously.
  
  
  RESULTS
  P(tc)O(2) measurements before (70.8+/-19.1 vs. 66.2+/-7.7 mmHg) and at the end of ischemic (2.7+/-1.2 vs. 3.6+/-1.7 mmHg) and reperfusion phases (72.2+/-3.6 vs. 68.4+/-8.9 mmHg) did not differ significantly using the Clark electrode vs. LLI. At both the initial ischemic and the reperfusion phases, the Clark electrode measured a faster decrease or increase, respectively, in p(tc)O(2) because of the oxygen consumption occurring in this method.
  
  
  CONCLUSIONS
  The presented method provides accurate and reproducible p(tc)O(2) values under changing microcirculatory conditions. The lack of oxygen consumption during measurement allows both a more realistic estimation of p(tc)O(2) than compared with the gold standard and permanent use in regions with critical oxygen supply.
authors.affiliation: Department of Dermatology, Regensburg University Medical Center, Regensburg, Germany. philipp.babilas@klinik.uni-regensburg.de
authors.forename: Philipp
authors.initials: P
authors.lastname: Babilas
authors.forename: Philipp
authors.initials: P
authors.lastname: Lamby
authors.forename: Lukas
authors.initials: L
authors.lastname: Prantl
authors.forename: Stephan
authors.initials: S
authors.lastname: Schreml
authors.forename: Ernst Michael
authors.initials: EM
authors.lastname: Jung
authors.forename: Gregor
authors.initials: G
authors.lastname: Liebsch
authors.forename: Otto S
authors.initials: OS
authors.lastname: Wolfbeis
authors.forename: Michael
authors.initials: M
authors.lastname: Landthaler
authors.forename: Rolf-Markus
authors.initials: RM
authors.lastname: Szeimies
authors.forename: Christoph
authors.initials: C
authors.lastname: Abels
mesh_terms: D000293:Adolescent; D000328:Adult; D001785:Blood Gas Monitoring, Transcutaneous / Q000295:instrumentation* / Q000379:methods; D004867:Equipment Design; D019544:Equipment Failure Analysis; D005260:Female; D005542:Forearm / Q000098:blood supply*; D006801:Humans; D007511:Ischemia / Q000175:diagnosis* / Q000503:physiopathology; D008297:Male; D055096:Optical Devices; D010100:Oxygen / Q000032:analysis*; D011048:Polarography / Q000295:instrumentation*; D015203:Reproducibility of Results; D012680:Sensitivity and Specificity; D014111:Tourniquets; D014159:Transducers; D055815:Young Adult
chemical_list: D010100:Oxygen