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).
Statistics: 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.