Measurement of arterial, venous, and interstitial pO2 during acute hypoxia in rat brain using a time-resolved luminescence-based oxygen sensor

This is the first publication using a fiber optic "optode" and a luminescence based pO(2) detection method for assessing neural tissue oxygenation. The system was used to simultaneously monitor pO(2) in tissue (PtO2) and venous blood (PvO2) during normoxia, hyperoxia and hypoxia, PaO2 was varied by changing inspired oxygen (FiO(2)) from 0.3 to 0.13. Tissue and arterial pO(2) were measured in 5 rats while the simultaneous venous measurements were undertaken in 3 animals. The PtO2 was 29 +/- 10 at an arterial PO2 of 116 +/- 10 (mean +/- SE, n = 5). The PvO2 was consistently higher than PtO2 although PvO2 approached PtO2 as PaO2 declined to 50 mmHg and was lower than tissue pO(2) during the complete hypoxic period in one animal. These data indicate that brain venous pO(2) is not representative of brain tissue pO(2) and support published models predicting that in brain PvO2 is higher than PtO2.