Brain tissue
oxygen tension (PbtO2)-guided care, a therapeutic strategy to treat or prevent
cerebral hypoxia through modifying determinants of cerebral
oxygen delivery, including arterial
oxygen tension (PaO2), end-tidal
carbon dioxide (ETCO2), and mean arterial pressure (MAP), has recently been introduced. Studies have reported that
cerebral hypoxia occurs after
cardiac arrest in the absence of
hypoxemia or
hypotension. To obtain preliminary information on the degree to which PbtO2 is responsive to changes in the common target variables for PbtO2-guided care in conditions without
hypoxemia or
hypotension, we investigated the relationships between the common target variables for PbtO2-guided care and PbtO2 using data from an experimental study in which the animals did not experience
hypoxemia or
hypotension after
resuscitation. We retrospectively analyzed 170 sets of MAP, ETCO2, PaO2, PbtO2, and cerebral microcirculation parameters obtained during the 60-min post-
resuscitation period in 10 pigs resuscitated from
ventricular fibrillation cardiac arrest. PbtO2 and cerebral microcirculation parameters were measured on parietal cortices exposed through burr holes. Multiple linear mixed effect models were used to test the independent effects of each variable on PbtO2. Despite the absence of arterial
hypoxemia or
hypotension, seven (70%) animals experienced
cerebral hypoxia (defined as PbtO2 <20 mmHg). Linear mixed effect models revealed that neither MAP nor ETCO2 were related to PbtO2. PaO2 had a significant linear relationship with PbtO2 after adjusting for significant covariates (P = 0.030), but it could explain only 17.5% of the total PbtO2 variance (semi-partial R2 = 0.175; 95% confidence interval, 0.086-0.282). In conclusion, MAP and ETCO2 were not significantly related to PbtO2 in animals without
hypoxemia or
hypotension during the early post-
resuscitation period. PaO2 had a significant linear association with PbtO2, but its ability to explain PbtO2 variance was small.