Threshold-based Use of Brain Oxygen Monitor and Seizure Detection

Brain tissue oxygen (PbtO2) monitors are threshold-based, and so trigger actions based on presumption of tissue compromise when PbtO2 is less than 20 mmHg. Some published practice guidelines suggest that a seizure is a potential culprit when PbtO2 crosses this threshold. The evidence for this assumption is slim. Data were collected as part of a prospective observational database. PbtO2 monitors and continuous EEG were placed by clinical protocol in patients with aneurysmal subarachnoid hemorrhage (aSAH) or traumatic brain injury (TBI) and a Glasgow Coma Scale of less than 8. Eight of these patients had one or more discrete seizures during an overlapping monitored period (both PbtO2 and EEG) and were selected for review. Probability of seizure given PbtO2 value less than 20 mmHg (and the inverse) were calculated by logistic regression, clustered by