Cerebral Hypoxia in Severely Brain-Injured Patients Is Associated with Admission Glasgow Coma Scale Score, Computed Tomographic Severity, Cerebral Perfusion Pressure, and Survival

Background: The purpose of this study was to determine the relationship of cerebral hypoxia with admission Glasgow Coma Scale (GCS) score, brain computed tomographic (CT) severity, cerebral perfusion pressure (CPP), and survival in patients with severe brain injury. Methods: CPP and noninvasive transcranial oximetry (Stco₂) were recorded hourly for 6 days in patients with a GCS score ≤ 8 (3,722 observations). CT score was derived from midline shift (0/1) plus abnormal cisterns (0/1) plus subarachnoid hemorrhage (SAH) (0/1) (range, 0-3). Results: Brain CT results were as follows: shift, 10 (56%); abnormal cisterns, 14 (78%); SAH, 9 (50%); epidural hematoma, 2 (11%); subdural hematoma, 11 (61%); and contusion, 17 (94%). The incidences of Stco₂ < 60 were: GCS score 3-4, 26.5%; GCS score 5-7, 12.4%; and GCS score 8, 2.8% (p < 0.0001); CT score 2/3, 26.4%; and CT score 0/1, 10.0% (p < 0.0001); nonsurvivors 36.1%; and survivors 16.3% (p < 0.0001). For incidence of CPP < 70, the results were as follows: Stco₂ < 60%, 33% of observations; Stco₂ ≥ 60%, 10% of observations (odds ratio, 4.3; p < 0.01). Despite CPP ≥ 70, Stco₂ < 60 incidence was 16% of observations. Conclusion: Cerebral hypoxia is common, even with CPP ≥ 70, and is associated with GCS score, CT scan severity, and mortality. Cerebral hypoxia is related to cerebral hypoperfusion. Additional studies may prove that Stco₂ monitoring will enhance the treatment of severe brain injury.