Correlations of Focal Lesion Volume with Intracranial Hypertension and Brain Tissue Hypoxia after severe Traumatic Brain Injury (TBI) (P7.180)

Objective: To determine correlations between focal lesion volume, elevated intracranial pressure (high ICP) and brain tissue hypoxia (low PbtO2) in patients with traumatic intracranial hematomas (tICHs) enrolled in the Brain Oxygen Optimization in Severe TBI (BOOST) Phase 2 trial. Background: BOOST Phase 2 was a 10-center randomized clinical trial designed to test the physiologic efficacy of neurocritical care management aimed at preventing brain tissue hypoxia. Placement of the probe measuring PbtO2 (Licox, Integra Neurosciences) has been controversial, and some argue that the probe should be placed in pericontusional region. In the BOOST-2 trial, investigators were directed to place the PbtO2 probe in normal-appearing cortex, contralateral to tICHs. Design/ Methods: CT scans obtained from participants in the BOOST-2 study were rated using the NINDS Common Data Elements CT Variables. For those with tICH, hematoma and edema volumes were measured using MIPAV software. Spearman’s correlation was used to determine the relationships between duration of intracranial hypertension (ICP 蠅 20 mm Hg), brain tissue hypoxia (PbtO2 < 20 mm Hg) and tICH volumes. Results: Of 120 BOOST-2 patients, only 37 had tICH as the predominant pathology. Of these, 16 (43[percnt]) required a craniectomy. There was no correlation between baseline tICH hematoma volume and incidence of either hypertension or hypoxia. There was a significant correlation between baseline edema volume and low PbtO2, but it was paradoxically negative (r = -0.675, p = 0.004). Edema volume did not correlate with elevated ICP. Conclusions: tICHs are not the major cause of elevated ICP or low PbtO2 after severe TBI. These findings support the hypothesis that intracranial hypertension and brain tissue hypoxia after TBI are primarily due to diffuse pathologies. Disclosure: Dr. Harburg has nothing to disclose. Dr. McCormack has nothing to disclose. Dr. Moore has nothing to disclose. Dr. Kenney has received royalty payments from the National Institutes of Health Technology Transfer. Dr. Barber has nothing to disclose. Dr. Temkin has nothing to disclose. Dr. Diaz-Arrastia has nothing to disclose.