(1731) Impact of Weighted Cumulative Exposure of Intracranial Pressure on Outcome in Traumatic Brain Injury

Introduction: Intracranial pressure (ICP) in patients with traumatic brain injury (TBI) is a therapeutic target for management during acute phase. Previous studies have shown the association between ICP spikes and poor neurologic outcomes. But the cumulative impact of ICP has not been well elucidated. In this study, we evaluated the cumulative effects of duration, intensity and timing of ICP on ICU outcomes in patients with acute TBI.

Methods: All patients ≥ 18 years of age admitted with severe TBI in the eICU Collaborative Research Database (eICU-CRD) were eligible. Patients without recorded ICP values were excluded. The area under the curve (AUC) of the total ICP curve (AUCT), the spikes (AUCS) and the number of spikes (NS) were used as measures of cumulative ICP burden. A binary composite outcome categorized into ‘Poor’ and ‘Not Poor’ was defined based on 7-day ICU mortality and last available neurologic exam. Cox proportional hazards with weighted cumulative exposure (WCE) modeling was utilized to evaluate the effects of ICP exposure (AUCT, AUCS and NS) on the composite outcome. Models were adjusted for severity of illness covariates (injury severity score (ISS), predicted ICU mortality based on APACHE IVa and admission GCS).

Results: A total of 52 patients with severe TBI who have available ICP data were identified in the eICU-CRD. Mean (± SD) age, ISS, predicted ICU mortality and admission GCS of the cohort were 43 (± 20) years, 22 (± 13), 0.25 (± 0.32) % and 5 (± 4), respectively. Patients with ‘Poor’ outcome differed significantly from ‘Not-Poor’ outcome, with respect to predicted ICU mortality (p 0.014) and admission GCS (p 0.006). AUCT and AUCS for 24-168 hours (normalized to the length of stay) were higher in the ‘Poor’ outcome group (p 0.070). WCE modeling showed higher weights for early AUCT (24-48 hours), early AUCS and NS. The hazard ratio for AUCT was 1.75.

Conclusions: In this small cohort of severe TBI, we used a novel approach (WCE modeling) to show the relationship between weighted cumulative exposure of ICP on 7-day outcome. If this relationship can be further evaluated in a larger prospective cohort, cumulative AUC could be a potential factor for decision-making regarding timing and need for interventions in ICP management.