(665) Low-Resolution Pressure Reactivity Index in Pediatric Traumatic Brain Injury

Introduction: High pressure reactivity index (PRx), an indicator of impaired cerebral autoregulation, has been associated with increased mortality in traumatic brain injury (TBI). Since PRx is obtained with expensive equipment, its use may not be feasible in resource-limited settings. In this study, we introduce a novel calculation method called low-resolution PRx (LR-PRx) and evaluate its association with outcome in pediatric TBI.

Methods: 1000 patients in the ADAPT Trial pediatric TBI database admitted for severe TBI (GCS < 9 with ICP monitoring) were studied. Data included 7 days of vital signs, ICP, cerebral perfusion pressure (CPP), demographics, GCS, abuse status, hypotension, hypoxia, seizure, length of stay (LOS), and hospital mortality. The Spearman correlation coefficient between hourly pairs of mean arterial pressure and ICP was used over 24 hours to obtain the daily LR-PRx for 7 total days. All variables, including LR-PRx, were used in a multiple binomial logistic regression model to assess associations with hospital death and dichotomized Glasgow Outcome Scale Extended (GOS-E). Quantile regression was performed for LOS analysis.

Results: In a multivariable analysis, maximum LR-PRx (2.18, CI 1.17–6.76), GCS 3 vs. GCS 6-8 (OR 2.07, 1.43–3.02), GCS 4-5 vs. GCS 6-8 (OR 1.99, CI 1.25–3.18), abuse status (OR 2.75, CI 1.57–4.85), and median ICP (OR 1.06, CI 1.03–1.09) were independently associated with worse GOS-E. GCS 3 vs GCS 6-8 (OR 2.30, CI 1.72–5.21), GCS 4-5 vs GCS 6-8 (OR 2.23, CI 1.13–4.39), cardiac arrest (OR 7.63, CI 2.68–21.74), median CPP (OR 0.96, CI 0.93–0.99), and median ICP (OR 1.07, CI 1.03–1.10) were independently associated with hospital death, but there was no statistical association between maximum LR-PRx and mortality. In a multivariable analysis, GCS 3, maximum LR-PRx, median CPP, and median ICP were associated with increased LOS, while cardiac arrest, hypotension, and lower minimum LR-PRx were independently associated with reduced LOS in survivors.

Conclusions: In our study, maximum LR-PRx was independently associated with worse GOS-E, possibly due to impaired cerebral autoregulation. These findings are consistent with previously published studies on PRx and outcome in TBI, and may have utility in prognostication in resource-limited settings.