Mean Arterial Pressure and Discharge Outcomes in Severe Pediatric Traumatic Brain Injury

Optimizing blood pressure is an important target for intervention following pediatric traumatic brain injury (TBI). The existing literature has examined the association between systolic blood pressure (SBP) and outcomes. Mean arterial pressure (MAP) is a better measure of organ perfusion than SBP and is used to determine cerebral perfusion pressure but has not been previously examined in relation to outcomes after pediatric TBI. We aimed to evaluate the strength of association between MAP-based hypotension early after hospital admission and discharge outcome and to contrast the relative strength of association of hypotension with outcome between MAP-based and SBP-based blood pressure percentiles.

We examined the association between lowest age-specific MAP percentile within 12 h after pediatric intensive care unit admission and poor discharge outcome (in-hospital death or transfer to a skilled nursing facility) in children with severe (Glasgow Coma Scale score < 9) TBI who survived at least 12 h. Poisson regression results were adjusted for maximum head Abbreviated Injury Scale (AIS) severity score, maximum nonhead AIS, and vasoactive medication use. We also examined the ability of lowest MAP percentile during the first 12 h to predict discharge outcomes using receiver operating curve characteristic analysis without adjustment for covariates. We contrasted the predictive ability and the relative strength of association of blood pressure with outcome between MAP and SBP percentiles.

Data from 166 children aged < 18 years were examined, of whom 20.4% had a poor discharge outcome. Poor discharge outcome was most common among patients with lowest MAP < 5th percentile (42.9%; aRR 5.3 vs. 50-94th percentile, 95% CI 1.2, 23.0) and MAP 5-9th percentile (40%; aRR 8.5, 95% CI 1.9, 38.7). Without adjustment for injury severity or vasoactive medication use, lowest MAP percentile was moderately predictive of poor discharge outcome (AUC: 0.75, 95% CI 0.66, 0.85). In contrast, lowest SBP was associated with poor discharge outcome only for the < 5th percentile (50%; aRR 5.4, 95% CI 1.3, 22.2). Lowest SBP percentile was moderately predictive of poor discharge outcome (AUC: 0.82, 95% CI 0.74, 0.91).

In children with severe TBI, a single MAP < 10th percentile during the first 12 h after Pediatric Intensive Care Unit admission was associated with poor discharge outcome. Lowest MAP percentile during the first 12 h was moderately predictive of poor discharge outcome. Lowest MAP percentile was more strongly associated with outcome than lowest SBP percentile but had slightly lower predictive ability than SBP.