Cerebral pressure autoregulation and optimal cerebral perfusion pressure during neurocritical care of children with traumatic brain injury

Abstract

OBJECTIVE The management of cerebral perfusion pressure (CPP) is a challenge in children with traumatic brain injury (TBI) because the normal blood pressure is age dependent and the role of cerebral pressure autoregulation (CPA) is unclear. In this study, the authors aimed to examine the pressure reactivity index (PRx), CPP, optimal CPP (CPPopt), and deviations from CPPopt (ΔCPPopt) in a series of children with TBI generally and regarding age relations, temporal changes, and the influence on outcome. METHODS Intracranial pressure (ICP) and mean arterial pressure (MAP) monitoring data were collected during neurointensive care in 57 children who sustained a TBI and were ≤ 17 years of age. CPP, PRx, CPPopt, and ΔCPPopt (actual CPP − CPPopt) were calculated. Clinical outcomes at 6 months postinjury were dichotomized into favorable outcomes (Glasgow Outcome Scale [GOS] score 4 or 5) and unfavorable outcomes (GOS scores 1–3). RESULTS The median patient age was 15 (range 0.5–17) years, and the median Glasgow Coma Scale motor score at admission was 5 (range 2–5). Forty-nine (86%) of the 57 patients had favorable outcomes. For the entire group, lower PRx (better preserved CPA) was associated with a more favorable outcome (p = 0.023, ANCOVA adjusted for age). When the children were divided into age groups, this finding was statistically significant in children ≤ 15 years of age (p = 0.016), but not in children ≥ 16 years (p = 0.528). In children ≤ 15 years, a lower proportion of time with ΔCPPopt < −10% was significantly associated with a favorable outcome (p = 0.038), but not in the older age group. Temporal analysis indicated that PRx was higher (more impaired CPA) from day 4 and CPPopt was higher from day 6 in the unfavorable outcome group compared with the favorable outcome group, although those findings were not significant. CONCLUSIONS Impaired CPA is related to poor outcome, particularly in children ≤ 15 years of age. In that age group, actual CPP below the CPPopt level contributed significantly to unfavorable outcome, while levels close to or above the CPPopt were unrelated to outcome. CPPopt appears to be higher during the time period when CPA is most impaired.