Introduction: Impaired cerebral autoregulation following TBI may be associated with secondary brain injury and poor outcome. The purpose of this study was to examine: (1) the incidence of impaired cerebral autoregulation and (2) the relationship between cerebral autoregulation and outcome following severe pediatric TBI.
Methods: Children <18 years with diffuse TBI and Glasgow Coma Scale (GCS) score <9 were prospectively enrolled at Harborview Medical Center's (level 1 Pediatric Trauma Center) Pediatric Intensive Care Unit, Seattle, WA between May 2002-March 2005.
Transcranial Doppler (TCD) ultrasonography was used to measure bilateral middle cerebral artery flow velocities (Vmca). Static autoregulation testing was performed within 48 hours of admission by administering intravenous phenylephrine to increase cerebral perfusion pressure (CPP) to the greater of either 20% above baseline or age dependent thresholds (80mmHg for age < 9 years or 90mmHg for age 9-16 years). Simultaneous changes in CPP and Vmca were continuously measured. Cerebral autoregulation was quantified using the Autoregulatory Index (ARI; % change in estimated cere-brovascular resistance in response to the % change in CPP).
Autoregulatory capacity was dichotomized to reflect impaired (ARI < 0.4) and intact (ARI ≥ 0.4) cerebral autoregulation. Glasgow outcome score (GOS) < 4 represented poor outcome and was tested at 3, 6 and 12 months. Data are given as mean ± SD. Fishers' Exact test and Student's T test were used. p < 0.05 reflected significance.
Results: 28 children (20M and 8F) 1.3-17 years (10 ± 5) were enrolled. ARI was <0.4 in 12/28 (43%) patients. GOS was <4in 12/28 (43%) at 3 months vs. 10/27 (37%) at 6 months and 7/23 (30%) at 12 months. ARI < 0.4 was associated with GOS < 4 at 6 and 12 months (Tables 1, 2).
Conclusions: A significant number of children had impaired cerebral autoregulation during the first 48 hours after severe TBI. Although outcome improved following discharge, early impaired cerebral autoregulation was associated with poor outcome at 6 and 12 months.
1 Vavilala, MS, Lee LA, Newell DW, Lam AM. Cerebral autoregulation in children with traumatic brain injury. Pediatr Crit Care Med