• Jennifer Mytar, Kathleen K Kibler, R Blaine Easley, Peter Smielewski, Marek Czosnyka, Dean B Andropoulos, and Ken M Brady.
• College of Osteopathic Medicine, Touro University, Vallejo, CA, USA.
• Neurosurgery. 2012 Jul 1;71(1):138-45.

BackgroundAutoregulation is impaired by traumatic brain injury. Cerebral blood flow disturbances are spatially heterogeneous, but autoregulation is often reported as a global metric.ObjectiveWe tested lateralization of autoregulatory responses in the neonatal piglet brain during hypotension early after unilateral injury.MethodsNeonatal piglets (5-7 days old) had controlled cortical impact (severe, n = 12; moderate, n = 13; sham, n = 13) and recovery for 6 hours. The lower limit of autoregulation (LLA) and static rate of autoregulation (SRoR) were determined for each subject and compared among groups and between the ipsilateral and contralateral hemispheres.ResultsThe LLA was not increased by injury (sham, 34 mm Hg [29-39 mm Hg]; moderate injury, 37 mm Hg [33-41 mm Hg]; severe injury, 35 mm Hg [32-38 mm Hg]; P = .93, mean [95% confidence interval]). SRoR, when measured ipsilateral to injury and above the LLA, showed intact autoregulation and was not lower than SRoR in uninjured subjects (sham, 0.82 [0.53-1.1]; moderate injury, 1.0 [0.60-1.5]; severe, 0.91 [0.33-1.5]; P = .44). The average hemispheric LLA difference was 2.7 mm Hg, (95% limits of agreement, -7.5 to 7.0; bias, -0.25; Spearman r = 0.73; P < .0001). Ipsilateral and contralateral SRoR measurements also showed correlation in the injured groups (Spearman r = 0.85, P < .0001).ConclusionLLA was not increased by controlled cortical impact, nor did SRoR measurements demonstrate ineffective autoregulation when cerebral perfusion pressure was greater than and within 10 mm Hg of the LLA. Cerebral perfusion pressure optimization, indicated by autoregulation measurements, was significantly similar in the 2 hemispheres despite severe unilateral injury.

23 keywords...

hide…