Static autoregulation is intact early after severe unilateral brain injury in a neonatal swine model

Jennifer Mytar, Kathleen K. Kibler, R. Blaine Easley, Peter Smielewski, Marek Czosnyka, Dean B. Andropoulos, Kenneth Martin Brady*

*Corresponding author for this work

Research output: Contribution to journalArticlepeer-review

12 Scopus citations

Abstract

BACKGROUND: Autoregulation is impaired by traumatic brain injury. Cerebral blood flow disturbances are spatially heterogeneous, but autoregulation is often reported as a global metric. OBJECTIVE: We tested lateralization of autoregulatory responses in the neonatal piglet brain during hypotension early after unilateral injury. METHODS: Neonatal 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. RESULTS: The 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). CONCLUSION: LLA 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.

Original languageEnglish (US)
Pages (from-to)138-145
Number of pages8
JournalNeurosurgery
Volume71
Issue number1
DOIs
StatePublished - Jul 2012

Keywords

  • Autoregulation
  • Neurotrauma
  • Pediatric

ASJC Scopus subject areas

  • Surgery
  • Clinical Neurology

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