• Neurosurgery · Aug 2014

    The upper limit of cerebral blood flow autoregulation is decreased with elevations in intracranial pressure.

    • Matthew Pesek, Kathleen Kibler, R Blaine Easley, Jennifer Mytar, Christopher Rhee, Dean Andropoulos, and Ken Brady.
    • *Department of Pediatrics, Division of Pediatric Critical Care, ‡Department of Anesthesiology, Division of Pediatric Anesthesiology, §College of Osteopathic Medicine, Touro University, Vallejo, California; Baylor College of Medicine, Texas Children's Hospital, Houston, Texas; ¶Department of Pediatrics, Division of Neonatology, Baylor College of Medicine, Texas Children's Hospital, Houston, Texas.
    • Neurosurgery. 2014 Aug 1; 75 (2): 163-70; discussion 169-70.

    BackgroundThe upper limit of cerebrovascular pressure autoregulation (ULA) is inadequately characterized.ObjectiveTo delineate the ULA in an infant swine model.MethodsNeonatal piglets with sham surgery (n = 9), interventricular fluid infusion (INF) (n = 10), controlled cortical impact (CCI) (n = 10), or CCI + INF (n = 11) had intracranial pressure monitoring and bilateral cortical laser-Doppler flowmetry recordings during arterial hypertension to lethality using an aortic balloon catheter. An increase of red cell flux as a function of cerebral perfusion pressure was determined by piecewise linear regression, and static rates of autoregulation were determined above and below this inflection. The ULA was rendered as the first instance of an upward deflection of Doppler flux causing a static rate of autoregulation decrease greater than 0.5.ResultsULA was identified in 55% of piglets after sham surgery, 70% after INF, 70% after CCI, and 91% after CCI with INF (P = .36). When identified, the median (interquartile range) ULA was as follows: sham group, 102 mm Hg (97-109 mm Hg); INF group, 75 mm Hg (52-84 mm Hg); CCI group, 81 mm Hg (69-101 mm Hg); and CCI + INF group, 61 mm Hg (52-57 mm Hg) (P = .01). In post hoc analysis, both groups with interventricular INF had significantly lower ULA than that observed in the sham group.ConclusionNeonatal piglets without intracranial pathology tolerated acute hypertension with minimal perturbation of cerebral blood flow. Piglets with acutely increased intracranial pressure with or without trauma demonstrated loss of autoregulation when subjected to arterial hypertension.

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