Cerebral blood flow and metabolism in severely head-injured children

Abstract

Autoregulation of cerebral blood flow ("CBF15") was tested in a series of 26 pediatric patients (mean age 13.2 years) with severe head injury (average Glasgow Coma Scale (GCS) score 5.5) in the acute stage. A baseline 133Xe CBF measurement was performed and then repeated, after blood pressure was increased by 29% with intravenous phenylephrine or decreased by 26% with intravenous trimethaphan camsylate. Correlations were made between CBF and clinical condition, outcome, time after injury, intracranial pressure (ICP), and pressure-volume index (PVI) changes, and the site of injury (hemispheres, diencephalon, or brain stem). The site of injury was determined with multimodality evoked potential measurements. Autoregulation was intact in 22 (59%) of 37 measurements. There was no correlation with GCS score, outcome, time after injury, site of injury, or way of testing (decreasing or increasing blood pressure). Autoregulation was statistically significantly more often impaired when CBF was either below normal -2 standard deviations (SD) (reduced flow) or above normal +2 SD (absolute hyperemia). In cases with intact autoregulation, mean ICP decreased from 17.5 to 15.0 mm Hg with higher blood pressure and increased from 19.0 to 21.3 mm Hg with lower blood pressure. When PVI was measured during the blood pressure manipulations, it was found to change in a direction opposite to the ICP change. The consequences of these findings in the management of ICP problems with blood pressure control are discussed.

Critical Thresholds for Transcranial Doppler Indices of Cerebral Autoregulation in Traumatic Brain Injury

“…Very early studies indicated that cerebral autoregulation may be a strong discriminant of outcome following head injury [18][19][20][21]. Several decades later, this subject is still open to investigation, taking advantage of availability of new, more precise and feasible methods for continuous monitoring.…”

Impaired Cerebral Autoregulation in Infants and Young Children Early after Inflicted Traumatic Brain Injury: A Preliminary Report

“…Previous studies in children describe a 40% incidence of impaired cerebral autoregulation after severe nTBI (Muizelaar et al, 1989;Sharples et al, 1995). Similar to adults, the incidence of impairment appears to vary with severity of injury, with 17% of children with mild TBI having impaired autoregulatory capacity (Vavilala et al, 2004).…”

“…This process, termed cerebral autoregulation, is a homeostatic process that may become disturbed during pathological conditions such as traumatic brain injury (TBI). Although impaired cerebral autoregulation has been documented in noninflicted TBI (nTBI) in children (Muizelaar et al, 1989;Sharples et al, 1995;Vavilala et al, 2004Vavilala et al, , 2007, there is no information on cerebral autoregulation in children with inflicted TBI (iTBI).…”

Treatment of traumatic brain injury in pediatrics

“…Quantitative determination of CBF has long been performed with xenon CT scanning, but the use of this method in pediatric patients has been limited because of the radioisotope required [45]. Noninvasive measures using transcranial Doppler can give surrogate measures for CBF or the cerebral autoregulatory index and are beginning to be implemented in the study and management of pediatric patients with TBI [27].…”