Acta neurochirurgica. Supplement
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Acta Neurochir. Suppl. · Jan 2018
Occurrence of CPPopt Values in Uncorrelated ICP and ABP Time Series.
Optimal cerebral perfusion pressure (CPPopt) is a concept that uses the pressure reactivity (PRx)-CPP relationship over a given period to find a value of CPP at which PRx shows best autoregulation. It has been proposed that this relationship be modelled by a U-shaped curve, where the minimum is interpreted as being the CPP value that corresponds to the strongest autoregulation. Owing to the nature of the calculation and the signals involved in it, the occurrence of CPPopt curves generated by non-physiological variations of intracranial pressure (ICP) and arterial blood pressure (ABP), termed here "false positives", is possible. Such random occurrences would artificially increase the yield of CPPopt values and decrease the reliability of the methodology.In this work, we studied the probability of the random occurrence of false-positives and we compared the effect of the parameters used for CPPopt calculation on this probability. ⋯ This value can be minimised by tuning some of the calculation parameters, such as increasing the calculation window and increasing the minimum PRx span accepted on the curve.
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Acta Neurochir. Suppl. · Jan 2018
Induced Dynamic Intracranial Pressure and Cerebrovascular Reactivity Assessment of Cerebrovascular Autoregulation After Traumatic Brain Injury with High Intracranial Pressure in Rats.
In previous work we showed that high intracranial pressure (ICP) in the rat brain induces a transition from capillary (CAP) to pathological microvascular shunt (MVS) flow, resulting in brain hypoxia, edema, and blood-brain barrier (BBB) damage. This transition was correlated with a loss of cerebral blood flow (CBF) autoregulation undetected by static autoregulatory curves but identified by induced dynamic ICP (iPRx) and cerebrovascular (iCVRx) reactivity. We hypothesized that loss of CBF autoregulation as correlated with MVS flow would be identified by iPRx and iCVRx in traumatic brain injury (TBI) with elevated ICP. ⋯ In TBI with high ICP, high-velocity MVS flow is responsible for the loss of CBF autoregulation identified by iPRx and iCVRx.
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Acta Neurochir. Suppl. · Jan 2018
What Determines Outcome in Patients That Suffer Raised Intracranial Pressure After Traumatic Brain Injury?
Episodes of raised intracranial pressure (ICP) after traumatic brain injury (TBI) are responsible for the majority of secondary brain injury events and thereby strongly affect long-term outcome. However, not all patients with major episodes of raised ICP suffer a poor outcome. The aim of the current analysis was to identify variables contributing to good outcome in patients suffering episodes of high ICP. ⋯ Prolonged episodes of disturbed dynamic cerebral autoregulation contribute to detrimental outcome in patients with increased ICP. Autoregulation seems to have an important protective role in tolerating episodes of raised ICP.
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Acta Neurochir. Suppl. · Jan 2018
Visualizing Cerebrovascular Autoregulation Insults and Their Association with Outcome in Adult and Paediatric Traumatic Brain Injury.
The aim of this study is to assess visually the impact of duration and intensity of cerebrovascular autoregulation insults on 6-month neurological outcome in severe traumatic brain injury. ⋯ The colour-coded plots indicate that cerebrovascular autoregulation is disturbed in a dynamic manner, such that duration and intensity play a role in the determination of a zone associated with better neurological outcome.
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Acta Neurochir. Suppl. · Jan 2018
Comparative StudyComparison of Intracranial Pressure and Pressure Reactivity Index Obtained Through Pressure Measurements in the Ventricle and in the Parenchyma During and Outside Cerebrospinal Fluid Drainage Episodes in a Manipulation-Free Patient Setting.
We investigated the effect of cerebrospinal fluid (CSF) drainage on the intracranial pressure (ICP) signal measured in the parenchyma and the ventricle as well as the effect on the pressure reactivity index (PRx) calculated from both signals. ⋯ Drainage of CSF reduces ICP magnitude and amplitude through the EVD. This effect was only marginal in parenchymal ICP measurements. In manipulation-free circumstances, agreement of PRx obtained through parenchymal and ventricular measurements was moderate to good, depending on the statistical method, and was not necessarily influenced by drainage.