Occurrence of CPPopt Values in Uncorrelated ICP and ABP Time Series.

Objectives: 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.

Effect of Mild Hypocapnia on Critical Closing Pressure and Other Mechanoelastic Parameters of the Cerebrospinal System.

Objective: Brain arterial critical closing pressure (CrCP) has been studied in several diseases such as traumatic brain injury (TBI), subarachnoid haemorrhage, hydrocephalus, and in various physiological scenarios: intracranial hypertension, decreased cerebral perfusion pressure, hypercapnia, etc. Little or nothing so far has been demonstrated to characterise change in CrCP during mild hypocapnia.

Method: We retrospectively analysed recordings of intracranial pressure (ICP), arterial blood pressure (ABP) and blood flow velocity from 27 severe TBI patients (mean 39.

Critical Closing Pressure During a Controlled Increase in Intracranial Pressure.

Objectives: The objectives were to compare three methods of estimating critical closing pressure (CrCP) in a scenario of a controlled increase in intracranial pressure (ICP) induced during an infusion test in patients with suspected normal pressure hydrocephalus (NPH).

Methods: We retrospectively analyzed data from 37 NPH patients who underwent infusion tests. Computer recordings of directly measured intracranial pressure (ICP), arterial blood pressure (ABP) and transcranial Doppler cerebral blood flow velocity (CBFV) were used.

Are Slow Waves of Intracranial Pressure Suppressed by General Anaesthesia?

Objectives: Slow waves of intracranial pressure (ICP) are spontaneous oscillations with a frequency of 0.3-4 cycles/min. They are often associated with pathological conditions, following vasomotor activity in the cranial enclosure.

Comparison of Different Calibration Methods in a Non-invasive ICP Assessment Model.

Objective: Previously we described the method of continuous intracranial pressure (ICP) estimation using arterial blood pressure (ABP) and cerebral blood flow velocity (CBFV). The model was constructed using reference patient data. Various individual calibration strategies were used in the current attempt to improve the accuracy of this non-invasive ICP (nICP) assessment tool.

Non-invasive Intracranial Pressure Assessment in Brain Injured Patients Using Ultrasound-Based Methods.

Background: Non-invasive measurement of intracranial pressure (ICP) can be invaluable in the management of critically ill patients. Invasive measurement of ICP remains the "gold standard" and should be performed when clinical indications are met, but it is invasive and brings some risks. In this project, we aim to validate the non-invasive ICP (nICP) assessment models based on arterious and venous transcranial Doppler ultrasonography (TCD) and optic nerve sheath diameter (ONSD).

Visualisation of the 'Optimal Cerebral Perfusion' Landscape in Severe Traumatic Brain Injury Patients.

Objective: An 'optimal' cerebral perfusion pressure (CPPopt) can be defined as the point on the CPP scale corresponding to the greatest autoregulatory capacity. This can be established by examining the pressure reactivity index PRx-CPP relationship, which is approximately U-shaped but suffers from noise and missing data. In this paper, we present a method for plotting the whole PRx-CPP relationship curve against time in the form of a colour-coded map depicting the 'landscape' of that relationship extending back for several hours and to display this robustly at the bedside.

Increased ICP and Its Cerebral Haemodynamic Sequelae.

Objectives: Increased intracranial pressure (ICP) is a pathological feature of many neurological diseases; however, the local and systemic sequelae of raised ICP are incompletely understood. Using an experimental paradigm, we aimed to describe the cerebrovascular consequences of acute increases in ICP.

Materials And Methods: We assessed cerebral haemodynamics [mean arterial blood pressure (MAP), ICP, laser Doppler flowmetry (LDF), basilar artery Doppler flow velocity (Fv) and estimated vascular wall tension (WT)] in 27 basilar artery-dependent rabbits during experimental (artificial lumbar CSF infusion) intracranial hypertension.

Computed Tomography Indicators of Deranged Intracranial Physiology in Paediatric Traumatic Brain Injury.

Objective: Computed tomography (CT) of the brain can allow rapid assessment of intracranial pathology after traumatic brain injury (TBI). Frequently in paediatric TBI, CT imaging can fail to display the classical features of severe brain injury with raised intracranial pressure. The objective of this study was to determine early CT brain features that influence intracranial or systemic physiological trends following paediatric TBI.

Do ICP-Derived Parameters Differ in Vegetative State from Other Outcome Groups After Traumatic Brain Injury?

Objective: In nearly 1,000 traumatic brain injury (TBI) patients monitored in the years 1992-2014, we identified 18 vegetative state (VS) cases. Our database provided access to continuous computer-recorded signals, which we used to compare primary signals, intracranial pressure (ICP)-derived indices and demographic data between VS patients, patients who survived but who were not VS (S), and patients who died (D).

Method: Mean values of ICP, arterial blood pressure (ABP) and cerebral perfusion pressure (CPP) from the whole monitoring periods were compared between the different outcome groups.

Pre-hospital Predictors of Impaired ICP Trends in Continuous Monitoring of Paediatric Traumatic Brain Injury Patients.

Objective: Although secondary insults such as raised intracranial pressure (ICP) or cardiovascular compromise strongly contribute to morbidity, a growing interest can be noticed in how the pre-hospital management can affect outcomes after traumatic brain injury (TBI). The objective of this study was to determine whether pre-hospital co-morbidity has influence on patterns of continuously measured waveforms of intracranial physiology after paediatric TBI.

Materials And Methods: Thirty-nine patients (mean age, 10 years; range, 0.

Intracranial and Extracranial Injury Burden as Drivers of Impaired Cerebrovascular Reactivity in Traumatic Brain Injury.

Impaired cerebrovascular reactivity has been associated with outcome following traumatic brain injury (TBI), but it is unknown how it is affected by trauma severity. Thus, we aimed to explore the relationship between intracranial (IC) and extracranial (EC) injury burden and cerebrovascular reactivity in TBI patients. We retrospectively included critically ill TBI patients.

Estimating Pressure Reactivity Using Noninvasive Doppler-Based Systolic Flow Index.

The study objective was to derive models that estimate the pressure reactivity index (PRx) using the noninvasive transcranial Doppler (TCD) based systolic flow index (Sx_a) and mean flow index (Mx_a), both based on mean arterial pressure, in traumatic brain injury (TBI). Using a retrospective database of 347 patients with TBI with intracranial pressure and TCD time series recordings, we derived PRx, Sx_a, and Mx_a. We first derived the autocorrelative structure of PRx based on: (A) autoregressive integrative moving average (ARIMA) modeling in representative patients, and (B) within sequential linear mixed effects (LME) models with various embedded ARIMA error structures for PRx for the entire population.

Optimal Cerebral Perfusion Pressure in Centers With Different Treatment Protocols.

Objectives: The three centers in this study have different policies regarding cerebral perfusion pressure targets and use of vasopressors in traumatic brain injury patients. The aim was to determine if the different policies affected the estimation of cerebral perfusion pressure which optimizes the strength of cerebral autoregulation, termed "optimal cerebral perfusion pressure."

Design: Retrospective analysis of prospectively collected data.

Critical Thresholds of Intracranial Pressure-Derived Continuous Cerebrovascular Reactivity Indices for Outcome Prediction in Noncraniectomized Patients with Traumatic Brain Injury.

The aim of the study was to compare intracranial pressure (ICP)-derived cerebrovascular reactivity indices in their ability to predict six-month outcome, and to determine/compare critical thresholds related to outcome for each index in adult noncraniectomized traumatic brain injury (TBI). Using a retrospective cohort of nondecompressive craniectomy (non-DC) patients with TBI, we performed univariate and multi-variate binary logistic regression outcome analysis of: pressure reactivity index (PRx), pulse amplitude index (PAx), and a newly described index (RAC) calculated as the regression coefficient between ICP waveform amplitude and cerebral perfusion pressure (CPP). Finally, we performed sequential chi-square threshold analysis for each index as it related to six-month binary outcomes.

A Description of a New Continuous Physiological Index in Traumatic Brain Injury Using the Correlation between Pulse Amplitude of Intracranial Pressure and Cerebral Perfusion Pressure.

To describe a new continuous index of physiologic measurement in a traumatic brain injury (TBI) population, the moving correlation coefficient between intracranial pressure (ICP) pulse amplitude (AMP) and cerebral perfusion pressure (CPP), which we refer to as RAC. We use patient examples of sustained intracranial hypertension, systemic arterial hypotension, and plateau waves, as well as the retrospective analysis of 358 non-decompressive craniectomy (DC) TBI patients with high-frequency ICP and arterial blood pressure data, to explore the relationships of this new index, RAC, with AMP, ICP, CPP, RAP (correlation coefficient between AMP and ICP), pressure reactivity index (PRx), and pulse amplitude index (PAx). We compared the RAC-CPP relationship to that observed between CPP and both PRx and PAx.

Corrigendum: Glycemia Is Related to Impaired Cerebrovascular Autoregulation after Severe Pediatric Traumatic Brain Injury: A Retrospective Observational Study.

[This corrects the article on p. 205 in vol. 5, PMID: 28993802.

Multimodality neuromonitoring in severe pediatric traumatic brain injury.

Each year, the annual hospitalization rates of traumatic brain injury (TBI) in children in the United States are 57.7 per 100K in the <5 years of age and 23.1 per 100K in the 5-14 years age group.

Impacts of Simulated Weightlessness by Dry Immersion on Optic Nerve Sheath Diameter and Cerebral Autoregulation.

Dry immersion (DI) is used to simulate weightlessness. We investigated in healthy volunteers if DI induces changes in ONSD, as a surrogate marker of intracranial pressure (ICP) and how these changes could affect cerebral autoregulation (CA). Changes in ICP were indirectly measured by changes in optic nerve sheath diameter (ONSD).

Transcranial Doppler Systolic Flow Index and ICP-Derived Cerebrovascular Reactivity Indices in Traumatic Brain Injury.

The purpose of our study was to explore relationships between transcranial Doppler (TCD) indices of cerebrovascular reactivity and those derived from intracranial pressure (ICP). Goals included: A) confirming previously described co-variance patterns of TCD/ICP indices, and B) describing thresholds for systolic flow index (Sx; correlation between systolic flow velocity [FVs] and cerebral perfusion pressure [CPP]) associated with outcome. In a retrospective cohort of traumatic brain injury (TBI) patients: with TCD and ICP monitoring, we calculated various continuous indices of cerebrovascular reactivity: A) ICP (pressure reactivity index [PRx]: correlation between ICP and mean arterial pressure [MAP]; PAx: correlation between pulse amplitude of ICP [AMP] and MAP; RAC: correlation between AMP and CPP) and B) TCD (mean flow index [Mx]: correlation between mean flow velocity [FVm] and CPP; Mx_a: correlation between FVm and MAP; Sx: correlation between FVs and CPP; Sx_a: correlation between FVs and MAP; Dx: correlation between diastolic flow velocity [FVd] and CPP; Dx_a: correlation between FVd and MAP).

Compensatory-Reserve-Weighted Intracranial Pressure and Its Association with Outcome After Traumatic Brain Injury.

Objective: We introduced 'compensatory-reserve-weighted intracranial pressure (ICP),' named 'weightedICP' for brevity, as a variable that may better describe changes leading to mortality after traumatic brain injury (TBI) over the standard mean ICP.

Methods: ICP was monitored prospectively in over 1023 sedated and ventilated patients. The RAP coefficient (R-correlation, A-amplitude, and P-pressure) was calculated as the running correlation coefficient between slow changes in the pulse amplitude of ICP and the mean ICP.

ICP Versus Laser Doppler Cerebrovascular Reactivity Indices to Assess Brain Autoregulatory Capacity.

Background: To explore the relationship between various autoregulatory indices in order to determine which approximate small vessel/microvascular (MV) autoregulatory capacity most accurately.

Methods: Utilizing a retrospective cohort of traumatic brain injury patients (N = 41) with: transcranial Doppler (TCD), intracranial pressure (ICP) and cortical laser Doppler flowmetry (LDF), we calculated various continuous indices of autoregulation and cerebrovascular responsiveness: A. ICP derived [pressure reactivity index (PRx)-correlation between ICP and mean arterial pressure (MAP), PAx-correlation between pulse amplitude of ICP (AMP) and MAP, RAC-correlation between AMP and cerebral perfusion pressure (CPP)], B.

Glycemia Is Related to Impaired Cerebrovascular Autoregulation after Severe Pediatric Traumatic Brain Injury: A Retrospective Observational Study.

Introduction: A strong association exists between hyperglycemia and outcome in pediatric traumatic brain injury (TBI). Herein, we describe observations of serum markers of glucose metabolism in a cohort of pediatric TBI patients and how these variables are related to parameters of intracranial pathophysiology.

Methods: A retrospective analysis was performed on pediatric severe TBI patients admitted to Addenbrookes Hospital Paediatric Intensive Care Unit (PICU) between January 2001 and December 2013.