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Clinical Applications of Neuromonitoring Following Acute Brain Injury


Type

Thesis

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Authors

Calviello, Leanne Alexis  ORCID logo  https://orcid.org/0000-0001-5012-2725

Abstract

Various invasive and non-invasive cranial monitoring techniques can be applied clinically to describe the extent to which cerebral hemodynamics and subsequently, patient outcome, have been impacted following acute brain injury (ABI).

This Ph.D. thesis examines both prospective and retrospective patient data in both neurocritical and general intensive care patients. Thirty neurotrauma patients and forty general intensive care patients with neurological complications were prospectively monitored after ABI. Retrospective patient data was harvested from a database of 1,023 traumatic brain injury (TBI) patients with invasive intracranial pressure (ICP), arterial blood pressure (ABP), and transcranial Doppler ultrasonography (TCD) recordings. Data analysis focused on ICP microsensor accuracy, compensatory reserve, the pulsatility of brain signals (ICP and TCD), and cerebral arterial blood volume (CaBV) based on TCD. The main results are summarized below:

I. Intracranial hypertension has a profound negative influence on cerebrovascular parameters and patient outcome.

II. ICP microsensor accuracy is limited, with an average error of approximately ± 6.0 mm Hg.

III. ICP weighted with the compensatory reserve better predicts outcome than mean ICP alone.

IV. ICP and TCD pulsatility are functions of mean ICP and cerebral perfusion pressure (CPP).

V. Continuous blood flow forward (CFF) and pulsatile blood flow forward (PFF) models can approximate CaBV with derived TCD signals; CFF best models TCD pulsatility.

VI. The pressure reactivity index (PRx) and the pulse amplitude index (PAx) can be estimated non-invasively using slow waves of TCD estimated by CaBV with similar outcome-predictive power.

VII. Multi-parametric TCD-based monitoring of general intensive care patients is clinically feasible; the joint estimation of autoregulation, dysautonomia, non-invasive ICP, and critical closing pressure is possible.

The culmination of these projects should have an impact on current monitoring practices in ABI patients, emphasizing the continued validation and refinement of TCD methodology in clinical neurosciences.

Description

Date

2019-10-07

Advisors

Czosnyka, Marek
Smielewski , Peter

Keywords

traumatic brain injury, cerebral autoregulation, neurocritical care, transcranial Doppler ultrasound, neurosurgery, neuromonitoring, intracranial pressure, cerebral hemodynamics

Qualification

Doctor of Philosophy (PhD)

Awarding Institution

University of Cambridge