Intracranial Pressure in Traumatic Brain Injury
Licentiatavhandling, 2009

Traumatic Brain Injury (TBI) continues to be a major problem worldwide. Today, intensive care of patients with TBI is mainely focused on preventing and treating secondary brain injuries. High pressure inside the intracranial cavity (ICP) has been found to be an important feature of disturbed cerebral dynamics and secondary injuries. Thus, invasive measurement of ICP has been turned into a well established routine in modern neuro-intensive care. ICP can be regarded as a response of the cerebrospinal system to different stimuli. Within this system, parameters are affected by each other, often through complex nonlinear relationships. An evaluation of the brain state is often performed using the time average of the ICP signal. Although this feature provides important information, it is far too simple to grasp and reflect the complete picture. The development of more informative features through ICP signal processing has been the center of attention in many TBI-related investigations as well as in this thesis. This study considers the ICP signal as a composed wave, which contains contributions by circulatory and respiratory mechanisms. By this we avail ourself of studying the cerebrospinal system through its dynamic response upon circulatory and respiratory excitations. Such study is conducted through two different methods. First, arterial blood pressure (ABP) and ICP is defined as the cerebrospinal system input and output, respectively. The associated transfer function is empirically estimated and its amplitude at the fundamental cardiac frequency is compared to the index of compensatory reserve. Linear correlation between two estimates is approximately 0.82, suggesting that the transfer function between ABP and ICP conveys the same sort of information as the index of compensatory reserve. The second method is more concerned with morphology aspects of the ICP. A harmonic model is proposed to decompose the pressure signals of human body to the cardiac and respiratory components. Both linear and nonlinear approaches to the problem are discussed. Results then are compared to the tidal component of ICP, tracked over time. In this study, the fundamental cardiac component is found to have the most significant contribution in the construction of the tidal peak, implying that time evolution of this component can be tracked by tracking the fundamental cardiac component in ICP.

Brain Swelling

Cerebral Autoregulation

Secondary Brain Injury

Traumatic Brain Injury

Cerebral Compliance

Intracranial Dynamics

Intracranial Pressure

Room EF, Floor 6, Hörsalsvägen 11
Opponent: Dr. Tim Howells, Department of Neuroseience, Uppsala University Hospital, Sweden


Sima Shahsavari

Chalmers, Signaler och system, Signalbehandling och medicinsk teknik

Transfer function of arterial blood pressure to intracranial pressure and its relationship with index of compensatory reserve in traumatic brain injury

Proc. 13th International Symposum on Intracranial Pressure and Brain Monitoring,; (2007)

Paper i proceeding

Frequency Interpretation of Tidal Peak in Intracranial Pressure Wave

30th Annual International Conference of the IEEE Engineering in Medicine and Biology Society, EMBS'08; Vancouver, BC; Canada; 20 August 2008 through 25 August 2008,; (2008)p. 2689-2692

Paper i proceeding

Harmonics Tracking of Intracranial and Arterial Blood Pressure Waves

Proceedings of the 30th Annual International Conference of the IEEE. Engineering in Medicine and Biology Society.,; (2008)p. 2644-2647

Paper i proceeding



Ex - Institutionen för signaler och system, Chalmers tekniska högskola: R006/2009

Room EF, Floor 6, Hörsalsvägen 11

Opponent: Dr. Tim Howells, Department of Neuroseience, Uppsala University Hospital, Sweden

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