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Burgess, M.D., Ph.D. Center UMI Number: 9941449 UMI Microform 9941449 Copyright 1999, by UMI Company. All rights reserved. This microform edition is protected against unauthorized copying under Title 17, United States Code. UMI 300 North Zeeb Road Ann Arbor, MI 48103 ABSTRACT In the neurointensive care unit (NICU) there is a need for a single bedside moni­ tor for continuously monitoring the function of the patient’s central nervous system. This dissertation describes the development of a system of hardware and software for continuously and automatically monitoring the ongoing neurological condition of patients in the NICU. The system samples several electrophysiological waveforms at regular intervals along with routinely monitored physiological parameters. The electrophysiological data consists of brainstem auditor}", somatosensor}' and visual evoked potentials and epochs of the electroencephalogram (EEC) . The system ap­ plies peak detection and spectral analysis to extract salient parameters from the raw waveforms. These parameters are assembled into a state vector representing the patient’s neurophysiological state. The parameters include the latencies and ampli­ tudes of the significant peaks in the brainstem auditor}", somatosensory and visual evoked potentials, the spectral pole positions, peak frequencies and energy distribu­ tions of the EEC and such physiological parameters as heart rate, blood pressure and intracranial pressure. A display summarizing the history of the patient’s state is provided for visual review. The results are also made available on the network for review and further analysis on the local network. A web-based interface makes review possible anywhere within the hospital’s secure intranet during and after monitoring. Experimental data from six intensive care patients show that certain regions of the 11 State space correspond with particular pathologies and this may have diagnostic value in particular patients. Experimental data from angioplasty and stent patients sug­ gest that the electrophysiological changes correspond with the induced physiological changes in the central nervous system as they occur in real time. If these results are extrapolated to NICU patients, it implies that further analysis of the state space djmamics may be of prognostic value in these patients. In particular, the results suggest that continuous multimodality electrophysiological monitoring of this type may potentially contribute to the quality of care of stroke patients with hemorrhagic and edematous brain injuries during the critical period during which tissue shifts and possible herniation may give rise to pressure on the brainstem and other structures, with associated morbidity or mortality. I ll Dedicated to my parents and Evelina IV ACKNOWLEDGMENTS I am ver\' grateful to my research adviser, Dr. Richard C. Burgess of the Cleve­ land Clinic Foundation, for his expert knowledge and guidance in this research, for his patience and enthusiasm and his authoritative suggestions. He has been a con­ tinuous source of knowledge and inspiration. His efficient and valuable review of any material at short notice are greatly appreciated. I would also like to thank him for his optimistic and confident attitude and his concern not only for my progress in this research project, but also for the development of my personal career. 1 appreciate his provision of the hardware necessary to build up this monitoring system,together with the supporting infrastructure and environment for testing it. Thanks are due to Professor Wang for his careful review of the final manuscript, and his assistance and authority in parallel research and coursework. My thanks also to Professors Mitra and Waldron for their helpful and wise suggestions related to the manuscript. A special debt of thanks is due to Linda Gagnon, who is an evoked potential and intraoperative monitoring technologist with vast experience and enthusiasm. I appre­ ciate her tireless enthusiasm and assistance even at short notice, meticulous attention to the experimental setup, cheerfulness and encouragement. Her compassionate in­ teraction with her patients and colleagues has been a great source of inspiration. Thanks also to the other technologists on this qualified team for their assistance in the experimental sections of the research. I wish to thank Dr. Jeffrey I. Frank of the Neurointensive Care Unit for his willingness to host the testing of the monitoring system in his unit, his assistance in identifying suitable patients, and his suggestions as to the most appropriate subjects to include in the protocol. I would like to thank the intensive care fellows. Dr. Waleed El-Feky and Dr. Harold McGrade, for their help in identifying suitable patients for the NICU study. Thanks to Dr. Derek Krieger of the Neurolog}' Department for his helpful sugges­ tions, logistical assistance, explanations and encouragement. Thanks to Doctors Thomas Masaryk and Perl for their willingness to assist in the evaluation of the monitoring system in the interventional neuroradiology suite, and for their suggestions and advice. I would like to express my appreciation to the members of the Section of Neu­ rological Computing who contributed to this project by providing expert technical advice. In particular, Martin Andrews always had the answers to my UNIX-related questions, trivial or complex, tolerating interruptions at any time with advice and solutions. Thanks also to Misha Rekhson for his advice related to hardware drivers and communications on the UNIX platform. Thanks to John Turnbull for mathe­ matical contributions. Thanks also to Karl Horning for his support in issues related to purchasing the components for the system and assembling the hardware, and for his great sense of humor. It was a privilege to work with this accomplished team of scientists and engineers. VI Finally, my thanks to the Graduate School of the Ohio State University for their investment in this research in the form of a Graduate Student Alumni Research Award. vu VITA 30 December, 1970 ............................................ Bom - Jonquière, Canada 1992 .......................................................................... B. Eng. Electronics, University of Pre­ toria 1995 .......................................................................... M. Eng. Electronics (Bioeng.), Univer- sitv of Pretoria PUBLICATIONS Research Publications A..1.W. van der Kouwe and R.C. Burgess, "Peak detection in auditor}- and so­ matosensory evoked potentials by means of the zero-crossings wavelet transfor- m", Proc. 34th Rocky Mnt. Bioeng. Sv-mp., Dayton, OH, (1996). 2. .A..J.W. van der Kouwe and D.L. Wang, “Temporal alignment, spatial spread and the linear independence criterion for blind separation of voices", Proc. 19th Int. Conf. of IEEE EMBS, Chicago, IL, (1997). 3. -\..I.W. van der Kouwe and R.C. Burgess, “Examining the dynamics of a vector representing neurophysiological state during intensive care". InterJ. Complex Systems, doc. no. 257, (1998). A.J.W. van der Kouwe and R.C. Burgess, “Long-term evoked potential and EEC monitoring system for the neurointensive care unit", J. Clin. Neurophys., 16 (2), (1999). V lll 5. A.J.W. van der Kouwe and R.C. Burgess, "A continuous electrophysiological monitoring system with web-based review for the neurological intensive care unit”, Proc. 3rd Int. Workshop on Biosig. Interp., Chicago, IL, (1999). 6. A.J.W. van der Kouwe, D.L. Wang and G.J. Brown, "A Comparison of Auditor}' and Blind Separation Techniques for Speech Segregation", Tech. Rep. OSÜ- CISRC-6/99-TR15, Dept, of Comp, and Info. Sci., The