University of Nebraska - Lincoln DigitalCommons@University of Nebraska - Lincoln Biological Systems Engineering--Dissertations, Theses, and Student Research Biological Systems Engineering Fall 11-30-2012 Design and Development of a Novel Transcranial Doppler Headset for Assessment of Cerebral Blood Flow Brian P. Watt University of Nebraska-Lincoln, [email protected] Follow this and additional works at: https://digitalcommons.unl.edu/biosysengdiss Watt, Brian P., "Design and Development of a Novel Transcranial Doppler Headset for Assessment of Cerebral Blood Flow" (2012). Biological Systems Engineering--Dissertations, Theses, and Student Research. 33. https://digitalcommons.unl.edu/biosysengdiss/33 This Article is brought to you for free and open access by the Biological Systems Engineering at DigitalCommons@University of Nebraska - Lincoln. It has been accepted for inclusion in Biological Systems Engineering--Dissertations, Theses, and Student Research by an authorized administrator of DigitalCommons@University of Nebraska - Lincoln. i DESIGN AND DEVELOPMENT OF A NOVEL TRANSCRANIAL DOPPLER HEADSET FOR ASSESSMENT OF CEREBRAL BLOOD FLOW by Brian P. Watt Title page A THESIS Presented to the Faculty of The Graduate College at the University of Nebraska In Partial Fulfillment of Requirements For the Degree of Master of Science Major: Agricultural and Biological Systems Engineering Under the Supervision of Professor Gregory Bashford Lincoln, Nebraska December, 2012 ii DESIGN AND DEVELOPMENT OF A NOVEL TRANSCRANIAL DOPPLER HEADSET FOR ASSESSMENT OF CEREBRAL BLOOD FLOW Brian P. Watt, M.S. University of Nebraska, 2012 Adviser: Gregory R. Bashford Examining physiologic responses of cerebral blood flow (CBF) for subjects in challenging situations requires development of new technology. Challenging circumstances include strenuous physical activity, intensive care, and surgical procedures involving the head, neck and thorax. Headset technology to employ transcranial Doppler (TCD), which is commercially available, fails to meet several requirements for monitoring in these situations. These requirements include stable signal acquisition, non- interference with other physiological monitors, ability to fit all head sizes including infants and children. The design and development of a novel TCD headset was performed to meet these requirements. The new device theoretically allows the user to use TCD to challenging situations (e.g. cardiac surgery, pediatric use, exercise study, and concussion study). The fixation described is intended to improve the quality of care and better inform physicians, research professionals, and clinicians on CBF parameters during long-term monitoring. To test feasibility of the design, the prototype of this fixation device was tested in two populations: 1) healthy individuals and 2) stroke affected participants. Both populations were engaged in exercise, cognitive, and dual task challenges in order to ascertain the ability of the new headset to provide stable signal acquisition. Monitoring was successfully conducted while subjects were engaged in these tasks for a period of more than 20 minutes. This novel TCD fixation system is currently being used in several ongoing investigations focused on determining changes in CBF in subjects recovering from stroke and concussion. Further work is also planned to examine alterations in CBF in children and neonates who are undergoing corrective and palliative surgery for congenital heart disease. iii Copyright 2012, Brian P. Watt iv Dedication Dedicated to – Grandma Anderson v Acknowledgments I would like to thank Dr. Bashford for his guidance. His support and encouragement is remarkable. The example he sets as an engineer and mentor is truly amazing. I would also like to thank Dr. Truemper, Dr. Burnfield, and Dr. Jones for serving on my M.S. committee. Each committee member was incredibly involved in the work presented in this thesis. It would not have been possible to produce this work without the input, guidance, and support of the three members. Another thank you goes out to the Biomedical Imaging and Biosignal Analysis Laboratory members: Dr. Tiantian Xu, Evan Curtis, Mohsen Hozan, Max Twedt, and Aaron Engel. Every member within the lab has provided me with valuable help, encouragement, and support. The time spent working within the lab has been enjoyable. Thank you to my parents David and Debbi Watt along with my sister Riley. Without the support of my family completing the graduate program would have not been possible. The love, support, and guidance provided throughout this period and my life is greatly appreciated. vi Contents Title page .......................................................................................................................... i Copyright 2012, Brian P. Watt ....................................................................................... iii Dedication ...................................................................................................................... iv Acknowledgments ........................................................................................................... v Contents .......................................................................................................................... vi Table of Figures ............................................................................................................. ix List of Tables .................................................................................................................. xi Chapter 1 ............................................................................................................................. 1 1.1 Transcranial Doppler ............................................................................................ 1 1.2 Current State of TCD ........................................................................................... 2 1.3 Problem Addressed .............................................................................................. 4 1.4 Need ..................................................................................................................... 4 1.4.1 The Problems with Current Transcranial Doppler Fixation ......................... 5 1.5 Motivation ............................................................................................................ 6 1.6 Objectives ............................................................................................................. 6 1.7 Thesis Organization.............................................................................................. 7 Chapter 2 ............................................................................................................................. 9 2.1 Cerebral Blood Flow in the Circle of Willis ........................................................ 9 2.1.1 Middle Cerebral Artery ............................................................................... 11 2.1.2 Flow Influencing Factors ............................................................................ 12 2.1.3 Challenges of Exercise on Cerebral Blood Flow ........................................ 17 2.2 Transcranial Doppler .......................................................................................... 19 2.2.1 Acoustic Windows ...................................................................................... 19 2.2.2 Ultrasound Operation .................................................................................. 21 2.2.3 Current Methods and Limitations ............................................................... 25 2.2.4 Spectral Doppler Principles ........................................................................ 26 Chapter 3 ........................................................................................................................... 30 Device Development of Transcranial Fixation for Challenging ....................................... 30 vii 3.1 Introduction ........................................................................................................ 30 3.2 Prior Art.............................................................................................................. 32 3.2.1 Technology Gap .......................................................................................... 34 3.3 Design and Discussion ....................................................................................... 35 3.3.1 Functional Requirements ............................................................................ 35 3.3.2 Morphology................................................................................................. 37 3.3.3 Product Specifications ................................................................................ 38 3.4 Concept............................................................................................................... 38 3.4.1 Materials ..................................................................................................... 38 3.4.2 Pugh Analysis ............................................................................................. 41 3.4.3 Quality Function Deployment..................................................................... 43 3.5 Design for Manufacture and Assembly .............................................................. 46 3.6 Failure Mode and Effects Analysis .................................................................... 47 Chapter 4 ..........................................................................................................................