Kovacsova, Zuzana;
(2020)
A novel approach to monitor tissue oxygen saturation with broadband near-infrared spectroscopy.
Doctoral thesis (Ph.D), UCL (University College London).
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Abstract
Cerebral oximetry is the measurement of tissue oxygen saturation, StO2, with near-infrared spectroscopy (NIRS). The technique offers a non-invasive assessment of cerebral oxygenation and has potential to be used as a biomarker in neonatal critical care, particularly hypoxic-ischaemic-encephalopathy (HIE). HIE is a major cause of neonatal mortality and affected neonates need continuous cerebral monitoring to guide treatment and improve patient outcome. While multiple algorithms to recover StO2 have been published, issues with low measurement accuracy or extracranial tissue signal contamination remain. This thesis is focused on the exploration of recovering StO2 from continuous-wave broadband NIRS measurements with the aim to develop a novel algorithm to recover StO2 with increased dynamic range and depth resolution. The novel algorithm, broadband multidistance oximetry (BRUNO), recovers StO2 from a broadband multidistance measurement of the attenuation slope against distance. BRUNO combines and expands two other StO2 algorithms, spatially resolved spectroscopy (SRS) and broadband fitting (BF). The evaluation of algorithm performance was done in data obtained in computational simulations and phantoms. The median error of brain StO2 recovered in simulations of brain and extracerebral tissue oxygenation changes was 1.1% with BRUNO, 2.3% with BF and 3.8% with SRS. Measurements during full oxygenation-deoxygenation cycles in a homogeneous blood phantom showed differences in the dynamic range of the algorithms; BRUNO recovered StO2 over 0–100%, BF over 0–90% and SRS over 40–80%. These results show higher accuracy of BRUNO StO2, higher sensitivity to brain oxygenation and wider dynamic range. Measurements of StO2 in one neonate with HIE showed that the StO2 algorithms led to different baseline values. Including an automated data assessment step in BRUNO to evaluate the suitability of collected spectra for analysis ensured BRUNO reliability. These findings highlight the effect of StO2 algorithm selection on oxygenation recovery; applying BRUNO in the clinical care setting could reveal further insight into complex oxygenation processes occurring during neonatal brain injury.
| Type: | Thesis (Doctoral) |
|---|---|
| Qualification: | Ph.D |
| Title: | A novel approach to monitor tissue oxygen saturation with broadband near-infrared spectroscopy |
| Event: | UCL (University College London) |
| Open access status: | An open access version is available from UCL Discovery |
| Language: | English |
| Additional information: | Copyright © The Author 2020. Original content in this thesis is licensed under the terms of the Creative Commons Attribution 4.0 International (CC BY 4.0) Licence (https://creativecommons.org/licenses/by/4.0/). Any third-party copyright material present remains the property of its respective owner(s) and is licensed under its existing terms. Access may initially be restricted at the author’s request. |
| UCL classification: | UCL UCL > Provost and Vice Provost Offices > UCL BEAMS UCL > Provost and Vice Provost Offices > UCL BEAMS > Faculty of Engineering Science UCL > Provost and Vice Provost Offices > UCL BEAMS > Faculty of Engineering Science > Dept of Med Phys and Biomedical Eng |
| URI: | https://discovery.ucl.ac.uk/id/eprint/10115224 |
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