Field-Cycled Proton-Electron Double Resonance Imaging (FC-PEDRI) is a new imaging technique that has potential for detecting and monitoring concentrations of dissolved oxygen in aqueous solutions. This technique is based upon the magnetic interactions that can occur between nitroxide free radicals and water molecules. This thesis describes why the FC-PEDRI signal is sensitive to dissolved oxygen and explores different methods of making quantitative measurements of oxygen concentration using FC-PEDRI. It starts by developing a comprehensive theoretical model which describes all the relevant magnetic interactions which can occur between nitroxide molecules, molecules of dissolved oxygen and solvent water protons. It was found that the complicated chemical structure of nitroxide molecules can greatly affect the oxygen-sensitivity of the FC-PEDRI signal. Methods of correcting for some of these effects are discussed. The instrumentation necessary to perform FC-PEDRI oximetry is also described, as is the implementation of oxygen-sensitive FC-PEDRI pulse sequences. The success of these sequences was found to be strongly dependent on the performance of the field-cycling apparatus. Two different FC-PEDRI instruments are described in this thesis. The construction and commissioning of one of these instruments is fully discussed. This instrument was large enough to allow in-vivo FC-PEDRI experiments to be undertaken and was based upon the use of novel field-cycling control electronics. The improved operation of this machine, in comparison to that of the older instrument, allowed the oxygen-sensitive pulse sequences developed in this thesis to be performed much more satisfactorily.

Thesis (Ph. D.)--University of Chicago, Committee on Medical Physics, December 2003. / Includes bibliographical references. Also available on the Internet.

Thesis (Ph.D.) - University of Queensland, 2006. / Includes bibliography.

Recent guidelines recommend oxygen saturation (SpO(2)) levels of 90%-95% for preterm neonates on supplemental oxygen but it is difficult to discern such levels with current pulse oximetry sonifications. We tested (1) whether adding levels of tremolo to a conventional log-linear pulse oximetry sonification would improve identification of SpO(2) ranges, and (2) whether adding a beacon reference tone to conventional pulse oximetry confuses listeners about the direction of change. Participants using the Tremolo (94%) or Beacon (81%) sonifications identified SpO(2) range significantly more accurately than participants using the LogLinear sonification (52%). The Beaton sonification did not confuse participants about direction of change. The Tremolo sonification may have advantages over the Beacon sonification for monitoring SpO(2) of preterm neonates, but both must be further tested with clinicians in clinically representative scenarios, and with different levels of ambient noise and distractions. Crown Copyright (C) 2016 Published by Elsevier Ltd. All rights reserved.

SAS has become an increasingly important public-health problem in recent years. It can abversely affect neurocognitive, cardiovascular, respiratory diseases and can also cause behavior disorder. Moreover, up to 90¢H of these cases are obstructive sleep apnea (OSA). Therefore, it is important that how to diagnose, detect and treat OSA. The respiratory disturbance index is one parameter of estimating OSA. Polysomnography can monitor the OSA with relatively fewer invasive techniques. However, polysomnography-based sleep studies are expensive and time-consuming because they require overnight evaluation in sleep laboratories with dedicated systems and attending personnel. Based on the digital oximetry, this work introduces the estimating respiratory disturbance index. In particular, via signal processing, feature parameters and artificial intelligence, this thesis describes an off-line SpO2-based RDI estimating system.

This dissertation documents the development of a new illumination technique for use in the studies of retinal oximetry and fundus spectroscopy. Intravitreal illumination is a technique where the back of the eye is illuminated trans-sclerally using a scanning monochromator coupled into a fiber optic illuminator. Retinal oximetry is the processof measuring the oxygen saturation of blood contained in retinal vessels by quantitative measurement of the characteristic color shift seen as blood oxygen saturation changes from oxygenated blood (reddish) to deoxygenated blood (bluish). Retinal oximetry was first attempted in 1963 but due to a variety of problems with accuracy and difficulty of measurement, has not matured to the point of clinical acceptabilityor commercial viability.Accurate retinal oximetry relies in part on an adequate understanding of the spectral reflectance characteristics of the fundus. The use of intravitreal illumination allows new investigations into the spectral reflectance properties of the fundus. The results of much research in fundus reflectance and retinal oximetry is detailed in thisdocument, providing new insight into both of these related fields of study.Intravitreal illumination has been used to study retinal vessel oximetry and fundus reflectometry resulting in several important findings that are presented in this document. Studies on enucleated swine eyes have provided new insight into the bidirectional reflectance distribution function of the fundus. Research on live swine hasshown accurate measurement of retinal vessel oxygen saturation and provided the first in vivo spectral transmittance measurement of the sensory retina. A secondary discovery during this research suggests that vitrectomy alters the retinal vasculature,a finding that should spawn new research in its own right.

Thesis (Ph. D.)--Ohio State University, 2008. / Title from first page of PDF file. Includes bibliographical references (p. 117-137).

The goal of this project was to determine the feasibility of non-invasively monitoring the blood gases of construction workers for carbon monoxide exposure via pulse oximetry. In particular, this study sought to understand the impact of motion artifacts caused by the worker's activities and to determine if those activities would prevent the blood gas sensor from detecting the onset of carbon monoxide poisoning. This feasibility study was conducted using a blood oxygen sensor rather than a blood carbon monoxide sensor for several reasons. First, blood gas sensors that measure blood carbon monoxide are not readily available in suitable physical form factors. Second, sensors for blood oxygen and blood carbon monoxide operate on the same physical principles and thus will be affected in the same way by worker motions. Finally, using a blood oxygen sensor allowed the study to be conducted without exposing the human subjects to carbon monoxide. A user study was conducted to determine the distribution of motion artifacts that would be created during a typical work day. By comparing that distribution to a worst-case estimate of time to impairment, the probability that helmet will adequately monitor the worker can be established. The results of the study show that the helmet will provide a measurement capable of warning the user of on setting carbon monoxide poisoning with a probability greater than 99%. / Master of Science

Pulse oximetry is used to measure heart rate (HR) and arterial oxygen saturation (SpO2) from photoplethysmographic (PPG) waveforms. PPG waveforms are highly sensitive to motion artifact (MA), limiting the implementation of pulse oximetry in mobile physiological monitoring using wearable devices. Previous studies have shown that multichannel pulse oximetry can successfully acquire diverse signal information during simple, repetitive motion, thus leading to differences in motion tolerance across channels. In this study, we introduce a multichannel forehead-mounted pulse oximeter and investigate the performance of this novel sensor under a variety of intense motion artifacts. We have developed a multichannel template-matching algorithm that chooses the channel with the least amount of motion artifact to calculate HR and SpO2 every 2 seconds. We show that for a wide variety of random motion, channels respond differently to motion, and the multichannel estimate outperforms single channel estimates in terms of motion tolerance, signal quality, and HR and SpO2 error. Based on 31 data sets of PPG waveforms corrupted by random motion, the mean relative HR error was decreased by an average of 5.6 bpm when the multichannel-switching algorithm was compared to the worst performing channel. The percentage of HR measurements with absolute errors ≤ 5 bpm during motion increased by an average of 27.8 % when the multichannel-switching algorithm was compared to the worst performing channel. Similarly, the mean relative SpO2 error was decreased by an average of 4.3 % during motion when the multichannel-switching algorithm was compared to each individual channel. The percentage of SpO2 measurements with absolute error ≤ 3 % during motion increased by an average of 40.7 % when the multichannel-switching algorithm was compared to the worst performing channel. Implementation of this multichannel algorithm in a wearable device will decrease dropouts in HR and SpO2 measurements during motion. Additionally, the differences in motion frequency introduced across channels observed in this study shows precedence for future multichannel-based algorithms that make pulse oximetry measurements more robust during a greater variety of intense motion.

The ability to measure the oxygen saturation, oximetry, of retinal blood both non-invasively and in-vivo has been a goal of eye research for years. Retinal oximetry can in principle be achieved from the measurement of the reflectance spectrum of the ocular fundus. Oximetry calculations are however complicated by the scattering of red blood cells, the different pathways of light through blood and the ocular tissues that light interacts with before exiting the eye. The goal of this thesis was to investigate the influence of red blood cell scattering for different light paths relevant to retinal oximetry. Results of in-vitro whole blood experiments found calculated oxygen saturation differences between blood samples measured under different retinal light paths, and these differences did not depend on the absorbance path length. We also showed that the calculated oxygen saturation value determined by a multiple linear regression Beer-Lambert absorbance model depended on the wavelength range chosen for analysis. The wavelength dependency on the calculated oxygen saturation value is due in part to the correlation that exists between the oxyhaemoglobin and deoxyhaemoglobin extinction coefficient spectra and to errors in the assumptions built into the Beer-Lambert absorbance model. A wavelength region with low correlation between the oxyhaemoglobin and deoxyhaemoglobin extinction coefficients was found that is hypothesized to be a good range to calculate oxygen saturation using a multiple linear regression approach.