Noninvasive pulse oximetry represents an area of potential interest to the army, because it could provide cost-effective, safe, fast and real-time physiological assessment in a combat injured soldier. Consequently, there is a need to develop a reliable, battery-powered, wearable pulse oximeter to acquire and process photoplethysmographic (PPG) signals using an optimized sensor configuration. A key requirement in the optimal design of a wearable wireless pulse oximeter is low power management without compromising signal quality. This research investigated the advantage gained by increasing the area of the photodetector and decreasing the light emitting diode (LED) driving currents to reduce the overall power requirement of a reflectance mode pulse oximeter sensor. In vitro and preliminary in vivo experiments were conducted to evaluate a multiple photodetector reflectance sensor setup to simulate a varying detection area. It was concluded that a reflection pulse oximeter sensor employing a large area photodetector is preferred over a similar transmission type sensor for extending the battery life of a wireless pulse oximeter intended for future telemedicine applications.

A wireless, battery operated pulse oximeter system with a forehead mounted optical sensor was designed in our laboratory. This wireless pulse oximeter (WPO) would enable field medics to monitor arterial oxygen saturation (SpO2) and heart rate (HR) information accurately following injuries, thereby help to prioritize life saving medical interventions when resources are limited. Pulse oximeters developed for field-based applications must be resistant to motion artifacts since motion artifacts degrade the signal quality of the photoplethysmographic (PPG) signals from which measurements are derived. This study was undertaken to investigate if accelerometer-based adaptive noise cancellation (ANC) can be used to reduce SpO2 and HR errors induced by motion artifacts typically encountered during field applications. Preliminary studies conducted offline showed that ANC can minimize SpO2 and HR errors during jogging, running, and staircase climbing. An 8th order LMS filter with ì = 0.01 was successfully implemented in the WPO's embedded microcontroller. After real-time adaptive filtering of motion corrupted PPG signals, errors for HR values ranging between 60 - 180BPM were reduced from 12BPM to 6BPM. Similarly, ambient breathing SpO2 errors were reduced from 5% to 2%.

The ROx is a retinal oximeter under development with the purpose of non-invasively and accurately measuring oxygen saturation (SO₂) in vivo. It is novel in that it utilizes the blue-green oximetry technique with on-axis illumination. ROx calibration tests were performed by inducing hypoxia in live anesthetized swine and comparing ROx measurements to SO₂ values measured by a CO-Oximeter. Calibration was not achieved to the precision required for clinical use, but limiting factors were identified and improved. The ROx was used in a set of sepsis experiments on live pigs with the intention of tracking retinal SO₂ during the development of sepsis. Though conclusions are qualitative due to insufficient calibration of the device, retinal venous SO₂ is shown to trend generally with central venous SO₂ as sepsis develops. The novel sepsis model developed in these experiments is also described. The method of cecal ligation and perforation with additional soiling of the abdomen consistently produced controllable severe sepsis/septic shock in a matter of hours. In addition, the ROx was used to collect retinal images from a healthy human volunteer. These experiments served as a bench test for several of the additions/modifications made to the ROx. This set of experiments specifically served to illuminate problems with various light paths and image acquisition. The analysis procedure for the ROx is under development, particularly automating the process for consistency, accuracy, and time efficiency. The current stage of automation is explained, including data acquisition processes and the automated vessel fit routine. Suggestions for the next generation of device minimization are also described.

Στην διπλωματική εργασία αυτή παρουσιάζεται ένα μικρό σύστημα εντατικής παρακολούθησης. Παρουσιάζεται πλήρως η κατασκευή ενός οξύμετρου παλμού από πλευράς hardware και software αφού αυτό είναι συνδεδεμένο σε έναν κεντρικό υπολογιστή. Στο τέλος πήραμε μερικά δείγματα από άτομα εθελοντές για να δείξουμε πως λειτουργεί αυτό που έχει κατασκευαστεί. Επίσης παρουσιάζεται μια καινοτόμος ιδέα για την αντιμετώπιση του προβλήματος της υπνικής άπνοιας, που αφορά όχι τόσο πολύ στο θέμα πρόληψη, αλλά στην αντιμετώπιση δύσκολων, ακραίων καταστάσεων. / The current thesis presents a patient’s monitoring system for emergency rooms. It fully presents the construction of a pulse oximeter, including software and hardware development, which is connected to a server computer. Finally, some samples were taken from various volunteers to show how the pulse oximeter works. Also, the thesis presents an innovative idea for the problem of sleep apnea, for dealing critical situations.

Remote healthcare is a demanding as well as emergent research area. The rise of healthcare costs in the developed countries have made the policy makers for trying to find an alternate model of healthcare rather than relying on traditional healthcare system. Although advancement in the sensor technology, forthcomingness of devices like smart phones and improvement in artificial intelligence technology have made the remote healthcare close to reality but still there are plenty of issues to be solved before it becomes a commonly used healthcare model. In this thesis, studies of two vital physiological parameters pulse rate and oxygen saturation were done to unearth some patterns using Case-Based Reasoning technique. A three-tiered application is developed focusing remote healthcare. The results of the thesis could be used as a starting point of further research of two above mentioned physiological parameters in order to detect anomalous condition of health.

Remote healthcare is a demanding as well as emergent research area. The rise of healthcare costs in the developed countries have made the policy makers for trying to find an alternate model of healthcare rather than relying on traditional healthcare system. Although advancement in the sensor technology, forthcomingness of devices like smart phones and improvement in artificial intelligence technology have made the remote healthcare close to reality but still there are plenty of issues to be solved before it becomes a commonly used healthcare model. In this thesis, studies of two vital physiological parameters pulse rate and oxygen saturation were done to unearth some patterns using Case-Based Reasoning technique. A three-tiered application is developed focusing remote healthcare. The results of the thesis could be used as a starting point of further research of two above mentioned physiological parameters in order to detect anomalous condition of health.

This thesis works with measuring possibilities of blood oxygen saturation, analysis methods used and their calibration. It also deals with design of the block diagram of pulse oximeter for measuring blood oxygen saturation.

No description available.

Optical Point-of-Care (POC) devices provide a low-cost platform for real-time, non-invasive diagnosis of disease and quantitative estimation of physiological biomarkers, allowing use in a wide variety of institutional settings ranging from acute surgical care to long-term clinical monitoring. POC optical value has resulted in their widespread adoption with great interest in at-home monitoring and explosive growth within wearable consumer electronics. However, recent studies have highlighted the fact that well-established devices such as pulse oximeters can exhibit subtle but dangerous inaccuracies in measurements from some darker skin pigmentation patients whose basis is not completely understood. Emerging optical technologies, such as near-infrared spectroscopy (NIRS) monitoring of bone quality are promising, yet similarly suffer from an incomplete understanding of the relationship between probe design and performance.The focus of this dissertation is to develop next-generation approaches to improve the performance of optical diagnostic devices informed by computational simulations of light-tissue interactions using Monte Carlo (MC) modeling. Although MC simulations have been previously used to design and simulate devices such as Pulse Oximeters or Transcutaneous Bilirubinometers (TcB), the simulations were incapable of capturing population-level heterogeneity and thus evaluating underlying factors contributing to measurement bias. Here, an in-silico MC platform was developed to investigate how population-level heterogeneity impacts Pulse Oximeters and TcB devices. The results demonstrate that fundamental biases in optical measurements exist and are exacerbated by inequitable regulatory guidelines. These findings were used to further demonstrate the impact of changes in regulatory guidelines that can affect measurement accuracy and clinical decision-making. Additionally, simulation results were used to inform the development of spectroscopic oximetry and demonstrate the techniques clinical feasibility and potential to improve accuracy in a human-subjects pilot study. In the case of the NIRS bone quality assessment, a lack of fundamental knowledge of tissue optical properties to allow simulations to inform relative contributions from different tissue features to the overall signal or explore optimization of device design. Studies were performed to collect previously unreported optical properties from musculoskeletal tissues, and this data was used to perform MC simulations which informed bone contribution to NIRS signals and in turn resulted in the design and preliminary characterization of next-generation fiber optic probes for real-time non-ionizing assessment of bone quality. Collectively, this dissertation demonstrates the impact of advances in MC simulations of light-tissue interaction across pressing clinically focused engineering challenges. / Bioengineering

A utilização de equipamentos para monitoração de parâmetros fisiológicos não é apenas crucial em pacientes que são submetidos a alguns procedimentos médicos, mas é também de extremo valor para animais em uso similar. Este projeto tem como principal objetivo o desenvolvimento de um sistema de monitoração de saturação de oxigênio e freqüência cardíaca para roedores; tal sistema é composto por um dispositivo protótipo compacto e sensor óptico. No presente trabalho, foram utilizadas as tecnologias dos microcontroladores da Microchip para realizar as diversas digitalizações; a tecnologia USB, para realizar a comunicação com computadores e o desenvolvimento da interface desenvolvida com o software disponível da National Instruments, o LabVIEW. Neste estudo, o sistema desenvolvido foi empregado em camundongos e foram realizadas diversas avaliações em laboratório e em campo para a validação do dispositivo protótipo. Os batimentos cardíacos e a saturação de oxigênio, tanto em repouso quanto em movimento, foram detectados pelo protótipo. Os valores de freqüência cardíaca variaram entre 545 e 700 bpm enquanto os valores de saturação de oxigênio variaram entre 80 a 95%. / The equipments use to monitoring physiological parameters isnt just crucial in patients who are submitted to some medical procedures but it is also of extreme value for animals in similar use. This project has as main objective the development of a monitor oxygen saturation and cardiac frequency for mice; the system is compound of a compact prototype device and optic sensor. In the present work, the Microchip microcontrollers technologies had been used, to realize many digitalization; the USB technology interface, to realize the communication with computers and the interface development developed with the available National Instruments software, the LabVIEW. In this study, the developed system was used in mice and have been realized many evaluations in laboratory and field for the prototype validation device. The cardiac beatings and oxygen saturation, as much in rest how in movement they had been detected by the prototype. The values of heart rate had varied of 545 to 700 while the values of oxygen saturation had varied of 80 to 95%.