A control engineer with over 40 years of experience in advanced control, Guy Dumont has for the last 18 years focused on applications of signal processing and control to biomedical applications with a focus on critical care and mobile health.
Biophotonics in Exercise Science, Sports Medicine, Health Monitoring Technologies, and Wearables
Electroencephalography (EEG) and cerebral near-infrared spectroscopy (NIRS) are both well-known m... more Electroencephalography (EEG) and cerebral near-infrared spectroscopy (NIRS) are both well-known monitoring methods to quantify cerebral neurophysiology and hemodynamics states of the brain. A stable regulatory system operates to guarantee sufficient spatial and temporal distribution of energy substrates for ongoing neuronal activity. Most EEG signals are associated with the neural activity of an enormous number of neurons that are interconnected and firing concurrently. The conventional EEG bandwidth is 0.16Hz to 70Hz. In this study, the EEG recording bandwidth is extended in low frequency (0.016Hz to 70Hz) by using a novel EEG amplifier. We aimed to investigate the low-frequency EEG and brain tissue deoxygenation by using novel multi-modal measurements. We used combined NIRS and EEG measurements for estimating the electrophysiological activity and hemodynamic changes in the adult human forehead during a hypoxic breathing condition. For the experiment, an altitude simulation kit was used to restrict the concentration of oxygen in the air that was inhaled by the subjects. The hypoxic breathing conditions led to variations in CO2 concentration (pCO2). Prolong (low-frequency) EEG signal shift, accompanied by an increase of deoxygenated hemoglobin during simulated hypoxic breathing were observed in this experiment.
Optics and Biophotonics in Low-Resource Settings V, 2019
According to the WHO, 15,000 children under five years are dying every day from preventable cause... more According to the WHO, 15,000 children under five years are dying every day from preventable causes with 80% of these children being born in low-income countries. Portable optical medical diagnostic devices can help physicians, nurses and untrained health workers to objectively identify children who are at a higher risk of dying. In the last 2 years, we collected the oxygenation values of the brachioradialis muscle, using a commercial Near Infrared Spectroscopy (NIRS) device, in 200 children under 5 years admitted in two hospitals in Uganda. Data revealed that the tissue oxygen saturation decrease during a vascular occlusion predicts children at higher risk better than other vital signs (SpO2, respiration rate, heart rate and temperature). Based on these results, we designed a low cost Continuous Wave Spatially Resolved NIRS device controlled by a smartphone in order to extend our study to a larger population and confirm our observation. The total cost of this device (excluding the smartphone) is less than $100. The preliminary tests suggest a significant potential of our low cost mobile NIRS device and oxygenation values closely matching those reported by the best device on the market.
We propose to use noncausal transfer functions to model the spatial behavior of cross-directional... more We propose to use noncausal transfer functions to model the spatial behavior of cross-directional (CD) processes so as to circumvent the high-dimensionality of a causal transfer function. This noncausal representation is shown to have a causal-equivalent form. We prove that the covariance of maximum likelihood estimate of the causal-equivalent model asymptotically converges to that of the noncausal model. This result is then used to design optimal inputs in closed-loop for the original noncausal model of the CD process. An illustrative example is provided to highlight the advantage of using optimally designed excitation signal for CD closed-loop identification over white noise excitation or the current industrial practice of spatial bump excitation.
Introduction Respiration can modulate the intensity, frequency and amplitude of the photoplethysm... more Introduction Respiration can modulate the intensity, frequency and amplitude of the photoplethysmogram (PPG) waveform [1]. During respiration, the pressure variation in the thoracic cavity causes blood to be exchanged with the pulmonary circuit, resulting in a baseline perfusion variation (intensity variation). There is a corresponding decrease in cardiac output due to reduced ventricular filling, causing an amplitude variation in the peripheral pulse. Also, there is an autonomic response, where the heart rate (HR) variation synchronizes with the respiratory cycle, causing a respiratory induced frequency variation of the PPG waveform. Physical experiments demonstrate varying levels of correlation between the individual respiratory-induced variations of the PPG signal and the reference respiratory measurements [1]. To solve the STA Annual Meeting 2012 Engineering Challenge, we suggest improving the predictive value of the non-invasive estimation of respiratory rate (RR) from the PPG ...
In response to: Spurr R, Ng E, Onchiri FM, Rapha B, Nakatumba-Nabende J, Rosenfeld M, Najjingo I,... more In response to: Spurr R, Ng E, Onchiri FM, Rapha B, Nakatumba-Nabende J, Rosenfeld M, Najjingo I, Stout J, Nantanda R, Ellington LE. Performance and usability of a new mobile application for measuring respiratory rate in young children with acute lower respiratory infections. Pediatr Pulmonol. 2022 Aug 22. doi: 10.1002/ppul.26125.
Biophotonics in Exercise Science, Sports Medicine, Health Monitoring Technologies, and Wearables
Electroencephalography (EEG) and cerebral near-infrared spectroscopy (NIRS) are both well-known m... more Electroencephalography (EEG) and cerebral near-infrared spectroscopy (NIRS) are both well-known monitoring methods to quantify cerebral neurophysiology and hemodynamics states of the brain. A stable regulatory system operates to guarantee sufficient spatial and temporal distribution of energy substrates for ongoing neuronal activity. Most EEG signals are associated with the neural activity of an enormous number of neurons that are interconnected and firing concurrently. The conventional EEG bandwidth is 0.16Hz to 70Hz. In this study, the EEG recording bandwidth is extended in low frequency (0.016Hz to 70Hz) by using a novel EEG amplifier. We aimed to investigate the low-frequency EEG and brain tissue deoxygenation by using novel multi-modal measurements. We used combined NIRS and EEG measurements for estimating the electrophysiological activity and hemodynamic changes in the adult human forehead during a hypoxic breathing condition. For the experiment, an altitude simulation kit was used to restrict the concentration of oxygen in the air that was inhaled by the subjects. The hypoxic breathing conditions led to variations in CO2 concentration (pCO2). Prolong (low-frequency) EEG signal shift, accompanied by an increase of deoxygenated hemoglobin during simulated hypoxic breathing were observed in this experiment.
Optics and Biophotonics in Low-Resource Settings V, 2019
According to the WHO, 15,000 children under five years are dying every day from preventable cause... more According to the WHO, 15,000 children under five years are dying every day from preventable causes with 80% of these children being born in low-income countries. Portable optical medical diagnostic devices can help physicians, nurses and untrained health workers to objectively identify children who are at a higher risk of dying. In the last 2 years, we collected the oxygenation values of the brachioradialis muscle, using a commercial Near Infrared Spectroscopy (NIRS) device, in 200 children under 5 years admitted in two hospitals in Uganda. Data revealed that the tissue oxygen saturation decrease during a vascular occlusion predicts children at higher risk better than other vital signs (SpO2, respiration rate, heart rate and temperature). Based on these results, we designed a low cost Continuous Wave Spatially Resolved NIRS device controlled by a smartphone in order to extend our study to a larger population and confirm our observation. The total cost of this device (excluding the smartphone) is less than $100. The preliminary tests suggest a significant potential of our low cost mobile NIRS device and oxygenation values closely matching those reported by the best device on the market.
We propose to use noncausal transfer functions to model the spatial behavior of cross-directional... more We propose to use noncausal transfer functions to model the spatial behavior of cross-directional (CD) processes so as to circumvent the high-dimensionality of a causal transfer function. This noncausal representation is shown to have a causal-equivalent form. We prove that the covariance of maximum likelihood estimate of the causal-equivalent model asymptotically converges to that of the noncausal model. This result is then used to design optimal inputs in closed-loop for the original noncausal model of the CD process. An illustrative example is provided to highlight the advantage of using optimally designed excitation signal for CD closed-loop identification over white noise excitation or the current industrial practice of spatial bump excitation.
Introduction Respiration can modulate the intensity, frequency and amplitude of the photoplethysm... more Introduction Respiration can modulate the intensity, frequency and amplitude of the photoplethysmogram (PPG) waveform [1]. During respiration, the pressure variation in the thoracic cavity causes blood to be exchanged with the pulmonary circuit, resulting in a baseline perfusion variation (intensity variation). There is a corresponding decrease in cardiac output due to reduced ventricular filling, causing an amplitude variation in the peripheral pulse. Also, there is an autonomic response, where the heart rate (HR) variation synchronizes with the respiratory cycle, causing a respiratory induced frequency variation of the PPG waveform. Physical experiments demonstrate varying levels of correlation between the individual respiratory-induced variations of the PPG signal and the reference respiratory measurements [1]. To solve the STA Annual Meeting 2012 Engineering Challenge, we suggest improving the predictive value of the non-invasive estimation of respiratory rate (RR) from the PPG ...
In response to: Spurr R, Ng E, Onchiri FM, Rapha B, Nakatumba-Nabende J, Rosenfeld M, Najjingo I,... more In response to: Spurr R, Ng E, Onchiri FM, Rapha B, Nakatumba-Nabende J, Rosenfeld M, Najjingo I, Stout J, Nantanda R, Ellington LE. Performance and usability of a new mobile application for measuring respiratory rate in young children with acute lower respiratory infections. Pediatr Pulmonol. 2022 Aug 22. doi: 10.1002/ppul.26125.
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Papers by Guy Dumont