"This thesis presents a real-time noncontact system that can monitor an infant's respiration and detect apnea when it occurs. For infants, bedside monitoring of respiratory signals using non-contact sensors is desirable at the hospital and for in-home care. Traditional approach employs acoustic sensors which can hardly detect infant breathing due to low SNR. In this thesis, a novel method is introduced by using a ultra-wideband (UWB) radar that obtains breathing signal from an infant's weak chest vibration. Furthermore, advanced signal processing techniques are proposed to monitor the breathing signal and to detect apnea. Since an infant may move in the crib, a location algorithm is applied periodically to track the current location of the infant's chest. An apnea warning is issued when the respiration is absent for a pre-defined period of time."

The focus of this thesis was to capture and measure carbon dioxide concentrations upon exhalation to determine if an apnea event is occurring. Research in the fields of respiratory physiology and apnea built the foundation for the design of the standoff infant apnea monitor. The monitor is designed to track infant respiration using carbon dioxide and sound signatures of breath without touching the infant. Each detection system, audio and carbon dioxide, were designed separately and brought together for a final proof-of-concept device. The software was developed using LabView and run on a Netbook. Testing was conducted on healthy adults to fine tune the carbon dioxide sensor and measure its response during simulated apnea events. Overnight testing showed that the combined system detected fewer false alarms than either system alone. Infant testing was conducted to determine if the proof-of-concept standoff monitor could detect infant breath at specified distance. The results showed that both detection systems can detect infant breath consistently at distances less than one foot from the infant and poorly at distances exceeding one foot. Finally, conclusions were drawn and interpreted to aid in the design of future generations of the standoff infant apnea monitor. Other research avenues where this technology may be useful were also discussed.

Introdução: O conhecimento de parâmetros respiratórios em recém-nascidos a termo saudáveis pode contribuir para a construção de critérios poligráficos utilizados no diagnóstico da Apneia do Sono Central do Lactente. No período neonatal tais critérios não se encontram bem estabelecidos. Método: Foi realizado estudo descritivo de 60 poligrafias de recém-nascidos a termo saudáveis, entre 37 e 44 semanas de idade pósconcepcional, entre os anos de 2017 e 2018, com controle de variáveis maternas, do recém-nascido e variáveis ambientais durante a aquisição de exames. Eventos respiratórios foram identificados conforme critérios do Manual para estadiamento do sono e dos eventos associados da Academia Americana de Medicina do Sono. Foram adicionalmente contabilizados apneias centrais com durações >= 3 segundos, >= 10 segundos, >= 15 segundos, >= 20 segundos; episódios de dessaturação < 90% e 85%; bradicardia < 100 e < 80 batimentos por minuto (bpm). Resultados: A frequência cardíaca (FC) em sono variou entre 82 e 199 bpm, com média de 120,3 ± 10,6 bpm. Antecedente positivo para tabagismo materno prévio foi associado a menores valores de frequência cardíaca mínima, em relação ao antecedente negativo (94 ± 8,4 bpm x 104,9 ± 10,5 bpm). Não foram registrados eventos de bradicardia com FC < 80 bpm. A saturação de oxigênio (SatO2) em sono variou entre 85% e 100%, com média de 97,6% ± 1,5. Não houve episódio de dessaturação com SatO2 < 85%. O percentil 90 para o índice de apneias e hipopneias foi 41,4/hora, e para o índice de apneias centrais foi 10,8/hora. A maioria (90%) dos recém-nascidos apresentou respiração periódica ausente ou presente em < 3% do tempo total de sono. Indivíduos com menores perímetros cefálicos apresentaram maiores índices totais de apneias, e indivíduos com menores perímetros torácicos apresentaram maiores índices de apneias e hipopneias. Conclusões: Não houve episódio de dessaturação com SatO2 < 85% ou eventos de bradicardia com FC< 80 bpm em recém-nascidos a termo saudáveis, e eventos prolongados de apneia foram raros. O percentil 90 para o índice de apneias e hipopneias foi 41,4/hora, e para o índice de apneias centrais foi 10,8/hora. Respiração periódica esteve geralmente ausente ou ocupando menos que 3% do tempo total de sono. Menores perímetros cefálicos e menores perímetros torácicos estiveram associados a maiores índices de eventos respiratórios. / Introduction: The knowledge of respiratory parameters in healthy term newborns can contribute to construction of diagnostic polygraphic criteria in Central Sleep Apnea of Infancy. In the neonatal period these criteria are not well established. Methods: A descriptive study of 60 polygraphic recordings of healthy term newborns (37-44 weeks of postconceptional age) was carried out between 2017 and 2018, with control of maternal, newborn and environmental variables during exams acquisition. Respiratory events were identified according to the American Academy of Sleep Medicine criteria. Central apneas >= 3 seconds, >= 10 seconds, >= 15 seconds, >= 20 seconds were analyzed as well as desaturation <90% and 85%; bradycardia <100 and <80 beats per minute (bpm). Results: The heart rate in sleep ranged from 82 to 199 bpm, with an average of 120.3 ± 10.6 bpm. Previous maternal smoking was associated with lower values in minimum heart rate, as compared to negative antecedent (94 ± 8.4 bpm x 104.9 ± 10.5 bpm). No bradycardia of <80 bpm events was recorded. Oxygen saturation in sleep ranged from 85% to 100%, with an average of 97.6% ± 1.5. There was no episode of desaturation <85%. Central apneas longer than 10 seconds were rare. The 90th percentile for apnea and hypopnea index was 41.4/hour, and for central apnea index was 10.8/hour. The majority (90%) of the newborns did not experience periodic breathing or presented it in <3% of total sleep time. Lower cephalic perimeters were associated with higher total apnea indices, and lower thoracic perimeters with higher apnea and hypopnea indices. Conclusions: There were no episodes of desaturation <85% or bradycardia < 80 bpm in healthy term newborns and prolonged apneas were rare. The 90th percentile for apnea and hypopnea index was 41.4/hour, and for central apnea index was 10.8/hour. Periodic breathing was usually absent in normal term newborns occupying less than 3% of total sleep time. Lower cephalic perimeters and lower thoracic perimeters were associated with higher rates of respiratory events.