Thesis. 1976. Sc.D.--Massachusetts Institute of Technology. Dept. of Mechanical Engineering. / Microfiche copy available in Archives and Engineering. / Vita. / Includes bibliographical references. / by Nathan Clay Martin II. / Sc.D.

Thesis (B.S.)--Massachusetts Institute of Technology, Dept. of Mechanical Engineering; and, (B.S.)--Massachusetts Institute of Technology, Dept. of Mathematics, 1982. / MICROFICHE COPY AVAILABLE IN ARCHIVES AND ENGINEERING / Includes bibliographical references and index. / by Richard J. Tello. / B.S.

Thesis (Nav. Arch.)--Massachusetts Institute of Technology, Dept. of Ocean Engineering; and, (M.S.)--Massachusetts Institute of Technology, Dept. of Mechanical Engineering, 1975. / Bibliography: leaves 248-249. / M.S. / Nav. Arch.

Finally, the effects of external physical factors, such as temperature and contact force, on BP estimation based on m-NHA, were discussed and verified by experiments. Especially, a computational efficient algorithm was developed based on an optical model for motion resistant BP estimation, as well as the estimation of blood oxygen saturation (SaO2). We first developed an optical model with motion effect based on the photon-diffusion analysis, instead of the Beer-Lambert's law, which generally describes the light absorption but fails to account for light scattering in tissue. Based on the optical model, a novel motion resistant algorithm, minimum correlation discreet saturation transform (MCDST), was proposed for the estimation of arterial BP and SaO 2 as well. The novel algorithm is based on the time and time-delayed independence of the "true" signal and motion noise by use of dual PPGs (pulse oximeter). Experimental results indicate that MCDST has a comparable performance in SaO2 estimation and m-NHA calculation, as compared to another clinically verified motion-resistant algorithm---discreet saturation transform (DST). Most importantly, MCDST is much more computationally efficient than DST, because the former only uses simple linear algebra, while the latter uses the adaptive filter. It indicates that MCDST can reduce the required power consumption and circuit complexity of the implementation. It is vitally important for wearable devices, where the small physical size and long battery life are crucial. / First of all, a modified left-ventricle (LV) arterial coupling model was developed by incorporating a nonlinear pressure dependent compliance and two resistances for valve stenosis. A modified LV-arterial coupling model with pressure dependent compliance and taking into account the hypertensives with valve stenosis is quite necessary for proper description of the BP regulation for hypertensives with mitral and/or aortic stenosis, as well as normal people. / Hypertension is the most common cardiovascular disease and is a major public health problem in both developed and developing countries. As hypertension is often asymptomatic, continuous monitoring of blood pressure (BP) for the initiate treatment before the onset of organ damage is of vital importance for home healthcare. However, most of current BP meters, such as sphygmomanometer, are not suitable for the targeted applications because they provide only intermittent blood pressure readings and may cause circulatory interference with the usage of cuff. Moreover, they are not applicable in mobile environment due to the bulky design and the lack of efficient motion resistant algorithms. The objective of this research is to propose a motion resistant method for noninvasive and continuous BP measurement using dual photoplethysmograms (PPG), which could be potentially embedded in the portable or wearable devices for long term BP monitoring. / In summary, the research in this thesis not only covers the fundamental work, such as the modification of heart-arterial system coupling model and the proposal of a novel signal processing method MCDST, but also includes the practical techniques for the estimation of arterial BP as well as oxygen saturation. Expectations for further studies are suggested at the end of this thesis. / Secondly, based on the modified model, a novel parameter, normalized harmonic area (NHA), was proposed for BP estimation by quantifying the frequency distribution in the simulated aortic pressure waveforms. The excellent relationship between NHA and BP was verified by the simulation results. To establish a measurable parameter corresponding to NHA, PPG is investigated because it is widely used for the peripheral circulation monitoring and can be easily obtained at any location on the skin surface. Based on the assumption of quadratic transfer function from aortic pressure to PPG at fingertip, the discreet period transform (DPT) was applied on PPG signal to produce a modified NHA (m-NHA) for BP estimation. For the clinical tests on 85 subjects, the difference between the estimated and the measured blood pressure by m-NHA is 0.97+/-7.9mmHg for systolic blood pressure (SBP) and 0.40+/-4.5mmHg for diastolic blood pressure (DBP), respectively. This result is as good as that (0.73+/-7.6mmHg for SBP, and 0.40+/-4.5mmHg for DBP) from the widely reported pulse transit time (PTT) approach. / Yan Yongsheng. / "November 2005." / Source: Dissertation Abstracts International, Volume: 67-11, Section: B, page: 6561. / Thesis (Ph.D.)--Chinese University of Hong Kong, 2005. / Includes bibliographical references. / Electronic reproduction. Hong Kong : Chinese University of Hong Kong, [2012] System requirements: Adobe Acrobat Reader. Available via World Wide Web. / Electronic reproduction. [Ann Arbor, MI] : ProQuest Information and Learning, [200-] System requirements: Adobe Acrobat Reader. Available via World Wide Web. / Abstracts in English and Chinese. / School code: 1307.

Thesis (M.S.)--Massachusetts Institute of Technology, Dept. of Mechanical Engineering, 1981. / MICROFICHE COPY AVAILABLE IN ARCHIVES AND ENGINEERING. / Bibliography: leaves 59-62. / by John Luigi Battaglioli. / M.S.

O diagnóstico, controle e prevenção das doenças cardiovasculares, dentre elas a Hipertensão Arterial, dependem obrigatoriamente da obtenção de valores de pressão arterial precisos. Para isso, é fundamental que a medida da pressão arterial seja realizada de maneira correta, padronizada e com aparelhos calibrados, para subsidiar condutas multidisciplinares assertivas e garantir a segurança do paciente. A literatura traz evidências de que o conhecimento dos profissionais de saúde está aquém das recomendações de diretrizes, e a prática nem sempre cumpre todas as etapas da técnica. Estudos sugerem que esse problema pode estar relacionado à formação profissional, com evidências de falhas no conhecimento teórico e prático entre estudantes da área da saúde. Por outro lado, exige-se do profissional, principalmente em Terapia Intensiva, conhecimentos e habilidades complexas, que incluem manuseio de equipamentos, materiais e medicamentos de alto custo, o que por vezes, se traduz em sobrecarga de trabalho, e execução de rotinas de forma automatizada. Partindo da hipótese de que uma intervenção educativa pode melhorar o conhecimento, e assim, favorecer a prática isenta de erros, o presente estudo avaliou o efeito de uma intervenção educativa sobre o conhecimento teórico e prático de profissionais de enfermagem (n=31) de Unidade Coronariana, relativos à medida indireta da pressão arterial, num hospital-escola no interior paulista. Trata-se de um estudo quasi- experimental, do tipo antes e depois, para determinar o conhecimento prático, utilizou- se check list validado, que avaliou a execução da técnica em simulação clínica. Para o conhecimento teórico, optou-se por elaborar e validar um questionário para a população de profissionais de enfermagem de Unidade Coronariana, por meio de um estudo metodológico de validação de conteúdo, semântica e pré-teste, pelo método DISABIKIDS®. A etapa de validação produziu um questionário de conhecimento teórico da medida indireta da PA, com 28 questões, sendo 8 de caracterização sociodemográfica, e 20 relativas às etapas da medida indireta da PA, baseadas nas principais diretrizes disponíveis. Em seguida, implementou-se a intervenção educativa, com estratégias expositivo-dialogadas, baseadas na Teoria do Arco de Maguerez, com a observação da realidade na prática simulada. Os resultados evidenciaram melhora estatisticamente significante no conhecimento teórico e prático após a intervenção, nas etapas de Preparo do cliente, Preparo do ambiente, Posição do cliente, Cuidados com os aparelhos, e Obtenção e Registro dos valores (p<0.05). Resultados indicaram que algumas etapas da medida indireta da pressão arterial são mais valorizadas na prática, em detrimento do respectivo conhecimento teórico. Por outro lado, há etapas cujo conhecimento teórico é satisfatório, porém a prática foi discrepante. O questionário validado nesse estudo representa um instrumento viável para estudos que visem determinar conhecimento teórico da medida indireta da pressão arterial em profissionais de saúde, em todos os níveis de atenção. A melhoria do conhecimento foi efetiva na teoria e na pratica simulada. Etapas voltadas à Posição do Cliente parecem estar sendo executadas de forma automatizada, enquanto que etapas voltadas à Checagem da calibração, Medida da circunferência braquial, Anotação sem arredondamento de valores, podem estar sendo negligenciadas, até mesmo por sobrecarga de rotinas, e necessitam especial atenção nas intervenções educativas e supervisão diária. A utilização da simulação contribuiu fortemente para o cumprimento dos objetivos propostos, proporcionou ao participante a oportunidade de autoavaliação, de maneira espontânea, e foi o canal de discussões sobre problemas da prática da medida indireta da pressão arterial. Discutiu-se a importância da medida indireta da pressão arterial isenta de erros, a responsabilidade individual, que deve contemplar o conhecimento sobre prazos de calibração de aparelhos. Além disso, discutiu-se o papel da instituição na busca de rotinas padronizadas e políticas voltadas à gestão de equipamentos. Diante desses achados, entende-se que uma intervenção educativa sobre a medida indireta da pressão arterial, voltada aos profissionais da saúde, aplicada de maneira sistemática, com periodicidade alinhada às diretrizes, representa grande possibilidade de melhoria do conhecimento, fornece subsídios para melhoria da qualidade da assistência, para os clientes e seus familiares, merecedores de todos os esforços possíveis na busca e obtenção da assistência e promoção do cuidado seguro e isento de erros / The diagnostics, prevention and control of cardiovascular diseases, among them arterial hypertension, depends wholesomely in obtaining precise blood pressure values. For this reason, it is paramount that blood pressure be measured correctly, in a standardized manner, and by using calibrated monitors and apparatuses to allow assertive multidisciplinary actions and guarantee patient safety. Medical literature brings evidence that health professional knowledge falls short of the necessary recommendations and directives, and procedures not always fulfill all technique requirements. Studies suggest that this problem might relate to professional qualification, attesting to some flaws in theoretical and practical understanding among health care students. On the other hand, it is demanded from the health professional, especially in Intensive Care Units, a complex understanding of abilities and knowledge, which include the handling of intricate machines, materials and high cost medication, frequently leading to work overload and the automated execution of work routines. Bearing in mind that an educational intervention might improve overall comprehension and understanding, thus, favoring error-free practices, this current study has evaluated the effects of an educational intervention on the theoretical and practical knowledge of nursing health professionals (n=31) in a Coronary Unit, concerning indirect blood pressure measurement in a teaching hospital in the state of São Paulo. It is a quasi- experimental study, type before and after, to determine practical knowledge, a validated checklist was used to evaluate technique execution under clinical simulation. For theoretical knowledge, a questionnaire was elaborated and validated for our Coronary Unit health professionals thought content validation, methodological studies, semantics and pre-tests using DISABIKIDS(TM) method. Validation stage produced a 28-question questionnaire of theoretical knowledge for indirect blood pressure measurement comprising 8 questions on social-demographics and 20 on indirect blood pressure measurement sequence, based upon the main available directives. Following this stage, an educational intervention with dialogue-expository strategies was implemented based upon Maguerez Arch Theory by observing reality in our simulated practice. The results evidenced statistically significant improvement in practical and theoretical knowledge following intervention in these stages: Client preparation, Environment preparation, Client positioning, Monitors and apparatus upkeep, Value registration and acquisition (p<0.05). Results indicate that some stages of blood pressure measurement are overvalued in practice, in detriment of acquired theoretical instruction. On the other hand, there are stages whose theoretical knowledge is satisfactory, but their practice discrepant. The validated questionnaire in this study represents a viable instrument for studies aimed at determining theoretical knowledge in indirect blood pressure measurement by health care professionals encompassing all their levels of action. Knowledge improvement was effective both in theoretical and simulated practices. Stages related to Client positioning seem to have been carried out mechanically, while stages related to Calibration check, Brachial circumference measurement, Non-rounded-value annotations might have been neglected by routine work overload, and require special attention during educational interventions and daily supervision. The use of simulation has strongly contributed to the fulfillment of the proposed objectives, allowed the participants to spontaneously evaluate themselves and was a channel of discussion about practical problems in indirect blood pressure measurement. The importance of error-free indirect blood pressure measurement was discussed, along with the health professional responsibility which must also contemplate knowledge about apparatus calibration frequency. Furthermore, the role of the institution was discussed in the search for standardized policies concerning equipment management. In the light of such findings, it can be understood that an educational intervention about indirect blood pressure measurement aimed at health professionals, systematically applied, frequency-aligned with the ongoing directives represents great possible knowledge improvement, subsidizes improvement in quality assistance for clients and their families, the well-deserving recipients of all possible efforts for high quality assistance and error-free health care

Abstract not available

University of Macau / Faculty of Science and Technology / Department of Electrical and Computer Engineering

Single-probe formation testers have been used since the 1950s to measure pore pressure and estimate mobility in fluid-bearing formations penetrated by a well. They are widely used in the oil and gas industry, with tens of measurements often made in every newly drilled well as part of the formation evaluation program. Each measurement consists of placing the tool in the wellbore in direct contact with the face of the formation, extracting a small amount of fluid (from 1 to 50 cc) from the rock and analyzing the fluid pressure response of the system. Pressure interpretation is based on models that assume that temperature within the formation tester flowline remains constant during the tool operation. However, formation pressure measurement involves relatively fast volume and pressure changes within the flowline, which result in temperature changes. These temperature changes are modeled semi-analytically and their effect on pressure transients is analyzed. Temperature variations are accounted for by describing the pressure and temperature dependence of fluid density in the continuity equation, and that temperature varies with both space and time. It is considered here that once a temperature change is imposed on the system, the primary mechanism of thermal transport to achieve equilibrium is conduction. Including temperature in the analysis requires taking into account flowline geometry, and well environmental conditions during the measurement-- namely, wellbore temperature and type of drilling fluid in the wellbore, all of which are immaterial in the isothermal analysis. Arguably, pressure behavior during formation tester measurements could be influenced by several factors. All previous studies related to formation testers assume perfect tool performance and provide explanations to pressure behaviors from the reservoir point of view (e.g., Stewart and Witmmann, 1979; Phelps et al., 1984; Proett and Chin, 1996, etc.). The approach followed here is diametrically opposite. The formation is considered `perfect' from the point of view of pressure measurement, and physical phenomena (thermal transients) that may affect the measured pressure signal are studied. The focus is to understand fundamental aspects of the tool performance that can be studied analytically while minimizing, as much as possible, external parameters that add uncertainty. This dissertation was motivated by inconsistencies observed between the pressure behavior in field measurements and existing (isothermal) theory. For instance, false buildups, buildup overshoots and long time required to reach pressure equilibration, have puzzled those involved in the interpretation of formation tester pressure transients for many years. These behaviors can be reproduced in pressure computations when accounting for temperature variations. The focus of this dissertation is on modeling the tool capability to sense pressure transients associated with recompression of formation fluids several inches away from the wellbore, accounting for temperature variations during the measurement. This is relevant because it is desirable to characterize formation properties beyond the region affected by drilling mud filtrate invasion. In practice, a discrepancy is often observed between formation mobility obtained from drawdown, which depends mostly on formation properties near the wellbore, and mobility obtained from the analysis of late-time buildup pressure, which in theory depends on formation properties farther from the wellbore (Moran and Finklea, 1962). This dissertation examines the influence of late-time tool storage effects caused by thermal equilibration of the flowline fluid on the pressure equilibration and buildup mobility interpretation. It was found that in some cases such late-time storage effects could exhibit a behavior that resembles that expected from spherical flow, that is, the flow regime characteristic of single-probe formation testers; and could therefore invalidate mobility determined by isothermal transient pressure analysis. Formation tester flowline and probe design, test parameters (rate and volume), and environmental conditions during the measurement, mostly type of drilling fluid and wellbore temperature, are important variables in determining the magnitude of late-time storage effects, and hence the tool capability to detect a deep formation signal (spherical flow). Temperature variations affecting late-buildup pressure transients were observed to be more pronounced (listed in order of importance): as wellbore temperature increases; drilling fluid is oil-based mud; flowline with large radius components (e.g. > 1 cm); large flowline volume; small probe radius (< 1 cm); and, large drawdown rate. Temperature effects on the late-buildup also tend to be more significant when mobility is in the 0.1 to 10 md/cp range, that is for those formations more likely, in theory, to exhibit spherical flow regime during buildup. / text

published_or_final_version / Mechanical Engineering / Master / Master of Philosophy