2. A modified model of heart-arterial system was proposed for describing the timing of the second heart sound as a result of the heart-arterial interaction. Simulation results suggest that RS2 bears a significant negative correlation with both SBP and DBP as heart rate, cardiac contractility and peripheral resistance varies. The hypothesis was supported by the experimental data. To our knowledge, it is the first study describing the relation of the timing of S2 to BP by both the model-based study and experimental data. / 3. As a preliminary study, a linear predication model using RS2 with a novel calibration scheme was proposed for BP estimation and it has been evaluated in clinical test on 85 volunteers including 18 hypertensives. The results indicate that the approach has the potential to achieve the accuracy required for medical diagnosis. / Cuffless BP measurement has been proposed as a new concept in recent years to realize the continuous monitoring of BP. This research focuses on the investigation of cuffless BP monitoring technique using heart sound information. Specifically, the thesis proposes a new cuffless technique based on the timing of the second heart sound (S2), which will enable a novel wearable design of BP monitor, for instance, a multifunctional electronic stethoscope. / Finally, based on the findings on both theoretical and experimental studies, a linear prediction model with a novel calibration scheme has been proposed to estimate the BP using 1/RS2. The proposed method was evaluated in a clinical test on 85 volunteers aged 40+/-13 years, including 18 hypertensives. The average of BP measured by simultaneous ausculatory and oscillometric approaches was used as a reference. The results of clinical test shows that the RS2 based approach can estimate SBP and DBP within the 2.1+/-7.4 mmHg and 0.8+/-6.6 mmHg of the reference respectively, indicating the approach has the potential to achieve the accuracy required for medical diagnosis according to AAMI standard (mean error within +/-5mmHg and SD less than 8mmHg) and BHS protocol. / First, a mathematical model has been developed to investigate the effects of aortic BP on the aortic component (A2) in S2 produced by the vibration of the closed aortic valve. The nonlinear elasticity of aortic wall has been introduced to the model, reflecting the nature of aortic wall tissue and extending the model to the applications involving wide BP variations. The results of simulation show that the fundamental frequency and amplitude of A2 increases as aortic systolic blood pressure (SBP) is elevated, which is able to explain the 'accentuated S2' usually heard in the hypertensives. Nevertheless, the possibility of BP measurement using spectral information of externally recorded heart sounds still needs a careful examination because the frequency characteristics tends to be blurred during sound transmission. / Hypertension, known as 'a silent killer', is an important public health challenge, afflicting approximately 1 billion adults around the world. The monitoring of blood pressure (BP) is vitally important in order to identify hypertension and treat it earlier before serious health problems are developed. The conventional BP measurement provides only intermittent BP and causes circulatory interference if the cuff is inflated frequently. There is an urgent need to develop new devices which are fully wearable and unobtrusive for noninvasive and continuous monitoring of arterial BP in daily life. / Second, a modified model of heart-arterial system has been proposed in this thesis for describing the timing of aortic valve closure as a result of heart-arterial interaction. A timing parameter, RS2, was defined as the time delay from the peak of ECG R wave to the onset of S2. The study has investigated the relation between RS2 and aortic BP under varying peripheral resistance, arterial compliance, heart rate, cardiac contractility and preload. Based on the simulation results of parametric analysis, it is hypothesized that RS2 bears a significant negative correlation with both SBP and diastolic blood pressure (DBP) as the peripheral resistance, heart rate or cardiac contractility varies. / Third, in order to verify the findings of the model-based study, three experiments were carried out to explore the relationship between RS2 and BP. The alterations of RS2 in the dynamic-exercise experiments are mainly attributable to the interactive effect of the changes in heart rate, cardiac contractility and peripheral resistance, and the effect of heart rate is dominant. In two dynamic-exercise experiments, the timing parameter, RS2, exhibited a close inverse correlation with SBP (r =0.892 and r =0.845, p<0.05 in both experiments) and a moderate inverse correlation with diastolic blood pressure (DBP) (r = 0.687, p<0.05 and r =0.660, p>0.05). The correlations are comparable to those of PTT-based parameters. However, due to the restricted range of the BP variation, there was no significant correlation observed in long-term rest monitoring experiment. Moreover, the standard deviation (SD) of the errors for SBP and DBP estimated by linear fitting of 1/RS2 is close to that of PTT-based estimation. The results also suggest that the ability of RS2 on BP estimation is as good as that of the PTT based parameters. / To summarize, the original contributions of the thesis are: 1. By the introduction of the nonlinear elasticity of aortic wall, a mathematical model for the vibration of the closed aortic valve was improved and extended to the applications involving wide variations of BP To my knowledge, this represents the first study to look into the effects of aortic BP on the frequency characteristic of S2 from the theoretical point of view. / Zhang Xin-Yu. / "September 2006." / Adviser: Yuan-Ting Zhang. / Source: Dissertation Abstracts International, Volume: 68-09, Section: B, page: 6125. / Thesis (Ph.D.)--Chinese University of Hong Kong, 2006. / 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 (Ph. D.)--University of Hawaii at Manoa, 1995. / Includes bibliographical references (leaves 80-94). / Microfiche. / vii, 94 leaves, bound 29 cm

This research presents a pulse-by-pulse analysis of Oscillometric blood pressure waveform at systolic, diastolic and mean arterial pressure points. Using a mathematical optimization technique, pulses are characterized into component harmonic by minimizing the least square error. The results at the important pressure points are analyzed and compared for different subject using different waveform extraction techniques. Blood pressure is estimated using the harmonic parameters. The approach studies changes in the parameters as oscillometric blood pressure recording is done. 8 harmonic parameters are obtained from the pulse characterization and are used to estimate Systolic arterial Blood Pressure, Mean arterial Blood Pressure, and Diastolic arterial Blood Pressure. The estimates are compared with our reference value to determine which has the best agreement. The proposed method is further compared with Maximum Amplitude Algorithm and Pulse Morphology Algorithm. The effect of oscillometric waveform extraction methods on the proposed method is observed. The experiment established the fact that the extraction technique can alter the shape of oscillometric pulses. The methods were compared and it was observed that the used extraction methods did not make any significant difference on the accuracy, using this technique.

This study was aimed at determining whether the digital volume pulse waveform using the Pulse Sensor can be used to extract features related to arterial compliance. The Pulse Sensor, a low-cost photoplethysmograph, measures green light reflection in the finger and generates output, which is indicative of blood flow and can be read by the low-cost Arduino UNO™. The Pulse Sensor code was modified to increase the sampling frequency and to capture the data in a file, which is subsequently used for waveform analysis using programs written in the R system. Waveforms were obtained using the Pulse Sensor during two 30-s periods of seated rest, in each of 44 participants, who were between the ages of 20 and 80 years. For each cardiac cycle, the first four derivatives of the waveform were calculated and low-pass filtered by convolution before every differentiation step. The program was written to extract 19 features from the pulse waveform and its derivatives. These features were selected from those that have been reported to relate to the physiopathology of hemodynamics. Results indicate that subtle features of the pulse waveform can be calculated from the fourth derivative. Feature misidentification occurred in cases of saturation or low voltage and resulted in outliers; therefore, trimmed means of the features were calculated by automatically discarding the outliers. There was a high efficiency of extraction for most features. Significant relationships were found between several of the features and age, and systolic, diastolic, and mean arterial blood pressure, suggesting that these features might be employed to predict arterial compliance. Further improvements in experimental design could lead to a more detailed evaluation of the Pulse Sensor with respect to its capability to predict factors related to arterial compliance.

Direct measurement of blood pressure using a fluid-filled catheter and an electromechanical transducer is widely accepted in clinical practice. However, errors associated with the measurement are often not appreciated and these catheter-manometer systems are frequently unable to accurately reproduce applied pressures. To assess the accuracy of catheter-manometer systems used for invasive arterial blood pressure measurements, in vitro and in vivo evaluations were performed. The frequency response (described in terms of damped natural frequency and damping factor) for a variety of cannulae, pressure tubing and stopcocks (and combinations thereof) and their dependence on various parameters (catheter length, lumen diameter, fluid temperature and catheter material) were measured using an hydraulic pressure generator. The design and construction details of the pressure generator are presented. It was found that the damped natural frequency of the catheter-manometer system is directly proportional to lumen diameter of the pressure tubing/catheter. Furthermore, damping factor is inversely related to the damped natural frequency and stiffer catheter material (for identical radius ratios) results in higher damped natural frequency. Catheter length is inversely related to damped natural frequency and the resonant frequency decreases for an increase in fluid operating temperature. It was established that all catheter-manometer systems tested were under-damped (0.15 < β < 0.37) and that the damped natural frequency ranged from 10.5 Hz for 1500 mm to 27.0 Hz for pressure tubing of 300 mm in length. Furthermore, catheter-manometer systems which had pressure tubing in excess of 300 mm in length did not comply with the bandwidth requirements for accurate dynamic blood pressure measurement. For the in vivo assessment of the catheter-manometer system, the blood pressure waveform was analysed in the time and frequency domains. It was established that in 60 percent of the cases, the systolic pressure peak was higher when measured by a narrow bandwidth catheter-manometer system compared to that measured by a wide bandwidth system. Furthermore, values of dp/dt maximum were lower for wide bandwidth catheter-manometer systems than those measured by narrow bandwidth systems for heart rates above 90 beats per minute. In the frequency domain analysis, artifact was sometimes found to occur at frequencies higher than the bandwidth of the catheter-manometer system. This high frequency artifact was found to distort the blood pressure waveform and resulted in false high dp/dt and peak systolic pressures.

Yes / Inter-arm differences (IAD) ≥10mmHg in systolic blood pressure (BP) are associated with greater incidence of cardiovascular disease. The effect of ethnicity and the white coat effect (WCE) on significant systolic inter-arm differences (ssIADs) are not well understood. Methods: Differences in BP by ethnicity for different methods of BP measurement were examined in 770 people (300 White British, 241 South Asian, 229 African-Caribbean). Repeated clinic measurements were obtained simultaneously in the right and left arm using two BP-Tru monitors and comparisons made between the first reading, mean of second and third and mean of second to sixth readings for patients with, and without known hypertension. All patients had ambulatory monitoring (ABPM). WCE was defined as systolic Clinic BP ≥10mmHg higher than daytime ABPM. Results: No significant differences were seen in the prevalence of ssIAD between ethnicities whichever combinations of BP measurement were used and regardless of hypertensive status. ssIADs fell between the 1st measurement (161, 22%), 2nd/3rd (113, 16%) and 2nd-6th (78, 11%) (1st vs 2nd/3rd and 2nd-6th, p<0.001). Hypertensives with a WCE were more likely to have ssIADs on 1st, (OR 1.73 (95% CI 1.04-2.86), 2nd/3rd, (OR 3.05 (1.68-5.53) and 2nd-6th measurements, (OR 2.58 (1.22-5.44). Non-hypertensive participants with a WCE were more likely to have a ssIAD on their first measurement (OR 3.82 (1.77 -8.25) only. Conclusion: ssIAD prevalence does not vary with ethnicity regardless of hypertensive status but is affected by the number of readings, suggesting the influence of WCE. Multiple readings should be used to confirm ssIADs. / This report presents independent research funded by the National Institute for Health Research (NIHR).

Introdução: A hipertensão arterial apresenta controle insatisfatório em todo o mundo, fazendo-se necessária a busca de estratégias que incrementem seu controle. Neste contexto inserem-se a educação em saúde e a medida residencial da pressão arterial. Objetivos: Identificar o controle da hipertensão arterial em Unidades Básicas de Saúde antes e após implementação de programa educativo aos hipertensos; comparar o controle obtido pela medida casual com o controle pela medida residencial; e associar o controle com as demais variáveis do estudo. Casuística e Método: O estudo foi realizado com hipertensos de duas Unidades Básicas de Saúde da região oeste da cidade de São Paulo divididos em dois grupos, um que participou de programa educativo em hipertensão (grupo I) e outro que não participou (grupo II). A pressão arterial foi verificada antes e depois do programa educativo na unidade de saúde por enfermeiro e na residência pelo próprio paciente. Utilizou-se para medida da pressão arterial aparelho automático validado (OMROM-HEM 705 CP). O nível de significância adotado foi de 0,05. Resultados: Foram estudados 82 hipertensos com as seguintes características: sexo feminino (56,1%), cor branca (63,0%), com companheiro (68,0%), com ensino fundamental (70,7%), com renda familiar até 3 salários mínimos (56,1%) idade de 60,0±10,8 anos, índice de massa corporal (IMC) 29,4±5,4 Kg/m2 e circunferência da cintura 99,9±13,9 cm. Eram tabagistas 8,5% dos hipertensos, 24,4% consumiam bebida alcoólica, 40,7% foram considerados \"com presença\" de transtornos mentais comuns e 30,4% praticavam exercícios físicos. Quanto a atitudes frente ao tratamento 76,9 % relataram ter o hábito de medir a pressão, 74,4% afirmaram não interromper o tratamento e 75,6% referiram não faltar às consultas médicas. Foram classificados como não aderentes, pelo Teste de Morisky e Green 69,3% da amostra e 29,9% apresentaram moderada ou muita dificuldade de aderir ao tratamento. A MRPA dos pacientes que participaram do programa educativo (grupo I) apresentou significativo decréscimo ao término das intervenções (131,4±15,6 vs 127,3±17,4 para pressão sistólica; 79,2±12,2 vs 74,7±9,7 para pressão diastólica, p<0,05). O controle da pressão arterial aumentou nos dois grupos do estudo pela medida realizada na unidade de saúde (62,0% vs 71,0%, para grupo I e 40,0% vs 50,0% para grupo II). O controle pela medida da pressão na unidade de saúde foi similar ao controle residencial para hipertensos do grupo I (71,0% vs 68,3%) e menor do que o residencial para hipertensos do grupo II (50,0% vs 62,5%). O controle da pressão arterial avaliado na unidade de saúde se associou (p<0,05) com sexo feminino, renda salarial acima de três salários e prática de exercício físico. Valores mais elevadas da MRPA se associaram com menor renda salarial, presença de transtornos mentais comuns, não interrupção do tratamento, e moderada ou muita dificuldade de aderir ao tratamento. O efeito do avental branco foi mais expressivo nos pacientes que não participaram das intervenções educativas. Conclusão: O controle da pressão arterial aumentou após programa educativo para hipertensos e a MRPA pode ser usada para essa avaliação. A influência do observador foi mais expressiva em hipertensos do grupo II, em que não houve interação profissional-paciente / Introduction: The hypertension presents unsatisfactory control in the whole world, becoming necessary the search of strategies that develop its control. In this context it insert health education and home blood pressure measurement. Objectives: To identify the control of hypertension in Health Basic Units before and after implementation of educative program to hypertensive patients; to compare the control gotten for the casual measurement with the control for the home measurement; to associate the control with the variables studied. Material and Method: The study was carried out with patients of two Health Basic Units of the city of São Paulo divided in two groups, one that participated of educative program in hypertension (group I) and another who did not participate (group II). The blood pressure was measured before and after the educative program in the health unit for nurse and at home for the own patient. Validated automatic device was used for measuring blood pressure (OMROM-HEM 705 CP). The significant level adopted 0,05. Results: 82 patients with the following characteristics had been studied: feminine sex (56.1%), white (63.0%), married (68.0%), with primary school level (70.7%), with familiar income until 3 minimum wages (56.1%) age of 60,0±10,8 years, index body mass of 29,4±5,4 Kg/m2 and waist circumference of 99,9±13,9 cm. 8.5% were smokers, 24.4% alcohol consumers , 40.7% had been considered \"with presence\" of common mental disturbs and 30.4% practiced physical exercises. About the attitudes face to treatment 76.9% had told to have the habit to measure the pressure, 74.4% had affirmed not to interrupt the treatment and 75.6% had related not to absent to the medical visits. They had been classified as not adherent, by the Test of Morisky and Green, 69.3% of sample and 29.9% had presented moderate or much difficulty to adhere to the treatment. The HBPM of the patients who had participated of the educative program (group I) presented significant decrease to the ending of the interventions (131,4±15,6 versus 127,3±17,4 for systolic pressure; 79,2±12,2 vs 74,7±9,7 for diastolic pressure, p< 0,05). The control of blood pressure increased in the two groups of the study by measurement carried through in the health unit (62.0% vs 71.0%, for group I and 40.0% vs 50.0% for group II). The control by pressure measurement in the health unit was similar to the home control for patients of group I (71.0% versus 68.3%) and minor of home one for patients of group II (50.0% versus 62.5%). The control of the blood pressure evaluated in the health unit was associated (p< 0,05) with feminine sex, wage income above of three salaries and pratice of physical exercise. Higher values of HBPM was associated with minor wage income, presence of common mental disturbs, interruption of the treatment, and moderate or much difficulty to adhering to the treatment. The effect of the white coat was bigger in the patients who had not participated of the educative interventions. Conclusion: Hypertensive control increased after educative program for hypertensive patients and HBPM can be used for this evaluation. The influence of the observer was more intense for patients of group II, which did not have interaction professional-patient

Introdução: A hipertensão arterial apresenta controle insatisfatório em todo o mundo, fazendo-se necessária a busca de estratégias que incrementem seu controle. Neste contexto inserem-se a educação em saúde e a medida residencial da pressão arterial. Objetivos: Identificar o controle da hipertensão arterial em Unidades Básicas de Saúde antes e após implementação de programa educativo aos hipertensos; comparar o controle obtido pela medida casual com o controle pela medida residencial; e associar o controle com as demais variáveis do estudo. Casuística e Método: O estudo foi realizado com hipertensos de duas Unidades Básicas de Saúde da região oeste da cidade de São Paulo divididos em dois grupos, um que participou de programa educativo em hipertensão (grupo I) e outro que não participou (grupo II). A pressão arterial foi verificada antes e depois do programa educativo na unidade de saúde por enfermeiro e na residência pelo próprio paciente. Utilizou-se para medida da pressão arterial aparelho automático validado (OMROM-HEM 705 CP). O nível de significância adotado foi de 0,05. Resultados: Foram estudados 82 hipertensos com as seguintes características: sexo feminino (56,1%), cor branca (63,0%), com companheiro (68,0%), com ensino fundamental (70,7%), com renda familiar até 3 salários mínimos (56,1%) idade de 60,0±10,8 anos, índice de massa corporal (IMC) 29,4±5,4 Kg/m2 e circunferência da cintura 99,9±13,9 cm. Eram tabagistas 8,5% dos hipertensos, 24,4% consumiam bebida alcoólica, 40,7% foram considerados \"com presença\" de transtornos mentais comuns e 30,4% praticavam exercícios físicos. Quanto a atitudes frente ao tratamento 76,9 % relataram ter o hábito de medir a pressão, 74,4% afirmaram não interromper o tratamento e 75,6% referiram não faltar às consultas médicas. Foram classificados como não aderentes, pelo Teste de Morisky e Green 69,3% da amostra e 29,9% apresentaram moderada ou muita dificuldade de aderir ao tratamento. A MRPA dos pacientes que participaram do programa educativo (grupo I) apresentou significativo decréscimo ao término das intervenções (131,4±15,6 vs 127,3±17,4 para pressão sistólica; 79,2±12,2 vs 74,7±9,7 para pressão diastólica, p<0,05). O controle da pressão arterial aumentou nos dois grupos do estudo pela medida realizada na unidade de saúde (62,0% vs 71,0%, para grupo I e 40,0% vs 50,0% para grupo II). O controle pela medida da pressão na unidade de saúde foi similar ao controle residencial para hipertensos do grupo I (71,0% vs 68,3%) e menor do que o residencial para hipertensos do grupo II (50,0% vs 62,5%). O controle da pressão arterial avaliado na unidade de saúde se associou (p<0,05) com sexo feminino, renda salarial acima de três salários e prática de exercício físico. Valores mais elevadas da MRPA se associaram com menor renda salarial, presença de transtornos mentais comuns, não interrupção do tratamento, e moderada ou muita dificuldade de aderir ao tratamento. O efeito do avental branco foi mais expressivo nos pacientes que não participaram das intervenções educativas. Conclusão: O controle da pressão arterial aumentou após programa educativo para hipertensos e a MRPA pode ser usada para essa avaliação. A influência do observador foi mais expressiva em hipertensos do grupo II, em que não houve interação profissional-paciente / Introduction: The hypertension presents unsatisfactory control in the whole world, becoming necessary the search of strategies that develop its control. In this context it insert health education and home blood pressure measurement. Objectives: To identify the control of hypertension in Health Basic Units before and after implementation of educative program to hypertensive patients; to compare the control gotten for the casual measurement with the control for the home measurement; to associate the control with the variables studied. Material and Method: The study was carried out with patients of two Health Basic Units of the city of São Paulo divided in two groups, one that participated of educative program in hypertension (group I) and another who did not participate (group II). The blood pressure was measured before and after the educative program in the health unit for nurse and at home for the own patient. Validated automatic device was used for measuring blood pressure (OMROM-HEM 705 CP). The significant level adopted 0,05. Results: 82 patients with the following characteristics had been studied: feminine sex (56.1%), white (63.0%), married (68.0%), with primary school level (70.7%), with familiar income until 3 minimum wages (56.1%) age of 60,0±10,8 years, index body mass of 29,4±5,4 Kg/m2 and waist circumference of 99,9±13,9 cm. 8.5% were smokers, 24.4% alcohol consumers , 40.7% had been considered \"with presence\" of common mental disturbs and 30.4% practiced physical exercises. About the attitudes face to treatment 76.9% had told to have the habit to measure the pressure, 74.4% had affirmed not to interrupt the treatment and 75.6% had related not to absent to the medical visits. They had been classified as not adherent, by the Test of Morisky and Green, 69.3% of sample and 29.9% had presented moderate or much difficulty to adhere to the treatment. The HBPM of the patients who had participated of the educative program (group I) presented significant decrease to the ending of the interventions (131,4±15,6 versus 127,3±17,4 for systolic pressure; 79,2±12,2 vs 74,7±9,7 for diastolic pressure, p< 0,05). The control of blood pressure increased in the two groups of the study by measurement carried through in the health unit (62.0% vs 71.0%, for group I and 40.0% vs 50.0% for group II). The control by pressure measurement in the health unit was similar to the home control for patients of group I (71.0% versus 68.3%) and minor of home one for patients of group II (50.0% versus 62.5%). The control of the blood pressure evaluated in the health unit was associated (p< 0,05) with feminine sex, wage income above of three salaries and pratice of physical exercise. Higher values of HBPM was associated with minor wage income, presence of common mental disturbs, interruption of the treatment, and moderate or much difficulty to adhering to the treatment. The effect of the white coat was bigger in the patients who had not participated of the educative interventions. Conclusion: Hypertensive control increased after educative program for hypertensive patients and HBPM can be used for this evaluation. The influence of the observer was more intense for patients of group II, which did not have interaction professional-patient

Abstract Brain disorders such as epilepsy, dementia and other mental illnesses induce increasing costs on health care systems with aging populations. The most effective treatment of these disorders would be either prevention or intervention of the disorder before irreversible damage develops. However, despite the increased interest in different brain diseases, many of them are still detected too late. One reason for this is the lack of appropriate functional imaging modality that can critically sample the targeted physiological phenomenon. Furthermore, it has been shown that one imaging modality is not enough to cover brain functionality properly; a multimodal approach is required. The main goal of this thesis was to validate near-infrared spectroscopy (NIRS) for brain measurement and to integrate it into a multimodal neuroimaging setup that can critically sample basic human physiological phenomena. A novel key element was the combined use of NIRS with ultra-fast magnetic resonance encephalography (MREG), electroencephalography (EEG), continuous non-invasive blood pressure and anesthesia monitoring as a synchronous system. This unique multimodal neuroimaging set-up with a new functional magnetic resonance imaging sequence, MREG, can sample human brain physiology at 10 Hz sampling rate without cardiorespiratory aliasing. The implemented setup was successfully used in scanning multiple patient and control populations. With the help of critical sampling rate, non-stationarity between the measured signals reflecting brain pulsations could be detected. Combined NIRS and EEG showed the capability to monitor therapeutic opening of the blood-brain barrier during treatment of central nervous system lymphoma for the first time in humans. Furthermore, our multimodal neuroimaging setup enabled the mapping of the recently described brain avalanches and glymphatic pulsation mechanisms of the brain. In conclusion, the ultra-fast multimodal laboratory with integrated NIRS offers novel and more comprehensive views on basic brain physiology. The measures from this thesis also have the potential to offer new, quantitative biomarkers for the detection of different brain disorders prior to irreversible damage. / Tiivistelmä Aivosairaudet kuten epilepsia, dementia ja muut mielenterveyden häiriöt aiheuttavat kasvavissa määrin kuluja ikääntyvien ihmisten terveydenhuollossa. Näiden tautien tehokkain hoitokeino olisi joko ennaltaehkäisy tai varhainen havaitseminen ennen peruuttamattomien kudosvaurioiden kehittymistä. Lisääntyneestä kiinnostuksesta huolimatta monet aivosairaudet havaitaan edelleen liian myöhään. Osasyy tähän on sopivan toiminnallisen kuvausmenetelmän puuttuminen, jolla voitaisiin kuvata haluttu fysiologinen ilmiö riittävän nopeasti. Onkin osoitettu, ettei yksittäinen kuvausmenetelmä riitä aivojen toiminnan riittävän tarkkaan ymmärtämiseen, vaan siihen tarvitaan eri menetelmien yhdistämistä. Tämän väitöskirjatutkimuksen päätarkoituksena oli arvioida lähi-infrapunaspektroskopian (NIRS) soveltuvuutta aivojen toiminnan mittaamisessa sekä integroida se osaksi multimodaalista neurokuvantamisjärjestelmää. Uutena elementtinä NIRS:iä käytettiin yhdessä ultranopean magneettiresonanssienkefalogrammin (MREG), aivosähkökäyrän (EEG), jatkuva-aikaisen kajoamattoman verenpaineen mittauksen ja anestesiamonitoroinnin kanssa samanaikaisesti, ajallisesti synkronoituna. Yhdessä uuden toiminnallisen magneettikuvaussekvenssin, MREG:n, kanssa tällä ainutlaatuisella multimodaalisella neurokuvantamisjärjestelmällä voidaan kuvata ihmisen aivojen perusfysiologiaa 10 Hz näytteistysnopeudella ilman sydämen sykkeen ja hengityksen laskostumista. Toteutetulla multimodaalisella mittausjärjestelmällä tehtiin useita onnistuneita kuvauksia eri potilasryhmillä ja terveillä koehenkilöillä. Kriittisen näytteistämisen ansiosta voitiin havaita epästationaarisuutta aivojen pulsaatioita heijastelevien signaalien välillä. NIRS:n ja EEG:n samanaikainen mittaaminen mahdollisti ensimmäistä kertaa ihmisen veriaivoesteen aukeamisen monitoroinnin keskushermostolymfoomapotilaiden hoidossa. Lisäksi multimodaalinen neurokuvantamisjärjestelmä mahdollisti hiljattain havaittujen aivojen vyöryjen (engl. avalanches) ja glymfaattisten pulsaatioiden kartoittamisen. Yhteenvetona voidaan todeta, että väitöskirjatyön aikana toteutettu multimodaalinen laboratorio yhdessä NIRS:n kanssa mahdollistaa aivojen perusfysiologian edistyksellisen ja tarkan tutkimisen. Nyt kehitetyt mittarit saattavat myös tarjota uusia, kvantitatiivisia biomarkkereita eri aivosairauksiin ennen vakavien vaurioiden syntymistä.

This thesis deals with the design and realization of a prototype of non-invasive blood pressure monitor based on the principle of Korotkoff sound detection. The design compares this method of measuring blood pressure with other methods. This design of an automated measuring system, which is controlled by a microprocessor, utilizes the scanning of Korotkoff sounds with an electret microphone placed in the cuff. The microphone signal is then amplified, filtered and adjusted for evaluation. The prototype uses processor-controlled inflation by the compressor and deflation of the cuff by a valve that is open without applied voltage.