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Xiang Xiaoyan. / Thesis (M.Phil.)--Chinese University of Hong Kong, 2006. / Includes bibliographical references. / Abstracts in English and Chinese. / Chapter Chapter 1 --- Introduction --- p.1 / Chapter 1.1 --- Background of Hypertension --- p.1 / Chapter 1.1.1 --- Definition of Blood Pressure --- p.1 / Chapter 1.1.2 --- Hypertension and Its Prevalence --- p.2 / Chapter 1.2 --- Blood Pressure Measurement Techniques --- p.5 / Chapter 1.2.1 --- Invasive Blood Pressure Measurement Techniques --- p.5 / Chapter 1.2.2 --- Non-invasive Blood Pressure Measurement Techniques --- p.6 / Chapter 1.3 --- Accurate BP Measurements --- p.12 / Chapter 1.3.1 --- Error Source for BP Measurement by Conventional Techniques --- p.12 / Chapter 1.3.2 --- Accurate BP Measurement --- p.13 / Chapter 1.4 --- Objectives of the Thesis --- p.15 / Chapter 1.5 --- Organization of the Thesis --- p.16 / References --- p.17 / Chapter Chapter 2 --- Current Standards for the Conventional Blood Pressure Measurement Devices --- p.20 / Chapter 2.1 --- Introduction --- p.20 / Chapter 2.2 --- Current Standards for the Cuff-based BP Measurement Devices --- p.21 / Chapter 2.2.1 --- AAMI Standard --- p.21 / Chapter 2.2.2 --- BHS Protocol --- p.22 / Chapter 2.2.3 --- Other Protocols --- p.23 / Chapter 2.3 --- Comparison of the 2002 AAMI and 1993 BHS Protocols - Protocol Setup --- p.25 / Chapter 2.4 --- Comparison of the 2002 AAMI and 1993 BHS Protocols 一 Accuracy Criteria --- p.29 / Chapter 2.5 --- Relationship between the AAMI Accuracy Criteria and the BHS Grading System --- p.31 / Chapter 2.5.1 --- Theoretical Mapping Relationship --- p.31 / Chapter 2.5.2 --- Application of the Mapping Model: Estimate the BHS Grades from the Reported Sample ME and SD --- p.34 / Chapter 2.5.3 --- Application of the Mapping Model: Explain the Evaluation of the Results from the Clinical Survey by the ESH --- p.36 / Chapter 2.6 --- Discussion --- p.36 / References --- p.40 / Chapter Chapter 3 --- Distribution Analysis of the Blood Pressure Measurement Errors --- p.42 / Chapter 3.1 --- Introduction --- p.42 / Chapter 3.2 --- Error Distribution Estimated from the Published Data --- p.43 / Chapter 3.2.1 --- Methodology --- p.43 / Chapter 3.2.2 --- Data Analysis --- p.44 / Chapter 3.2.3 --- Session Summary --- p.46 / Chapter 3.3 --- Error Distribution Estimated from the Experimental Data --- p.46 / Chapter 3.3.1 --- BP Measurement Error Obtained from Automatic BP Meter --- p.46 / Chapter 3.3.2 --- Distribution Analysis by the Normal Quantile-Quantile Plot --- p.47 / Chapter 3.3.3 --- Background of Student's t Distribution --- p.48 / Chapter 3.3.4 --- Parameter Estimation - Maximum Likelihood Method --- p.50 / Chapter 3.3.5 --- Goodness-of-fit Test - Kolmogorov-Smirnov Test --- p.53 / Chapter 3.3.6 --- Goodness-of-fit Test ´ؤ Chi-Square Test --- p.56 / Chapter 3.4 --- Discussion --- p.63 / References --- p.65 / Chapter Chapter 4 --- A Model Based Study of the Parameters Used by Existing Standards --- p.67 / Chapter 4.1 --- Introduction --- p.67 / Chapter 4.2 --- Background of Method Comparison Study --- p.68 / Chapter 4.2.1 --- Four Areas in Method Comparison Study --- p.68 / Chapter 4.2.2 --- Analysis of Previous Methodology and Statistical Parameters --- p.70 / Chapter 4.3 --- Theoretical Mapping Relationship: Based on the General t Distribution --- p.72 / Chapter 4.3.1 --- "Relationship among CP5, CP10 and CP15 in Each Grade for the 1993 BHS Protocol" --- p.76 / Chapter 4.3.2 --- Relationships between the Criteria in Each Grade for the 1993 BHS Protocol and the AAMI Standard --- p.77 / Chapter 4.3.3 --- Comparison of Parameters --- p.80 / Chapter 4.4 --- Mean of the Absolute Errors (MAE) and Its Estimation --- p.81 / Chapter 4.4.1 --- The Relationship between MAE and Other Parameters --- p.81 / Chapter 4.4.2 --- Analysis of the Example Data --- p.84 / Chapter 4.4.3 --- Estimation of MAEt --- p.84 / Chapter 4.5 --- Discussion --- p.88 / References --- p.90 / Chapter Chapter 5 --- Experimental Study and an Evaluation Protocol Proposed for the Wearable BP Measurement Devices --- p.92 / Chapter 5.1 --- Introduction --- p.92 / Chapter 5.2 --- Description of the Experiment --- p.93 / Chapter 5.3 --- Data Analysis --- p.95 / Chapter 5.3.1 --- Data Used for the Study --- p.95 / Chapter 5.3.2 --- Error Distribution Analysis --- p.96 / Chapter 5.3.3 --- Evaluation of the Automatic BP Meter and the PTT-Based BP Measurement Device by AAMI and 1993 BHS Standards --- p.99 / Chapter 5.3.4 --- Evaluation the Automatic BP Meter and the PTT-Based BP Measurement Device by the Proposed Parameter --- p.101 / Chapter 5.4 --- Proposed Evaluation Procedure --- p.101 / Chapter 5.4.1 --- Introduction --- p.101 / Chapter 5.4.2 --- Determination of Parameters and Criteria --- p.102 / Chapter 5.4.3 --- Proposed Evaluation Procedure --- p.103 / Chapter 5.5 --- Discussion --- p.105 / References --- p.108 / Chapter Chapter 6 --- Conclusion and Future Work --- p.110 / Chapter 6.1 --- Conclusion and Major Contributions --- p.110 / Chapter 6.2 --- Future Works --- p.113 / References --- p.115 / Appendix A Deviation of Some Equations --- p.116 / Chapter A.1 --- CP for Certain Limit of L as a Function of ME and SD --- p.116 / Chapter A.2 --- MAE as a Function of Location and Scale Parameters --- p.119 / Chapter A.3 --- "Relationship between ME, MAE and Root Mean Squared Error (RMSE) if the error distribution is unknown" --- p.121 / Appendix B List of Publications and Awards Related to This Study --- p.123

心血管疾病持續成為世界上第一大死亡原因。在眾多危險因素中，動脈血壓，尤其是夜間血壓和血壓變化率，是心血管疾病發病率和死亡率的關鍵指標。 / 由於需要用到充氣式袖帶，現有的血壓測量技術只能提供瞬時血壓，並且使用起來極不舒適。因此，本文致力於研究另一種無袖帶式血壓測量方法。此方法的原理基於血壓波在血管上的傳導速度，即脈搏波傳導速度（PWV）取決於血壓作用下的血管力學特性。因此，血壓可以從脈搏波傳導速度，或者其倒數：脈搏波傳輸時間（PTT）估計得到。由於脈搏波傳導時間可以方便的從心電信號及光電容積描記信號獲取，這種新型的無袖帶式血壓測量技術近年來備受關注。 / 現有的基於脈搏波傳輸時間的血壓估計方法建立於一個被動的，薄壁的和均質的血管模型。但是，真實的血管卻是由彈性蛋白，膠原纖維和平滑肌共同組成的具有特殊層次結構的管道。事實上，以往許多研究已經表明了血管緊張度（VSM tone），即血管壁平滑肌細胞的激活程度，能顯著改變血管力學特性進而使脈搏波傳輸時間與血壓的關係惡化。特別地，血管緊張度主要受控于自主神經系統，尤其是交感神經系統。因此，本論文的目的在於研究自主神經系統對基於脈搏波傳輸時間的血壓估計的影響。 / 首先，基於血管微結構力學模型和Bramwell-Hill公式，本文建立了一個基於血管組分的脈搏波傳輸時間-血壓模型。并在此基礎上，推導出一個融合了血管結構和功能特性的解析數學公式來表徵脈搏波傳導時間和血壓的關係。仿真結果顯示，隨著血管緊張度增高，脈搏波傳輸時間-血壓曲綫會移向右上方，造成滯變現象（hysteresis）。 / 其次，爲了研究自主神經系統對血壓，脈搏波傳輸時間及心率的調節機制，本文利用時頻分析技術，對來自9個健康測試者跑步運動前後的實驗數據進行了分析。結果顯示，僅心率這一參數表現出運動中首先迷走神經活動減弱，然後交感神經增強的機制。此外，分析結果表明脈搏波傳輸時間與血壓的關係是頻率相關的。 / 爲了進一步研究自主神經系統在吞咽動作過程中對心血管參數的調控作用，本文設計了喝水實驗。對32個健康測試者的實驗數據分析結果表明，在喝水過程中，心率和血壓顯著上升，脈搏波傳輸時間顯著下降。另一方面，基於之前脈搏波傳輸時間與血壓的頻變關係的研究發現，本文設計了一種新的基於脈搏波傳輸時間，利用頻段特定的序列技術，來估計壓力反射敏感性（BRS）的新方法，並利用喝水實驗數據進行了驗證。結果顯示，利用此方法估計和利用傳統的利用血壓計算出的壓力反射敏感性具有高相關性（喝水前，中，后過程中，相關係數分別為0.90，0.70和0.81）。 / 最後，爲了驗證自主神經系統調控下的血管緊張度對脈搏波傳輸時間和血壓關係的影響，本文對來自46名測試者，其中包括17名心血管疾病患者，在人體仰臥姿態下的漸進式腳踏車運動實驗中的數據進行了分析。結果證實了仿真實驗中顯示的脈搏波傳輸時間和血壓的滯變現象。另外，本文提出了兩個新型量化指標衡量此滯變現象，即AreaN和ΔSBP20。結果顯示，相比于健康人，心血管疾病患者的滯變現象幅度顯著減弱，這與此類患者通常伴隨有交感神經系統過度活躍相關。基於以上發現，本文進一步提出利用AreaN和ΔSBP20來評估交感神經系統功能的建議。 / 綜上所述，本論文從理論和實驗的雙重角度研究了自主神經系統對脈搏波傳輸時間和血壓關係的影響。此工作將有利於提高基於脈搏波傳輸時間的血壓估計技術的準確度，并進一步對控制心血管疾病做出貢獻。 / Cardiovascular diseases (CVDs) remain the number one cause of death worldwide. Amongst various risk factors, arterial blood pressure (BP), especially BP measured during nighttime, and BP variability are major indicators of cardiovascular morbidity and mortality. / Most of the state-of-the-art BP meters are designed with an inflatable cuff, which provide snapshots of BP and are uncomfortable during measurements. An alternative cuffless BP measurement approach is therefore studied in this work. The estimation principle is derived based on the fact that velocity of a pressure wave propagating along an artery, i.e., pulse wave velocity (PWV) is related to the pressure-dependent mechanical property of the artery. Thus, BP can be possibly estimated from PWV, or its reciprocal, pulse transit time (PTT), which can be conveniently acquired from electrocardiogram and photoplethysmogram without using an inflatable cuff. / The current PTT-based BP estimation was built on a model that assumes the artery to be a passive, thin-wall and homogeneous tube. However, arterial wall in reality exhibits a specific layered structure and consists of elastin, collagen fibers and smooth muscles. In fact, the PTT-BP relationship was found by many studies to be easily deteriorated by vasoconstriction/dilation, which reflects the vascular smooth muscle (VSM) activation level, i.e., VSM tone. In particular, innervating most blood vessels, the autonomic nervous system (ANS), primarily sympathetic nervous system, plays an important role in determining the arterial mechanical behavior thus PTT-BP relationship via regulating the VSM tone. It is therefore the aim of this thesis to investigate the effects of ANS on the PTT-based BP estimation. / Firstly, a constituent-based PTT-BP model was developed in the thesis, based on the micro-structurally motivated arterial mechanical model and Bramwell-Hill equation. Specifically, analytic PTT-BP relationship incorporating arterial structural and functional properties was deduced. Theoretical effects of various arterial properties on the relationship have been evaluated by simulation. The results revealed that PTT-BP curve will shift to the top right when VSM tone elevates, producing PTT-BP hysteresis. / Next, the mechanism of regulation of BP, PTT as well as heart rate (HR) by ANS was evaluated in 9 normotensive subjects in treadmill exercise by using time-frequency technique. Vagal withdrawal and subsequent sympathetic activity enhancement by exercise have been observed in only HR. In addition, the results indicate a frequency-dependent PTT-BP relationship. / Then we conducted water drinking experiments in a total of 32 healthy subjects to investigate the ANS controlled cardiovascular responses by the act of swallowing. Significant increment in HR and BP, and decrease in PTT were observed during drinking. On the other hand, considering the frequency-dependent nature of PTT-BP relationship, a novel method that estimates baroreflex sensitivity (BRS) from PTT based on the band-specified sequence technique has been proposed. The results showed high correlations between BRS estimated from BP and PTT. (γ=0.90, 0.70 and 0.81 before, during and after drinking respectively). / Lastly, the effects of ANS mediated VSM tone on the PTT-BP relationship were validated in 46 subjects including 17 patients with CVDs in graded bicycle exercise stress test in supine position. The results demonstrated PTT-BP hysteresis as predicted by the simulation. Furthermore, two novel parameters, i.e., AreaN and ΔSBP20 were proposed to evaluate the hysteresis phenomenon. Significant attenuation was observed in CVD patients with sympathetic overactivity. The two quantifications were proposed accordingly to be indices for assessing sympathetic function. / To conclude, this work addressed the effects of ANS on the PTT-BP relationship from both theoretical and experimental aspects. The work can help to improve the accuracy of PTT-based BP estimation and CVD control. / Detailed summary in vernacular field only. / Detailed summary in vernacular field only. / Detailed summary in vernacular field only. / Detailed summary in vernacular field only. / Detailed summary in vernacular field only. / Detailed summary in vernacular field only. / Detailed summary in vernacular field only. / Detailed summary in vernacular field only. / Liu, Qing. / Thesis (Ph.D.)--Chinese University of Hong Kong, 2013. / Includes bibliographical references. / Electronic reproduction. Hong Kong : Chinese University of Hong Kong, [2012] System requirements: Adobe Acrobat Reader. Available via World Wide Web. / Abstracts also in Chinese. / Abstract --- p.i / Acknowledgement --- p.v / List of figures --- p.vi / List of tables --- p.x / List of abbreviations --- p.xi / Chapter Chapter 1. --- Introduction --- p.1 / Chapter 1.1. --- Current Status of Blood Pressure Management --- p.1 / Prevalence of Cardiovascular Diseases --- p.1 / Healthcare System Transformation --- p.2 / Blood Pressure A Crucial Role in CVD Control --- p.4 / Chapter 1.2. --- Overview of Blood Pressure Measurement Techniques --- p.7 / Chapter 1.3. --- Motivations and Objectives of the Thesis --- p.15 / Chapter 1.4. --- Organization of the Thesis --- p.16 / References: --- p.17 / Chapter Chapter 2. --- Basics of Cardiovascular System, Autonomic Nervous System and PTT-BP Relationship --- p.20 / Chapter 2.1. --- Cardiovascular System --- p.20 / Heart Physiology --- p.20 / Arterial Physiology --- p.24 / Chapter 2.2. --- Autonomic Nervous System --- p.35 / Autonomic Histology and Pharmacology --- p.35 / Autonomic Nervous Control of Cardiovascular System --- p.37 / Assessment of ANS Activity --- p.41 / Chapter 2.3. --- PWV and Its Relationship with BP --- p.43 / Pulse Wave Velocity --- p.44 / PWV-BP Relationship --- p.50 / Chapter 2.4. --- Section Summary --- p.54 / References: --- p.55 / Chapter Chapter 3. --- A Model-based Study on the Effects of Arterial Properties on the Relationship between Pulse Transit Time and Blood Pressure --- p.62 / Chapter 3.1. --- Introduction to Constitutive Modeling of Arteries --- p.62 / Experimental Methods --- p.63 / Modeling of Mechanical Behavior: Pressure-Radius Relationship --- p.64 / Chapter 3.2. --- A Novel Constitutive Model of the Relationship between PTT and BP --- p.76 / Chapter 3.3. --- Simulation Study of Effects of Arterial Properties on the PTT-BP Relationship --- p.82 / Chapter 3.4. --- Section Summary --- p.93 / References: --- p.94 / Chapter Chapter 4. --- Evaluation Study on the Autonomic Nervous System Control of Heart Rate, Blood Pressure and Pulse Transit Time Before and After Dynamic Exercise --- p.96 / Chapter 4.1. --- Introduction --- p.96 / Chapter 4.2. --- Methodology --- p.98 / Experiment Protocol --- p.98 / Signal Processing and Spectral Estimation --- p.99 / Chapter 4.3. --- Results --- p.101 / Chapter 4.4. --- Discussion --- p.104 / Chapter 4.5. --- Section Summary --- p.108 / References: --- p.110 / Chapter Chapter 5. --- Investigation on Autonomic Nervous System Control of Heart Rate, Blood Pressure and Pulse Transit Time During Water Drinking --- p.113 / Chapter 5.1. --- Responses of HR, BP and PTT during Water Drinking --- p.113 / Chapter 5.1.1. --- Introduction --- p.113 / Chapter 5.1.2. --- Methodology and Results --- p.115 / Chapter 5.1.3. --- Discussion and Conclusion --- p.118 / Chapter 5.2. --- Potential Application of PTT in Baroreflex Sensitivity Assessment --- p.121 / Chapter 5.2.1. --- Introduction --- p.121 / Chapter 5.2.2. --- Methodology --- p.122 / Chapter 5.2.3. --- Discussion and Conclusion --- p.125 / Chapter 5.3. --- Section Summary --- p.127 / References: --- p.129 / Chapter Chapter 6. --- Experimental Validation of the ANS Effects on the Relationship between Pulse Transit Time and Blood Pressure in Human Stress Test --- p.131 / Chapter 6.1. --- Introduction --- p.131 / Chapter 6.2. --- Methodology --- p.133 / Chapter 6.3. --- Results --- p.137 / Chapter 6.4. --- Discussion and Conclusion --- p.139 / Chapter 6.5. --- Section Summary --- p.144 / References: --- p.145 / Chapter Chapter 7. --- Conclusions and Suggestions for Future Work --- p.148 / Chapter 7.1. --- Summary --- p.148 / Chapter 7.1.1. --- A model-based study on the effects of arterial properties on the PTT-BP relationship --- p.148 / Chapter 7.1.2. --- Evaluation study on the ANS control of HR, BP and PTT before and after dynamic exercise --- p.149 / Chapter 7.1.3. --- Investigation on ANS control of HR, BP and PTT during water drinking --- p.150 / Chapter 7.1.4. --- Experimental validation of the ANS mediated VSM tone on the PTT-BP relationship --- p.151 / Chapter 7.2. --- Suggestions for Future Work --- p.152 / Chapter 7.2.1. --- Modifications on the constituent-based PTT-BP model --- p.152 / Chapter 7.2.2. --- Improvement of PTT-based BP estimation by considering VSM tone effects --- p.153 / Chapter 7.2.3. --- Improvement of PTT-based BP estimation by considering the frequency-dependent PTT-BP relationship --- p.154 / Chapter 7.2.4. --- Validation of the PTT-BP hysteresis quantifications to be indicators of sympathetic function --- p.154 / References: --- p.155 / Appendix --- p.156 / List of Publications --- p.156

Thesis (Ph. D.)--University of Florida, 2003. / Title from title page of source document. Includes vita. Includes bibliographical references.

This study examined the effects of isometric handgrip (IHG) training on resting blood pressure (RBP), heart rate variability (HRV) and blood pressure variability (BPV) in older adults with hypertension. Nine subjects performed four 2-minute IHG contractions at 30% maximal voluntary contraction (MVC) 3 days/week for 10 weeks and 8 subjects served as controls. Power spectral analysis (PSA) of HRV and BPV was used to assess changes in modulation of the autonomic nervous system. After training, there was a marked attenuation in arterial pressure and evidence for a shift in HR.V and BPV sympathovagal balance. There was a reduction in systolic blood pressure (156 ± 9.4 to 137 ± 7.8 mm Hg; p<0.05), diastolic blood pressure (82 ± 9.3 to 75 ± 10.9 mm Hg; N.S), mean arterial pressure (107 ± 8.53 to 96 ± 8.7 mm Hg; p<0.05) and resting heart rate (RHR) (70 ± 14.2 to 68 ± 12.1 beats/min). In addition, PSA of HRV showed a decrease in sympathetic modulation represented by low frequency (LF) area, an increase in parasympathetic modulation represented by high frequency (HF) area (p<0.05) and a decrease in LF:HF area ratio. After training, BPV PSA showed a decrease in systolic blood pressure LF area (p<0.05), an increase in HF area (p<0.05) and decrease in LF:HF area (p<0.05). Similar, but non-significant changes occurred in diastolic BPV. It is concluded that isometric training at a moderate intensity can elicit a hypotensive response and can potentially alter sympathovagal balance of HRV and BPV in older adults with hypertension. / Thesis / Master of Science (MS)

Thesis (M.S.)--University of Michigan, 2002. / eContent provider-neutral record in process. Description based on print version record. Includes bibliographical references (leaves 51-61).

Thesis (M.S.)--University of Michigan, 2002. / Includes bibliographical references (leaves 51-61).

Thesis (MMed (Obstetrics and Gynaecology))--University of Stellenbosch, 2010. / ENGLISH ABSTRACT: OBJECTIVE: The aim of this study was to compare the accuracy of non-invasive blood pressure measurements, using automated and manual devices, against invasive intra-arterial blood pressure measurements in patients with pre-eclampsia, during a hypertensive blood pressure peak. STUDY DESIGN: In this prospective study, women admitted to the Obstetrics Critical Care Unit, with confirmed pre-eclampsia and acute severe hypertension, who had an intra-arterial line in situ, were asked to participate. During an intra-arterial blood pressure peak, both an automated oscillometric and a blinded manual aneroid sphygmomanometric blood pressure was recorded. These two methods of blood pressure measurements were compared to intra-arterial blood pressure measurements. The accuracy of a mean arterial pressure (MAP) ≥ 125mmHg in detecting a systolic blood pressure (SBP) ≥ 160mmHg, using all three methods, was also determined. RESULTS: There was poor correlation between intra-arterial SBP and automated and manual SBP (r = 0.34, p < 0.01; r = 0.41, p < 0.01 respectively). The mean differences between automated and manual SBP compared to the intra-arterial SBP was 24 ± 17mmHg (p < 0.01) and 20 ± 15 mmHg (p < 0.01) respectively. There was better correlation between intra-arterial diastolic blood pressure (DBP) and automated and manual DBP (r = 0.61, p < 0.01; r = 0.59, p < 0.01 respectively). The mean differences of the automated and manual DBP was not statistically significant when compared to the intra-arterial DBP. There was poor correlation between the intra-arterial MAP and the automated MAP (r = 0.44, p < 0.01) and good correlation with the manual MAP (r = 0.56, p < 0.01). The mean differences of the automated and manual MAP were statistically significant (5 ± 13mmHg, p < 0.01; 8 ± 11mmHg, p < 0.01 respectively). The sensitivity of automated and manual methods in detecting a SBP ≥ 160mmHg was 23.4% and 37.5% respectively. A MAP ≥ 125mmHg in detecting a SBP ≥ 160mmHg, when using intra-arterial, automated and manual methods of blood pressure measurements showed low sensitivity (35.9%, 21.9% and 17.2% respectively). CONCLUSION: This study demonstrated that both the automated and manual methods of blood pressure measurements were not an accurate measure of the true systolic intra-arterial blood pressure, when managing pre-eclamptic patients with acute severe hypertension. In such situations, intra-arterial blood pressure monitoring should be used when possible. When this is not possible, manual aneroid sphygmomanometry is recommended. Underestimating blood pressure, particularly SBP, may lead to severe maternal morbidity and mortality. / AFRIKAANSE OPSOMMING: DOELWIT: Die doel van hierdie studie is om die akuraatheid van nie invasiewe bloeddruk metings, wanneer geneem met outomatiese en manuele aparate, te vergelyk met intra-arteriele bloed druk metings in pasiente met pre-eklampsie, gedurende ‘n hipertensiewe bloeddruk piek. STUDIE ONTWERP: In hierdie prospektiewe beskrywende dwarssnit studie, was pasiente wat toegelaat was tot die Obstetriese Kritieke Sorg Eenheid met pre-eklampsie, akute erge hipertensie en ‘n intra-arteriele lyn in situ gevra om deel te neem. Gedurende ‘n intra-arteriele erge hipertensiewe piek is beide die outomatiese ossilometriese en die geblinde aneroide sfigmometer lesing neergeskryf. Hierdie twee metodes van non invasiewe bloed druk lesings is vergelyk met intra-arteriele bloed druk lesings. Die akuraatheid van ‘n gemiddelde arteriele bloeddruk ≥ 125mmHg om ‘n sistoliese bloeddruk ≥ 160mmHg op te tel met gebruik van al die drie metodes is ook uitgewerk. RESULTATE: Daar was swak korrelasie tussen intra-arteriele sistoliese bloed druk (SBD) metings en outomatiese en manuele SBD (r = 0.34, p < 0.01; r = 0.41, p < 0.01 onderskeidelik). Die gemiddelde verskille tussen outomatiese en manuele SBD wanneer vergelyk met intra-arteriele SBD was 24 ± 17mmHg (p < 0.01) en 20 ± 15 mmHg (p < 0.01) onderskeidelik. Beter korrelasie was gevind tussen intra-arteriele diastoliese bloed druk (DBD) en outomatiese en manuele DBD (r = 0.61, p < 0.01; r = 0.59, p < 0.01 onderskeidelik). Die gemiddelde verskille tussen outomatiese en manuele DBD wanneer dit vergelyk was met intra-arteriele DBD was nie statisties betekenisvol nie. Daar was swak korrelasie tussen intra arteriele gemiddelde arteriele bloeddruk en outomatiese gemiddelde arteriele bloeddruk (r = 0.44, p < 0.01) en beter korrelasie met manuele gemiddelde arteriele bloeddruk (r = 0.56, p < 0.01). Die gemiddelde verskille van outomatiese en manuele gemiddelde arteriele bloeddruk was betekenisvol (5 ± 13mmHg, p < 0.01; 8 ± 11mmHg, p < 0.01 onderskeidelik). Die sensitiwiteit van outomatiese en manuele metodes om ‘n intra-arteriele SBD ≥ 160mmHg op te tel was 23.4% en 37.5% onderskeidelik. Die vermoë van ‘n gemiddelde arteriele bloeddruk ≥ 125mmHg om ‘n SBD ≥ 160mmHg op te tel, gemeet deur intra-arterieel, outomatiese en manuele metodes het lae sensitiwiteit getoon (35.9%, 21.9% en 17.2% onderskeidelik). GEVOLGTREKKING: Hierdie studie het gedemonstreer dat outomatiese en manuele metodes van bloeddruk meting nie akurate metodes is om ware intra-arteriele sistoliese bloeddruk te meet in pasiente met erge pre-eklampsie tydens ‘n erge hipertensiewe episode nie. In hierdie omstandighede moet intra-arteriele bloeddruk gemeet word indien beskikbaar. Indien dit nie beskikbaar is nie moet die manuele aneroiede sfigmomanometer gebruik word. Onderskatting van bloeddruk, veral sistoliese bloeddruk, kan lei tot erge moederlike morbiditeit en mortaliteit.

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&lt;0.05 in both experiments) and a moderate inverse correlation with diastolic blood pressure (DBP) (r = 0.687, p&lt;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.