Journal of biomedical engineering最新文献_第4页

Volume profiles obtained by a conductimetric method 用电导法得到的体积轮廓

Journal of biomedical engineering Pub Date : 1993-07-01 DOI: 10.1016/0141-5425(93)90001-F

M.C. Herrera, M.E. Valentinuzzi, J.M. Olivera

{"title":"Volume profiles obtained by a conductimetric method","authors":"M.C. Herrera, M.E. Valentinuzzi, J.M. Olivera","doi":"10.1016/0141-5425(93)90001-F","DOIUrl":"10.1016/0141-5425(93)90001-F","url":null,"abstract":"<div><p>One problem faced by intracardiac conductance volumetry is the non-uniform distribution of the injected current. Salo, in 1989, proposed a method to correct this undesirable effect. The objective here is to test Salo's method in known volumes of simple geometry by obtaining volume profiles. A plastic rod with 15 metallic rings simulated the conductance catheter. Five sections were used for the resistance measurements employing the upper electrode as fixed current source and the lowest one as the shifting source. This is part of Salo's procedure. The source-to-section distance was measured from the moving source to the section (linear definition) or using the equivalent distance concept (Salo's). Thereafter, each sectional resistance set of values was plotted as a function of the inverse of the source-to-section distance (either definition) elevated to an empirical exponent k to obtain the corrected sectional resistance by extrapolation back to zero of the regression line, i.e., a value produced by a source theoretically placed at infinity. In addition, a mathematical analysis was attempted, searching for an optimum k based on minimum volume error. The best volume profiles for two cylinders and a frustum were obtained with k = 2 using the linear definition of distance (errors of − 3.49%, − 1.25% and − 3.65%, respectively). Moreover, the frustum angle was determined within 0.4° (2.7%) of the real value. The theoretical analysis led to an inverse logarithmic relationship between the exponent k and the source-to-section distance. In conclusion: (1) The linear definition of source-to-section distance applying Salo's correction with k = 2 produced the smallest errors, both in volume and angle estimations; (2) there is no optimum k; (3) for very large distance, k tends to a low value (about 0.8); (4) for heart sizes, k = 2.1 can be suggested for all sections.</p></div>","PeriodicalId":75992,"journal":{"name":"Journal of biomedical engineering","volume":"15 4","pages":"Pages 267-273"},"PeriodicalIF":0.0,"publicationDate":"1993-07-01","publicationTypes":"Journal Article","fieldsOfStudy":null,"isOpenAccess":false,"openAccessPdf":"https://sci-hub-pdf.com/10.1016/0141-5425(93)90001-F","citationCount":null,"resultStr":null,"platform":"Semanticscholar","paperid":"19346910","PeriodicalName":null,"FirstCategoryId":null,"ListUrlMain":null,"RegionNum":0,"RegionCategory":"","ArticlePicture":[],"TitleCN":null,"AbstractTextCN":null,"PMCID":"","EPubDate":null,"PubModel":null,"JCR":null,"JCRName":null,"Score":null,"Total":0}

引用次数: 6

Microcomputer-based system for automatic analysis of M-mode echocardiograms m型超声心动图自动分析微机系统

Journal of biomedical engineering Pub Date : 1993-07-01 DOI: 10.1016/0141-5425(93)90002-G

G. Pelle, M.-Y. Belamari

引用次数: 1

Quantification of soft-tissue imbalance in condylar knee arthroplasty 髁状膝关节置换术中软组织失衡的定量分析

Journal of biomedical engineering Pub Date : 1993-07-01 DOI: 10.1016/0141-5425(93)90013-O

A. Sambatakakis , S.F. Attfield , G. Newton

{"title":"Quantification of soft-tissue imbalance in condylar knee arthroplasty","authors":"A. Sambatakakis , S.F. Attfield , G. Newton","doi":"10.1016/0141-5425(93)90013-O","DOIUrl":"10.1016/0141-5425(93)90013-O","url":null,"abstract":"<div><p>Soft-tissue balance has been debated in recent publications in connection with the long-term survival of the ‘condylar-type’ knee prostheses. Present methods of assessment have all assumed that the soft tissues around the knee are inelastic strings. The authors have developed two instruments to quantify soft-tissue imbalance, at the time of the operation, with the assumption that the soft tissues are viscoelastic structures. These two soft-tissue balancing devices were consequently used on 121 patients undergoing condylar knee arthroplasties at the Derbyshire Royal Infirmary and Bretby Hall Orthopaedic Hospital. The first instrument consisted of two flat plates separated by four standard compression springs and provided a qualitative measure of imbalance assuming that the soft tissues were viscoelastic. It was used on 55 patients before being replaced by the quantitative measure of the second instrument. The authors have redefined soft-tissue imbalance, to take into account the viscoelastic nature of the soft tissues, as the resultant trapezoidal geometry of the knee after the bony cuts have been made and when the knee is tensed by equal forces both medially and laterally. The second balancer eliminates the requirement to quantify the individual tensions in the medial and lateral structures by introducing to the system a low-friction, central pivot in the coronal plane. Once the pivot is situated at the centre of the knee, an equilibrium position is achieved where the clockwise and counter-clockwise moments are equal. The tensions exerted by soft tissues can be assumed to be equal and opposite as their moment arms are the same. Imbalance is quantified by the angular displacement of the top plate of the instrument in finding its equilibrium position. This instrument was subsequently used on 66 knees at the Bretby Hall Orthopaedic Hospital.</p></div>","PeriodicalId":75992,"journal":{"name":"Journal of biomedical engineering","volume":"15 4","pages":"Pages 339-343"},"PeriodicalIF":0.0,"publicationDate":"1993-07-01","publicationTypes":"Journal Article","fieldsOfStudy":null,"isOpenAccess":false,"openAccessPdf":"https://sci-hub-pdf.com/10.1016/0141-5425(93)90013-O","citationCount":null,"resultStr":null,"platform":"Semanticscholar","paperid":"19347537","PeriodicalName":null,"FirstCategoryId":null,"ListUrlMain":null,"RegionNum":0,"RegionCategory":"","ArticlePicture":[],"TitleCN":null,"AbstractTextCN":null,"PMCID":"","EPubDate":null,"PubModel":null,"JCR":null,"JCRName":null,"Score":null,"Total":0}

引用次数: 47

Accuracy of interface pressure measurement systems 界面压力测量系统的精度

Journal of biomedical engineering Pub Date : 1993-07-01 DOI: 10.1016/0141-5425(93)90014-P

V. Allen , D.W. Ryan , N. Lomax , A. Murray

{"title":"Accuracy of interface pressure measurement systems","authors":"V. Allen , D.W. Ryan , N. Lomax , A. Murray","doi":"10.1016/0141-5425(93)90014-P","DOIUrl":"10.1016/0141-5425(93)90014-P","url":null,"abstract":"<div><p>Interface pressure measurement is needed to assess beds designed to prevent pressure sores, so it is therefore important to establish the accuracy of interface pressure measuring systems. In this study, the Talley SA500 pressure evaluator (with 28 mm and 100 mm sensor pads), the DIPE (with 100 mm sensor pad), and a water-filled bladder system (with 0.1 ml and 0.3 ml water) were assessed. Measurement errors were evaluated using a loading system with pressures up to 7.4 kPa (55 mm Hg) in steps of 0.9 kPa (6.9 mm Hg). All systems tested over-measured interface pressure, the error being approximately linearly proportional to the loading pressure. The repeatability for a given system was approximately constant. The mean error (± SD) (%) and repeatability (kPa) for the systems were: 28 mm Talley 12 ± 1%, ± 0.07 kPa; 100 mm Talley 15 ± 1%, ± 0.07 kPa; DIPE 27 ± 3%, ± 0.12 kPa; 0.1 ml water bladder 17 ± 1%, ± 0.13 kPa; 0.3 ml water bladder 26 ± 3%, ± 0.07 kPa. Different interfaces affected accuracy markedly, and repeatability was affected when an inhomogeneous interface was used. The study shows that the errors associated with interface pressure measurement systems can be substantial, and can vary from one system to another.</p></div>","PeriodicalId":75992,"journal":{"name":"Journal of biomedical engineering","volume":"15 4","pages":"Pages 344-348"},"PeriodicalIF":0.0,"publicationDate":"1993-07-01","publicationTypes":"Journal Article","fieldsOfStudy":null,"isOpenAccess":false,"openAccessPdf":"https://sci-hub-pdf.com/10.1016/0141-5425(93)90014-P","citationCount":null,"resultStr":null,"platform":"Semanticscholar","paperid":"19347538","PeriodicalName":null,"FirstCategoryId":null,"ListUrlMain":null,"RegionNum":0,"RegionCategory":"","ArticlePicture":[],"TitleCN":null,"AbstractTextCN":null,"PMCID":"","EPubDate":null,"PubModel":null,"JCR":null,"JCRName":null,"Score":null,"Total":0}

引用次数: 52

Changes in oscillometric pulse amplitude envelope with cuff size: implications for blood pressure measurement criteria and cuff size selection 脉搏振幅包络随袖带尺寸的变化:对血压测量标准和袖带尺寸选择的影响

Journal of biomedical engineering Pub Date : 1993-07-01 DOI: 10.1016/0141-5425(93)90003-H

K.-G. Ng, C.F. Small

{"title":"Changes in oscillometric pulse amplitude envelope with cuff size: implications for blood pressure measurement criteria and cuff size selection","authors":"K.-G. Ng, C.F. Small","doi":"10.1016/0141-5425(93)90003-H","DOIUrl":"10.1016/0141-5425(93)90003-H","url":null,"abstract":"<div><p>Oscillometric blood pressures are derived from the amplitude envelope of oscillometric pulses generated in an occlusive cuff during cuff inflation or deflation; one factor which will affect the characteristics of these pulses is the size of the cuff bladder. Because limiting values are stipulated in recommendations and standards for bladder sizes, there is a wide variety of acceptable cuff sizes for any particular application. An experimental and theoretical study was undertaken to show the dependence of oscillometric blood pressures on bladder size. Actual cuff-arm compliance data were obtained from two subjects for two cuffs of different bladder size. Theoretical analysis was then applied to the data to predict the effects of different bladder sizes on the characteristics of the pulses. The results show that cuff-arm compliance and bladder size interact to affect the pulse amplitude and hence oscillometric blood pressure determination. These results suggest that blood pressures obtained using the oscillometric method may vary depending on cuff size, and in particular that replacement cuffs for oscillometric non-invasive blood pressure monitors should be chosen carefully.</p></div>","PeriodicalId":75992,"journal":{"name":"Journal of biomedical engineering","volume":"15 4","pages":"Pages 279-282"},"PeriodicalIF":0.0,"publicationDate":"1993-07-01","publicationTypes":"Journal Article","fieldsOfStudy":null,"isOpenAccess":false,"openAccessPdf":"https://sci-hub-pdf.com/10.1016/0141-5425(93)90003-H","citationCount":null,"resultStr":null,"platform":"Semanticscholar","paperid":"19346912","PeriodicalName":null,"FirstCategoryId":null,"ListUrlMain":null,"RegionNum":0,"RegionCategory":"","ArticlePicture":[],"TitleCN":null,"AbstractTextCN":null,"PMCID":"","EPubDate":null,"PubModel":null,"JCR":null,"JCRName":null,"Score":null,"Total":0}

引用次数: 26

Dynamic model of the bronchial tree 支气管树的动态模型

Journal of biomedical engineering Pub Date : 1993-07-01 DOI: 10.1016/0141-5425(93)90004-I

I. Ginzburg , D. Elad

{"title":"Dynamic model of the bronchial tree","authors":"I. Ginzburg , D. Elad","doi":"10.1016/0141-5425(93)90004-I","DOIUrl":"10.1016/0141-5425(93)90004-I","url":null,"abstract":"<div><p>We present a distributed model of the bronchial tree which simulates the global dynamic characteristics of the lung. Local mechanical characteristics of each airway are represented by RCL circuits and parameters of the electrical components are determined from local physiological data. The bronchi geometry is described by Weibel's symmetric model, the flow in each airway is assumed laminar and mixing effects at the bifurcations are neglected; the transpulmonary pressure is assumed to be sinusoidal. In simulations of quiet breathing the resistance to airflow is found to be dominant, the flow amplitude decreasing as breathing frequency increases, but remaining almost constant in all the generations. Simulations of ventilation through obstructed lungs show frequency dependence of the dynamic characteristics in very compliant lungs. The global resistance to airflow and the dynamic compliance of the bronchi decrease as the forced oscillation frequency increases in a pattern similar to <em>in vivo</em> measurements in diseased lungs. This may be an outcome of the RCL properties of the network rather than due to uneven distribution of mechanical properties of the lung.</p></div>","PeriodicalId":75992,"journal":{"name":"Journal of biomedical engineering","volume":"15 4","pages":"Pages 283-288"},"PeriodicalIF":0.0,"publicationDate":"1993-07-01","publicationTypes":"Journal Article","fieldsOfStudy":null,"isOpenAccess":false,"openAccessPdf":"https://sci-hub-pdf.com/10.1016/0141-5425(93)90004-I","citationCount":null,"resultStr":null,"platform":"Semanticscholar","paperid":"19346913","PeriodicalName":null,"FirstCategoryId":null,"ListUrlMain":null,"RegionNum":0,"RegionCategory":"","ArticlePicture":[],"TitleCN":null,"AbstractTextCN":null,"PMCID":"","EPubDate":null,"PubModel":null,"JCR":null,"JCRName":null,"Score":null,"Total":0}

引用次数: 21

Stress analysis of endosseous implants using the Boundary Integral Equation (BIE) method 应用边界积分方程(BIE)方法分析骨内种植体的应力

Journal of biomedical engineering Pub Date : 1993-07-01 DOI: 10.1016/0141-5425(93)90009-N

L.A. Wolfe

引用次数: 3

Mathematical modelling of the enteric nervous network II: facilitation and inhibition of the cholinergic transmission 肠神经网络的数学模型II:促进和抑制胆碱能传递

Journal of biomedical engineering Pub Date : 1993-07-01 DOI: 10.1016/0141-5425(93)90008-M

R.N Miftakhov, D.L Wingate

{"title":"Mathematical modelling of the enteric nervous network II: facilitation and inhibition of the cholinergic transmission","authors":"R.N Miftakhov, D.L Wingate","doi":"10.1016/0141-5425(93)90008-M","DOIUrl":"10.1016/0141-5425(93)90008-M","url":null,"abstract":"<div><p>The pharmacokinetic responses of the cholinergic enteric neurone to treatment with acetylcholinesterases, tetrodotoxin, some chloride salts of divalent cations, botulinum toxin, β -bungarotoxin and changes in the concentration of calcium ions in the external medium and repetitive stimulation are presented. The numerical results obtained reproduce quantitatively the effects of toxins and salts of divalent cations acting at different levels of acetylcholine release from the nerve-terminal. The addition of cholinergic agonists potentiates the action of acetylcholine and increases the amplitude of the generated excitatory postsynaptic potential. A decrease in the concentration of extracellular Ca<sup>2+</sup> ions reduces the amplitude of the excitatory postsynaptic potential and significantly increases synnaptic transmision time. The effect of tetrodotoxin is the blockade propagation of the action potential along the nerve axon and, as a consequence, acetylcholine release from the vesicular store. All these effects have been shown to be dose-dependent. The repetitive stimulation of the neurone reproduces the effects of accumulation and potentiation. The possible applications of the model for the analysis of the enteric nervous system function are discussed.</p></div>","PeriodicalId":75992,"journal":{"name":"Journal of biomedical engineering","volume":"15 4","pages":"Pages 311-318"},"PeriodicalIF":0.0,"publicationDate":"1993-07-01","publicationTypes":"Journal Article","fieldsOfStudy":null,"isOpenAccess":false,"openAccessPdf":"https://sci-hub-pdf.com/10.1016/0141-5425(93)90008-M","citationCount":null,"resultStr":null,"platform":"Semanticscholar","paperid":"19381442","PeriodicalName":null,"FirstCategoryId":null,"ListUrlMain":null,"RegionNum":0,"RegionCategory":"","ArticlePicture":[],"TitleCN":null,"AbstractTextCN":null,"PMCID":"","EPubDate":null,"PubModel":null,"JCR":null,"JCRName":null,"Score":null,"Total":0}

引用次数: 12

Stresses at the meniscofemoral joint: elastostatic investigations on the applicability of interface elements 半月板股骨关节处的应力:界面单元适用性的弹静力学研究

Journal of biomedical engineering Pub Date : 1993-07-01 DOI: 10.1016/0141-5425(93)90010-V

M. Lengsfeld

引用次数: 13

Repeatability of subject/bed interface pressure measurements 受试者/床界面压力测量的可重复性

Journal of biomedical engineering Pub Date : 1993-07-01 DOI: 10.1016/0141-5425(93)90011-M

V. Allen , D.W. Ryan , A. Murray

引用次数: 31