{"title":"Transmural pressure-area relation for veins and arteries","authors":"G. Drzewiecki, I. Moubarak","doi":"10.1109/NEBC.1988.19403","DOIUrl":"https://doi.org/10.1109/NEBC.1988.19403","url":null,"abstract":"Experiments on isolated dog carotid arteries and jugular veins are performed to examine the effects of altered transmural pressure on the cross-sectional area of the blood vessel lumen. The data serves to provide a foundation describing the collapse of both arteries and veins for both positive and negative transmural pressures. In all normal and paralyzed vessels studied, change from a circular shape to collapsed occurred in the positive transmural pressure range, while in an elastic tube of similar geometry it occurred in the negative range. Over normal physiological pressure range, the veins showed a maximum normalized compliance (dA/dP)A/sub 0/ nearly ten times greater than that in the arteries. At higher transmural pressures the veins were considerably stiffer than the arteries. The veins assumed a circular shape at lower positive transmural pressures than did the arteries. The lumen normalized cross-sectional area from a paralyzed vessel showed a decrease for a given transmural pressure when compared with that of a normal vessel at the same transmural pressure.<<ETX>>","PeriodicalId":165980,"journal":{"name":"Proceedings of the 1988 Fourteenth Annual Northeast Bioengineering Conference","volume":"45 1","pages":"0"},"PeriodicalIF":0.0,"publicationDate":"1988-03-10","publicationTypes":"Journal Article","fieldsOfStudy":null,"isOpenAccess":false,"openAccessPdf":"","citationCount":null,"resultStr":null,"platform":"Semanticscholar","paperid":"123277946","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}
{"title":"Pressure gradient determination by three dimensional Doppler ultrasound (medical haemodynamics)","authors":"W. M. Gardiner, M. Fox","doi":"10.1109/NEBC.1988.19402","DOIUrl":"https://doi.org/10.1109/NEBC.1988.19402","url":null,"abstract":"A three-dimensional formulation was used to quantitate the maximal velocity in a flow jet produced by circulating a Doppler acoustic fluid through a Pasteur pipette in an open recirculating system. The flow jet velocity, as determined from the three-dimensional vector magnitude, was 119.7+or-3.17 cm/s; the actual velocity of 119.6 cm/s was determined with an Aalborg ball flowmeter. Doppler velocities for calculation of pressure using the Bernoulli equation were within 3.9% of actual jet stream velocities. The three-dimensional ultrasound Doppler velocity of a flow jet detemined at the site of the maximal pressure gradient should lead to a more accurate determination of pressure drop through a structure, stenosis, or septal defect using the Bernoulli equation.<<ETX>>","PeriodicalId":165980,"journal":{"name":"Proceedings of the 1988 Fourteenth Annual Northeast Bioengineering Conference","volume":"11 1","pages":"0"},"PeriodicalIF":0.0,"publicationDate":"1988-03-10","publicationTypes":"Journal Article","fieldsOfStudy":null,"isOpenAccess":false,"openAccessPdf":"","citationCount":null,"resultStr":null,"platform":"Semanticscholar","paperid":"116052054","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}
{"title":"The closed-loop regulation of blood glucose in diabetics","authors":"E. A. Woodruff, S. Gulaya, R. Northrop","doi":"10.1109/NEBC.1988.19342","DOIUrl":"https://doi.org/10.1109/NEBC.1988.19342","url":null,"abstract":"The development of a system for the closed-loop regulation of blood glucose concentration (BGC) in a Type-1 diabetic when sparse measurements of the blood glucose concentration are available is discussed. A model reference technique to provide an estimate of the BGC is implemented. Whenever, a BGC measurement is not available, the BGC estimate is used in the controller realization. After developing the model reference offline, a computer simulation is realized for closed-loop regulation of blood glucose concentration in a Type-1 diabetic. A recursive parameter-estimation scheme is implemented to update the parameters of the model reference throughout the closed-loop simulation. These parameter estimates can be used to adjust some of the controller parameters to enhance the robustness of the controller.<<ETX>>","PeriodicalId":165980,"journal":{"name":"Proceedings of the 1988 Fourteenth Annual Northeast Bioengineering Conference","volume":"42 1","pages":"0"},"PeriodicalIF":0.0,"publicationDate":"1988-03-10","publicationTypes":"Journal Article","fieldsOfStudy":null,"isOpenAccess":false,"openAccessPdf":"","citationCount":null,"resultStr":null,"platform":"Semanticscholar","paperid":"121049604","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}
{"title":"A microwave interferometer as a non-contacting cardio-pulmonary monitor","authors":"P. Engler, S. Reisman, C.Y. Ho","doi":"10.1109/NEBC.1988.19344","DOIUrl":"https://doi.org/10.1109/NEBC.1988.19344","url":null,"abstract":"A coherent, phase-locked microwave interferometer radar system that records the mechanical vibrations of the surface of the chest cavity resulting from the cardiac activity within the chest is described. The instrument operates at 9.3 GHz, which corresponds to a free-space wavelength of 3.1 cm. With a phase resolution of about 0.01 degrees of carrier phase shift, the system has the capability to detect target displacements of roughly 1 mu m. With this resolution, the vibration of the anterior wall of the chest cavity of a cooperating supine subject is readily detected. The microwave energy passes through normal clothing; the subject can be fully clothed and no physical contact whatever between the subject and instrument is required. The analog data from the interferometer are digitized and subjected to digital signal processing on an IBM-PC/AT personal computer. The processed recording from a group of young male students reveals distinct peaks during each cardiac cycle that represent high-velocity displacements of the chest wall. Studies are currently in progress to relate these peaks to mechanical events in the cardiac cycle.<<ETX>>","PeriodicalId":165980,"journal":{"name":"Proceedings of the 1988 Fourteenth Annual Northeast Bioengineering Conference","volume":"16 1","pages":"0"},"PeriodicalIF":0.0,"publicationDate":"1988-03-10","publicationTypes":"Journal Article","fieldsOfStudy":null,"isOpenAccess":false,"openAccessPdf":"","citationCount":null,"resultStr":null,"platform":"Semanticscholar","paperid":"123021440","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}
{"title":"Numerical simulation of unsteady biomedical flows","authors":"J. Ekaterinaris, A. Mazher","doi":"10.1109/NEBC.1988.19398","DOIUrl":"https://doi.org/10.1109/NEBC.1988.19398","url":null,"abstract":"Solutions of unsteady internal flows which are of interest in biomedical studies are presented. Pulsatile flows in a channel with a step constriction and in a cylindrical duct with closed end were examined. The steady motion was imposed by the time variation of the inflow axial velocity. The solution was obtained for laminar flow and low Mach number. The low Mach number compressible solution in a channel with a step construction was in good agreement with the incompressible LDV measurements. The velocities in the confined duct were in good agreement with numerical results presented in the literature. The authors demonstrated the ability of the numerical scheme to capture complex unsteady phenomena such as large separated regions and vortical structures, whose study is of interest in biomechanics.<<ETX>>","PeriodicalId":165980,"journal":{"name":"Proceedings of the 1988 Fourteenth Annual Northeast Bioengineering Conference","volume":"617 1","pages":"0"},"PeriodicalIF":0.0,"publicationDate":"1988-03-10","publicationTypes":"Journal Article","fieldsOfStudy":null,"isOpenAccess":false,"openAccessPdf":"","citationCount":null,"resultStr":null,"platform":"Semanticscholar","paperid":"123066991","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}
{"title":"A distributed data acquisition system","authors":"J. Lacourse, D.V. Shahane, W.J. Proulx","doi":"10.1109/NEBC.1988.19341","DOIUrl":"https://doi.org/10.1109/NEBC.1988.19341","url":null,"abstract":"This system acquires the human ocular pulse, digitizes it, and saves it in the digitized form for processing. It is easily modifiable for processing other low-frequency signals. The archiving system utilizing an IBM PC/XT saves the processed information permanently and/or displays it for analysis. The system software controls all the peripheral devices, input-output, and maintains the logical links between the distributed software modules.<<ETX>>","PeriodicalId":165980,"journal":{"name":"Proceedings of the 1988 Fourteenth Annual Northeast Bioengineering Conference","volume":"70 1","pages":"0"},"PeriodicalIF":0.0,"publicationDate":"1988-03-10","publicationTypes":"Journal Article","fieldsOfStudy":null,"isOpenAccess":false,"openAccessPdf":"","citationCount":null,"resultStr":null,"platform":"Semanticscholar","paperid":"127763427","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}
{"title":"Aortic compliance indices in the assessment of hypertension","authors":"S. Iantorno, J. Li","doi":"10.1109/NEBC.1988.19389","DOIUrl":"https://doi.org/10.1109/NEBC.1988.19389","url":null,"abstract":"Changes in compliance has been used to diagnose cardiovascular diseases. Their use for the evaluation of different types of hypertension, however, has been limited. The authors examine this aspect. Results indicate the mean decrease in compliance is more pronounced in systolic hypertensives than either the diastolic hypertensives or the systolic/diastolic hypertensives.<<ETX>>","PeriodicalId":165980,"journal":{"name":"Proceedings of the 1988 Fourteenth Annual Northeast Bioengineering Conference","volume":"16 5","pages":"0"},"PeriodicalIF":0.0,"publicationDate":"1988-03-10","publicationTypes":"Journal Article","fieldsOfStudy":null,"isOpenAccess":false,"openAccessPdf":"","citationCount":null,"resultStr":null,"platform":"Semanticscholar","paperid":"113984721","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}
{"title":"An anisotropic thermal phantom of perfused tissue","authors":"J. Baish, E. Cheever","doi":"10.1109/NEBC.1988.19363","DOIUrl":"https://doi.org/10.1109/NEBC.1988.19363","url":null,"abstract":"Initial development and test of instruments for measuring anisotropic conductivity in vivo is difficult to carry out in animal models and would benefit from trials in a nonbiological physical model, a phantom. Here, a phantom that conducts heat anisotropically is described. The phantom also mimics the small-scale temperature nonuniformities that may be found near individual blood vessels. Design criteria, along with modeled and experimental results, are presented. Based on the analysis and experimental results, the time-dependence of the conductivity observed in living tissue is explained.<<ETX>>","PeriodicalId":165980,"journal":{"name":"Proceedings of the 1988 Fourteenth Annual Northeast Bioengineering Conference","volume":"12 1","pages":"0"},"PeriodicalIF":0.0,"publicationDate":"1988-03-10","publicationTypes":"Journal Article","fieldsOfStudy":null,"isOpenAccess":false,"openAccessPdf":"","citationCount":null,"resultStr":null,"platform":"Semanticscholar","paperid":"115337714","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}
{"title":"Stabilized retinal mapping of known retinal loci","authors":"J. H. Bertera, G. Timberlake","doi":"10.1109/NEBC.1988.19366","DOIUrl":"https://doi.org/10.1109/NEBC.1988.19366","url":null,"abstract":"Stabilization of a test spot of light on specific portions of the retina can improve visual perimetry data that disclose the presence and extent of visual loss due to eye disease. In conventional visual perimetry, small test spots of light are displayed at various spatial locations in the visual field to determine the local sensitivity of the retina. These methods are subject to errors from eye movements which can shift the spatial relationships between the test display and known retina loci. A method of stabilizing test displays on the human retina and of relating this stabilized test display to known retinal loci is described. The stabilized retinal mapping has higher resolution than conventional maps, minimizes eye movement errors, reduces fatigue, and shortens testing time. The current method for stabilizing the test points on the retina uses a dual Purkinje tracker, which limits the application if there is yellowing of the eye lens with age, corneal abnormalities, or a small pupil.<<ETX>>","PeriodicalId":165980,"journal":{"name":"Proceedings of the 1988 Fourteenth Annual Northeast Bioengineering Conference","volume":"14 1","pages":"0"},"PeriodicalIF":0.0,"publicationDate":"1988-03-10","publicationTypes":"Journal Article","fieldsOfStudy":null,"isOpenAccess":false,"openAccessPdf":"","citationCount":null,"resultStr":null,"platform":"Semanticscholar","paperid":"124147274","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}
{"title":"Multi-microelectrode probe for neurophysiological experiments","authors":"N. Blum, H. Charles","doi":"10.1109/NEBC.1988.19331","DOIUrl":"https://doi.org/10.1109/NEBC.1988.19331","url":null,"abstract":"Four-site, passive microprobes for use in acute neurophysiological experiments are described. These microprobes allow simultaneous recordings of action potential activity to be made from multiple neurons at different locations in the neural tissue. The microprobe is a planar structure, fabricated using integrated-circuit techniques. It consists of gold electrode structures sandwiched between two polyimide dielectric layers and bonded to a 15- mu m-thick molybdenum substrate. The top dielectric layer has windows to expose the bonding pads and electrode sites. The bonding pads and interconnect wires at the probe head are entirely encapsulated in a polycarbonate resin tube filled with silicone sealant to protect the interconnections from contact with body fluids. The four recording sites are approximately 25- mu m square and arranged colinearly, 500 mu m apart, on a dagger-shaped structure 2.7 mm long by 0.15 mm wide at the lowest electrode site. The site impedances, measured in saline solution at 1 kHz, were between 3 and 4 M Omega . Probe lifetime was characterized; the more recent design has three sites that survived over 750 hours.<<ETX>>","PeriodicalId":165980,"journal":{"name":"Proceedings of the 1988 Fourteenth Annual Northeast Bioengineering Conference","volume":"44 1","pages":"0"},"PeriodicalIF":0.0,"publicationDate":"1988-03-10","publicationTypes":"Journal Article","fieldsOfStudy":null,"isOpenAccess":false,"openAccessPdf":"","citationCount":null,"resultStr":null,"platform":"Semanticscholar","paperid":"132036221","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}