A new technique to measure and track blood resistivity in intracardiac impedance volumetry.

Journal of clinical monitoring Pub Date : 1997-11-01 DOI:10.1023/a:1007407807068

B Gopakumaran, P Osborn, J H Petre, P A Murray

{"title":"A new technique to measure and track blood resistivity in intracardiac impedance volumetry.","authors":"B Gopakumaran, P Osborn, J H Petre, P A Murray","doi":"10.1023/a:1007407807068","DOIUrl":null,"url":null,"abstract":"Objective: To propose and verify a technique by which blood resistivity can be measured continuously and instantaneously with a conductance catheter used to measure ventricular volume by intracardiac impedance volumetry.Methods: Intracardiac impedance volumetry involves the measurement of ventricular blood volume using a multi-electrode conductance catheter. Ventricular volume measurement with the conductance catheter requires the value of blood resistivity. Previously, blood resistivity has been determined by drawing a sample of blood and measuring resistivity in a separate measuring cell. A new technique is proposed that allows the resistivity of blood to be measured with the conductance catheter itself. Two adjacent electrodes of the catheter are chosen to establish a localized electric field. With a localized field, the resistance measured between the adjacent electrodes bears a constant ratio (resistivity ratio) to the resistivity of blood. Finite element cylindrical models with exciting electrodes were created to determine the resistivity ratio. Blood resistivity was determined by dividing the resistance found due to the localized electric field by the resistivity ratio. The proposed scheme was verified in cylindrical physical models and in in vivo canine hearts.Results: Finite element simulations showed the resistivity ratio to be 1.30 and 1.43 for two custom-made catheters (Ohmeda Inc. and Biosensors Inc., respectively). The resistivity ratio remained constant as long as the cylindrical volume of blood around the adjacent electrodes had a radius larger than the electrode spacing. In addition, this ratio was found to be a function of electrode width. The new technique allowed us to measure saline resistivity with an error, -0.99+/-0.25% in a physical model, and blood resistivity with an error, -0.625+/-2.75% in an in vivo canine model.Conclusion: The new in vivo technique can be used to measure and track blood resistivity instantaneously and continuously without drawing blood samples.","PeriodicalId":77199,"journal":{"name":"Journal of clinical monitoring","volume":"13 6","pages":"363-71"},"PeriodicalIF":0.0000,"publicationDate":"1997-11-01","publicationTypes":"Journal Article","fieldsOfStudy":null,"isOpenAccess":false,"openAccessPdf":"https://sci-hub-pdf.com/10.1023/a:1007407807068","citationCount":"7","resultStr":null,"platform":"Semanticscholar","paperid":null,"PeriodicalName":"Journal of clinical monitoring","FirstCategoryId":"1085","ListUrlMain":"https://doi.org/10.1023/a:1007407807068","RegionNum":0,"RegionCategory":null,"ArticlePicture":[],"TitleCN":null,"AbstractTextCN":null,"PMCID":null,"EPubDate":"","PubModel":"","JCR":"","JCRName":"","Score":null,"Total":0}

引用次数: 7

Abstract

Objective: To propose and verify a technique by which blood resistivity can be measured continuously and instantaneously with a conductance catheter used to measure ventricular volume by intracardiac impedance volumetry.

Methods: Intracardiac impedance volumetry involves the measurement of ventricular blood volume using a multi-electrode conductance catheter. Ventricular volume measurement with the conductance catheter requires the value of blood resistivity. Previously, blood resistivity has been determined by drawing a sample of blood and measuring resistivity in a separate measuring cell. A new technique is proposed that allows the resistivity of blood to be measured with the conductance catheter itself. Two adjacent electrodes of the catheter are chosen to establish a localized electric field. With a localized field, the resistance measured between the adjacent electrodes bears a constant ratio (resistivity ratio) to the resistivity of blood. Finite element cylindrical models with exciting electrodes were created to determine the resistivity ratio. Blood resistivity was determined by dividing the resistance found due to the localized electric field by the resistivity ratio. The proposed scheme was verified in cylindrical physical models and in in vivo canine hearts.

Results: Finite element simulations showed the resistivity ratio to be 1.30 and 1.43 for two custom-made catheters (Ohmeda Inc. and Biosensors Inc., respectively). The resistivity ratio remained constant as long as the cylindrical volume of blood around the adjacent electrodes had a radius larger than the electrode spacing. In addition, this ratio was found to be a function of electrode width. The new technique allowed us to measure saline resistivity with an error, -0.99+/-0.25% in a physical model, and blood resistivity with an error, -0.625+/-2.75% in an in vivo canine model.

Conclusion: The new in vivo technique can be used to measure and track blood resistivity instantaneously and continuously without drawing blood samples.

查看原文

微信好友朋友圈 QQ好友复制链接

本刊更多论文

心内阻抗容量法测量和跟踪血液电阻率的新技术。

目的:提出并验证一种可连续、即时测量血电阻率的方法，该方法可用于心内阻抗容积法测量心室容积。方法:心内阻抗容量法包括使用多电极导尿管测量心室血容量。电导导管测量心室容积需要血液电阻率值。以前，血液电阻率是通过抽取血液样本并在单独的测量细胞中测量电阻率来确定的。提出了一种新技术，允许用导尿管本身测量血液的电阻率。选择导管的两个相邻电极来建立局部电场。在局部场中，相邻电极之间测量的电阻与血液的电阻率具有恒定的比率(电阻率比)。建立了带激励电极的圆柱有限元模型来确定电阻率。血液的电阻率是通过将局部电场产生的电阻除以电阻率来确定的。该方案在圆柱形物理模型和犬心脏体内得到了验证。结果:有限元模拟显示，两种定制导管(Ohmeda Inc.和Biosensors Inc.)的电阻率比分别为1.30和1.43。只要邻近电极周围的圆柱形血液体积的半径大于电极间距，电阻率比就保持不变。此外，还发现该比率是电极宽度的函数。新技术使我们能够测量生理盐水电阻率，在物理模型中误差为-0.99+/-0.25%，在犬体内模型中误差为-0.625+/-2.75%。结论:该技术可在不抽血的情况下，实时、连续地测量和跟踪血液电阻率。

本文章由计算机程序翻译，如有差异，请以英文原文为准。

求助全文

约1分钟内获得全文去求助