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Biomedical Engineering Design Projects

Impedance Cardiography

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Project Overview

Current methods for measuring cardiac output are invasive. Impedance Cardiography is a non-invasive medical procedure utilized in order to properly analyze and depict the flow of blood through the body. With this technique, four electrodes are attached to the body—two on the neck and two on the chest—which take beat by beat measurements of blood volume and velocity changes in the aorta. However, our client hypothesizes that the current method withholds degrees of inaccuracy due to the mere fact that the electrodes are placed too far from the heart. The goal of this project is to design an accurate, reusable, spatially specific system that ensures more accurate and reliable cardiographic readings. Furthermore, this system must produce consistent results able to be accurately interpreted by industry professionals. More specifically, our primary goal is to ensure the device must not only collect an impedance signal, it must also isolate the signal in its output using a variety of filters. Impedance Cardiography
David, Jacob, Tian, Ross David, Jacob, Tian, Ross

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Project Status

Results from week 5 This week we made a conference call to our colleges in China to discuss our project status and what we need of them. They will be working on collecting the same impedance data via a demodulator, once we have determined the best positioning. In lab we collected more data of impedance measurements for more positions. The initial results indicate an angle across the heart delivers the strongest and clearest signal. We also began to collect measurements of the way impedance is currently measured in clinics. Once we have collected all of our data, we will be able to draw conclusions as to what positioning is ideal for collecting impedance signals directly over the heart.

Progress Report Archive.

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Project Timeline

Week Reporting Period Beginning Activities
1 January 22 First group meeting, met with client, began brainstorming ideas.
2 January 29 Finished building the amp, attempted to eliminate the ekg signal.
3 February 5 Succesfully eliminated the ekg signal with low and high pass filters.
4 February 12 Beginning human testing.
5 February 19 We ran a human signal through the amplifier/filter system and obtained some results hinting at a possible impedance signal. We are also pleased to announce the addition of a new team member, Bichao, from China.
6 February 26 This week we have focused our time on preparing our mid-semester presentation. We are looking forward to presenting our project and our progress. Furthermore, we are developing our written report.
7 March 5 Presented our powerpoint on Friday and finshed our Mid-Semester Report
8 March 12 This week in lab we gathered cardiac output by means of the method currently in place, that is, we placed two electrodes on the neck and two on the abdomen. We then tested the electrodes placed on the same side and opposite sides. These will lay down a basis for comparison to our method of placing electrodes directly over the heart. We then began to test different electrode angles.
9 March 19 After realizing our old design was unreliable, we came up with a new design that would provide us with quicker and more time-efficient testing methods.
10 March 26 SPRING BREAK
11 April 2 We have successfully constructed a new electrode matrix that will aid in our consistent collection of data. The matrix is made of Tyvek (a paper and fiberglass product), in which holes are cut at equal lengths and at several angles. The variety of angles will make data collection at angles easy to do, with minimal adjustment between each test. The matrix is held on the body with elastic bands, ensuring all electrodes keep in contact with the body at all times. Furthermore, the electrodes can be reused between tests, but can also be replaced very quickly if need be. Using this matrix, we will be able to determine the best electrode angles for conducting cardiography tests.
12 April 9 This week we made a conference call to our colleges in China to discuss our project status and what we need of them. They will be working on collecting the same impedance data via a demodulator, once we have determined the best positioning. In lab we collected more data of impedance measurements for more positions. The initial results indicate an angle across the
13 April 16 After some initial tests, our results indicate the 45-degree angle offers the strongest
14 April 23 This past week we worked on our poster and organized for our presentation on Friday. We also discussed future work, and determined that we will in fact be spending an extra week on campus. We will concentrate on soldering our circuitry and taking more measurements. We will also be applying to the IRB for human testing in the fall. We are excited to continue our work.
15 April 30

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Presentations and Reports

pdf icon Mid Semester Presentation (Mar 4 2010, 1548 kb)
pdf icon Mid Semester Report (Mar 10 2010, 265 kb)
pdf icon IC Poster (May 9 2010, 12227 kb)
pdf icon Project Design Specifications (May 9 2010, 101 kb)
pdf icon Electrode Placement Testing Results (May 10 2010, 2033 kb)

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Contact Information

Project Team

Project Advisor and Client

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Created: Feb 3 2010
Content updated: May 10 2010

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