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Eli Lily: Cardiac Output Indices Measurement Using LabVIEW
The Challenge: Acquire, analyze and store massive cardiac output data in the research for developing new medicine.
The Solution: Use a PC, together with data acquisition board and LabVIEW, to acquire, analyze and archive data electronically.
The Old System
Researchers in Eli Lilly, a pharmaceutical company, want to study the cardiac output patterns of mice that have undergone different heart surgery operations. A custom-built Doppler frequency analyzer was used to measure the blood flow speeds in the mice's hearts during each heartbeat. The Doppler quadrature signals were feed through a DSP board to generate the speed pattern, which was displayed on a monitor. To calculate the cardiac output indices, the display on the monitor was frozen and printed out on a paper, then the indices (such as slope, peak, area) were calculated manually. By doing in this way, only a small number of beats could be analyzed with considerable amount of time. Besides, the archiving of raw data, which is crucial in the pharmaceutical business, required lots of space and effort.
LabVIEW System
V I Engineering, Inc. provides a solution by using plug-in data acquisition board and LabVIEW. National Instruments AT-MIO-16E-1 board is used to acquire the Doppler quadrature signals. The Electro Cardiac Graph signal is also acquired to detect the start and end of each beat. The sampling rate is 64KS/sec. for each signal. A complex FFT is done for the quadrature signals using the LabVIEW analysis toolkit to get the Doppler frequency shift pattern, which is directly related to the speed of the blood flow in the mice's hearts. Then a custom written algorithm is used to calculate the cardiac output indices. The acquisition of data is hardware triggered by a foot pedal.
This system greatly improves the ability to analyze cardiac output indices.
- The number of beats can be analyzed each time is increased from several beats to several dozens of beats. This also provides a statistical pattern for each cardiac output index.
- The calculation is done by simply clicking on several buttons on the front panel. This saves considerable time and effort in analyzing the data.
- The LabVIEW graphing utility provides an easy way to study the pattern more closely.
- All the data are saved digitally, which provides an easy way to record and retrieve all the test information.
Conclusion
With LabVIEW and data acquisition board, V I Engineering have provided an efficient system in doing cardiac research. This is a great application potential in this area.
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