Phoenix Ambulatory Blood Pressure Monitor Project
8/13/2006 Meeting Notes




Status Review:

* Larry Beatty, getting Visual Basic Unit test framework, enabling him to write tests, then apply to Germaine's Sphygmochron prototype.

* Bob: Why is piezo film signal so big when you put it on a human. The amplifier has 30 dB of gain.

* Mary Jo: Working on the piezo file sensor and looking at how we are gathering the data. She is working on the second set of data and refining it. We are comparing the Systolic with the Chen data. We get a strong S wave, stronger than Chen, probably because ours is mechanical, while Chen's is opto-electric. But, the diastolic signal is weak. Next step is to get more data.

* Dave: Been meeting in the lab, taking various data sets, got the oscilloscope software installed and operating, Alex has written MatLab applications to create time series with brachial and radial measurements, we get a good peak, but are having trouble getting the valleys, from which the diastolic pressure is computed. We need LabView, can obtain a student version for ~$259 that could be transferred to the project for use. Mary Jo could buy it and transfer ownership to the project, and Dave Skramstad sign as Sensor project lead for the Phoenix Project. Mary Jo will examine the license to make sure there is no prohibit on transferring ownership to the project, make the purchase and send El the receipt. El will use Phoenix funds reimburse Mary Jo.

* Mike: Will define the pressure wave as a Finite Element Analysis (FEA) using Ansys.

* Alex: Developing a framework in Mathlab for analyzing waverforms. Analyzed the first series of measurements, got a best mean squared errors, 7 mmHg, and worst was 18 mmHg, uncertainty in the measurement. Looking a ways to improve, look at a single measurement and average out the noise. The way it is done is with two waveforms, on the elbow and wrist and perform a cross correlation, using the entire waveform. Dave said the FDA requires that error be within 8 mmHg. Then, Penrose tubing may be another need.

* Gerry: Working on the clinical side, and make a more flexible way to provide slide show presentations, web-based presentations and files.

Topic: Systolic & Diastolic Waveform questions for Germaine.

Alex: We drew graphs of the systolic and diastolic waveforms. We got nice peaks, but very noisy measurements in the valleys. How are these measurements performed in practice? Are there features in the wave itself that can be used to extract the valleys?

Germaine: When we look at the composite pressure wave, the systolic corresponds to the peak and the diastolic corresponds to the valley. Some assume that 1/3 of the time in spent in Systole, while 2/3 is spend on Diastole, though the time spent in Diastole is variable. So you need a start point, perhaps an inflection point of the systole rise or the peak, and use the time lag from one point to another.


Gerry Werth - Clinical Information Systems Minitopic

Diagnosis - Why Clinical Diagnosis is Different?

Technical Diagnosis
* Troubleshooting Man Made Systems
- Technological artifacts: Cars/Computers
* Patterns of Signs and Symptoms
- Sign: visible to an External Observable
- Symptom: Noted and Reported by the System (like computer or car).
* Not Man-Made Systems (Yet have the Variability and Complexity of Biological System.
- Physicians talk about differential diagnosis, sometimes a specific set of signs and symptoms are unique to a disease and are referred to as pathopneumonic.

Troubleshooting Biological Systems
- Living Organisms (and Ecosystems)
* Patterns of Signs and Symptoms (SSx)
- Signs: Visible to an External Observer
- Symptom: Known by the Organism/ Person
* Emotions: Fear / Embarrassment...
- Embarrassment to Talk about Symptoms
- Fear of Illness and Death.

Clinical Diagnosis
* Is your car ever Embarrassed?
* Is your Computer ever afraid?
* Clinical Diagnosis is Different from Technical Diagnosis because:
* Cars and Computer have no conscious or unconscious incentives to conceal their Signs and Symptoms.
* People Do.

Summary: Why Clinical Diagnosis is Different from Technical Diagnosis?
* Technical Diagnosis
- Troubleshooting Man-Made Systems
- Signs and Symptoms (SSx)
- No Man-Made Systems (Yet) Have the Variability and Complexity of Biological Systems
* Clinical Diagnosis
- Troubleshooting Biological Systems
- Signs and Symptoms (SSx)
- Emotions: Fear/ Embarrassment

Next Phoenix Project meeting: Sunday, August 27 at 2:30 p.m. in Mayo 748



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