Phoenix Ambulatory Blood Pressure Monitor Project
2/22/2004 Meeting Notes

 

Attendees
Mary Jo Rawson,
Germaine Cornelissen-Guillaume
Wade Peterson
Bob Schlentz
El Nolley
Srilakshimi Bathina
Srikanta Kolluru

 

Status presentations

Germaine Cornellsen - Methods

Vectors, how data will flow, what will be remembered, decisions made, then the code can be written.
Trying to assess rhythms, predictable values, esp. circadian rhythms - 24 hrs, others are ½ hr rhythms, Circadian is no simple sine but has harmonics, other variations around the months and years. For an immediate diagnosis and treatment, circadian is most useful because of the daily schedule, taking medications in morning, afternoon, evening, bedtime.

Different kinds of monitors, automonitors have collected data every 15 min or 30 min, times of data were determined by light or buzzer, but whenever there was a disruption, the process would begin again, at the regular interval, but now not equidistant from the previous data and not comparable. The newer monitors are 15, 30, 45, 60 minutes, and when there is an interruption, there is just missing values. Germaine's process is least squares so it isn't as susceptible to such problems, but it requires sufficient data in the intervals for minimal errors. Transform the polar coordinates r, theta into Cartesian x, y with trig functions with gamma & beta. Least squares/ Gaussian assumes: 1) normal curve (mean, sdev), 2) independence, 3) correct function. Now we use non-parametric approach which merely compares data with reference values to compute residuals and report the distribution. Currently, they use two harmonics: 24 hrs and 12 hrs.

Use the timing of excess to time the treatment.
Sphygma count, the measured blood pressure.
Treatment.

Measuring the change in amplitude due to medication, parameter tests with CuSums,
Statistical Process control to determine if there is a change outside of the decision interval (eg.in the qsum1 goes up and qsum2 goes down), to indicate a change. Douglas Hawkins CuSum, self-starting (seeks a target), professor of statistics. Applied to the MESOR. Works with running means. Works with very short spans of data.

Methods Summary: method - (hole):
1) Least squares of BP (function, distribution of data - systemic lack of data eg. At night when sleeping or repeatly interrupted),
2) Non-parametric, residuals between measured and reference values regardless of function. (more difficult to get measures of uncertainty),
3) Measuring the change in amplitude due to medication, parameter tests with CuSums, (long periods of data, eg. 16 years, the cuSums are designed for 500 measurements, beyond that - indications outside the decision interval are more likely - false positives).

Windowing (storing data), Compacting (process into parameters & "information) and Recycling (can write over the raw data). - can solve 1st order high frequency problems into lower frequency.

Wish List
1. Have capability to go as you go, operate without memory and get the entire summary. Acquire & analyze simultaneously
2. Using reference values is cumbersome, but to compute the ; to get a real reference database, ; accumulating reference data, computing reference data, following up on the people who provide the reference data to determine if there was morbidity and re-analyze the reference data. - eg. 90% prediction limits.

Mary Jo - what would you like from Diaries.
Germaine - exercise. Found that excessive amplitudes were related to grief, anxiety, anger, … The diaries are used for descriptive information to determine if outlying data is significant to physical condition. For example if excessive emotion is brief and non-recurrent, no treatment may be appropriate, but if it recurs then treatment may be appropriate.

Wade Peterson

What would people want to wear? What size of unit. Power consumption? What can we afford in terms of current.

Specific examples:
AA or AAA, needed 3.6 volts to run it.
Blood velocity propagation: cuff sensor affects.

10 day service life
emitter & receive : $1.16

His pickup circuit to "this" is almost the same as the pickup circuit to Wade's emerging design. Eg. BP via motion or velocity.

Piezoelectric film, to power the sensor, perhaps to measure the blood pressure, heart rate and blood velocity.

Next meeting 3/7. Continue with Wade, Mary Jo & Bob.

 

 

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