Phoenix Ambulatory Blood Pressure Monitor Project
Sub-project: Sphygmochron Spreadsheet User Guide
Project Description
The purpose of this page is to serve as a staging area for writing a User Guide for the Sphygmochron Spreadsheet.
At this time, all that's here is the very beginning of the User
Guide that I envision we'll eventually have. I expect that we'll
(eventually) write all the text here in a style accessible to lay
people.
Project Deliverables
Table of Contents
Background Information
An Excel program to analyze a blood pressure profile can be
downloaded from our website at: ________________ . The program
provides a parametric and non-parametric assessment of the data
for the purposes described in a Healthwatch (URL: _______).
Parametrically, a two-component model consisting of cosine curves
with periods of 24 and 12 hours is fitted by least squares to the
data. The parameters: MESOR (rhythm-adjusted mean), double
circadian amplitude (extent of change within a day predictable by
the 24-hour component), and circadian acrophase (measure of timing
of overall high values recurring each day) are compared with 90%
prediction limits established from an admittedly interim still to
be extended database on presumably 'clinically' healthy subjects
of the same gender and similar age (rather than on individuals
with proved outcome over a complete lifespan, as should eventually
be the case).
Non-parametrically, the data are stacked over an idealized 24-hour
span and the average circadian profile thus obtained is compared
by computer with the upper time-specified 95% prediction limit of
healthy peers matched by gender and age, yielding the following
endpoints: the percentage time elevation (the percentage time the
average profile is above acceptable time-varying limits), the
timing of excess (calculated as the center of gravity of the area
of excess delineated by the profile when it is excessive and the
upper limit of acceptability itself), and the
hyperbaric/tachycardic index (a measure of the area of excess
defined above).
The program also provides a list of the data, a plot of the
time course of systolic and diastolic blood pressure and heart
rate, global and daily mean values and standard deviations
(calculated from midnight to midnight), global and daily estimates
of daytime, nighttime and 24-hour means and standard deviations as
well as day-night ratios (calculated over 24 hours from time to
awakening and/or bedtime), and plots of average circadian systolic
and diastolic blood pressure and heart rate profiles with their
respective chronodesmic limits, computed as time-specified 90%
prediction limits.
Instructions
To use the program, the data need to be retrieved from the monitor
(e.g., the TM-2421 or TM-2430 from A&D) . Two data files must
be prepared, with a specific column-oriented structure.
The file containing the data needs to have the suffix ".pr0". The "setup" file containing control information and patient data must have the suffix ".s". An illustrative case (.pr0 and .s files) can also be downloaded.
Data file format (the .pr0 file):
Cols. 1- 5: identification
Col. 6: ','
Cols. 7-18: date and time of actual data collection as year (4 chars),
month, day, hour, and minute (2 chars each)
Cols. 19-21: ', ,'
Cols. 22-24: value of systolic blood pressure (oscillometric)
Cols. 25-29: ', ,'
Cols. 30-32: value of diastolic blood pressure (oscillometric)
Col. 33: ','
Cols. 34-36: value of heart rate
Col. 37: ','
Control and Patient information file (the .s file):
Line 1: Col. 4: '1'
Line 2: Cols. 1-10: '24.0'
Col 12: '0'
Cols. 13-14: '10'
Cols. 16-20: '0.050'
Line 3: Cols. 1-80: Title 'Ambulatory Cardiovascular Monitoring'
Line 4: Cols. 1-80: Format to read the values of systolic blood pressure
'(6x,6f2.0,3x,f3.0)'
Line 5: Cols. 1-80: Format to read the values of diastolic blood pressure
'(6x,6f2.0,11x,f3.0)'
Line 6: Cols. 1-80: Format to read the values of heart rate
'(6x,6f2.0,15x,f3.0)'
Line 7: Col. 25: '1'
Line 8: Cols. 1- 4: (right-adjusted): number of lines in data (.pr0)
file to be analyzed
Line 9: Cols. 1-16: Identification
Col. 17: M for male subject, F for female
subject,
and P for pregnant woman
Cols. 19-20: Age in years (needs to be between 20 and 99)
Line 10: Col. 4: '2' (number of components in model)
Disclaimer
Results depend in part on the reference database, which
presently consists mostly of Caucasians 20 to 99 years of age.
Efforts are needed to improve the current reference limits, that
are intended to replace targets now prevailing for adults irrespective
of age and gender.
It must be emphasized that our data base is not yet checked for the degree to which it is representative of healthy people following their usual daytime activities and schedules,
and sleeping at night, yet it includes valuable information on the
anticipated circadian variation in blood pressure and heart rate
in health.
BIOCOS Project
The BIOCOS Project (http://www.msi.umn.edu/~halberg/) collects
blood pressure profiles (time-series blood pressure measurements) from
volunteers around the world. It focuses on group results as a
requisite for joint publications, for improving the reference database,
and for initiating outcome studies which will be indispensable as our
chronobiological approach becomes more common among physicians and
at-home users.
To improve the Reference Database that is built into the Sphygmochron,
efforts are needed to obtain data on children and on
healthy people from different ethnic groups, different social
classes in different geographic locations, and to extend
longitudinal focus to
individuals studied until demise monitored around the clock, as
some individuals now do for decades. Clinically healthy
volunteers as well as individuals with blood pressure disorders
are invited
to participate in the BIOCOS Project (http://www.msi.umn.edu/~halberg/) by contacting the Halberg Chronobiology Center at corne001@umn.edu.
We encourage people to run their own analyses. A copy of the
data, preferably with the accompanying Sphygmochron, the proper
identification and subject information (gender, age, ethnicity,
health status, any medication, including dose and timing of
administration, ...) is still requested as a basis for
participation in the BIOCOS Project (http://www.msi.umn.edu/~halberg/).
It is anticipated that those using this program will credit its source
on this website and will provide batches of time series as these
accumulate on a quarterly basis to corne001@umn.edu.
About This Page
This page is maintained by Larry A. Beaty. It was last updated on 10 December 2006.
The author(s) provide this information as a public service,
and agree to place any novel and useful inventions disclosed herein
into the public domain. They are not aware that this material
infringes on the patent, copyright, trademark or trade secret
rights of others. However, there is a possibility that such infringement
may exist without their knowledge. The user assumes all responsibility
for determining if this information infringes on the intellectual
property rights of others before applying it to products or services.
(C) 2006 Larry A. Beaty. Copying and distribution of this
page is permitted in any medium, provided this notice is preserved.
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