Biomedical Engineering Reference
In-Depth Information
this AQ signal from a Hewlett-Packard Sonos Ultrasound
Machine. This signal is available as an analog voltage
(
1to
þ
1 volts) through the Sonos Dataport option
(BNC connector).
Figure 5.5-23
illustrates the measured parameters and
the specific hardware used for this application. Although
this application was initially developed on a Macintosh
platform, the system can run on multiple platforms, in-
cluding Windows 9x//NT/2000/XP. The CPDA also
takes advantage of the latest hardware developments,
and form-factors and can be used on either a desktop or
a laptop computer.
Figure 5.5-23 Schematic diagram of the CPDA system.
Data acquisition and analysis
system allows cardiologists and researchers to perform
online pressure-dimension and stroke work analyses
during routine cardiac catheterizations and open-heart
surgery.
The system has been designed to work with standard
computer hardware. Analog signals for ECG, pressure,
and area/volume (AQ) are connected to a standard BNC
terminal board. Automated calibration routines ensure
that each signal is properly scaled and that it allows the
user to immediately collect and analyze pressure-
dimension relationships.
The development of an automated, online method of
tracing endocardial borders (Hewlett-Packard's AQ
Technology) (Hewlett-Packard Medical Products Group,
Andover, MA) has provided a method for rapid online
area and volume determinations.
Figure 5.5-22
illustrates
Upon launching this application, the user is presented
with a dialog box that reviews the license agreement and
limited warranty. Next, the main menu is displayed,
allowing the user to select from one of six options as
shown in
Figure 5.5-24
.
When conducting a test, an automated calibration
sequence for the pressure and ultrasound signals (AQ) is
generally performed. If the user elects not to perform
a calibration, the most recent calibration values are
accessed from the integrated calibration log. Pressure-
calibration data are retrieved from a ''lookup table''
containing specific gain and offset values for a variety of
different manufacturers' pressure monitors. The AQ
calibration procedure involves ''scaling'' and ''mapping''
the display image signal over the
1to
þ
1 volt output
Figure 5.5-24 CPDA main menu.
