New Insights into Gastric Pressure Activity

Diseases in the gastric cavity are, to some extent, related to with gastric motility. Using a telemetric
device, which is composed of a capsule robot, an in-vitro pocket data recorder, an ultrasonic locating
unit, and an in-vitro data processing computer, to obtain gastric physiological digestive or
interdigestive pressure activity is a good way to get the pattern of gastric motility. This chapter of the
book first presents such a telemetric device. Then, general data processing and analysis method, as
well as reasonable interpretation on how to generate such gastric pressure activity are given. Such
general process for processing pressure recordings includes removal of abnormal values, five-three-
Hanning (53H) weighted average smoothing and estimation of pressure activity fluctuation frequency.
Finally, an analysis method for detecting quadratic phase coupling (QPC) behavior of human gastric
interdigestive pressure activity is proposed. They are the Fourier transforms of the diagonal slices of
the triple correlations, and can actually detect the phase coupling and coupled components
respectively by expanding the real process into the complex counterpart through Hilbert transform. In
order to learn more about the QPC structure in a certain frequency band that we are mostly interested
in and obtain higher frequency resolution, the method, named the wavelet packet based diagonal slice
spectrum, is introduced. It shows that the nonlinear QPC behavior occurs during gastric contractions
(phase II), whereas no distinct phase coupling occurs during gastric motor quiescence (phase I). It is
the nonlinear cell-to-cell coupling mechanisms, existence of fast and slow waves and their interactions
that nonlinear QPC structure of the gastric pressure activity occurs. These findings in this chapter
could be considered as some new insights into gastric pressure activity.