Intraluminal Multiple Electric Impedance Procedure for Measurement of Gastrointestinal Motility

TLDR

The impedance of the volume conductor surrounding the catheter varies with bolus, organ wall, and body fluids, providing characteristic values for each segment and contraction phase, as shown by theory and experiments. A new catheter‑related procedure for high‑resolution measurements of gastrointestinal motility is presented. The method acquires electric impedance simultaneously from annular electrodes along the catheter, and a simplified model shows impedance varies logarithmically with bolus thickness, yielding highest sensitivity at small lumen size with unipolar or bipolar setups. The high‑resolution impedance method enables detailed evaluation of functional stages, contraction wave onset, offset, and type, and its thin, flexible catheter with over 32 segments allows long‑term physiological and pathological studies of gastrointestinal motility.

Abstract

A new catheter‐related procedure for high‐resolution measurements of gastrointestinal motility is presented. The method is based on simultaneous acquisition of the electric impedance in the surrounding body volume conductor from a number of annular electrodes, successively arranged on the catheter. The impedance of a volume conductor around the catheter, consisting of a bolus, the organ wall, body fluids, and so forth, has a characteristic value for each segment and phase of contraction wave, as theoretical and experimental investigations revealed. A calculation on the basis of a simplified model reveals that the impedance changes as a logarithmic function of the bolus thickness, in which the highest sensitivity is advantageously obtained at a small lumen size and utilizing unipolar or bipolar electrode setups. The high resolution in time, space, and amplitude of the changes in the bolus shape allow us to use this impedance method for evaluation of functional stages in each measuring segment and of the beginning, end, and type of contraction wave, as well as their characteristics. The unique mechanical properties of the catheter (thinner than 3 mm, several meters long, flexible, closed surface) and the ability to distribute more than 32 measuring segments of different lengths on the catheter make this procedure suitable even for long‐term physiologic and pathologic studies of gastrointestinal motility.