Luminal Electrical Resistivity at 50 kHz of the Pig Large Intestinal Wall

In GruBIE we are interested in finding the best conditions to, in the future, carry out in vivo transendoscopic measurements on the colon wall in humans. Pressure applied by the probe to the tissue being measured and probe/electrodes size, as well as thickness of the large intestine (LI) wall may well play a crucial role in the values obtained when readings to the studied tissue are made. In this article, in resected colon specimens from 3 adult pigs, two different approaches are explored, with a probe previously used for in vitro and in vivo measurements in humans and other animals as pigs and rabbits. These two approaches differ, basically, on probe position (tip upside down or tip upside up), with high pressure being applied in the first case (about 27.5 kPa) and low pressure in the second case (about 1.8 kPa for the pieces of colon and about 7.2 kPa for measurements on the rectum). The main finding of this initial study is that both aspects, pressure applied with the tip of the probe and thickness of the tissue, seem to affect the impedance readings. For future work, these two aspects have to be considered and this should be reflected in the probe and electrode sizes.