Quantitative analysis of motility recordings in the human small intestine

Analysis of Intestinal Movements with Spatiotemporal Maps: Beyond Anatomy and Physiology

Over 150 years ago, methods for quantitative analysis of gastrointestinal motor patterns first appeared. Graphic representations of physiological variables were recorded with the kymograph after the mid-1800s. Changes in force or length of intestinal muscles could be quantified, however most recordings were limited to a single point along the digestive tract.In parallel, photography and cinematography with X-Rays visualised changes in intestinal shape, but were hard to quantify. More recently, the ability to record physiological events at many sites along the gut in combination with computer processing allowed construction of spatiotemporal maps. These included diameter maps (DMaps), constructed from video recordings of intestinal movements and pressure maps (PMaps), constructed using data from high-resolution manometry catheters. Combining different kinds of spatiotemporal maps revealed additional details about gut wall status, including compliance, which relates forces to changes in length. Plotting compliance values along the intestine enabled combined DPMaps to be constructed, which can distinguish active contractions and relaxations from passive changes. From combinations of spatiotemporal maps, it is possible to deduce the role of enteric circuits and pacemaker cells in the generation of complex motor patterns. Development and application of spatiotemporal methods to normal and abnormal motor patterns in animals and humans is ongoing, with further technical improvements arising from their combination with impedance manometry, magnetic resonance imaging, electrophysiology, and ultrasonography.

Noninvasive Measurement and Analysis of Intestinal Myoelectrical Activity Using Surface Electrodes

Intestinal myoelectrical activity (IMA), which determines bowel mechanical activity, is the result of two components: a low-frequency component [slow wave (SW)] that is always present, and a high-frequency component [spike bursts (SB)] which is associated with bowel contractions. Despite of the diagnostic significance of internal recordings of IMA, clinical application of this technique is limited due to its invasiveness. Thus, surface recording of IMA which is also called electroenterogram (EEnG) could be a solution for noninvasive monitoring of intestinal motility. The aim of our work was to identify slow wave and spike burst activity on surface EEnG in order to quantify bowel motor activity. For this purpose, we conducted simultaneous recordings of IMA in bowel serosa and on abdominal surface of five Beagle dogs in fast state. Surface EEnG was studied in spectral domain and frequency bands for slow wave and spike burst energy were determined. Maximum signal-to-interference ratio (7.5 dB +/- 36%) on SB frequency band was obtained when reducing upper frequency limit of signal analysis. Energy of external EEnG in reduced SB frequency band (2-7.9 Hz) presented a high correlation (0.71 +/- 7%) with internal intensity of contractions. Our results suggest that energy of SB can be quantified on external EEnG which could provide a noninvasive method for monitoring intestinal mechanical activity.

Non-invasive electrogastrography. Part 1: Correlation between the gastric electrical activity in dogs with implanted and cutaneous electrodes

Experiments were made on dogs with bipolar silver ball-shaped electrodes chronically implanted on the muscle wall of the stomach. The electrical activity of the gastric muscle wall (electrogastromyogram-EGMG) was characterized by slow potential changes during the quiescent period of the migrating myoelectric complex (MMC) and bursts of spike potentials during the activity period of MMC. Cutaneous (surface) electrodes were placed on the abdominal wall. Waves with a rhythm of 4.5-5 cpm were led off by the cutaneous electrodes (electrogastrogram-EGG), simultaneously with the EGMg. The bursts of spike potentials with the slow gastric potentials in the EGMG corresponded to an increase of the amplitude of the waves in the EGG. Good correlation was found between the number and frequency of spike potentials in a group and the wave amplitude in the EGG. EGG recorded on an electrogastrograph designed by us was characterized by low-amplitude waves corresponding to the slow waves during the period of quiescence of MMC and high-amplitude waves corresponding to the bursts of spike potentials during the activity period of MMC. Therefore it is possible to determine the MMC of the stomach by the changes in the amplitude of the waves in the EGG.

A double-blind comparative study of the inhibitory effect of intraduodenally administered hyoscine-N-butylbromide on human duodenal motility

In a double-blind crossover study hyoscine-N-butylbromide (HBB) was compared with placebo in its inhibitory effect on duodenal motility stimulated by metoclopramide. Measurements were made both by the balloon technique and the open-tipped tube method with pressure transducer. 20 mg or 50 mg HBB or placebo were instilled in random sequence into the intestinal tract of 12 healthy volunteers. The frequency of Type II waves was determined in each experiment after administration of the test substance following prior metoclopramide stimulation. This frequency was used as the inhibitory index for each drug. The test substance was administered 15 minutes before a second stimulation. A four-way analysis of variance (mixed model) was applied to the calculated number of waves per period. Subjects were required to respond equally to stimulation with increased motility on both trial days as evidenced by a minimal difference in the averages following the first stimulation on each trial day and before application of the test substance. The frequency of Type II waves after 20 mg and 50 mg HBB was reduced in a statistically significant manner in each case when compared with placebo. The probabilities of error were p less than 0-05 and p less than 0-025.

Effects of cholecystokinin on the motility of the distal duodenum and the proximal jujunum in man

Electrical spike potentials and intraluminal pressure variations were recorded in the distal part of the duodenum and proximal part of the jejunum in 5 normal human subjects before and after a bolus injection of cholecystokinin. A considerable increase in activity was observed in the jejunum after the hormone, whereas there was no response in the distal duodenum. Absence of reaction in the proximal duodenum and an increase in the motility in the distal ileum has previously been demonstrated after cholecystokinin administration. It is concluded that the human duodenum differs from the rest of the small intestine in its reaction to cholecystokinin. The change in reaction appears to occur on a level with the ligament of Treitz.