This study compares the differences in the gastrointestinal transit time between the conventional capsule endoscope and a minimized capsule endoscope model in normal dogs to verify whether the minimization of capsule endoscope can help relief retention in the gastrointestinal tract, especially in the pyloric passage. Three male beagles were used as the experimental group for which the minimized capsule endoscope model was orally administered and the control group consisted of three beagle dogs for which the conventional capsule endoscope was orally administered. Nine experiments were conducted with three experiments for each dog in each group. The results showed a significant difference in the gastric transit time (GTT) by the minimization of the capsule endoscope between the two groups (control group: 123.3 ± 80 min, experimental group: 63.3 ± 40.9 min, p=0.019). In contrast, the difference in the small bowel transit time (SBTT) by the minimization of the capsule endoscope between the two groups (control group: 86.6 ± 58.9 min, experimental group: 80 ± 33.5 min, p=0.863) was not significant. In this study, the capsule endoscopes reached the large intestine without retention in the small intestine in all subjects. The significant difference in the GTT between the control group using the conventional capsule endoscope and the experimental group using the minimized capsule endoscope model suggests that the smaller size of the capsule endoscope is helpful in resolving retention in the gastrointestinal tract, thus shorting the GTT.

This study investigated the prokinetic effect of metoclopramide and mirtazapine on gastric transit time (GTT), small bowel transit time (SBTT) and gastrointestinal transit time (GITT) during capsule endoscopy in four healthy beagle dogs. Four beagle dogs participated in the experiment as four groups at intervals of more than three days as the following: Control group 1 (capsule alone), Control group 2 (capsule alone), Metoclopramide administered group (metoclopramide + capsule) and Mirtazapine administered group (mirtazapine + capsule). The results of this study demonstrated there was no significant difference in GTT ([min] control group 1: 105 ± 90, control group 2: 172.5 ± 102 vs metoclopramide administered group: 247.5 ± 93, p = 0.07, 0.10) and SBTT ([min] control group 1: 120 ± 88, control group 2: 75 ± 39 vs metoclopramide administered group: 37.5 ± 15, p = 0.20, 0.18) for capsule only administered groups (control group 1 & 2) compared to metoclopramide administered group. In addition, there was no significant difference in GTT ([min] control group 1: 105 ± 90, control group 2: 172.5 ± 102 vs mirtazapine administered group: 127.5 ± 45, p = 0.56, 0.36) and SBTT ([min] control group 1: 120 ± 88, control group 2: 75 ± 39 vs mirtazapine administered group: 157.5 ± 38, p = 0.29, 0.07) between capsule only administered groups (control group 1 & 2) and mirtazapine administered group. In this study, the fact that metoclopramide might be ineffective and administration of mirtazapine might be inadequate in dogs were confirmed.

For diagnoses of digestive organs, capsule endoscopes are widely used and offer valuable information without patient’s discomfort. A general capsule endoscope which consists of image sensing module, telemetry module and battery is able to move along gastro-intestinal tracts passively only through peristaltic waves. Thus, it is likely to have some limitations for doctor to acquire images from the desired organs and to diagnose them effectively. As solutions to these problems, a locomotive function of capsule endoscopes has being developed. We have proposed a capsule-type microrobot with synchronized multiple legs. However, the proposed capsular microrobot also has some limitations, such as low speed in advancement, inconvenience to controlling the microrobot, lack of an image module, and deficiency in a steering module. In this paper, we will describe the limitations of the locomotive microrobot and propose solutions to the drawbacks. The solutions are applied to the capsular microrobot and evaluated by in-vitro tests. Based on the experimental results, we conclude that the proposed solutions are effective and appropriate for the locomotive microrobot to explore inside intestinal tracts.