Pilot study of longitudinal ultrasonic sensor for dynamic volumetric assessment of gastroesophageal reflux.

In patients with gastroesophageal reflux disease (GERD), esophageal symptoms are traditionally diagnosed by monitoring the contact time between the reflux content and the esophagus using multichannel intraluminal impedance and pH (MII-pH) catheters. However, esophageal catheter for quantifying the volume of reflux content is still lacking. The present work proposes an innovative method to develop a longitudinal ultrasonic catheter and an information extraction system for reflux event detection and reflux volume estimation. Gastroesophageal model that mimics reflux events was developed to test the proposed catheter. Ultrasonic sensing was evaluated by simulating different volumes of reflux. The obtained signals showed good consistency in detecting reflux events and measuring reflux volume. During an in vivo human testing, a MII-pH catheter was used simultaneously to compare the ultrasonic output. Both in vitro and in vivo human testing results demonstrated the feasibility of utilizing the proposed method for gastroesophageal reflux (GER) detection and reflux volume estimation.

Use of multichannel electrogastrography for noninvasive assessment of gastric myoelectrical activity in dogs.

OBJECTIVE: To evaluate whether changes in gastric myoelectrical activity in healthy, awake dogs can be detected via multichannel electrogastrography (EGG). ANIMALS: 6 healthy hound-breed dogs. PROCEDURES: For each dog, 8-channel EGG was performed after food had been withheld for 12 hours and at 30 minutes after subsequent feeding; 60 minutes after feeding, atropine (0.04 mg/kg) was administered IM to induce ileus, and 30 minutes later, EGG was again performed. Mean cycles per minute (cpm) values of the dominant frequency (a measure of the rhythmicity of gastric electrical activity) and mean power ratios (ie, power measured after treatment divided by the power measured when food was withheld) were calculated. Motility of the gastric antrum was assessed via B-mode ultrasonography during the same phases; contractions determined ultrasonographically were correlated with EGG power for each channel in each phase. RESULTS: The criterion for stability (SD of the dominant frequency < 15% of the cpm value in at least 3 of the 8 EGG channels) was met in 4 of the 6 dogs (only in long-distance channels). The mean power ratios were significantly higher in the postprandial phase than in the ileus phase. Compared with the postprandial phase, significantly fewer contractions per minute were evident ultrasonographically in the ileus and food-withholding phases. There was a significant and good correlation between EGG power and ultrasonographic findings in all 8 channels. CONCLUSIONS AND CLINICAL RELEVANCE: Electrogastrography may be useful in assessing gastric myoelectrical activities in awake dogs with naturally occurring gastrointestinal disease, including gastric dilatation-volvulus.

Use of multichannel electrointestinography for noninvasive assessment of myoelectrical activity in the cecum and large colon of horses.

OBJECTIVE: To evaluate whether changes in myoelectrical activity in the cecum and large colon of horses can be detected via multichannel electrointestinography (EIG). ANIMALS: 6 healthy mature horses. PROCEDURES: Each horse underwent 3 EIG procedures. Intestinal myoelectrical activity (cecum and large colon) was recorded during a 20-minute period following i.v. administration of physiologic saline (0.9% NaCl) solution (20 mL; baseline), erythromycin lactobionate (0.5 mg/kg), or detomidine (0.015 mg/kg); intestinal contractions were concurrently viewed via B-mode ultrasonography. By use of computer software, 8-channel EIG recordings were analyzed and the mean of the dominant frequency (a measure of the rhythmicity of gastric electrical activity) expressed in cycles per minute (cpm) was obtained. Total power (muV(2)) was calculated, and treatment effect was expressed as the power ratio (ie, treatment-associated power divided by the baseline power). RESULTS: The dominant frequency cpm values were not stable, and no significant differences between treatments were detected. Compared with the effects of saline solution treatment, detomidine significantly reduced the mean cecal and colonic power ratios. Erythromycin significantly reduced the cecal power ratio and increased the colonic power ratio, although the increase was significant in only 1 channel. Ultrasonographic findings and total power (predominantly from the long-distance electrode pairs) were significantly correlated. CONCLUSIONS AND CLINICAL RELEVANCE: In horses, EIG was useful for assessment of changes in myoelectrical activity in the cecum and large colon. Multiple electrodes should be used to cover a larger area of the intestine, and agreement between multiple channels is needed to make the analysis meaningful.