Browsing by Author "Andrews, Christopher N."

Now showing 1 - 3 of 3
  • Thumbnail Image
    ItemOpen Access
    In vivo experimental validation of detection of gastric slow waves using a flexible multichannel electrogastrography sensor linear array
    (2022-06-27) Sukasem, Atchariya; Calder, Stefan; Angeli-Gordon, Timothy R.; Andrews, Christopher N.; O’Grady, Gregory; Gharibans, Armen; Du, Peng
    Abstract Background Cutaneous electrogastrography (EGG) is a non-invasive technique that detects gastric bioelectrical slow waves, which in part govern the motility of the stomach. Changes in gastric slow waves have been associated with a number of functional gastric disorders, but to date accurate detection from the body-surface has been limited due to the low signal-to-noise ratio. The main aim of this study was to develop a flexible active-electrode EGG array. Methods: Two Texas Instruments CMOS operational amplifiers: OPA2325 and TLC272BID, were benchtop tested and embedded in a flexible linear array of EGG electrodes, which contained four recording electrodes at 20-mm intervals. The cutaneous EGG arrays were validated in ten weaner pigs using simultaneous body-surface and serosal recordings, using the Cyton biosensing board and ActiveTwo acquisition systems. The serosal recordings were taken using a passive electrode array via surgical access to the stomach. Signals were filtered and compared in terms of frequency, amplitude, and phase-shift based on the classification of propagation direction from the serosal recordings. Results: The data were compared over 709 cycles of slow waves, with both active cutaneous EGG arrays demonstrating comparable performance. There was an agreement between frequencies of the cutaneous EGG and serosal recordings (3.01 ± 0.03 vs 3.03 ± 0.05 cycles per minute; p = 0.75). The cutaneous EGG also demonstrated a reduction in amplitude during abnormal propagation of gastric slow waves (310 ± 50 µV vs 277 ± 9 µV; p < 0.01), while no change in phase-shift was observed (1.28 ± 0.09 s vs 1.40 ± 0.10 s; p = 0.36). Conclusion: A sparse linear cutaneous EGG array was capable of reliably detecting abnormalities of gastric slow waves. For more accurate characterization of gastric slow waves, a two-dimensional body-surface array will be required.
  • Thumbnail Image
    ItemOpen Access
    Transcutaneous Intraluminal Impedance Measurement for Minimally Invasive Monitoring of Gastric Motility: Validation in Acute Canine Models
    (2014-12-09) Poscente, Michael D.; Wang, Gang; Filip, Dobromir; Ninova, Polya; Muench, Gregory; Yadid-Pecht, Orly; Mintchev, Martin P.; Andrews, Christopher N.
    Transcutaneous intraluminal impedance measurement (TIIM) is a new method to cutaneously measure gastric contractions by assessing the attenuation dynamics of a small oscillating voltage emitted by a battery-powered ingestible capsule retained in the stomach. In the present study, we investigated whether TIIM can reliably assess gastric motility in acute canine models. Methods. Eight mongrel dogs were randomly divided into 2 groups: half received an active TIIM pill and half received an identically sized sham capsule. After 24-hour fasting and transoral administration of the pill (active or sham), two force transducers (FT) were sutured onto the antral serosa at laparotomy. After closure, three standard cutaneous electrodes were placed on the abdomen, registering the transluminally emitted voltage. Thirty-minute baseline recordings were followed by pharmacological induction of gastric contractions using neostigmine IV and another 30-minute recording. Normalized one-minute baseline and post-neostigmine gastric motility indices (GMIs) were calculated and Pearson correlation coefficients (PCCs) between cutaneous and FT GMIs were obtained. Statistically significant GMI PCCs were seen in both baseline and post-neostigmine states. There were no significant GMI PCCs in the sham capsule test. Further chronic animal studies of this novel long-term gastric motility measurement technique are needed before testing it on humans.
  • Thumbnail Image
    ItemOpen Access
    Unsedated peroral wireless pH capsule placement vs. standard pH testing: A randomized study and cost analysis
    (BioMed Central, 2012-05-31) Andrews, Christopher N.; Sadowski, Daniel C.; Lazarescu, Adriana; Williams, Chad; Neshev, Emil; Storr, Martin; Au, Flora; Heitman, Steven J.