In vivo experimental validation of detection of gastric slow waves using a flexible multichannel electrogastrography sensor linear array

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.

Normative Values for Body Surface Gastric Mapping Evaluations of Gastric Motility Using Gastric Alimetry: Spectral Analysis

“…By focusing on the frequency associated with stable and persistent gastric activity, we find that the true reference interval is narrower at 2.65–3.35 cpm, which is also closer to that verified by direct serosal recordings (35). This refinement reflects the higher signal-to-noise ratio of BSGM and the pitfall that legacy EGG metrics could conflate scattered/unstable gastric activity or noise with low frequency gastric activity (15,35). As such, the metrics used for establishing the reference intervals here were intentionally structured to independently capture the gastric frequency and the stability of the activity at that frequency.…”

“…Although frequency has been the most prominent metric in the EGG literature, there has previously been no consensus on what constitutes normal, with intervals such as 2–4 and 2.5–3.7 cpm commonly cited (20,34). By focusing on the frequency associated with stable and persistent gastric activity, we find that the true reference interval is narrower at 2.65–3.35 cpm, which is also closer to that verified by direct serosal recordings (35). This refinement reflects the higher signal-to-noise ratio of BSGM and the pitfall that legacy EGG metrics could conflate scattered/unstable gastric activity or noise with low frequency gastric activity (15,35).…”

The effect of single and repeated doses of rivastigmine on gastric myoelectric activity in experimental pigs

“…Despite all technical progress and advanced software support of current EGG equipments, the capability of spatial resolution is still missing [32,33]. Future high-resolution electrical mapping will permit the recording and reconstruction of patterns of electrical activation in spatiotemporal detail [34][35][36][37]. However, routine clinical and experimental use has been still limited by the high cost of multichannel acquisition systems, difficulty in electrode construction, and the high complexity and time-intensiveness of analytical tasks [27].…”

Normative values for body surface gastric mapping evaluations of gastric motility using Gastric Alimetry: spectral analysis

“…22 This refinement reflects the higher signal-to-noise ratio of BSGM, as well as the pitfall that legacy EGG metrics could conflate scattered/unstable gastric activity or noise with low frequency gastric activity. 15,35 As such, the metrics used for establishing the reference intervals here were intentionally structured to independently capture the gastric frequency and the stability of the activity at that frequency. This concept is illustrated in Figure S4 , which depicts a challenging spectrogram for a subject with a normal gastric frequency but low GA-RI.…”