Gastric dysfunction in patients with chronic nausea and vomiting syndromes defined by a novel non-invasive gastric mapping device

Abstract

Importance Chronic nausea and vomiting syndromes (NVS) are prevalent and debilitating disorders. Putative mechanisms include gastric neuromuscular disease and dysregulation of brain-gut interaction, but clinical tests for objectively defining gastric motor function are lacking. Objective A novel medical device enabling non-invasive body surface gastric mapping (BSGM) was developed and applied to evaluate NVS pathophysiology. Design A case-control study where BSGM was performed in NVS patients and matched controls using Gastric Alimetry (Alimetry, New Zealand), comprising a conformable high-resolution array (8x8 electrodes; 20 mm inter-electrode spacing), wearable Reader, and validated symptom logging App. Continuous measurement encompassed a fasting baseline (30 min), 482 kCal meal (10 min), and 4-hr post-prandial recording. Setting Multicenter study in Auckland, New Zealand and Calgary, Canada. Participants 43 NVS patients (gastroparesis and Rome IV chronic NVS) and 43 matched controls. Main outcomes and measures Symptom severity and quality of life were measured using Patient Assessment of Upper Gastrointestinal Disorders-Symptom Severity Index (PAGI-SYM), Gastroparesis Cardinal Symptom Index (GCSI), and Patient Assessment of Upper Gastrointestinal Disorders-Quality of Life (PAGI-QOL) instruments. Health psychology metrics included the State Trait Anxiety Inventory Short Form (STAI-SF) and Patient Health Questionnaire-2 (PHQ-2) questionnaires. Spectral analyses including frequency, amplitude, and fed-fasting power ratio. Spatial biomarker analyses included spatial frequency stability and average spatial covariance. Results Meal responses were impaired in NVS, with reduced amplitudes compared to controls (median 23.3 vs 38.0 microV, p<0.001), impaired fed-fasting power-ratios (1.1 vs 1.6, p=0.02), and disorganized slow-waves (spatial frequency stability 13.6 vs 49.5; p<0.001). However, two distinct NVS subgroups were evident with indistinguishable symptoms (all p>0.05). A majority (62%) had normal BSGM studies (all biomarkers non-significant vs controls) with increased psychological comorbidities (43.5% vs 7.7%; p=0.03) and anxiety scores (median 16.5 vs 13.0; p=0.035). A smaller subgroup (31%) had markedly abnormal BSGM, with test biomarkers correlating with symptoms (nausea, pain, excessive fullness, early satiety, bloating; all r>0.35, p<0.05). Conclusions and Relevance NVS patients share overlapping symptoms, but comprise distinct underlying phenotypes as revealed by a novel BSGM device. These phenotypes correlate with symptoms, which should inform clinical management and allocations into therapeutic trials.

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

“…Early studies have confirmed improved symptom correlations and the ability to separate phenotypes at the individual patient level. 9,11 The optimized set of spectral metrics with reference intervals provided here will be fundamental in advancing the clinical application of BSGM, while promoting methodological and data standardization in research.…”

“…A recent study applying BSGM in patients with nausea/vomiting syndromes including gastroparesis demonstrated that nearly a third of cases featured abnormal spectrograms indicative of gastric neuromuscular dysfunction. 11 This phenotype was characterized by low amplitude or absent gastric frequency bands, poor rhythm stability, and limited meal responses, allowing identification of a distinct subgroup despite non-specific symptom profiles. However, this previous subgroup determination relied on subjective categorization by a consensus panel.…”

“…[10][11][12] Recent studies employing BSGM have revealed several disease signatures in adults and children suffering chronic nausea and vomiting syndromes, gastroparesis and functional dyspepsia, which correlated with symptoms. 9,11,13 The first commercial medical device for performing BSGM has recently become available, with United States Food and Drug Administration clearance (Gastric Alimetry®, Alimetry, New Zealand), enabling clinical use with the goal of reducing diagnostic uncertainty. 10,11,14 Standardised clinical application of a diagnostic medical physiology device requires a thorough understanding of normative metric intervals.…”

“…9,11,13 The first commercial medical device for performing BSGM has recently become available, with United States Food and Drug Administration clearance (Gastric Alimetry®, Alimetry, New Zealand), enabling clinical use with the goal of reducing diagnostic uncertainty. 10,11,14 Standardised clinical application of a diagnostic medical physiology device requires a thorough understanding of normative metric intervals. For BSGM, two categories of metrics are recognized: i) spectral metrics encompassing myoelectrical frequency, amplitude, rhythm stability, and meal responses; and ii) spatial metrics characterising wave propagation dynamics.…”

“…For BSGM, two categories of metrics are recognized: i) spectral metrics encompassing myoelectrical frequency, amplitude, rhythm stability, and meal responses; and ii) spatial metrics characterising wave propagation dynamics. [9][10][11] Spectral metrics are derived from a spectral plot, and represent a form of HR-EGG, achieving robust improvements over traditional EGG metrics. 8,10,12,15 Spectral metrics are currently the most established form of analytics, with a recent BSGM study principally employing these to identify a distinct subgroup of patients with gastric neuromuscular abnormalities in nausea and vomiting syndromes.…”