Gastric dysfunction in patients with chronic nausea and vomiting syndromes defined by a novel non-invasive gastric mapping device
Authors: Gharibans Armen A. , Calder Stefan , Varghese Chris , Waite Stephen , Schamberg Gabriel , Daker Charlotte , Du Peng , Alighaleh Saeed , Carson Daniel , Woodhead Jonathan , Farrugia Gianrico , Windsor John A. , Andrews Christopher N. , O’Grady Greg 
Published: February 2022

AbstractImportanceChronic 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.ObjectiveA novel medical device enabling non-invasive body surface gastric mapping (BSGM) was developed and applied to evaluate NVS pathophysiology.DesignA 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 (8×8 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.SettingMulticenter study in Auckland, New Zealand and Calgary, Canada.Participants43 NVS patients (gastroparesis and Rome IV chronic NVS) and 43 matched controls.Main outcomes and measuresSymptom 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.ResultsMeal responses were impaired in NVS, with reduced amplitudes compared to controls (median 23.3 vs 38.0 µV, 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 RelevanceNVS 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.Key PointsQuestionHow does body surface gastric mapping, a novel non-invasive medical device for evaluating gastric motility, aid assessment of patients with chronic nausea and vomiting.FindingsTwo subgroups were revealed in chronic nausea and vomiting syndromes, which could not be differentiated by symptoms alone. Where body surface gastric mapping was normal, symptoms correlated with psychological comorbidities, and where body surface gastric mapping was abnormal, symptoms correlated with gastric electrophysiology metrics.MeaningDistinct phenotypes revealed by body surface gastric mapping correlate with symptoms, which should inform targeted clinical management and allocations into therapeutic trials.