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Lim AH, Varghese C, Sebaratnam GH, Schamberg G, Calder S, Gharibans AA, Andrews CN, Foong D, Ho V, Ishida S, Imai Y, Wise MR, O'Grady G. Effect of menstrual cycle and menopause on human gastric electrophysiology. Am J Physiol Gastrointest Liver Physiol 2024; 327:G47-G56. [PMID: 38713629 PMCID: PMC11211038 DOI: 10.1152/ajpgi.00216.2023] [Citation(s) in RCA: 0] [Impact Index Per Article: 0] [Reference Citation Analysis] [Abstract] [Key Words] [MESH Headings] [Grants] [Track Full Text] [Journal Information] [Submit a Manuscript] [Subscribe] [Scholar Register] [Received: 09/27/2023] [Revised: 04/22/2024] [Accepted: 04/23/2024] [Indexed: 05/09/2024]
Abstract
Chronic gastroduodenal symptoms disproportionately affect females of childbearing age; however, the effect of menstrual cycling on gastric electrophysiology is poorly defined. To establish the effect of the menstrual cycle on gastric electrophysiology, healthy subjects underwent noninvasive Body Surface Gastric Mapping (BSGM; 8x8 array) with the validated symptom logging App (Gastric Alimetry, New Zealand). Participants included were premenopausal females in follicular (n = 26) and luteal phases (n = 18) and postmenopausal females (n = 30) and males (n = 51) were controls. Principal gastric frequency (PGF), body mass index (BMI) adjusted amplitude, Gastric Alimetry Rhythm Index (GA-RI), Fed:Fasted Amplitude Ratio (ff-AR), meal response curves, and symptom burden were analyzed. Menstrual cycle-related electrophysiological changes were then transferred to an established anatomically accurate computational gastric fluid dynamics model (meal viscosity 0.1 Pas) to predict the impact on gastric mixing and emptying. PGF was significantly higher in the luteal versus follicular phase [mean 3.21 cpm, SD (0.17) vs. 2.94 cpm, SD (0.17), P < 0.001] and versus males [3.01 cpm, SD (0.2), P < 0.001]. In the computational model, this translated to 8.1% higher gastric mixing strength and 5.3% faster gastric emptying for luteal versus follicular phases. Postmenopausal females also exhibited higher PGF than females in the follicular phase [3.10 cpm, SD (0.24) vs. 2.94 cpm, SD (0.17), P = 0.01], and higher BMI-adjusted amplitude [40.7 µV (33.02-52.58) vs. 29.6 µV (26.15-39.65), P < 0.001], GA-RI [0.60 (0.48-0.73) vs. 0.43 (0.30-0.60), P = 0.005], and ff-AR [2.51 (1.79-3.47) vs. 1.48 (1.21-2.17), P = 0.001] than males. There were no differences in symptoms. These results define variations in gastric electrophysiology with regard to human menstrual cycling and menopause.NEW & NOTEWORTHY This study evaluates gastric electrophysiology in relation to the menstrual cycle using a novel noninvasive high-resolution methodology, revealing substantial variations in gastric activity with menstrual cycling and menopause. Gastric slow-wave frequency is significantly higher in the luteal versus follicular menstrual phase. Computational modeling predicts that this difference translates to higher rates of gastric mixing and liquid emptying in the luteal phase, which is consistent with previous experimental data evaluating menstrual cycling effects on gastric emptying.
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Affiliation(s)
- Alexandria H Lim
- Department of Surgery, The University of Auckland, Auckland, New Zealand
| | - Chris Varghese
- Department of Surgery, The University of Auckland, Auckland, New Zealand
| | | | - Gabriel Schamberg
- Department of Surgery, The University of Auckland, Auckland, New Zealand
- Alimetry, Ltd., Auckland, New Zealand
| | - Stefan Calder
- Department of Surgery, The University of Auckland, Auckland, New Zealand
- Alimetry, Ltd., Auckland, New Zealand
| | - Armen A Gharibans
- Department of Surgery, The University of Auckland, Auckland, New Zealand
- Alimetry, Ltd., Auckland, New Zealand
| | | | - Daphne Foong
- School of Medicine, Western Sydney University, Sydney, New South Wales, Australia
| | - Vincent Ho
- School of Medicine, Western Sydney University, Sydney, New South Wales, Australia
| | - Shunichi Ishida
- Graduate School of Engineering, Kobe University, Kobe, Japan
| | - Yohsuke Imai
- Graduate School of Engineering, Kobe University, Kobe, Japan
| | - Michelle R Wise
- Department of Obstetrics and Gynaecology, The University of Auckland, Auckland, New Zealand
| | - Greg O'Grady
- Department of Surgery, The University of Auckland, Auckland, New Zealand
- Alimetry, Ltd., Auckland, New Zealand
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Law M, Schamberg G, Gharibans A, Sebaratnam G, Foong D, Varghese C, Fitt I, Daker C, Ho V, Du P, Andrews CN, O'Grady G, Calder S. Short- and long-term reproducibility of body surface gastric mapping using the Gastric Alimetry® system. Neurogastroenterol Motil 2024; 36:e14812. [PMID: 38689428 DOI: 10.1111/nmo.14812] [Citation(s) in RCA: 0] [Impact Index Per Article: 0] [Reference Citation Analysis] [Abstract] [Key Words] [MESH Headings] [Grants] [Track Full Text] [Journal Information] [Submit a Manuscript] [Subscribe] [Scholar Register] [Received: 10/23/2023] [Revised: 04/03/2024] [Accepted: 04/15/2024] [Indexed: 05/02/2024]
Abstract
BACKGROUND Many diagnostic tests for gastroduodenal symptoms, such as gastric emptying scintigraphy (GES), gastric emptying breath tests (GEBT), and electrogastrography (EGG) show variable intra-individual reproducibility over time. This study investigated the short- and long-term reproducibility of body surface gastric mapping (BSGM), a non-invasive test for assessing gastric function, in controls and patients with chronic gastroduodenal disorders. METHODS Participants completed three standardized BSGM tests using Gastric Alimetry® (Alimetry, New Zealand). The test encompassed a fasting baseline (30 min), a 482 kCal standard meal, and a 4 h postprandial recording. The first two tests were >6 months apart and the last occurred ~1 week after the second test, to evaluate long and short-term reproducibility. RESULTS Fourteen patients with upper gastrointestinal symptoms and 14 healthy controls were recruited. There were no significant differences in any BSGM metrics between the tests at short and long term (all p > 0.180). Lin's concordance correlation coefficients (CCC) for the primary metrics were high, ranging from 0.58 to 0.96, with intra-individual coefficients of variance (CVintra) ranging from 0.2% to 1.9%. Reproducibility was higher, and intra-individual variation lower, than in previous studies of GES (CCC = 0.54-0.83, CVintra = 3%-77%), GEBT (CVintra = 8%-11%), and EGG (CVintra = 3%-78%). CONCLUSIONS BSGM spectral metrics demonstrate high reproducibility and low intra-individual variation at both short and long term, with superior results to comparable tests. The high reproducibility of Gastric Alimetry supports its role as a diagnostic aid for gastric dysfunction and a reliable tool for evaluating treatment outcomes and disease progression over time.
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Affiliation(s)
- Mikaela Law
- The Department of Surgery, The University of Auckland, Auckland, New Zealand
- Alimetry Ltd., Auckland, New Zealand
| | - Gabriel Schamberg
- The Department of Surgery, The University of Auckland, Auckland, New Zealand
- Alimetry Ltd., Auckland, New Zealand
| | - Armen Gharibans
- The Department of Surgery, The University of Auckland, Auckland, New Zealand
- Alimetry Ltd., Auckland, New Zealand
- Perelman School of Medicine, University of Pennsylvania, Philadelphia, Pennsylvania, USA
| | | | - Daphne Foong
- Alimetry Ltd., Auckland, New Zealand
- School of Medicine, Western Sydney University, Sydney, New South Wales, Australia
| | - Chris Varghese
- The Department of Surgery, The University of Auckland, Auckland, New Zealand
| | - India Fitt
- The Department of Surgery, The University of Auckland, Auckland, New Zealand
| | - Charlotte Daker
- Alimetry Ltd., Auckland, New Zealand
- Department of Gastroenterology, Te Whatu Ora-Waitematā, Auckland, New Zealand
| | - Vincent Ho
- School of Medicine, Western Sydney University, Sydney, New South Wales, Australia
- Department of Gastroenterology and Hepatology, Campbelltown Hospital, Campbelltown, New South Wales, Australia
| | - Peng Du
- Alimetry Ltd., Auckland, New Zealand
- Auckland Bioengineering Institute, The University of Auckland, Auckland, New Zealand
| | - Christopher N Andrews
- Alimetry Ltd., Auckland, New Zealand
- Division of Gastroenterology, Cumming School of Medicine, University of Calgary, Calgary, Alberta, Canada
| | - Greg O'Grady
- The Department of Surgery, The University of Auckland, Auckland, New Zealand
- Alimetry Ltd., Auckland, New Zealand
| | - Stefan Calder
- The Department of Surgery, The University of Auckland, Auckland, New Zealand
- Alimetry Ltd., Auckland, New Zealand
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Liu H, You SS, Gao Z, Hu N, Zhao Y. Next generation of gastrointestinal electrophysiology devices. Nat Rev Gastroenterol Hepatol 2024; 21:457-458. [PMID: 38877210 DOI: 10.1038/s41575-024-00952-x] [Citation(s) in RCA: 0] [Impact Index Per Article: 0] [Reference Citation Analysis] [MESH Headings] [Track Full Text] [Journal Information] [Submit a Manuscript] [Subscribe] [Scholar Register] [Indexed: 06/16/2024]
Affiliation(s)
- Haitao Liu
- General Surgery Department, Children's Hospital, Zhejiang University School of Medicine, National Clinical Research Center for Children's Health, Hangzhou, China
- Department of Chemistry, Zhejiang-Israel Joint Laboratory of Self-Assembling Functional Materials, ZJU-Hangzhou Global Scientific and Technological Innovation Center, Zhejiang University, Hangzhou, China
| | - Siheng Sean You
- David H. Koch Institute for Integrative Cancer Research, Massachusetts Institute of Technology, Cambridge, MA, USA
- Division of Gastroenterology, Hepatology and Endoscopy, Brigham and Women's Hospital, Harvard Medical School, Boston, MA, USA
| | - Zhigang Gao
- General Surgery Department, Children's Hospital, Zhejiang University School of Medicine, National Clinical Research Center for Children's Health, Hangzhou, China
| | - Ning Hu
- General Surgery Department, Children's Hospital, Zhejiang University School of Medicine, National Clinical Research Center for Children's Health, Hangzhou, China.
- Department of Chemistry, Zhejiang-Israel Joint Laboratory of Self-Assembling Functional Materials, ZJU-Hangzhou Global Scientific and Technological Innovation Center, Zhejiang University, Hangzhou, China.
| | - Yunlong Zhao
- Dyson School of Design Engineering, Imperial College London, London, UK.
- National Physical Laboratory, Teddington, UK.
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Huang IH, Calder S, Gharibans AA, Schamberg G, Varghese C, Andrews CN, Tack J, O'Grady G. Meal effects on gastric bioelectrical activity utilizing body surface gastric mapping in healthy subjects. Neurogastroenterol Motil 2024:e14823. [PMID: 38764250 DOI: 10.1111/nmo.14823] [Citation(s) in RCA: 0] [Impact Index Per Article: 0] [Reference Citation Analysis] [Abstract] [Key Words] [Grants] [Track Full Text] [Journal Information] [Submit a Manuscript] [Subscribe] [Scholar Register] [Received: 10/31/2023] [Revised: 05/01/2024] [Accepted: 05/09/2024] [Indexed: 05/21/2024]
Abstract
BACKGROUND Gastric sensorimotor disorders are prevalent. While gastric emptying measurements are commonly used, they may not fully capture the underlying pathophysiology. Body surface gastric mapping (BSGM) recently emerged to assess gastric sensorimotor dysfunction. This study assessed varying meal size on BSGM responses to inform test use in a wider variety of contexts. METHODS Data from multiple healthy cohorts receiving BSGM were pooled, using four different test meals. A standard BSGM protocol was employed: 30-min fasting, 4-h post-prandial, using Gastric Alimetry® (Alimetry, New Zealand). Meals comprised: (i) nutrient drink + oatmeal bar (482 kcal; 'standard meal'); (ii) oatmeal bar alone; egg and toast meal, and pancake (all ~250 kcal). Gastric Alimetry metrics included BMI-adjusted Amplitude, Principal Gastric Frequency, Gastric Alimetry Rhythm Index (GA-RI) and Fed:Fasted Amplitude Ratio (ff-AR). KEY RESULTS 238 participants (59.2% female) were included. All meals significantly increased amplitude and frequency during the first postprandial hour (p < 0.05). There were no differences in postprandial frequency across meals (p > 0.05). The amplitude and GA-RI of the standard meal (n = 110) were significantly higher than the energy bar alone (n = 45) and egg meal (n = 65) (all p < 0.05). All BSGM metrics were comparable across the three smaller meals (p > 0.05). A higher symptom burden was found in the oatmeal bar group versus the standard meal and pancake meal (p = 0.01, 0.003, respectively). CONCLUSIONS & INFERENCES The consumption of lower calorie meals elicited different postprandial responses, when compared to the standard Gastric Alimetry meal. These data will guide interpretations of BSGM when applied with lower calorie meals.
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Affiliation(s)
- I-Hsuan Huang
- Translational Research Center for Gastrointestinal Disorders, University of Leuven, Leuven, Belgium
- Department of Gastroenterology and Hepatology, Tri-Service General Hospital, National Defense Medical Center, Taipei, Taiwan
| | - Stefan Calder
- Alimetry Ltd, Auckland, New Zealand
- Department of Surgery, University of Auckland, Auckland, New Zealand
| | - Armen A Gharibans
- Alimetry Ltd, Auckland, New Zealand
- Department of Surgery, University of Auckland, Auckland, New Zealand
| | - Gabriel Schamberg
- Alimetry Ltd, Auckland, New Zealand
- Department of Surgery, University of Auckland, Auckland, New Zealand
| | - Chris Varghese
- Department of Surgery, University of Auckland, Auckland, New Zealand
| | - Christopher N Andrews
- Alimetry Ltd, Auckland, New Zealand
- Division of Gastroenterology, Cumming School of Medicine, University of Calgary, Calgary, Canada
| | - Jan Tack
- Translational Research Center for Gastrointestinal Disorders, University of Leuven, Leuven, Belgium
| | - Greg O'Grady
- Alimetry Ltd, Auckland, New Zealand
- Department of Surgery, University of Auckland, Auckland, New Zealand
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Huang IH, Schol J, Calder S, Gharibans AA, Van den Houte K, Verheyden A, Broeders B, Carbone F, O'Grady G, Tack J. Effects of corticotropin-releasing hormone on gastric electrical activity and sensorimotor function in healthy volunteers: a double-blinded crossover study. Am J Physiol Gastrointest Liver Physiol 2024; 326:G622-G630. [PMID: 38375576 DOI: 10.1152/ajpgi.00298.2023] [Citation(s) in RCA: 0] [Impact Index Per Article: 0] [Reference Citation Analysis] [Abstract] [Key Words] [MESH Headings] [Track Full Text] [Journal Information] [Submit a Manuscript] [Subscribe] [Scholar Register] [Received: 12/12/2023] [Revised: 02/06/2024] [Accepted: 02/15/2024] [Indexed: 02/21/2024]
Abstract
Biopsychosocial factors are associated with disorders of gut-brain interaction (DGBI) and exacerbate gastrointestinal symptoms. The mechanisms underlying pathophysiological alterations of stress remain unclear. Corticotropin-releasing hormone (CRH) is a central regulator of the hormonal stress response and has diverse impact on different organ systems. The aim of the present study was to investigate the effects of peripheral CRH infusion on meal-related gastrointestinal symptoms, gastric electrical activity, and gastric sensorimotor function in healthy volunteers (HVs). In a randomized, double-blinded, placebo-controlled, crossover study, we evaluated the effects of CRH on gastric motility and sensitivity. HVs were randomized to receive either peripheral-administered CRH (100 µg bolus + 1 µg/kg/h) or placebo (saline), followed by at least a 7-day washout period and assignment to the opposite treatment. Tests encompassed saliva samples, gastric-emptying (GE) testing, body surface gastric mapping (BSGM, Gastric Alimetry; Alimetry) to assess gastric myoelectrical activity with real-time symptom profiling, and a gastric barostat study to assess gastric sensitivity to distention and accommodation. Twenty HVs [13 women, mean age 29.2 ± 5.3 yr, body mass index (BMI) 23.3 ± 3.8 kg/m2] completed GE tests, of which 18 also underwent BSGM measurements during the GE tests. The GE half-time decreased significantly after CRH exposure (65.2 ± 17.4 vs. 78.8 ± 24.5 min, P = 0.02) with significantly increased gastric amplitude [49.7 (34.7-55.6) vs. 31.7 (25.7-51.0) µV, P < 0.01], saliva cortisol levels, and postprandial symptom severity. Eleven HVs also underwent gastric barostat studies on a separate day. However, the thresholds for discomfort during isobaric distensions, gastric compliance, and accommodation did not differ between CRH and placebo.NEW & NOTEWORTHY In healthy volunteers, peripheral corticotropin-releasing hormone (CRH) infusion accelerates gastric-emptying rate and increases postprandial gastric response, accompanied by a rise in symptoms, but does not alter gastric sensitivity or meal-induced accommodation. These findings underscore a significant link between stress and dyspeptic symptoms, with CRH playing a pivotal role in mediating these effects.
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Affiliation(s)
- I-Hsuan Huang
- Translational Research Center for Gastrointestinal Disorders, University of Leuven, Leuven, Belgium
- Department of Gastroenterology and Hepatology, Tri-Service General Hospital, National Defense Medical Center, Taipei, Taiwan
| | - Jolien Schol
- Translational Research Center for Gastrointestinal Disorders, University of Leuven, Leuven, Belgium
| | | | | | - Karen Van den Houte
- Translational Research Center for Gastrointestinal Disorders, University of Leuven, Leuven, Belgium
| | - Annelies Verheyden
- Translational Research Center for Gastrointestinal Disorders, University of Leuven, Leuven, Belgium
| | - Bert Broeders
- Translational Research Center for Gastrointestinal Disorders, University of Leuven, Leuven, Belgium
| | - Florencia Carbone
- Translational Research Center for Gastrointestinal Disorders, University of Leuven, Leuven, Belgium
| | - Greg O'Grady
- Alimetry, Ltd., Auckland, New Zealand
- Surgical and Translational Research Centre, The University of Auckland, Auckland, New Zealand
| | - Jan Tack
- Translational Research Center for Gastrointestinal Disorders, University of Leuven, Leuven, Belgium
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Humphrey G, Keane C, Gharibans A, Andrews CN, Benitez A, Mousa H, O'Grady G. Designing, Developing, and Validating a Set of Standardized Pictograms to Support Pediatric-Reported Gastroduodenal Symptoms. J Pediatr 2024; 267:113922. [PMID: 38242317 DOI: 10.1016/j.jpeds.2024.113922] [Citation(s) in RCA: 0] [Impact Index Per Article: 0] [Reference Citation Analysis] [Abstract] [Key Words] [MESH Headings] [Track Full Text] [Journal Information] [Submit a Manuscript] [Subscribe] [Scholar Register] [Received: 08/21/2023] [Revised: 01/08/2024] [Accepted: 01/11/2024] [Indexed: 01/21/2024]
Abstract
OBJECTIVE To develop and validate a set of static and animated gastroduodenal symptom pictograms for children. STUDY DESIGN There were 3 study phases: 1: cocreation using experience design methods to develop pediatric gastroduodenal symptom pictograms (static and animated); 2: an online survey to assess acceptability, as well as face and content validity; and 3: a preference study. Phases 2 and 3 compared the novel pediatric pictograms with existing pictograms used with adult patients. RESULTS Eight children aged 6-15 years (5 female) participated in phase 1, and 69 children in phase 2 (median age 13 years: IQR 9-15); an additional 49 participants were included in phase 3 (median age 15: IQR 12-17). Face and content validity were higher for the pediatric static and animated pictogram sets compared with pre-existing adult pictograms (78% vs 78% vs 61%). Participants with worse gastric symptoms had superior comprehension of the pediatric pictograms (χ2 [8, N = 118] P < .001). All participants preferred the pediatric static pictogram set was over both the animated and adult sets (χ2 [2, N = 118] P < .001). CONCLUSIONS The cocreation phase resulted in the symptom concept confirmation and design of 10 acceptable static and animated gastroduodenal pictograms with high face and content validity when evaluated with children aged 6-18. Validity was superior when children reported more problematic symptoms. Therefore, these pictograms could be used in clinical and research practice to enable standardized symptom reporting for children with gastroduodenal disorders.
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Affiliation(s)
- Gayl Humphrey
- Department of Surgery, The University of Auckland, Aotearoa, New Zealand.
| | - Celia Keane
- Department of Surgery, The University of Auckland, Aotearoa, New Zealand; Te Whatu Ora: Te Tai Tokerau (Health New Zealand: Northland)
| | - Armen Gharibans
- Department of Surgery, The University of Auckland, Aotearoa, New Zealand; Alimetry Ltd, Auckland, Aotearoa, New Zealand; Perelman School of Medicine, University of Pennsylvania, PA
| | - Christopher N Andrews
- Alimetry Ltd, Auckland, Aotearoa, New Zealand; The Division of Gastroenterology, Cumming School of Medicine, University of Calgary, Canada
| | - Alain Benitez
- Division of Gastroenterology, Children's Hospital of Philadelphia, Philadelphia; Perelman School of Medicine, University of Pennsylvania, PA
| | - Hayat Mousa
- Division of Gastroenterology, Children's Hospital of Philadelphia, Philadelphia; Perelman School of Medicine, University of Pennsylvania, PA
| | - Gregory O'Grady
- Department of Surgery, The University of Auckland, Aotearoa, New Zealand; Alimetry Ltd, Auckland, Aotearoa, New Zealand
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Xu W, Wang T, Foong D, Schamberg G, Evennett N, Beban G, Gharibans A, Calder S, Daker C, Ho V, O'Grady G. Characterization of gastric dysfunction after fundoplication using body surface gastric mapping. J Gastrointest Surg 2024; 28:236-245. [PMID: 38445915 DOI: 10.1016/j.gassur.2023.12.023] [Citation(s) in RCA: 0] [Impact Index Per Article: 0] [Reference Citation Analysis] [Abstract] [Key Words] [MESH Headings] [Track Full Text] [Journal Information] [Submit a Manuscript] [Subscribe] [Scholar Register] [Received: 11/23/2023] [Revised: 12/09/2023] [Accepted: 12/22/2023] [Indexed: 03/07/2024]
Abstract
BACKGROUND Adverse gastric symptoms persist in up to 20% of fundoplication operations completed for gastroesophageal reflux disease, causing significant morbidity and driving the need for revisional procedures. Noninvasive techniques to assess the mechanisms of persistent postoperative symptoms are lacking. This study aimed to investigate gastric myoelectrical abnormalities and symptoms in patients after fundoplication using a novel noninvasive body surface gastric mapping (BSGM) device. METHODS Patients with a previous fundoplication operation and ongoing significant gastroduodenal symptoms and matched controls were included. BSGM using Gastric Alimetry (Alimetry Ltd) was employed, consisting of a high-resolution 64-channel array, validated symptom-logging application, and wearable reader. RESULTS A total of 16 patients with significant chronic symptoms after fundoplication were recruited, with 16 matched controls. Overall, 6 of 16 patients (37.5%) showed significant spectral abnormalities defined by unstable gastric myoelectrical activity (n = 2), abnormally high gastric frequencies (n = 3), or high gastric amplitudes (n = 1). Patients with spectral abnormalities had higher Patient Assessment of Upper Gastrointestinal Disorders-Symptom Severity Index scores than those of patients without spectral abnormalities (3.2 [range, 2.8-3.6] vs 2.3 [range, 2.2-2.8], respectively; P = .024). Moreover, 7 of 16 patients (43.8%) had BSGM test results suggestive of gut-brain axis contributions and without myoelectrical dysfunction. Increasing Principal Gastric Frequency Deviation and decreasing Rhythm Index scores were associated with symptom severity (r > .40; P < .05). CONCLUSION A significant number of patients with persistent postfundoplication symptoms displayed abnormal gastric function on BSGM testing, which correlated with symptom severity. Our findings advance the pathophysiologic understanding of postfundoplication disorders, which may inform diagnosis and patient selection for medical therapy and revisional procedures.
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Affiliation(s)
- William Xu
- Department of Surgery, University of Auckland, Auckland, New Zealand
| | - Tim Wang
- Department of Surgery, University of Auckland, Auckland, New Zealand
| | - Daphne Foong
- Alimetry Ltd, Auckland, New Zealand; School of Medicine, Western Sydney University, Penrith, Australia
| | - Gabe Schamberg
- Department of Surgery, University of Auckland, Auckland, New Zealand; Alimetry Ltd, Auckland, New Zealand
| | - Nicholas Evennett
- Department of Surgery, University of Auckland, Auckland, New Zealand
| | - Grant Beban
- Department of Surgery, University of Auckland, Auckland, New Zealand
| | - Armen Gharibans
- Alimetry Ltd, Auckland, New Zealand; Auckland Bioengineering Institute, University of Auckland, Auckland, New Zealand; Perelman School of Medicine, University of Pennsylvania, Philadelphia, Pennsylvania, United States
| | - Stefan Calder
- Alimetry Ltd, Auckland, New Zealand; Auckland Bioengineering Institute, University of Auckland, Auckland, New Zealand
| | - Charlotte Daker
- Alimetry Ltd, Auckland, New Zealand; Department of Gastroenterology, North Shore Hospital, Auckland, New Zealand
| | - Vincent Ho
- School of Medicine, Western Sydney University, Penrith, Australia; Department of Gastroenterology and Hepatology, Campbelltown Hospital, Campbelltown, Australia
| | - Greg O'Grady
- Department of Surgery, University of Auckland, Auckland, New Zealand; Alimetry Ltd, Auckland, New Zealand; Auckland Bioengineering Institute, University of Auckland, Auckland, New Zealand.
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Du P, Maharjan A, Calder S, Schultz M, Schamberg G, Gharibans A, O'Grady G, Cakmak YO. Transcutaneous Auricular Vagus Nerve Stimulation Normalizes Induced Gastric Myoelectrical Dysrhythmias in Controls Assessed by Body-Surface Gastric Mapping. Neuromodulation 2024; 27:333-342. [PMID: 36997454 DOI: 10.1016/j.neurom.2023.02.078] [Citation(s) in RCA: 0] [Impact Index Per Article: 0] [Reference Citation Analysis] [Abstract] [Key Words] [MESH Headings] [Track Full Text] [Journal Information] [Subscribe] [Scholar Register] [Received: 09/05/2022] [Revised: 01/24/2023] [Accepted: 02/13/2023] [Indexed: 03/31/2023]
Abstract
OBJECTIVES Transcutaneous auricular vagus nerve stimulation (TaVNS) is a supplementary treatment for gastric symptoms resulting from dysrhythmias. The main objective of this study was to quantify the effects of 10, 40, and 80 Hz TaVNS and sham in healthy individuals in response to a 5-minute water-load (WL5) test. MATERIALS AND METHODS Eighteen healthy volunteers aged between 21 and 55 years (body mass index: 27.1 ± 3.2) were recruited. Each subject fasted for up to eight hours and participated in four 95-minute sessions, which consisted of 30 fasted baseline, 30 minutes TaVNS, WL5, and 30 minutes post-WL5. Heart rate variability was assessed using sternal electrocardiogram. Body-surface gastric mapping and bloating (/10) were recorded. One-way ANOVA with post hoc Tukey test was performed to test the difference between TaVNS protocols in terms of frequency, amplitude, bloating scores, root mean square of the successive differences (RMSSD), and stress index (SI). RESULTS On average, the subjects consumed 526 ± 160 mL of water, with volume ingested correlated to bloating (mean score 4.1 ± 1.8; r = 0.36, p = 0.029). In general, the reduction in frequency and rhythm stability during the post-WL5 period in sham was normalized by all three TaVNS protocols. Both 40- and 80-Hz protocols also caused increases in amplitude during the stim-only and/or post-WL5 periods. RMSSD increased during the 40-Hz protocol. SI increased during the 10-Hz protocol but decreased during the 40- and 80-Hz protocols. CONCLUSION TaVNS proved effective in normalizing gastric dysrhythmias by WL5 in healthy subjects by altering both parasympathetic and sympathetic pathways.
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Affiliation(s)
- Peng Du
- Auckland Bioengineering Institute, The University of Auckland, Auckland, New Zealand
| | - Ashim Maharjan
- Department of Anatomy, University of Otago, Dunedin, New Zealand
| | - Stefan Calder
- Department of Surgery, The University of Auckland, Auckland, New Zealand; Alimetry Ltd, Auckland, New Zealand
| | - Michael Schultz
- Department of Medicine, University of Otago, Dunedin, New Zealand
| | | | - Armen Gharibans
- Department of Surgery, The University of Auckland, Auckland, New Zealand; Alimetry Ltd, Auckland, New Zealand
| | - Gregory O'Grady
- Department of Surgery, The University of Auckland, Auckland, New Zealand; Alimetry Ltd, Auckland, New Zealand
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9
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Wang WJ, Foong D, Calder S, Schamberg G, Varghese C, Tack J, Xu W, Daker C, Carson D, Waite S, Hayes T, Du P, Abell TL, Parkman HP, Huang IH, Fernandes V, Andrews CN, Gharibans AA, Ho V, O’Grady G. Gastric Alimetry Expands Patient Phenotyping in Gastroduodenal Disorders Compared with Gastric Emptying Scintigraphy. Am J Gastroenterol 2024; 119:331-341. [PMID: 37782524 PMCID: PMC10872929 DOI: 10.14309/ajg.0000000000002528] [Citation(s) in RCA: 0] [Impact Index Per Article: 0] [Reference Citation Analysis] [Abstract] [Key Words] [MESH Headings] [Grants] [Track Full Text] [Journal Information] [Submit a Manuscript] [Subscribe] [Scholar Register] [Received: 04/05/2023] [Accepted: 08/04/2023] [Indexed: 10/03/2023]
Abstract
INTRODUCTION Gastric emptying testing (GET) assesses gastric motility, however, is nonspecific and insensitive for neuromuscular disorders. Gastric Alimetry (GA) is a new medical device combining noninvasive gastric electrophysiological mapping and validated symptom profiling. This study assessed patient-specific phenotyping using GA compared with GET. METHODS Patients with chronic gastroduodenal symptoms underwent simultaneous GET and GA, comprising a 30-minute baseline, 99m TC-labelled egg meal, and 4-hour postprandial recording. Results were referenced to normative ranges. Symptoms were profiled in the validated GA App and phenotyped using rule-based criteria based on their relationships to the meal and gastric activity: (i) sensorimotor, (ii) continuous, and (iii) other. RESULTS Seventy-five patients were assessed, 77% female. Motility abnormality detection rates were as follows: GET 22.7% (14 delayed, 3 rapid), GA spectral analysis 33.3% (14 low rhythm stability/low amplitude, 5 high amplitude, and 6 abnormal frequency), and combined yield 42.7%. In patients with normal spectral analysis, GA symptom phenotypes included sensorimotor 17% (where symptoms strongly paired with gastric amplitude, median r = 0.61), continuous 30%, and other 53%. GA phenotypes showed superior correlations with Gastroparesis Cardinal Symptom Index, Patient Assessment of Upper Gastrointestinal Symptom Severity Index, and anxiety scales, whereas Rome IV Criteria did not correlate with psychometric scores ( P > 0.05). Delayed emptying was not predictive of specific GA phenotypes. DISCUSSION GA improves patient phenotyping in chronic gastroduodenal disorders in the presence and absence of motility abnormalities with increased correlation with symptoms and psychometrics compared with gastric emptying status and Rome IV criteria. These findings have implications for the diagnostic profiling and personalized management of gastroduodenal disorders.
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Affiliation(s)
- William Jiaen Wang
- Gastrointestinal Motility Disorders Unit, Western Sydney University, Australia
- Department of Gastroenterology and Hepatology, Campbelltown Hospital, Australia
- Gastroenterology and Hepatology, Princess Alexandra Hospital, Australia
| | - Daphne Foong
- Gastrointestinal Motility Disorders Unit, Western Sydney University, Australia
| | - Stefan Calder
- Department of Surgery, Auckland City Hospital, New Zealand
- Auckland Bioengineering Institute, University of Auckland, New Zealand
- Alimetry Ltd, Auckland, New Zealand
| | - Gabriel Schamberg
- Department of Surgery, Auckland City Hospital, New Zealand
- Alimetry Ltd, Auckland, New Zealand
| | - Chris Varghese
- Department of Surgery, Auckland City Hospital, New Zealand
| | - Jan Tack
- Translational Research Center for Gastrointestinal Disorders (TARGID), University of Leuven, Belgium
| | - William Xu
- Department of Surgery, Auckland City Hospital, New Zealand
| | - Charlotte Daker
- Department of Gastroenterology, North Shore Hospital, Auckland, New Zealand
| | - Daniel Carson
- Department of Surgery, Auckland City Hospital, New Zealand
| | | | - Thomas Hayes
- Department of Surgery, Auckland City Hospital, New Zealand
| | - Peng Du
- Auckland Bioengineering Institute, University of Auckland, New Zealand
| | - Thomas L. Abell
- Division of Gastroenterology, University of Louisville, KY, USA
| | - Henry P. Parkman
- Gastroenterology Section, Department of Medicine, Lewis Katz School of Medicine, Temple University, USA
| | - I-Hsuan Huang
- Translational Research Center for Gastrointestinal Disorders (TARGID), University of Leuven, Belgium
| | | | | | - Armen A. Gharibans
- Department of Surgery, Auckland City Hospital, New Zealand
- Auckland Bioengineering Institute, University of Auckland, New Zealand
- Alimetry Ltd, Auckland, New Zealand
| | - Vincent Ho
- Gastrointestinal Motility Disorders Unit, Western Sydney University, Australia
- Department of Gastroenterology and Hepatology, Campbelltown Hospital, Australia
| | - Greg O’Grady
- Department of Surgery, Auckland City Hospital, New Zealand
- Auckland Bioengineering Institute, University of Auckland, New Zealand
- Alimetry Ltd, Auckland, New Zealand
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Varghese C, Dachs N, Schamberg G, McCool K, Law M, Xu W, Calder S, Foong D, Ho V, Daker C, Andrews CN, Gharibans AA, O'Grady G. Longitudinal outcome monitoring in patients with chronic gastroduodenal symptoms investigated using the Gastric Alimetry system: study protocol. BMJ Open 2023; 13:e074462. [PMID: 38011983 PMCID: PMC10685974 DOI: 10.1136/bmjopen-2023-074462] [Citation(s) in RCA: 0] [Impact Index Per Article: 0] [Reference Citation Analysis] [Abstract] [Key Words] [MESH Headings] [Grants] [Track Full Text] [Journal Information] [Submit a Manuscript] [Subscribe] [Scholar Register] [Received: 04/10/2023] [Accepted: 11/07/2023] [Indexed: 11/29/2023] Open
Abstract
INTRODUCTION The Gastric Alimetry platform offers a multimodal assessment of gastric function through body surface gastric mapping (BSGM) and concurrent symptom-tracking via a validated App. We aim to perform a longitudinal cohort study to examine the impact of Gastric Alimetry, and changes in clinical management on patient symptoms, quality of life and psychological health. METHODS AND ANALYSIS This is a prospective multicentre longitudinal observational cohort study of participants with chronic gastroduodenal symptoms. Consecutive participants undergoing Gastric Alimetry will be invited to participate. Quality of life will be assessed via EuroQol-5D and the Patient Assessment of Upper Gastrointestinal Disorders-Quality of Life score. Gastrointestinal symptoms will be assessed via the Patient Assessment of Upper Gastrointestinal Symptom Severity index, and the Gastroparesis Cardinal Symptom Index. Psychometrics will be assessed, including anxiety via the General Anxiety Disorder-7, perceived stress using the Perceived Stress Scale 4, and depression via the Patient Health Questionnaire 9. Clinical parameters including diagnoses, investigations and treatments (medication and procedures) will also be captured. Assessments will be made the week after the BSGM test, at 30 days, 90 days, 180 days and 360 days thereafter. The primary outcome is feasibility of longitudinal follow-up of a cohort that have undergone Gastric Alimetry testing; from which patients' continuum of care can be characterised. Secondary outcomes include changes in patient-reported symptoms, quality of life and psychometrics (anxiety, stress and depression). Inferential causal analyses will be performed at the within patient level to explore causal associations between treatment changes and clinical outcomes. The impact of Gastric Alimetry on clinical management will also be captured. ETHICS AND DISSEMINATION The protocol has been approved in Aotearoa New Zealand by the Auckland Health Research Ethics Committee. Results will be submitted for conference presentation and peer-reviewed publication.
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Affiliation(s)
- Chris Varghese
- Department of Surgery, University of Auckland, Auckland, New Zealand
| | | | - Gabriel Schamberg
- Department of Surgery, University of Auckland, Auckland, New Zealand
- Alimetry Ltd, Auckland, New Zealand
| | | | - Mikaela Law
- Department of Surgery, University of Auckland, Auckland, New Zealand
- Alimetry Ltd, Auckland, New Zealand
| | - William Xu
- Department of Surgery, University of Auckland, Auckland, New Zealand
| | | | - Daphne Foong
- Western Sydney University, Penrith South, New South Wales, Australia
| | - Vincent Ho
- Western Sydney University, Penrith South, New South Wales, Australia
| | - Charlotte Daker
- Department of Gastroenterology, North Shore Hospital, Auckland, New Zealand
| | | | - Armen A Gharibans
- Department of Surgery, University of Auckland, Auckland, New Zealand
- Alimetry Ltd, Auckland, New Zealand
| | - Gregory O'Grady
- Department of Surgery, University of Auckland, Auckland, New Zealand
- Alimetry Ltd, Auckland, New Zealand
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11
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Varghese C, Daker C, Lim A, Sebaratnam G, Xu W, Kean B, Cederwall C. Gastric Alimetry in the Management of Chronic Gastroduodenal Disorders: Impact to Diagnosis and Health Care Utilization. Clin Transl Gastroenterol 2023; 14:e00626. [PMID: 37589479 PMCID: PMC10684143 DOI: 10.14309/ctg.0000000000000626] [Citation(s) in RCA: 2] [Impact Index Per Article: 2.0] [Reference Citation Analysis] [Abstract] [Key Words] [MESH Headings] [Grants] [Track Full Text] [Journal Information] [Submit a Manuscript] [Subscribe] [Scholar Register] [Received: 02/07/2023] [Accepted: 08/02/2023] [Indexed: 08/18/2023] Open
Abstract
INTRODUCTION Chronic gastroduodenal symptoms are frequently overlapping within existing diagnostic paradigms, and current diagnostic tests are insensitive to underlying pathophysiologies. Gastric Alimetry has emerged as a new diagnostic test of gastric neuromuscular function with time-of-test symptom profiling. This study aimed to assess the impact to diagnosis and health care utilization after the introduction of Gastric Alimetry into clinical care. METHODS Consecutive data of patients from 2 tertiary centers with chronic gastroduodenal symptoms (Rome-IV defined or motility disorder) having integrated care and Gastric Alimetry testing were evaluated. Changes in diagnoses, interventions, and management were quantified. Pretest and posttest health care utilization was reported. A preliminary management framework was established through experiential learning. RESULTS Fifty participants (45 women; median age 30 years; 18 with gastroparesis, 24 with chronic nausea and vomiting syndrome, and 6 with functional dyspepsia) underwent Gastric Alimetry testing. One-third of patients had a spectral abnormality (18% dysrhythmic/low amplitude). Of the remaining patients, 9 had symptoms correlating to gastric amplitude, while 19 had symptoms unrelated to gastric activity. Gastric Alimetry aided management decisions in 84%, including changes in invasive nutritional support in 9/50 cases (18%; predominantly de-escalation). Health care utilization was significantly lower post-Gastric Alimetry testing when compared with the average utilization cost in the year before Gastric Alimetry testing (mean ± SD $39,724 ± 63,566 vs $19,937 ± 35,895, P = 0.037). DISCUSSION Gastric Alimetry aided diagnosis and management of patients with chronic gastroduodenal symptoms by enabling phenotype-informed care. The high majority of results aided management decisions, which was associated with reduced health care utilization.
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Affiliation(s)
- Chris Varghese
- Department of Surgery, Auckland City Hospital, Auckland, New Zealand
| | - Charlotte Daker
- Department of Gastroenterology, North Shore Hospital, Auckland, New Zealand
| | - Alexandria Lim
- Department of Surgery, Auckland City Hospital, Auckland, New Zealand
| | | | - William Xu
- Department of Surgery, Auckland City Hospital, Auckland, New Zealand
| | - Bernard Kean
- Wellington Regional Hospital, Wellington, New Zealand
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12
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Foong D, Calder S, Varghese C, Schamberg G, Xu W, Daker C, Ho V, Andrews CN, Gharibans AA, O’Grady G. Gastric Alimetry ® Test Interpretation in Gastroduodenal Disorders: Review and Recommendations. J Clin Med 2023; 12:6436. [PMID: 37892572 PMCID: PMC10607701 DOI: 10.3390/jcm12206436] [Citation(s) in RCA: 0] [Impact Index Per Article: 0] [Reference Citation Analysis] [Abstract] [Key Words] [Grants] [Track Full Text] [Journal Information] [Subscribe] [Scholar Register] [Received: 07/21/2023] [Revised: 10/04/2023] [Accepted: 10/08/2023] [Indexed: 10/29/2023] Open
Abstract
Chronic gastroduodenal symptoms are prevalent worldwide, and there is a need for new diagnostic and treatment approaches. Several overlapping processes may contribute to these symptoms, including gastric dysmotility, hypersensitivity, gut-brain axis disorders, gastric outflow resistance, and duodenal inflammation. Gastric Alimetry® (Alimetry, New Zealand) is a non-invasive test for evaluating gastric function that combines body surface gastric mapping (high-resolution electrophysiology) with validated symptom profiling. Together, these complementary data streams enable important new clinical insights into gastric disorders and their symptom correlations, with emerging therapeutic implications. A comprehensive database has been established, currently comprising > 2000 Gastric Alimetry tests, including both controls and patients with various gastroduodenal disorders. From studies employing this database, this paper presents a systematic methodology for Gastric Alimetry test interpretation, together with an extensive supporting literature review. Reporting is grouped into four sections: Test Quality, Spectral Analysis, Symptoms, and Conclusions. This review compiles, assesses, and evaluates each of these aspects of test assessment, with discussion of relevant evidence, example cases, limitations, and areas for future work. The resultant interpretation methodology is recommended for use in clinical practice and research to assist clinicians in their use of Gastric Alimetry as a diagnostic aid and is expected to continue to evolve with further development.
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Affiliation(s)
- Daphne Foong
- School of Medicine, Western Sydney University, Campbelltown, NSW 2560, Australia
| | - Stefan Calder
- Department of Surgery, Auckland City Hospital, Auckland 1023, New Zealand
- Alimetry Ltd., Auckland 1010, New Zealand
- Auckland Bioengineering Institute, University of Auckland, Auckland 1010, New Zealand
| | - Chris Varghese
- Department of Surgery, Auckland City Hospital, Auckland 1023, New Zealand
| | - Gabriel Schamberg
- Alimetry Ltd., Auckland 1010, New Zealand
- Auckland Bioengineering Institute, University of Auckland, Auckland 1010, New Zealand
| | - William Xu
- Department of Surgery, Auckland City Hospital, Auckland 1023, New Zealand
| | - Charlotte Daker
- Department of Gastroenterology, North Shore Hospital, Auckland 0620, New Zealand
| | - Vincent Ho
- School of Medicine, Western Sydney University, Campbelltown, NSW 2560, Australia
- Department of Gastroenterology and Hepatology, Campbelltown Hospital, Sydney, NSW 2560, Australia
| | - Christopher N. Andrews
- Division of Gastroenterology, Cumming School of Medicine, University of Calgary, Calgary, AB T2N 1N4, Canada
| | - Armen A. Gharibans
- Department of Surgery, Auckland City Hospital, Auckland 1023, New Zealand
- Alimetry Ltd., Auckland 1010, New Zealand
- Auckland Bioengineering Institute, University of Auckland, Auckland 1010, New Zealand
| | - Greg O’Grady
- Department of Surgery, Auckland City Hospital, Auckland 1023, New Zealand
- Alimetry Ltd., Auckland 1010, New Zealand
- Auckland Bioengineering Institute, University of Auckland, Auckland 1010, New Zealand
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13
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O'Grady G, Varghese C, Schamberg G, Calder S, Du P, Xu W, Tack J, Daker C, Mousa H, Abell TL, Parkman HP, Ho V, Bradshaw LA, Hobson A, Andrews CN, Gharibans AA. Principles and clinical methods of body surface gastric mapping: Technical review. Neurogastroenterol Motil 2023; 35:e14556. [PMID: 36989183 PMCID: PMC10524901 DOI: 10.1111/nmo.14556] [Citation(s) in RCA: 12] [Impact Index Per Article: 12.0] [Reference Citation Analysis] [Abstract] [MESH Headings] [Grants] [Track Full Text] [Journal Information] [Submit a Manuscript] [Subscribe] [Scholar Register] [Received: 10/21/2022] [Revised: 01/29/2023] [Accepted: 02/12/2023] [Indexed: 03/30/2023]
Abstract
BACKGROUND AND PURPOSE Chronic gastric symptoms are common, however differentiating specific contributing mechanisms in individual patients remains challenging. Abnormal gastric motility is present in a significant subgroup, but reliable methods for assessing gastric motor function in clinical practice are lacking. Body surface gastric mapping (BSGM) is a new diagnostic aid, employs multi-electrode arrays to measure and map gastric myoelectrical activity non-invasively in high resolution. Clinical adoption of BSGM is currently expanding following studies demonstrating the ability to achieve specific patient subgrouping, and subsequent regulatory clearances. An international working group was formed in order to standardize clinical BSGM methods, encompassing a technical group developing BSGM methods and a clinical advisory group. The working group performed a technical literature review and synthesis focusing on the rationale, principles, methods, and clinical applications of BSGM, with secondary review by the clinical group. The principles and validation of BSGM were evaluated, including key advances achieved over legacy electrogastrography (EGG). Methods for BSGM were reviewed, including device design considerations, patient preparation, test conduct, and data processing steps. Recent advances in BSGM test metrics and reference intervals are discussed, including four novel metrics, being the 'principal gastric frequency', BMI-adjusted amplitude, Gastric Alimetry Rhythm Index™, and fed: fasted amplitude ratio. An additional essential element of BSGM has been the introduction of validated digital tools for standardized symptom profiling, performed simultaneously during testing. Specific phenotypes identifiable by BSGM and the associated symptom profiles were codified with reference to pathophysiology. Finally, knowledge gaps and priority areas for future BSGM research were also identified by the working group.
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Affiliation(s)
- Gregory O'Grady
- Department of Surgery, The University of Auckland, Auckland, New Zealand
- Alimetry Ltd, Auckland, New Zealand
- Auckland Bioengineering Institute, The University of Auckland, Auckland, New Zealand
| | - Chris Varghese
- Department of Surgery, The University of Auckland, Auckland, New Zealand
| | - Gabriel Schamberg
- Department of Surgery, The University of Auckland, Auckland, New Zealand
- Alimetry Ltd, Auckland, New Zealand
| | | | - Peng Du
- Alimetry Ltd, Auckland, New Zealand
- Auckland Bioengineering Institute, The University of Auckland, Auckland, New Zealand
| | - William Xu
- Department of Surgery, The University of Auckland, Auckland, New Zealand
| | - Jan Tack
- Department of Gastroenterology, University Hospitals, Leuven, Belgium
| | | | - Hayat Mousa
- Division of Gastroenterology, Lustgarten Motility Center, The Children's Hospital of Philadelphia, Philadelphia, Pennsylvania, USA
| | - Thomas L Abell
- Division of Gastroenterology, Hepatology and Nutrition, University of Louisville, Louisville, Kentucky, USA
| | - Henry P Parkman
- Department of Medicine, Temple University Hospital, Philadelphia, Pennsylvania, USA
| | - Vincent Ho
- Western Sydney University, Sydney, New South Wales, Australia
| | | | | | - Christopher N Andrews
- Division of Gastroenterology and Hepatology, University of Calgary, Calgary, Alberta, Canada
| | - Armen A Gharibans
- Department of Surgery, The University of Auckland, Auckland, New Zealand
- Alimetry Ltd, Auckland, New Zealand
- Auckland Bioengineering Institute, The University of Auckland, Auckland, New Zealand
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14
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Schamberg G, Calder S, Varghese C, Xu W, Wang WJ, Ho V, Daker C, Andrews CN, O'Grady G, Gharibans AA. Comparison of Gastric Alimetry ® body surface gastric mapping versus electrogastrography spectral analysis. Sci Rep 2023; 13:14987. [PMID: 37696955 PMCID: PMC10495352 DOI: 10.1038/s41598-023-41645-w] [Citation(s) in RCA: 0] [Impact Index Per Article: 0] [Reference Citation Analysis] [Abstract] [Key Words] [MESH Headings] [Grants] [Track Full Text] [Journal Information] [Subscribe] [Scholar Register] [Received: 03/16/2023] [Accepted: 08/29/2023] [Indexed: 09/13/2023] Open
Abstract
Electrogastrography (EGG) non-invasively evaluates gastric motility but is viewed as lacking clinical utility. Gastric Alimetry® is a new diagnostic test that combines high-resolution body surface gastric mapping (BSGM) with validated symptom profiling, with the goal of overcoming EGG's limitations. This study directly compared EGG and BSGM to define performance differences in spectral analysis. Comparisons between Gastric Alimetry BSGM and EGG were conducted by protocolized retrospective evaluation of 178 subjects [110 controls; 68 nausea and vomiting (NVS) and/or type 1 diabetes (T1D)]. Comparisons followed standard methodologies for each test (pre-processing, post-processing, analysis), with statistical evaluations for group-level differences, symptom correlations, and patient-level classifications. BSGM showed substantially tighter frequency ranges vs EGG in controls. Both tests detected rhythm instability in NVS, but EGG showed opposite frequency effects in T1D. BSGM showed an 8× increase in the number of significant correlations with symptoms. BSGM accuracy for patient-level classification was 0.78 for patients vs controls and 0.96 as compared to blinded consensus panel; EGG accuracy was 0.54 and 0.43. EGG detected group-level differences in patients, but lacked symptom correlations and showed poor accuracy for patient-level classification, explaining EGG's limited clinical utility. BSGM demonstrated substantial performance improvements across all domains.
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Affiliation(s)
- Gabriel Schamberg
- Department of Surgery, The University of Auckland, Auckland, New Zealand
- Alimetry Ltd, Auckland, New Zealand
| | - Stefan Calder
- Department of Surgery, The University of Auckland, Auckland, New Zealand
- Alimetry Ltd, Auckland, New Zealand
| | - Chris Varghese
- Department of Surgery, The University of Auckland, Auckland, New Zealand
| | - William Xu
- Department of Surgery, The University of Auckland, Auckland, New Zealand
| | - William Jiaen Wang
- School of Medicine, Western Sydney University, Sydney, Australia
- Department of Gastroenterology and Hepatology, Campbelltown Hospital, Sydney, Australia
- Department of Gastroenterology and Hepatology, Townsville University Hospital, Townsville, Australia
- Department of Gastroenterology and Hepatology, Princess Alexandra Hospital, Brisbane, Australia
| | - Vincent Ho
- School of Medicine, Western Sydney University, Sydney, Australia
- Department of Gastroenterology and Hepatology, Campbelltown Hospital, Sydney, Australia
| | - Charlotte Daker
- Department of Gastroenterology, North Shore Hospital, Auckland, New Zealand
| | | | - Greg O'Grady
- Department of Surgery, The University of Auckland, Auckland, New Zealand
- Alimetry Ltd, Auckland, New Zealand
- Auckland Bioengineering Institute, The University of Auckland, Auckland, New Zealand
| | - Armen A Gharibans
- Department of Surgery, The University of Auckland, Auckland, New Zealand.
- Alimetry Ltd, Auckland, New Zealand.
- Auckland Bioengineering Institute, The University of Auckland, Auckland, New Zealand.
- Perelman School of Medicine, University of Pennsylvania, Pennsylvania, United States.
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15
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Jain S, Shamrao Kulkarni S, Mahapatra JR, Todi D, Petare AU, Banerjee R, Rathod R, Naqvi S, Mane A, Dhanaki G, Kotak BP. Effectiveness of Omeprazole in Acid Peptic Disease: A Real-World, Patient-Reported Outcome Measures Study. Cureus 2023; 15:e41994. [PMID: 37593315 PMCID: PMC10428080 DOI: 10.7759/cureus.41994] [Citation(s) in RCA: 0] [Impact Index Per Article: 0] [Reference Citation Analysis] [Abstract] [Key Words] [Track Full Text] [Figures] [Journal Information] [Subscribe] [Scholar Register] [Accepted: 07/15/2023] [Indexed: 08/19/2023] Open
Abstract
Objectives This prospective study assessed the effectiveness and patient satisfaction of four-week omeprazole therapy in acid peptic disease (APD). Methods This was an observational, post-marketing, real-world evidence, patient-reported outcome (PRO) measures study. Patients visiting the five study sites across India with symptoms of APD, and who were prescribed oral omeprazole (20/40 mg per day) for at least four weeks were enrolled after obtaining informed consent. Study assessments included frequency and severity of symptoms and overall satisfaction reported by the patients using the Patient Assessment of Gastrointestinal Disorder Symptom Severity Index (PAGI-SYM) questionnaire. The satisfaction with therapy was reported by the patients using the Treatment Satisfaction Questionnaire for Medication (TSQM) questionnaire. Both PAGI-SYM and TSQM were reported by patients on days 14 and 28. Omeprazole safety was assessed based on the adverse events reported by the patients. Results A total of 96 (62 males and 34 females) patients were included in the study, of which 38.54% had significant findings related to APD at baseline. The proportion of patients with symptoms reduced to 16.67% on day 14 and 8.33% on day 28 with omeprazole therapy. The PAGI-SYM total scores at baseline were 41.32 (15.487), which reduced to 20.86 (11.620) on day 14 (p < 0.0001), and to 8.93 (8.361) on day 28 (p < 0.0001). Significant reductions were also seen in individual symptom scores. The TSQM total scores increased to 36.67 (range: 13 to 63) on day 28 from 34.69 (range: 12 to 58) on day 14. Improvement in scores for all domains of TSQM (effectiveness, convenience, and global satisfaction) was seen on day 28. Improvement in reflux symptoms was reported by 46.74% and 68.48% of patients on day 14 and day 28, respectively. Four (4.17%) patients reported adverse events, which were of mild severity and were unrelated to omeprazole. Conclusions Omeprazole provides significant improvement in PAGI-SYM and TSQM questionnaires on day 14 and day 28. Patients reported the omeprazole-based therapy as effective, convenient, and satisfactory. Omeprazole therapy is safe and effective for the treatment of APD and shows good improvement in APD in patients suffering from duodenal ulcers, gastric ulcers, and reflux oesophagitis.
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Affiliation(s)
- Suresh Jain
- Department of Gastroenterology, Digestive Endoscopy Clinic, Pune, IND
| | | | | | - Dilip Todi
- Department of Gastroenterology, Narayana Superspeciality Hospital, Kolkata, IND
| | - Anup U Petare
- Department of Medical Affairs, Dr. Reddy's Laboratories Ltd., Hyderabad, IND
| | - Ritwik Banerjee
- Department of Medical Affairs, Dr. Reddy's Laboratories Ltd., Hyderabad, IND
| | - Rahul Rathod
- Department of Medical Affairs, Dr. Reddy's Laboratories Ltd., Hyderabad, IND
| | - Syed Naqvi
- Department of Medical Affairs, Dr. Reddy's Laboratories Ltd., Hyderabad, IND
| | - Amey Mane
- Department of Medical Affairs, Dr. Reddy's Laboratories Ltd., Hyderabad, IND
| | - Gauri Dhanaki
- Department of Clinical Research, Dr. Reddy's Laboratories Ltd., Hyderabad, IND
| | - Bhavesh P Kotak
- Department of Medical Affairs, Dr. Reddy's Laboratories Ltd., Hyderabad, IND
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Varghese C, Schamberg G, Calder S, Waite S, Carson D, Foong D, Wang WJ, Ho V, Woodhead J, Daker C, Xu W, Du P, Abell TL, Parkman HP, Tack J, Andrews CN, O'Grady G, Gharibans AA. Normative Values for Body Surface Gastric Mapping Evaluations of Gastric Motility Using Gastric Alimetry: Spectral Analysis. Am J Gastroenterol 2023; 118:1047-1057. [PMID: 36534985 DOI: 10.14309/ajg.0000000000002077] [Citation(s) in RCA: 18] [Impact Index Per Article: 18.0] [Reference Citation Analysis] [Abstract] [Track Full Text] [Journal Information] [Submit a Manuscript] [Subscribe] [Scholar Register] [Received: 07/25/2022] [Accepted: 10/06/2022] [Indexed: 06/02/2023]
Abstract
INTRODUCTION Body surface gastric mapping (BSGM) is a new noninvasive test of gastric function. BSGM offers several novel and improved biomarkers of gastric function capable of differentiating patients with overlapping symptom profiles. The aim of this study was to define normative reference intervals for BSGM spectral metrics in a population of healthy controls. METHODS BSGM was performed in healthy controls using Gastric Alimetry (Alimetry, New Zealand) comprising a stretchable high-resolution array (8 × 8 electrodes; 196 cm 2 ), wearable Reader, and validated symptom-logging App. The evaluation encompassed a fasting baseline (30 minutes), 482 kCal meal, and 4-hour postprandial recording. Normative reference intervals were calculated for BSGM metrics including the Principal Gastric Frequency, Gastric Alimetry Rhythm Index (a measure of the concentration of power in the gastric frequency band over time), body mass index (BMI)-adjusted amplitude (μV), and fed:fasted amplitude ratio. Data were reported as median and reference interval (5th and/or 95th percentiles). RESULTS A total of 110 subjects (55% female, median age 32 years [interquartile range 24-50], median BMI 23.8 kg/m 2 [interquartile range 21.4-26.9]) were included. The median Principal Gastric Frequency was 3.04 cycles per minute; reference interval: 2.65-3.35 cycles per minute. The median Gastric Alimetry Rhythm Index was 0.50; reference interval: ≥0.25. The median BMI-adjusted amplitude was 37.6 μV; reference interval: 20-70 μV. The median fed:fasted amplitude ratio was 1.85; reference interval ≥1.08. A higher BMI was associated with a shorter meal-response duration ( P = 0.014). DISCUSSION This study provides normative reference intervals for BSGM spectral data to inform diagnostic interpretations of abnormal gastric function.
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Affiliation(s)
- Chris Varghese
- Department of Surgery, The University of Auckland, Auckland, New Zealand
| | - Gabriel Schamberg
- Department of Surgery, The University of Auckland, Auckland, New Zealand
- Alimetry, Auckland, New Zealand
| | - Stefan Calder
- Department of Surgery, The University of Auckland, Auckland, New Zealand
- Alimetry, Auckland, New Zealand
| | | | - Daniel Carson
- Department of Surgery, The University of Auckland, Auckland, New Zealand
| | | | | | - Vincent Ho
- Western Sydney University, Sydney, Australia
| | | | | | - William Xu
- Department of Surgery, The University of Auckland, Auckland, New Zealand
| | - Peng Du
- Alimetry, Auckland, New Zealand
- Auckland Bioengineering Institute, The University of Auckland, Auckland, New Zealand
| | - Thomas L Abell
- Division of Gastroenterology, Hepatology and Nutrition, University of Louisville, Kentucky, USA
| | - Henry P Parkman
- Department of Medicine, Temple University Hospital, Philadelphia, Pennsylvania, USA
| | - Jan Tack
- Department of Gastroenterology, University Hospitals, Leuven, Belgium
| | | | - Gregory O'Grady
- Department of Surgery, The University of Auckland, Auckland, New Zealand
- Alimetry, Auckland, New Zealand
- Auckland Bioengineering Institute, The University of Auckland, Auckland, New Zealand
| | - Armen A Gharibans
- Department of Surgery, The University of Auckland, Auckland, New Zealand
- Alimetry, Auckland, New Zealand
- Auckland Bioengineering Institute, The University of Auckland, Auckland, New Zealand
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17
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Wang WJ, Foong D, Calder S, Schamberg G, Varghese C, Tack J, Xu W, Daker C, Carson D, Waite S, Hayes T, Du P, Abell TL, Parkman HP, Huang IH, Fernandes V, Andrews CN, Gharibans AA, Ho V, O'Grady G. Gastric Alimetry ® improves patient phenotyping in gastroduodenal disorders compared to gastric emptying scintigraphy alone. MEDRXIV : THE PREPRINT SERVER FOR HEALTH SCIENCES 2023:2023.05.18.23290134. [PMID: 37292604 PMCID: PMC10246136 DOI: 10.1101/2023.05.18.23290134] [Citation(s) in RCA: 0] [Impact Index Per Article: 0] [Reference Citation Analysis] [Abstract] [Track Full Text] [Subscribe] [Scholar Register] [Indexed: 06/10/2023]
Abstract
Objectives Gastric emptying testing (GET) assesses gastric motility, however is non-specific and insensitive for neuromuscular disorders. Gastric Alimetry® (GA) is a new medical device combining non-invasive gastric electrophysiological mapping and validated symptom profiling. This study assessed patient-specific phenotyping using GA compared to GET. Methods Patients with chronic gastroduodenal symptoms underwent simultaneous GET and GA, comprising a 30-minute baseline, 99m TC-labelled egg meal, and 4-hour postprandial recording. Results were referenced to normative ranges. Symptoms were profiled in the validated GA App and phenotyped using rule-based criteria based on their relationships to the meal and gastric activity: i) sensorimotor; ii) continuous; and iii) other. Results 75 patients were assessed; 77% female. Motility abnormality detection rates were: GET 22.7% (14 delayed, 3 rapid); GA spectral analysis 33.3% (14 low rhythm stability / low amplitude; 5 high amplitude; 6 abnormal frequency); combined yield 42.7%. In patients with normal spectral analysis, GA symptom phenotypes included: sensorimotor 17% (where symptoms strongly paired with gastric amplitude; median r=0.61); continuous 30%; other 53%. GA phenotypes showed superior correlations with GCSI, PAGI-SYM, and anxiety scales, whereas Rome IV Criteria did not correlate with psychometric scores (p>0.05). Delayed emptying was not predictive of specific GA phenotypes. Conclusions GA improves patient phenotyping in chronic gastroduodenal disorders in the presence and absence of motility abnormalities with improved correlation with symptoms and psychometrics compared to gastric emptying status and Rome IV criteria. These findings have implications for the diagnostic profiling and personalized management of gastroduodenal disorders. Study Highlights 1) WHAT IS KNOWN Chronic gastroduodenal symptoms are common, costly and greatly impact on quality of lifeThere is a poor correlation between gastric emptying testing (GET) and symptomsGastric Alimetry® is a new medical device combining non-invasive gastric electrophysiological mapping and validated symptom profiling 2) WHAT IS NEW HERE Gastric Alimetry generates a 1.5x higher yield for motility abnormalities than GETWith symptom profiling, Gastric Alimetry identified 2.7x more specific patient categories than GETGastric Alimetry improves clinical phenotyping, with improved correlation with symptoms and psychometrics compared to GET.
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18
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Wang THH, Tokhi A, Gharibans A, Evennett N, Beban G, Schamberg G, Varghese C, Calder S, Duong C, O'Grady G. Non-invasive thoracoabdominal mapping of postoesophagectomy conduit function. BJS Open 2023; 7:7153161. [PMID: 37146206 PMCID: PMC10162678 DOI: 10.1093/bjsopen/zrad036] [Citation(s) in RCA: 2] [Impact Index Per Article: 2.0] [Reference Citation Analysis] [Grants] [Track Full Text] [Journal Information] [Subscribe] [Scholar Register] [Received: 01/13/2023] [Accepted: 02/26/2023] [Indexed: 05/07/2023] Open
Affiliation(s)
- Tim Hsu-Han Wang
- Department of Surgery, The University of Auckland, Auckland, New Zealand
| | - Ashraf Tokhi
- Division of Cancer Surgery, Peter MacCallum Cancer Centre, Melbourne, Victoria, Australia
| | - Armen Gharibans
- Department of Surgery, The University of Auckland, Auckland, New Zealand
- Alimetry Ltd, Auckland, New Zealand
- Auckland Bioengineering Institute, The University of Auckland, Auckland, New Zealand
| | - Nicholas Evennett
- Department of Surgery, Auckland City Hospital, Auckland, New Zealand
| | - Grant Beban
- Department of Surgery, Auckland City Hospital, Auckland, New Zealand
| | - Gabriel Schamberg
- Department of Surgery, The University of Auckland, Auckland, New Zealand
- Alimetry Ltd, Auckland, New Zealand
| | - Chris Varghese
- Department of Surgery, The University of Auckland, Auckland, New Zealand
| | - Stefan Calder
- Department of Surgery, The University of Auckland, Auckland, New Zealand
- Alimetry Ltd, Auckland, New Zealand
| | - Cuong Duong
- Division of Cancer Surgery, Peter MacCallum Cancer Centre, Melbourne, Victoria, Australia
| | - Greg O'Grady
- Department of Surgery, The University of Auckland, Auckland, New Zealand
- Alimetry Ltd, Auckland, New Zealand
- Auckland Bioengineering Institute, The University of Auckland, Auckland, New Zealand
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19
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Schamberg G, Varghese C, Calder S, Waite S, Erickson J, O'Grady G, Gharibans AA. Revised spectral metrics for body surface measurements of gastric electrophysiology. Neurogastroenterol Motil 2023; 35:e14491. [PMID: 36409749 DOI: 10.1111/nmo.14491] [Citation(s) in RCA: 11] [Impact Index Per Article: 11.0] [Reference Citation Analysis] [Abstract] [Key Words] [Track Full Text] [Journal Information] [Submit a Manuscript] [Subscribe] [Scholar Register] [Received: 07/06/2022] [Revised: 10/17/2022] [Accepted: 10/21/2022] [Indexed: 11/22/2022]
Abstract
BACKGROUND Electrogastrography (EGG) non-invasively evaluates gastric function but has not achieved common clinical adoption due to several technical limitations. Body Surface Gastric Mapping (BSGM) has been introduced to overcome these limitations, but pitfalls in traditional metrics used to analyze spectral data remain unaddressed. This study critically evaluates five traditional EGG metrics and introduces improved BSGM spectral metrics, with validation in a large cohort. METHODS Pitfalls in five EGG metrics were assessed (dominant frequency, percentage time normogastria, amplitude, power ratio, and instability coefficient), leading to four revised BSGM spectral metrics. Traditional and revised metrics were compared to validate performance using a standardized 100-subject database of BSGM tests (30 min baseline; 4-h postprandial) recorded using Gastric Alimetry® (Alimetry). KEY RESULTS BMI and amplitude were highly correlated (r = -0.57, p < 0.001). We applied a conservative BMI correction to obtain a BMI-adjusted amplitude metric (r = -0.21, p = 0.037). Instability coefficient was highly correlated with both dominant frequency (r = -0.44, p < 0.001), and percent bradygastria (r = 0.85, p < 0.001), in part due to misclassification of low frequency transients as gastric activity. This was corrected by introducing distinct gastric frequency and stability metrics (Principal Gastric Frequency and Gastric Alimetry Rhythm Index (GA-RI)TM ) that were uncorrelated (r = 0.14, p = 0.314). Only 28% of subjects showed a maximal averaged amplitude within the first postprandial hour. Calculating Fed:Fasted Amplitude Ratio over a 4-h postprandial window yielded a median increase of 0.31 (IQR 0-0.64) above the traditional ratio. CONCLUSIONS & INFERENCES The revised metrics resolve critical pitfalls impairing the performance of traditional EGG, and should be applied in future BSGM spectral analyses.
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Affiliation(s)
- Gabriel Schamberg
- Alimetry Ltd, Auckland, New Zealand.,Department of Surgery, The University of Auckland, Auckland, New Zealand
| | - Chris Varghese
- Department of Surgery, The University of Auckland, Auckland, New Zealand
| | - Stefan Calder
- Alimetry Ltd, Auckland, New Zealand.,Department of Surgery, The University of Auckland, Auckland, New Zealand
| | | | | | - Greg O'Grady
- Alimetry Ltd, Auckland, New Zealand.,Department of Surgery, The University of Auckland, Auckland, New Zealand.,Auckland Bioengineering Institute, The University of Auckland, Auckland, New Zealand
| | - Armen A Gharibans
- Alimetry Ltd, Auckland, New Zealand.,Department of Surgery, The University of Auckland, Auckland, New Zealand.,Auckland Bioengineering Institute, The University of Auckland, Auckland, New Zealand
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20
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O'Grady G, Carbone F, Tack J. Gastric sensorimotor function and its clinical measurement. Neurogastroenterol Motil 2022; 34:e14489. [PMID: 36371709 PMCID: PMC10078602 DOI: 10.1111/nmo.14489] [Citation(s) in RCA: 7] [Impact Index Per Article: 3.5] [Reference Citation Analysis] [Abstract] [Track Full Text] [Journal Information] [Submit a Manuscript] [Subscribe] [Scholar Register] [Received: 09/30/2022] [Revised: 10/24/2022] [Accepted: 10/24/2022] [Indexed: 11/15/2022]
Abstract
BACKGROUND Gastroduodenal symptoms are highly prevalent, with underlying sensorimotor dysfunction contributing in many patients. Common symptoms include early satiation, postprandial fullness, epigastric bloating, pain or burning, nausea and vomiting, which collectively affect over 7% of adults. However, the clinical evaluation of these symptoms remains challenging, with current tests of gastric function remaining limited in their ability or availability to separate specific patient subgroups or guide-targeted care. PURPOSE In the current edition of Neurogastroenterology & Motility, Silver et al. present new data showing correlations between patterns of intragastric meal distribution and symptom profiles in a large series of patients undergoing gastric emptying scintigraphy. Studies of this type are important, as they motivate understanding beyond existing disease labels, and orient focus toward deeper mechanistic profiling. This brief review provides an overview of gastric sensorimotor function and profiles several current and emerging methods of clinical evaluation. Perspectives are provided on accommodation testing, gastric emptying, measuring gastric myoelectrical activity including new approaches, and antroduodenal manometry. Although gastric physiology is complex, recent progress has been encouraging, with the heterogenous pathophysiology of gastric symptoms continuing to be unraveled, and new techniques for evaluating gastric function and symptoms emerging. CONCLUSIONS AND INFERENCES Ongoing progress will now depend on continuing to accurately profile the underlying mechanisms of gastroduodenal disorders to identify specific disease phenotypes that inform care.
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Affiliation(s)
- Greg O'Grady
- Department of Surgery, The University of Auckland, Auckland, New Zealand.,Alimetry Ltd, Auckland, New Zealand.,Auckland Bioengineering Institute, The University of Auckland, Auckland, New Zealand
| | - Florencia Carbone
- Department of Gastroenterology, University Hospital Leuven (UZ Leuven), Leuven, Belgium
| | - Jan Tack
- Department of Gastroenterology, University Hospital Leuven (UZ Leuven), Leuven, Belgium.,Translational Research Center for Gastrointestinal Diseases (TARGID), department of Chronic Diseases and Metabolism (ChroMeta), University of Leuven, Leuven, Belgium.,Sahlgrenska Academy, University of Gothenburg, Gothenburg, Sweden.,Rome Foundation, Raleigh, North Carolina, USA
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21
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Calder S, Schamberg G, Varghese C, Waite S, Sebaratnam G, Woodhead JST, Du P, Andrews C, O'Grady G, Gharibans AA. An automated artifact detection and rejection system for body surface gastric mapping. Neurogastroenterol Motil 2022; 34:e14421. [PMID: 35699347 PMCID: PMC9786272 DOI: 10.1111/nmo.14421] [Citation(s) in RCA: 15] [Impact Index Per Article: 7.5] [Reference Citation Analysis] [Abstract] [Key Words] [Track Full Text] [Download PDF] [Figures] [Journal Information] [Submit a Manuscript] [Subscribe] [Scholar Register] [Received: 04/02/2022] [Revised: 05/09/2022] [Accepted: 05/18/2022] [Indexed: 12/30/2022]
Abstract
BACKGROUND Body surface gastric mapping (BSGM) is a new clinical tool for gastric motility diagnostics, providing high-resolution data on gastric myoelectrical activity. Artifact contamination was a key challenge to reliable test interpretation in traditional electrogastrography. This study aimed to introduce and validate an automated artifact detection and rejection system for clinical BSGM applications. METHODS Ten patients with chronic gastric symptoms generated a variety of artifacts according to a standardized protocol (176 recordings) using a commercial BSGM system (Alimetry, New Zealand). An automated artifact detection and rejection algorithm was developed, and its performance was compared with a reference standard comprising consensus labeling by 3 analysis experts, followed by comparison with 6 clinicians (3 untrained and 3 trained in artifact detection). Inter-rater reliability was calculated using Fleiss' kappa. KEY RESULTS Inter-rater reliability was 0.84 (95% CI:0.77-0.90) among experts, 0.76 (95% CI:0.68-0.83) among untrained clinicians, and 0.71 (95% CI:0.62-0.79) among trained clinicians. The sensitivity and specificity of the algorithm against experts was 96% (95% CI:91%-100%) and 95% (95% CI:90%-99%), respectively, vs 77% (95% CI:68%-85%) and 99% (95% CI:96%-100%) against untrained clinicians, and 97% (95% CI:92%-100%) and 88% (95% CI:82%-94%) against trained clinicians. CONCLUSIONS & INFERENCES An automated artifact detection and rejection algorithm was developed showing >95% sensitivity and specificity vs expert markers. This algorithm overcomes an important challenge in the clinical translation of BSGM and is now being routinely implemented in patient test interpretations.
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Affiliation(s)
| | | | - Chris Varghese
- Department of SurgeryThe University of AucklandAucklandNew Zealand
| | | | | | | | - Peng Du
- Auckland Bioengineering InstituteThe University of AucklandAucklandNew Zealand
| | - Christopher N. Andrews
- Alimetry LtdAucklandNew Zealand,Division of GastroenterologyUniversity of CalgaryCalgaryAlbertaCanada
| | - Greg O'Grady
- Alimetry LtdAucklandNew Zealand,Department of SurgeryThe University of AucklandAucklandNew Zealand,Auckland Bioengineering InstituteThe University of AucklandAucklandNew Zealand
| | - Armen A. Gharibans
- Alimetry LtdAucklandNew Zealand,Department of SurgeryThe University of AucklandAucklandNew Zealand,Auckland Bioengineering InstituteThe University of AucklandAucklandNew Zealand
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