Introduction
The Atmo Capsule is a wireless motility capsule that senses and telemetrically transmits measurements of hydrogen (H2) and carbon dioxide (CO2) along the gut. In the colon, luminal concentrations of H2 and CO2 represent the metabolic activity of the microbial community. We hypothesized that delayed colonic transit would lead to altered gas profiles due to earlier depletion of fermentable substrates relative to transit time and/or facilitation of contact between methanogens and hydrogen (Levitt et al. CGH 2006).
Aims & Methods
The Atmo Capsule was administered to subjects with suspected upper and/or lower gut dysmotility. Colonic transit times (CTT) ≥ 59 h were considered delayed. Luminal H2 and CO2 concentrations (as time-normalized, area-under-the-curve [TN-AUC], [%.h]/h) were evaluated across the entire colon. Regional colonic profiles were evaluated per quartile of relative colonic transit, with quartiles 1 and 4 indicative of the proximal and distal colon, respectively. Gas measures were included if ≥ 50% of data were available for the corresponding segment. Fermentation profiles were estimated by the ratio of quartile 1:4 values, and time to peak concentrations were evaluated relative to CTT. Data were analyzed via Mann-Whitney test.
Results
The Atmo Capsule was administered to 209 subjects (median age 41; 188 female) with 170 yielding valid data on both colonic transit and colonic gas concentrations. Delayed colonic transit was identified in 60/170 (35%) subjects. In subjects with delayed CTT, H2 concentrations tended to be higher in the proximal colon and lower in the distal colon with no overall difference across the region compared with those with normal transit (Table 1). CO2 concentrations were higher throughout the colon except in the distal colon in subjects with delayed CTT. Peak concentrations of colonic H2 and CO2 were higher (H2, 8.7 h vs 5.9 %.h/h, p<0.01; CO2, 37.4 vs 29.9 %.h/h, p<0.01) and tended to occur earlier (H2, 35.9 vs 47.0 % of colonic transit p=0.14; CO2, 49.1 vs 86.8 % colonic transit, p<0.01) in patients with delayed compared with normal CTT.
Table 1. Gas profiles in patients with delayed colonic transit and correlation with symptom profiles. Data shown as median (interquartile range) and analyzed via Mann-Whitney test.
| Endpoint | Normal CTT, < 59 h
| Delayed CTT, ≥ 59 h
| P value
|
| Transit time, h | Colonic transit time
| 25 (16, 39)
| 93 (67, 117)
| <0.01
|
H2 concentration, TN-AUC (%.h)/h
| Overall
| 2.7 (1.3, 6.0)
| 3.4 (1.9, 7.1)
| 0.35
|
Quartile 1
| 2.0 (1.0, 3.9)
| 3.8 (1.4, 6.7)
| 0.01
|
Quartile 4
| 3.0 (1.0, 5.7)
| 1.5 (0.2, 3.7)
| 0.06
|
Fermentation profile (Q1:Q4)
| 0.7 (0.3, 1.6)
| 1.4 (0.7, 8.0)
| 0.03
|
CO2 concentration, TN-AUC (%.h)/h
| Overall
| 21.3 (16.4, 25.4)
| 27.4 (22.5, 35.1)
| <0.01
|
Quartile 1
| 15.7 (12.4, 19.7)
| 24.9 (20.5, 28.4)
| <0.01
|
Quartile 4
| 23.7 (17.9, 28.9)
| 24.2 (17.1, 34.4)
| 0.68
|
Fermentation profile (Q1:Q4)
| 0.6 (0.5, 0.8)
| 0.9 (0.7, 1.2)
| <0.01
|
Conclusion
Colonic gas profiles, as measured via the Atmo Capsule, differed in patients with delayed compared with normal CTT, with patterns suggesting progressive depletion of fermentable substrates and/or conversion of H2 to methane during transit in those with delayed transit.
References
Levitt MD, Furne JK, Kuskowski M, Ruddy J. Stability of human methanogenic flora over 35 years and a review of insights obtained from breath methane measurements. Clin Gastroenterol Hepatol. 2006 Feb;4(2):123-9. doi: 10.1016/j.cgh.2005.11.006. PMID: 16469670.
Disclosure
These authors disclose the following: Braden Kuo, Anthony J. Lembo, Eammon M.M. Quigley, Satish S.C. Rao, and William D. Chey serve on the Medical Advisory Board of Atmo Biosciences. Michael Cline and Baharak Moshiree served on the Medical Advisory Board of Atmo Biosciences. Braden Kuo has received funding from NIH, Vanda, Atmo Biosciences, and Takeda and has consulted for Evoke, Takeda, Ironwood, Novo Nordisk, Cindome, and Neurogastrx. Thomas Abell has received funding from Gastric Dysrhythmias, Neurogastrx, NIH GpCRC, and Vanda and has consulted for Enterra Medical, Novo Nordisk, Nuvaira, and Vanda. Anthony J. Lembo has received funding from Ardelyx, Biomerica, GSK, Ironwood, Takeda, and Vibrant and holds stock with Allurion, Bristol Myer Squibb, and J&J. Abigail Stocker has received funding from Cindome, Enterra Medical, and Vanda. William D. Chey has received funding from Atmo Biosciences, Commonwealth Diagnostics Intl, QOL Medical, and Salix; has consulted for AbbVie, Ardelyx, Biomerica, Comvita, Gemelli, Ironwood, Nestle, QOL Medical, Phathom, Redhill, Salix, Vibrant, and Takeda; has filed patents with My Nutrition Health, Digital Manometry, and Rectal Expulsion Device; and holds stock options with Coprata, Evinature, Food Marble, Kiwi Bioscience, and Modify Health. The remaining authors disclose no conflicts.