Assessment of the gastric emptying velocity by the 13C-octanoate breath test: deconvolution versus a Wagner-Nelson analysis.
BACKGROUND
The dynamic change in gastric emptying on a minute-by-minute basis (gastric velocity) is evaluated by the 13C-octanoate breath test with deconvolution analysis. However, deconvolution is impractical, because it requires dual experiments to obtain 13CO2 excretion profiles following intraduodenal and oral administration of 13C-octanoate. We investigated whether the Wagner-Nelson method, used in drug absorption studies, can determine the velocity profile based on a single experiment as accurately as deconvolution, and whether the velocity assessed by the Wagner-Nelson method is sensitive enough to detect subtle changes in gastric emptying induced by butylscopolamine.


METHODS
Five male volunteers underwent a 4-h breath test twice, after intraduodenal administration of 20 ml normal saline containing 100 mg 13C-octanoate and after ingestion of a 320-kcal muffin containing 100 mg 13C-octanoate. Deconvolution determined the velocity profile by subtracting duodenal from oral data, and the Wagner-Nelson method produced it from only oral data. The velocity profiles were compared between the two methods. Another six male subjects underwent the breath test by ingesting a muffin twice, once with and once without 20 mg oral butylscopolamine. The velocity profiles generated by the Wagner-Nelson analysis and the conventional 13CO2 excretion curves were compared between the two occasions.


RESULTS
The two techniques yielded identical velocity profiles. The velocity profile detected a significant change in the emptying pattern induced by butylscopolamine (initial acceleration with subsequent deceleration), while the conventional breath curves failed to detect this change.


CONCLUSIONS
Velocity assessment by a Wagner-Nelson analysis can precisely describe altered gastric emptying, based on a single experiment.
Sanaka
Masaki
M
Department of Internal Medicine, School of Medicine, Teikyo University, 2-11-1 Kaga, Itabashi-ku, Tokyo, 173-8605, Japan.
Yamamoto
Takatsugu
T
Osaki
Yukako
Y
Kuyama
Yasushi
Y
D000328:Adult; D001944:Breath Tests / Q000379:methods*; D002086:Butylscopolammonium Bromide / Q000494:pharmacology; D002210:Caprylates; D002245:Carbon Dioxide / Q000378:metabolism; D002247:Carbon Isotopes; D005746:Gastric Emptying / Q000187:drug effects / Q000502:physiology*; D006801:Humans; D008297:Male
D002210:Caprylates; D002247:Carbon Isotopes; D002245:Carbon Dioxide; D002086:Butylscopolammonium Bromide; C031492:octanoic acid