High-resolution impedance manometry characterizes the functional role of distal colonic motility in gas transit.

Abstract

The colonic motor patterns associated with gas transit are poorly understood. This study describes the application of high-resolution impedance manometry (HRiM) in the human colon in vivo to characterize distal colonic motility and gas transit; (a) after a meal and (b) after intraluminal gas insufflation into the sigmoid colon. HRiM recordings were performed in 19 healthy volunteers, with sensors positioned from the distal descending colon to the proximal rectum. Protocol 1 (n=10) compared pressure and impedance prior to and after a meal. Protocol 2 (n=9) compared pressure and impedance before and after gas insufflation into the sigmoid colon (60mL total volume). Both the meal and gas insufflation resulted in an increase in the prevalence of the 2-8/minute "cyclic motor pattern" (meal: (t(9)=-6.42, P<0.001); gas insufflation (t(8)=-3.13, P=0.01)), and an increase in the number of antegrade and retrograde propagating impedance events (meal: Z=-2.80, P=0.005; gas insufflation Z=-2.67, P=0.008). Propagating impedance events temporally preceded antegrade and retrograde propagating contractions, representing a column of luminal gas being displaced ahead of a propagating contraction. Three participants reported an urge to pass flatus and/or flatus during the studies. Initiation of the 2-8/minute cyclic motor pattern in the distal colon occurs both following a meal and/or as a localized sensorimotor response to gas. The near-absence of a flatal urge and the temporal association between propagating contractions and gas transit supports the hypothesis that the 2-8/minute cyclic motor pattern acts as a physiological "brake" modulating rectal filling.