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

Background: 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. Methods: 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 (60 mL total volume). Key Results: 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. Conclusions and Inferences: 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.