Abstract
Simultaneous pressure waves (SPWs) in manometry recordings of the human colon have been associated with gas expulsion. Our hypothesis was that the SPW might be a critical component of most colonic motor functions, and hence might act as a biomarker for healthy colon motility. To that end, we performed high-resolution colonic manometry (HRCM), for the first time using an 84-sensor (1 cm spaced) water-perfused catheter, in 17 healthy volunteers. Intraluminal pressure patterns were recorded during baseline, proximal and rectal balloon distention, after a meal and following proximal and rectal luminal bisacodyl administration. Quantification was performed using software, based on Image J, developed during this study. Gas expulsion was always associated with SPWs, furthermore, SPWs were associated with water or balloon expulsion. SPWs were prominently emerging at the termination of proximal high amplitude propagating pressure waves (HAPWs); we termed this motor pattern HAPW-SPWs; hence, SPWs were often not a pan-colonic event. SPWs and HAPW-SPWs were observed at baseline with SPW amplitudes of 12.0 ± 8.5 mmHg and 20.2 ± 7.2 mmHg respectively. The SPW occurrence and amplitude significantly increased in response to meal, balloon distention and luminal bisacodyl, associated with 50.3% anal sphincter relaxation at baseline, which significantly increased to 59.0% after a meal, and 69.1% after bisacodyl. Often, full relaxation was achieved. The SPWs associated with gas expulsion had a significantly higher amplitude compared to SPWs without gas expulsion. SPWs could be seen to consist of clusters of high frequency pressure waves, likely associated with a cluster of fast propagating, circular muscle contractions. SPWs were occasionally observed in a highly rhythmic pattern at 1.8 ± 1.2 cycles/min. Unlike HAPWs, the SPWs did not obliterate haustral boundaries thereby explaining how gas can be expelled while solid content can remain restrained by the haustral boundaries. In conclusion, the SPW may become a biomarker for normal gas transit, the gastrocolonic reflex and extrinsic neural reflexes. The SPW assessment reveals coordination of activities in the colon, rectum and anal sphincters. SPWs may become of diagnostic value in patients with colonic dysmotility.
Highlights
Patients with functional bowel disorders have abnormal bowel movements and/or outlet obstruction and often complain about bloating (Burri et al, 2014; Malagelada et al, 2017)
The Simultaneous pressure wave (SPW) component of the high-amplitude propagating pressure wave (HAPW)-SPW had an average amplitude of 20.2 ± 10.2 mmHg compared to pancolonic SPWs at 12.1 ± 7.3 (P < 0.05), and an average duration of 18.0 ± 12.3 s, associated with a proximal HAPW with an amplitude of 105.4 ± 49.7 mmHg (Figure 3 and Table 1)
SPWs in Response to Proximal Balloon Distension Proximal balloon distension did not, on average, increase the number of SPWs per unit time compared to baseline, but the number of SPWs associated with gas expulsion markedly increased
Summary
Patients with functional bowel disorders have abnormal bowel movements and/or outlet obstruction and often complain about bloating (Burri et al, 2014; Malagelada et al, 2017). Impaired gas clearance appears to involve tonic contractions of the small intestine (Tremolaterra et al, 2006; Serra et al, 2010) and abnormal motor activity of the colon (Malagelada et al, 2017). Proof of concept studies show a positive effect of prokinetics on gas related symptoms (Serra et al, 2001; Caldarella et al, 2002) which suggests that gut motor activity determines gas transit, and that bloating is caused by a motility disorder; the precise mechanisms underlying gas transit have not been established
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