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.
Manometry is used worldwide to assess motor function of the gastrointestinal tract, and the measured intraluminal pressure patterns are usually equated with contraction patterns. In the colon, simultaneous pressure increases throughout the entire colon are most often called simultaneous contractions, although this inference has never been verified. To evaluate the relationship between pressure and contraction in the colon we performed high-resolution manometry and measured diameter changes reflecting circular muscle contractions in the rabbit colon. We show that within a certain range of contraction amplitudes and frequencies, the intraluminal pressure pattern faithfully resembles the contraction pattern. However, when the frequency is very high (as in fast propagating contractions in a cluster) the consequent intraluminal pressures merge. When the contraction speed of propagation is very fast (above ~5 cm/s), the resulting pressure occurs simultaneous throughout the colon; hence simultaneous pressure is measured as are caused by fast propagating contractions. The very slow propagating, low amplitude haustral boundary contractions show a very characteristic pattern in spatiotemporal contraction maps that is not faithfully reproduced in the pressure maps. Correct interpretation of pressure events in high-resolution manometry is essential to make it a reliable tool for diagnosis and management of patients with colon motor dysfunction.
Background: High-resolution colonic manometry promises much deeper insight into human colon motor function and their control mechanisms than hitherto possible. One motor pattern in need of full understanding is the simultaneous pressure wave (SPW), an apparent instantaneous transient pressure development in the entire colon. Aims: Our aim was to provide a characterization of this motor pattern, its relationship to other motor patterns and its appearance in response to a meal, balloon distension and bisacodyl in healthy subjects. Methods: High-resolution colonic manometry (HRCM) was performed using an 84 sensor (1 cm spaced) water-perfused catheter in 16 healthy volunteers. Intraluminal pressure patterns were recorded during 90 min baseline, during balloon distension, 90 min after a meal and after luminal bisacodyl administration. Quantification was performed using software, based on Image J, developed during this study. Results: SPWs, with amplitudes ranging from 2.4 to 75.2 mmHg (average 12 mmHg) and duration from 2 to 75s (average 11s), occurred throughout the entire colon or they developed at the termination of proximal High-Amplitude Pressure Waves (HAPWs). SPWs progressed into the anal canal followed by anal sphincter relaxation, even at very low amplitudes. SPWs did not obliterate haustral boundary contractions, likely the mechanism by which in vivo gas can escape while stool is retained. SPWs consisted of multiple high frequency, high velocity, pressure waves that resulted in apparent instantaneous pressure development. Balloon distension, a meal or luminal bisacodyl stimulation (10 mg) resulted in high amplitude SPWs associates with gas, water or balloon expulsion. SPWs and HAPWs also occurred independently and then did not influence each other. SPWs occurred in a rhythmic fashion on 26 occasions, including responses to all different stimuli; a distinct rhythmicity was identifiable at an average frequency of 1.8 ± 0.8 cpm, ranging from 0.3 to 4.4 cpm; 13 of the clusters were observed in response to the meal where the average frequency was 2.1 ± 0.9 cpm. Conclusions: The SPWs need to be incorporated into colonic function assessment by HRCM alongside HAPWs. It is the dominant motor pattern that allows gas expulsion and internal anal sphincter relaxation. Low-and high-amplitude SPWs are observed during baseline and are evoked by a meal, balloon distension or luminal bisacodyl. The rhythmicity of SPWs suggests the involvement of the ICC network at the submucosal border of the colon. The associated gas/liquid/balloon expulsion and anal sphincter relaxation provide potential diagnostic value.
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