Colonic motor activity in slow-transit idiopathic constipation as identified by 24-h pancolonic ambulatory manometry

Colorectal motor activity in slow-transit idiopathic constipation has not been fully evaluated under physiological conditions. The aim of this study was to evaluate colorectal motor activity in chronic idiopathic constipation using 24-h ambulant pancolonic manometry. Ten healthy volunteers (six females) 19-31 years of age, and eight females 25-46 years of age with slow-transit idiopathic constipation were studied. Motor activity was measured using two custom-made silicone-coated catheters, each with five solid-state pressure transducers. Bowel preparation or sedation was not used. Frequency of high-amplitude propagated contractions was reduced in chronic idiopathic constipation, median 1.9/24 h vs 6/24 h (P = 0.01). Contractile frequency of low-amplitude complexes was reduced throughout the colon in slow-transit idiopathic constipation (P < 0.0001). The interval between contractile complexes was reduced in the transverse colon and splenic flexure (P < 0.0001). This study demonstrates that colonic motor activity is abnormal in slow-transit idiopathic constipation; decreased motor activity leads to a reduction in propulsion of intraluminal contents.     

The effects of acute exercise on colonie motility

Abstract Changes in colonic motor activity during aerobic exercise were investigated in ten regularly exercising volunteers (five males and five females) aged 27–70 years. Motility was recorded with a catheter containing three solid-state pressure transducers spaced 5 cm apart. The motility catheter was advanced 40–50 cm from the anal verge by flexible sigmoidoscope without anesthesia at least 60 min prior to testing. Manometric recordings were made from the colon during a 1-h pre-exercise rest period, 1 h of jogging at 70–80% maximum heart rate, and 1-h post-exercise rest period. The dominant frequency of contractile activity in the colon shifted from 1–4 cpm during rest, to 4–9 cpm with the onset of exercise. Activity also shifted from sporadic, isolated contractions to regular, propagated contractions in six of ten subjects, five of whom reported a history of runner's diarrhoea. The dominant frequency returned to 1–4 cpm during the post-exercise period. These changes in distal colonie motility may account for the diarrhoea which some subjects experience during intense, acute exercise.     

Oxytocin stimulates colonic motor activity in healthy women

The effects of oxytocin in the gastrointestinal tract are unclear. The aim of this study was to examine the effect of infusion of oxytocin on colonic motility and sensitivity in healthy women. Fourteen healthy women were investigated twice. A 6-channel perfusion catheter, with three recording points (2 cm apart) proximally and three recording points distally to a barostat balloon, was inserted to the splenic flexure. An intestinal feeding tube was placed in the mid-duodenum. A 90-min duodenal lipid infusion of 3 kcal min(-1) was administered. Thirty minutes after the start of the lipid infusion, the subject randomly received either 20 or 40 mU min(-1) of oxytocin, or isotonic saline as intravenous infusions for 90 min. Meanwhile, the colonic motility was recorded. During the last 30 min of oxytocin and saline infusion, the visceral sensitivity to balloon distensions was examined. During lipid infusion the number of antegrade contractions per hour was 0.7 +/- 0.3 after saline and 3.9 +/- 1.4 after oxytocin (P = 0.03), indicating more pronounced lumen-occlusive contractile activity after oxytocin administration. Some of these consisted of high-amplitude (> 103 mmHg in amplitude) antegrade contractions. Lipid infusion evoked a decrease of the balloon volume, reflecting increased colonic tone, but there was no difference between saline and oxytocin. Sensory thresholds did not differ significantly between saline and oxytocin. Infusion of oxytocin stimulates antegrade peristaltic contractions in stimulated colon in healthy women. The effects of oxytocin on colonic motor activity deserve to be further explored, especially in patients with colonic peristaltic dysfunction.     

Effect of motilin and erythromycin on the motor activity of the human colon

Motilin and motilin receptor agonist erythromycin were administered to healthy subjects where colonic motility was recorded manometrically from the hepatic flexure to the rectum. Experiments were carried out during the fasting basal state or when colonic motility was stimulated by the ingestion of a 1000 kcal lunch. A supraphysiological dose of motilin (100 ng kg^?1, i.v.) increased the motor activity of the fasting sigmoid colon, but the response was smaller than the meal induced activity. The administration of erythromycin (200 mg, i.v.) during the inter digestive period induced, on the sigmoid region, a motor response that was not significantly different in amplitude from the post-prandial contractile profile. However, on the more proximal segments of the colon, motilin and erythromycin were inactive. When both agents were administered during the digestive period, both failed to modify the contractile stimulation normally seen in all regions of the colon after a meal. Therefore the colonic motor response obtained with stimulation of motilin receptors in man appears limited;it is restricted to the sigmoid, it can be seen only during fasting and it is of weak amplitude.     

Characterization of colonic motor activity in conscious dogs

Diurnal changes in canine colonic motility were investigated by means of chronically implanted force transducers. A characteristic of the colonic motor profile in the fasted state was the occurrence of colonic motor complexes consisting of tonic contractions superimposed with phasic ones. On feeding, motor complexes were immediately induced in the whole colon and continued to occur at significantly shorter intervals than those in the fasted state, but the duration and the amplitude of the colonic motor complexes were not affected by feeding. This increased activity period lasted for 8–16 h after feeding, and 83.3% of the defecations were observed in this period. Of the defecations 33% occurred in the first 2 h after feeding (P < 0.05). More than 80% of the giant migrating contractions associated with defecation propagated from the middle to the distal colon, and the start of faeces evacuation coincided with the end of the relaxation period of the distal colon preceding the arrival of the giant migrating contractions. More than 90% of the giant migrating contractions not associated with defecation migrated from the proximal to the middle colon. More than 60% of the colonic motor complexes migrated in an aboral direction and about 18% of them in an oral direction. These results suggest that (1) defecations tend to occur immediately after feeding; (2) the regional distribution of giant migrating contractions was different between those associated and not associated with defecation.     

High amplitude propagated contractions

While most colonic motor activity is segmental and non‐propulsive, colonic high amplitude propagated contractions (HAPC) can transfer colonic contents over long distances and often precede defecation. High amplitude propagated contractions occur spontaneously, in response to pharmacological agents or colonic distention. A subset of patients with slow transit constipation have fewer HAPC. In this issue of Neurogastroenterology and Motility, Rodriguez et al. report that anal relaxation during spontaneous and bisacodyl‐induced HAPC exceeds anal relaxation during rectal distention in constipated children undergoing colonic manometry. Moreover, and consistent with a neural mechanism, anal relaxation often precedes arrival of HAPC in the left colon. High amplitude propagated contractions are also used to evaluate the motor response to a meal and pharmacological stimuli (e.g., bisacodyl, neostigmine) and to identify colonic inertia during colonic motility testing in chronic constipation. This editorial comprehensively reviews the characteristics, physiology and pharmacology of HAPC, their assessment by manometry, and relevance to constipation and diarrhea.     

Results of 24-h manometric recording of colonic motor activity with endoluminal instillation of bisacodyl in patients with severe chronic slow transit constipation

The aims of this study were to assess the prevalence of manometric colonic abnormalities and to evaluate the motor effect of intraluminal bisacodyl in a cohort of refractory constipated patients. Twenty-four hour colonic motility recordings were performed in 40 patients referred for a severe intractable chronic constipation. At the end of each recording session the motor effects of the endoluminal instillation of 10 mg bisacodyl were assessed. These patients were compared with 20 healthy subjects. The number of high-amplitude propagating contractions (HAPC) was significantly decreased in patients with slow transit constipation (12 +/- 11.6 vs 1 +/- 8.6, P < 0.001). Based on manometric patterns four groups of patients were isolated. Ten patients had no spontaneous HAPC, no food-induced colonic motor response and significantly lower colonic activity in transverse colon (374 +/- 1220 vs 3249 +/- 3458, P < 0.05). Five patients had significantly increased sigmoid segmental motility (20298 +/- 6364 vs 88780 +/- 3643, P < 0.001) and eight patients had significantly lower number of HAPC without other manometric abnormalities while 17 patients had normal colonic motility recordings. Endoluminal bisacodyl was able to induce HAPCs in all groups of patients. Patients with severe slow transit refractory constipation represented a heterogeneous group and endoluminal bisacodyl was able to promote a propagated motor activity in a majority of patients even in those suspected of having an inert colon.     

Proximal colonic propagating pressure waves sequences and their relationship with movements of content in the proximal human colon

Abstract  Abnormal colonic motor patterns have been implicated in the pathogenesis of severe constipation. Yet in health, the mechanical link between movement of colonic content and regional pressures have only been partially defined. This is largely due to current methodological limitations. Utilizing a combination of simultaneous colonic manometry, high-resolution scintigraphy and a quantitative technique for detecting discrete episodic flow, our aim was to examine the propulsive properties of colonic propagating sequences (PS) in the healthy colon. In six healthy volunteers a nasocolonic manometry catheter was positioned to record colonic pressures at 7.5 cm intervals from terminal ileum to the splenic flexure. With subjects positioned under a gamma camera, 30 MBq of ^99mTc sulfur colloid was instilled into the terminal ileum, 22.5 cm proximal to the ileocolonic junction. Isotopic images were recorded (10 s/frame) and synchronized with the manometric trace. In the proximal colon we identified 137 antegrade PSs, of which 93% were deemed to be associated temporally with movements of luminal content. Low amplitude PSs, with component pressure waves between 2 mmHg and 5 mmHg, were as likely to be associated with colonic movements as higher amplitude PSs. As such there was no correlation between the amplitude of the PS and the temporal relationship with colonic movements. Within the proximal colon, 24 retrograde PSs were identified, 23 of which were associated with retrograde movements of colonic content. We conclude that proximal colonic PSs are highly propulsive and are a major determinant of proximal colonic flow.     

Anatomical registration and three‐dimensional visualization of low and high‐resolution pan‐colonic manometry recordings

Background Colonic propagating sequences (PS) are important for the movement of colonic content and defecation, and aberrant PS patterning has been associated with slow transit constipation. However, because these motor patterns are typically recorded over long periods (24 h +), the visualization of PS spatiotemporal patterning is difficult. Here, we develop a novel method for displaying pan‐colonic motility patterns. Methods A 3D mesh representing the geometry of the human colon was created as follows: (i) Human colon images from the Visible Human Dataset were digitized to create a 3D data cloud, and (ii) A surface mesh was fitted to the cloud using a least‐squares minimization technique. Colonic manometry catheters were placed in the ascending colon of healthy controls and patients with slow transit constipation (STC), with the aid of a colonoscope. The colonic manometry data were interpolated and mapped to the model according to the following anatomical landmarks: cecum, hepatic flexure, splenic flexure, sigmoid‐descending junction, and anus. Key Results These 3D images clearly and intuitively communicate characteristics of normal and abnormal colonic motility. Specifically we have shown the reduced amplitude of the antegrade propagating pressure waves (PPW) throughout the colon and reduced frequency of PPWs at the mid‐colon in patients with STC. Conclusions and Inferences A novel method for the 3D visualization of PS is presented, providing an intuitive method for representing a large volume of physiological data. These techniques can be used to display frequency, amplitude or velocity data, and will help to convey regions of abnormally in patient populations.     

Mechanical activity of small and large intestine in normal and mdx mice: a comparative analysis

The aim of this study was to compare the motor pattern (recorded as changes in intraluminal pressure) of isolated duodenum and proximal colon between dystrophic mdx and normal mice. When duodenal recordings from control preparations were compared with mdx mice there was no significant difference in the spontaneous motor pattern, responses to electrical nerve stimulation or sensitivity to pharmacological agents. Colonic segments from mdx mice showed a more complex motor pattern, consisting of contractions with amplitude and frequency similar to those of controls and by additional contractions with lower amplitude and higher frequency. Moreover, 70% of the colonic preparations from mdx mice developed active tone. TTX (1 microM), both in control and in mdx mice, changed the motor pattern, revealing regular rhythmic contractions similar in both preparations. L-NAME (100 microM) in both preparations increased contractile activity, revealing additional low contractions in control and potentiating them in mdx colon. In both control and mdx mice, inhibitory responses elicited by electrical field stimulation (EFS) were significantly attenuated by L-NAME. Our results provide evidence for the presence of a different motor pattern in mdx proximal colon and suggest that mdx mice can be considered a suitable animal model for investigating the dystrophic process.     

Distention of the colon is associated with initiation of propagated contractions in children

Abstract  The presence of high-amplitude propagating contractions (HAPCs) has been identified as a marker of colonic neuromuscular integrity. The physiologic mechanisms of HAPCs initiation have yet to be determined. Distention secondary to colonic filling has been hypothesized as physiologic initiator. The aim of this study was to study the effect of intraluminal balloon distention in the colon of children with defecatory disorders. Colonic manometry was performed with a polyethylene balloon situated at the proximal end of the catheter, which was placed in the most proximal colonic segment reached during colonoscopy. A stepwise pressure controlled distention of the balloon was performed using barostat computer (10–50 mmHg). Propagated contractions were defined as those that migrated over at least three recording sites. They were divided into HAPCs, amplitude >60 mmHg and low-amplitude propagating contractions (LAPCs), amplitude <60 mmHg. Children with spontaneous HAPCs or HAPCs after bisacodyl provocation were considered to have normal motility. Twenty children completed the study. Among the 14 children with normal colonic motility, balloon distention elicited HAPCs in four and LAPCs in 10 children. No HAPC were elicited in six children with abnormal motility and LAPCs were seen in four of them. The balloon-induced propagated contractions had similar characteristics as those occurring spontaneously and after bisacodyl provocation but the pressure needed to elicit them and their amplitude was inconsistent. These findings suggest that intraluminal distention can trigger propagated contractions in children. This mechanism of action for induction of propagated contractions is not as consistent as the motor response found in response to bisacodyl administration.     

Propagation of giant migrating contractions between the small intestine,cecum and colon during radiation

Background Radiation increases the frequency of small intestinal and colonic giant migrating contractions (GMCs). These contractions contribute to the diarrhea and cramping after radiation therapy and are coordinated with one another across the ileocolonic (IC) junction. Methods We investigated the coordination of contractile activity between the small intestine, cecum and colon in five canines following circumferential myotomy on the ileum at the IC junction and compared it to intact animals. Studies were performed before and during a radiation schedule. Key Results Myotomy increased the frequency of small intestinal GMCs prior to irradiation. In intact animals, the duration and amplitude of cecal GMCs decreased when multiple contractions occurred in rapid succession. This is in contrast to small intestinal and colonic GMCs and suggests a different mechanism of propagation for GMCs within the cecum. Ileal myotomy dramatically decreased the frequency of propagating radiation‐induced colonic GMCs. The total number of colonic GMCs was not altered. Colonic contractile activity was disrupted in intact animals during irradiation. However, after ileal myotomy, irradiation did not affect the pattern of colonic contractile states. Diarrhea in irradiated animals with myotomy started earlier than intact animals. This may be related to the frequency of small intestinal GMCs. Conclusions & Inferences Our findings suggest importance of the enteric neural connections at the IC region to contractile disorders of both the small and large intestine. The anatomic relationship between the canine IC junction is similar to the human ileo‐appendiceal‐colonic region and surgical manipulations of this area may likewise affect human contractile activity.     

Colonic high-amplitude propagated contractions (mass movements): repeated 24-h manometric studies in healthy volunteers

Abstract Colonic contractile activity in man is still poorly understood and reported to be highly variable. In particular, little is known about colonic mass movements. We sought to gain greater information on mass movements by manometrically recording high-amplitude propagated contractions over three periods of 24 h in three healthy volunteers. Analysis of tracings showed that these events (a) are a relatively constant feature of the healthy colon (average [±SEM] number of mass movements for each subject was respectively 7 ± 1.7, 4 ± 1.5 and 6.3 ± 1.7); (b) display a diurnal variability, with a maximum of occurrence during the day and the waking state and a minimum during the night and the sleep; (c) are frequently related to specific physiological events     

Analysis of motor patterns in the isolated guinea-pig large intestine by spatio-temporal maps

We investigated and quantified the spontaneous patterns of motility in the isolated guinea-pig proximal and distal colon taken from adult animals. During spontaneous emptying, profiles of proximal and distal colon were recorded with a video camera, and image analysis was used to construct spatio-temporal maps of the motions of the intestinal wall. Four patterns of motility were recorded. In the proximal colon there were neurally mediated contractions that propagated in the aboral direction at 4.1 mm s(-1), gently pushing the soft contents aborally; these are likely to represent spontaneous peristaltic behaviour. A second pattern, insensitive to tetrodotoxin (TTX; 0.6 microM), consisted, in both oral and aboral propagation, of shallow contractions of the circular muscle (ripples). These contractions propagated aborally at 2.8 +/- 0.45 mm s(-1) and orally at 2.03 +/- 0.31 mm s(-1) (n=10). Of these TTX-resistant contractions, 22.5% propagated both orally and aborally from a common origin. The orally propagated component of these myogenic contractions is likely to correspond to the antiperistalsis widely described in the proximal colon. In the distal colon, two patterns of motor activity were observed. One, induced by natural or artificial pellets, consisted of peristaltic contractions that pushed the pellets aborally at 0.8 mm s(-1) and expelled a pellet every 108 s. In the interval between pellet propulsion and after the distal colon had emptied all of its pellets a second, nerve-mediated pattern of motor activity, consisting of clusters of annular circular muscle contractions separated by short dilated regions, slowly propagated aborally at 0.3 mm s(-1). Both of these motor patterns were abolished by TTX (0.6 microM). A latex balloon, inserted at the oral end of the empty isolated distal colon and inflated to a size similar to faecal pellets, was propelled at 1.4 mm s(-1). Epoxy resin-covered natural pellets were propelled at a similar speed of 1.6 mm s(-1).Our data revealed that myogenic and neurogenic patterns of propagated contractions in the colon occur in isolated preparations and are involved in emptying the colon.     

Altered periodic rectal motor activity: a mechanism for slow transit constipation

The pathophysiology of slow transit constipation is poorly understood. Both decreased and increased distal colonic motility have been reported. In healthy humans, a 3 cycles per minute (cpm), periodic rectal motor activity (PRMA) has been described. Our aim was to investigate the characteristics of PRMA and to assess its role in the pathogenesis of constipation. A six-sensor solid-state probe was placed with the tip sensor in the mid-transverse colon, without sedation, and prolonged colonic motility was recorded in nine patients with slow transit constipation (1M, 8F) and in 11 healthy subjects (3M, 8F). Subjects were free to ambulate. We examined the frequency, nocturnal vs. diurnal variation, and characteristics of PRMA, and its relationship to proximal colonic motility. All subjects showed PRMA. The rhythm was similar (2.5-4 cpm) in both groups. However, constipated patients exhibited a greater (P < 0.001) number of PRMA cycles than controls. The duration of each cycle and amplitude of pressure waves during PRMA were also greater (P < 0.05) at night in patients compared with controls. In patients, 40% of PRMA cycles were associated with a proximal colonic motor event compared with 81% in controls (P < 0.02). The area under the curve of all colonic pressure waves and incidence of specialized propagating pressure waves was lower (P < 0.05) in patients during daytime. When compared with controls, constipated patients exhibited reduced daytime colonic pressure waves and a higher frequency of PRMA. Most of the PRMA was unrelated to proximal colonic activity in constipated patients in contrast with findings in control patients. In addition to decreased colonic motility, this excessive and unco-ordinated phasic rectal activity may further impede stool transport and contribute to the pathogenesis of slow transit constipation.     

Fermentation of starch stimulates propagated contractions in the human colon

Background In healthy humans, up to 30 g of daily ingested starch escape small intestinal digestion, and are fermented in the colon. This physiological starch malabsorption could modify colonic motility through metabolites such as short‐chain fatty acids produced by fermentation. Methods Ten healthy volunteers swallowed a probe, consisting of an infusion catheter, six perfused catheters and a balloon connected to a barostat. On two consecutive days colonic motility was recorded in fasting subjects in the basal state (1 h), and then during (3 h), and after (2 h) the intracolonic infusion of 750 mL of isoosmotic and isovolumetric solutions containing sodium chloride with or without 15 g wheat starch. We determined (i) the volume of hydrogen and methane exhaled in breath, (ii) a global motility index and the number of high amplitude propagated contractions (HAPCs), and (iii) the mean balloon volume, reflecting the tonic motor activity. Key Results [median (IQR)] Compared to the basal period, colonic infusion of starch or saline did not modify the colonic motility index and tone. However, the number of HAPCs was significantly higher during and after infusion of starch than of saline [4.5 (2.75–6.5) vs 0.96 (0–2.66)/5 h, starch vs saline respectively; P = 0.011]. Conclusions & Inferences In healthy humans, colonic fermentation of a physiological malabsorbed amount of starch has no effect on the tonic and phasic colonic motor activities, but produces a significant increase in the number of HAPCs. This may participate in the physiological propulsion of colonic contents.     

Stimulatory action of mitemcinal (GM-611), an acid-resistant non-peptide motilin receptor agonist, on colonic motor activity and defecation: spontaneous and mitemcinal-induced giant migrating contractions during defecation in dogs

Abstract  The aim of this study was to characterize giant migrating contractions (GMCs) during spontaneous defecation in dogs and to investigate the effect of mitemcinal (an orally active and highly acid-resistant motilin receptor agonist) on colonic motility to assess the possibility of using it for the treatment of colonic motility disorders. To assess colonic motility, strain-gauge force transducers were implanted on the gastrointestinal tract of five dogs, and the behaviour of the dogs was monitored with a noctovision-video camera system. The effect of mitemcinal (0, 3, 10 or 30 mg per dog) and sennoside (300 mg per dog) on colonic motility was assessed 24 h after oral administration. During a 39-day period, the starting point of most of the 140 GMCs was between the transverse colon and the descending colon, but some variation was observed. In the daytime, the GMCs originated from somewhat more proximal positions than at night. Mitemcinal caused an increase in the GMC-index (integration of contractile amplitude and duration) and proximal translocation of the GMC starting point, but did not cause an increase in the number of defecations 12 h after administration. Sennoside, however, caused a significant increase in the number of defecations, an increase in the GMC-index, and prolongation of the duration of GMCs. The GMC starting point in the canine colon varied during spontaneous defecation. Mitemcinal was a potent prokinetic drug to mimic a spontaneous defecation compared with sennoside. Mitemcinal evacuates more intestinal luminal contents during the defecation than does sennoside.     

A comparison of the organization of longitudinal and circular contractions during pendular and segmental activity in the duodenum of the rat and guinea pig

Background Little is known of the spatiotemporal organization of pendular duodenal contractions. Methods We used longitudinal and radial spatiotemporal mapping to examine and compare pendular and segmental contractile activity in the proximal duodenum of the rat and guinea pig when the lumen was perfused with saline or micellar decanoic acid. Key Results Isolated phasic longitudinal contractions occurred along the rat duodenum with a frequency of 36 ± 2 cpm and strain rate amplitude of 26.8 ± 8.0% s^?1. These contractions occurred at fixed locations along the duodenum forming columns on the longitudinal strain rate map. The strain rate activity had local maxima at 4–6 points spaced at 7.7 ± 4.0 mm intervals along the duodenum and were uncoordinated between neighboring domains. Similarly disposed, less distinct, longitudinal contractions occurred in the guinea pig duodenum at a frequency of 25.2 ± 6.6 cpm with amplitude 6.8 ± 3.6% s^?1 but these were generally accompanied by numerous circular contractions that were distributed over 4–5 fixed locations and occurred with a frequency of 9 ± 3 cpm. Isolated static circular muscle contractions also occurred but at a lower rate in the rat than the guinea pig. Both types of contractions propagated after dosage with tetrodotoxin, lidocaine, atropine, or apamin. Conclusions & Inferences Localized contractions during segmental and pendular activity had some features of the spike patches that are normally associated with slow wave propagation. However, the commencement of propagation following administration of neural blocking agents and cholinergic inhibitors indicates their localization is maintained by inhibitory elements of the enteric nervous system.     

Comparison of simultaneous recordings of human colonic contractions by manometry and a barostat

Abstract Our hypothesis was that manometry in the colon was less sensitive than the electronic barostat in detection of colonic contractions. In ten healthy volunteers, we have characterised the pressure activity and tone of the colon by means of combined multilumen manometry and a barostatic balloon that was infinitely compliant, conformed to the colon's inner wall, and was clamped at a constant 'operating' pressure throughout the study. A computer program separated indices of the colon's motor function detected by the barostat: a baseline volume and phasic volume events. The barostat detects on average 70% more phasic pressure events than manometric sideholes located 2 em proximal to 7 cm distal to the balloon. Manometry becomes less sensitive than the barostat when the colonic diameter exceeds 5.6 em. The barostat detects on average 90% of all propagated and non-propagated (>30 mmHg) manometric peaks. The baseline volume changes significantly after the ingestion of a 1000-kcal meal, consistent with an increment in colonic tone, undetected by manometry. A combined barostat—manometry assembly appears to be preferable to manometry alone in the intraluminal evaluation of human colonic pressure activity and tone.     

In search of objective manometric criteria for colonic high-amplitude propagated pressure waves

Abstract The aims of this study were to explore all characteristics of high-amplitude propagated contractions (HAPCs) that would allow them to be distinguished from nonHAPC colonic pressure waves, and to develop computer algorithms for automated HAPC detection. Colonic manometry recordings obtained from 24 healthy volunteers were used. Automated analysis was performed to detect propagated pressure waves and to determine their amplitude, duration and area under the curve (AUC). For each of these variables distribution plots were made. Automated HAPC counts were compared to visual counts by experienced investigators. Distribution plots of 141093 colonic pressure waves lacked a bimodal pattern, as was also the case for propagated contractions (n = 8758). With increasing high-amplitude thresholds for HAPC detection, a gradual decrease in the automatically detected HAPC number was observed. These findings precluded determination of a threshold. Taking visually detected HAPCs as reference, amplitude thresholds of 100 mmHg in two channels, and 80 mmHg in one channel yielded the highest sensitivity (92%). In conclusion, objective criteria to distinguish HAPCs from other propagated pressure waves on the basis of their amplitude, duration or AUC do not exist. Automated detection of HAPCs using empirically derived criteria leads to an acceptable degree of correlation with visually detected HAPCs.