Gastric emptying of a non-digestible solid: assessment with simultaneous SmartPill pH and pressure capsule, antroduodenal manometry, gastric emptying scintigraphy

Abstract  Gastric emptying of digestible solids occurs after trituration of food particles. Non-digestible solids are thought to empty with phase III of the migrating motor complex (MMC). The aim of this study was to determine if a non-digestible capsule given with a meal empties from the stomach with return of the fasting phase III MMC or during the fed pattern with the solid meal. Fifteen normal subjects underwent antroduodenal manometry and ingestion of a radiolabelled meal and SmartPill wireless pH and pressure capsule. In five subjects, emptying of the SmartPill was studied in the fasting period by ingesting the SmartPill with radiolabelled water. The SmartPill emptied from the stomach within 6 h in 14 of 15 subjects. SmartPill pressure recordings showed high amplitude phasic contractions prior to emptying. SmartPill gastric residence time (261 ± 22 min) correlated strongly with time to the first phase III MMC (239 ± 23 min; r  = 0.813; P  < 0.01) and correlated moderately with solid-phase gastric emptying ( r  = 0.606 with T-50% and r  = 0.565 with T-90%). Nine of 14 subjects emptied the capsule with a phase III MMC. In five subjects, the SmartPill emptied with isolated distal antral contractions. In five subjects ingesting only water, SmartPill gastric residence time (92 ± 44 min) correlated with the time to the first phase III MMC (87 ± 30 min; r  = 0.979; P  < 0.01). The non-digestible SmartPill given with a meal primarily empties from the stomach with the return of phase III MMCs occurring after emptying the solid-phase meal. However, in some subjects, the SmartPill emptied with isolated antral contractions, an unappreciated mechanism for emptying of a non-digestible solid.     

Reproducibility of antroduodenal motility during prolonged ambulatory recording

Ambulatory recording of antroduodenal manometry is a novel technique with several advantages over standard stationary manometry recording. Although the feasibility of this technique in clinical practice has been demonstrated, reproducibility of antroduodenal motility recorded by means of ambulatory manometry has not been investigated. To test whether antroduodenal motility recorded by ambulatory manometry is reproducible, we performed two 24-h ambulatory antroduodenal manometry recordings in 18 healthy subjects according to an identical protocol with a 1-week interval. Motility was recorded with a five-channel solid-state catheter. Postprandial motility was recorded after consumption of two test meals and interdigestive motility was recorded nocturnally. Postprandial antroduodenal motor characteristics were identical between the separate recordings. The number and duration of nocturnal cycles of the interdigestive migrating motor complex were also in the same range. Phase III characteristics in general were not different between the two recordings. Only minor alterations were observed in the duration of phase III motor fronts with duodenal onset and in the number of interdigestive cycles concluded by duodenal onset phase III. Parameters obtained by qualitative analysis were comparable between the two recordings. The antroduodenal motility pattern, when measured by ambulatory recording with solid state catheters under standardized conditions, is very reproducible.     

Validation of antroduodenal motility measurements made by echo-planar magnetic resonance imaging

Echo planar imaging, a development of magnetic resonance imaging, can produce snapshot images of the stomach and antroduodenal segment in as little as 64 msec and can be more useful than conventional techniques when assessing motility. The aim of this study was to compare antroduodenal motility measured by simultaneous perfused tube manometry and echo planar imaging. Ten volunteers were studied following the ingestion of 500 mL water or 500 mL porridge. Antroduodenal images, with acquisition times of 130 msec, were taken at 3-sec intervals, synchronized with motility traces and presented as a split-screen video. This allowed direct visual comparison of gastric wall movement and motility to be made. Contractions were confined to either the stomach or the duodenum or propagated across the antroduodenal segment. Over 4550 images were available for analysis. A larger number of propagated contractions were recorded with echo planar imaging in both water (P = 0.03) and food (P = 0.02) groups, whereas manometry detected a greater number of isolated duodenal pressure waves (P = 0.005). The contraction rate for water and food studies was similar, but direct visualization indicated that the manometric technique under-detected propagated events. The ability of echo planar imaging to record antroduodenal contractile activity provides a new insight into the role of occlusive and nonocclusive contractions during gastric emptying.     

Interobserver variability in antroduodenal manometry

Abstract  Interobserver variability affects investigations involving assessment of complex visual data, such as histopathology, radiology and motility. This study assessed interobserver variation for interpretation of antroduodenal manometry (ADM), as this has not been previously investigated. Thirty-five ADM recordings from children aged 0.3–18 years were independently evaluated by five experienced paediatric gastroenterologists who were blinded to cases' clinical histories. Intra-class correlation (ICC) was analysed for detection and measurement of phase three of the migrating motor complex (MMC) and Cohen's kappa statistic was calculated between observer pairs for detection of specific motility features and final diagnosis. Observers were unanimous on the differentiation of normal and abnormal motility in 63% of cases. There was excellent interobserver agreement for the number of phase three of the MMC in fasting (ICC = 0.82, P  < 0.0001) and for measurements of phase three of the MMC (ICC = 0.9999, P  < 0.0001). Detection of other normal and abnormal motility patterns varied more. Objective findings such as the presence of phase three of the MMC correlated more closely than findings that involved the integration of several variables, such as final diagnosis. However, these data overall indicate that agreement between expert observers for the distinction of normal and abnormal antroduodenal motility compares favourably with other standard medical assessments.     

Gastrointestinal motor activity associated with postoperative ileus and emesis

The gastrointestinal motor activity associated with post-operative ileus and emesis has not been fully elucidated. This study has evaluated gastric and small-bowel motility in six patients before and after cholecystectomy and in six healthy volunteers, by solid-state manometry. Nausea and vomiting were recorded post-operatively. After surgery, fasting motor abnormalities including (a) total gastric quiescence and (b) small-bowel ‘phasic-bursts’ of contractions were observed in all patients. Phasic bursts (PB) resembled phase III of the migrating motor complex (MMC) on initial visual inspection, but further analysis revealed that they were of shorter duration (3.4 ±.2 min [PB] vs 6.4 ± 0.8 min [MMC], [mean ± SEM] P < 0.01), lower contraction frequency (6.4 ± 0.1 contractions min ^?1 [PBj vs 10 ± 0.3 contractions min^?1 [MMC] [mean ± SEM] P < 0.01) and shorter periodicity (36.4 ± 3 min [PB] vs 70.0 ± 6 min [MMC] [mean ± SEM] P < 0.01). Four patients experienced nausea during phasic burst activity. Vomiting was only observed in association with retrograde phasic-bursts, which migrated through the duodenum to the stomach. This study has shown consistent gastrointestinal motor abnormalities in the immediate post-operative state.     

Ileal manometry in children following ileostomies and pull-through operations

Our aim was to analyse the patterns of ileal contractions in children. We reviewed the charts of 23 children who had ileal manometry studies (16 males), mean age 7 years (range 2 months to 17 years). We positioned the manometry catheters with 4-8 recording sites, 5 or 15 cm apart, through ileostomies fashioned for clinically indicated reasons. We studied six additional children with persistent faecal soiling following endorectal pull through for Hirschsprung's disease; the catheters were positioned through the anus and colon into the ileum. We recorded phasic and tonic intermittent contractions in all the subjects, clustered contractions (rate 5-9 min-1, duration 20-120 s) in 19 subjects with ileostomies and four with endorectal pull throughs. In 13 children there were prolonged propagated contractions, > 60 mmHg in amplitude, > 15 s in duration, propagating at rates of 2-6 cm s-1 over at least 20 cm. The migrating motor complex was rare; in 55 h of fasting recording there were two phase III sequences. There are four distinctive features of ileal manometry recordings in children: random intermittent contractions, clustered contractions, prolonged propagated contractions and tonic contractions. The features of ileal motility differ from motility in the proximal small bowel.     

Ghrelin regulates gastric phase III-like contractions in freely moving conscious mice

Abstract  In humans and dogs, motilin regulates phase III contractions of migrating motor complex (MMC) in the interdigestive state, while ghrelin regulates MMC in rats. It still remains unclear whether ghrelin regulates phase III contractions of the mouse stomach. A miniature strain gauge transducer was sutured on the antrum to detect circular muscle contractions and gastric contractions of the interdigestive state were evaluated. Effects of ghrelin, a ghrelin receptor antagonist, and atropine on spontaneous gastric contractions were studied in freely moving conscious mice. Similar to the rat stomach, phase III-like contractions were observed in the interdigestive state, which disappeared immediately after the feeding. Ghrelin augmented spontaneous phase III-like contractions, while growth-hormone secretagogue receptor antagonists and atropine abolished the occurrence of spontaneous phase III-like contractions. The spontaneous phase III-like contractions were no more observed in vagotomized mice. These results suggest that ghrelin regulates phase III-like contractions in mice stomach via its own receptors. Ghrelin-induced gastric phase III-like contractions are mediated via vagal cholinergic pathways in mice. Our recording system of mice gastric motility may be useful to study the functional changes in gene knockout mice, in the future.     

Characteristic motor patterns of phase II and behaviour of phase III in the fed state

The motor pattern of the phase II of the migration motor complex (MMC) is poorly characterized and it remains to be determined whether it differs from the fed motor-pattern. Furthermore, discrepancy exists on the disruption of ongoing MMCs by feeding, and finally, the understanding of the behaviour of phase Ills during enteral nutrition is incomplete. Therefore, canine intestinal motility was studied after meal and during enteral infusion of nutrients (elemental diet, glucose, maltose, amino acids) or of hypertonic saline (300–1520 mosmol kg^?1). Motility of the proximal, mid- and distal jejunum was recorded with strain-gauge transducers. The motor patterns of the interdigestive phase II, after feeding and during enteral nutrition were analysed by a computer. Additionally, the disruption of the MMC by food and by enteral infusion of nutrients or hypertonic saline was investigated. The inter digestive phase II consisted of three different contractile patterns, clustered contractions, a mixed contractile pattern and non-migrating bursts of propagated contractions (NBPCs). NBPCs differed significantly from the phase III activity in several motility parameters and by the lack of aboral migration. Only small differences existed between the motor patterns of phase II and of the fed state, whereas the motor pattern induced by enteral infusion of an elemental diet differed significantly from that of phase II. Ongoing MMCs of the proximal jejunum often continued to migrate to the mid- and distal jejunum. During enteral infusion of nutrients or of hypertonic saline, phase Ills recurred. The migration of ongoing phase Ills and the recurrence of subsequent phase Ills decreased with increasing caloric or osmotic loads. The following conclusions were reached, (a) The phase II of the MMC is a complex motor-pattern. NBPCs represent a new contractile pattern, (b) The MMC is a characteristic feature of the empty gut. After meal and during enteral nutrition, phase Ills are usually suppressed but they can recur during the digestive period.     

Motility of the antroduodenum in healthy and gastroparetics characterized by wireless motility capsule

Background The wireless motility capsule (WMC) measures intraluminal pH and pressure, and records transit time and contractile activity throughout the gastrointestinal tract. Our hypothesis is that WMC can differentiate antroduodenal pressure profiles between healthy people and patients with upper gut motility dysfunctions. This study aims to analyze differences in the phasic pressure profiles of the stomach and small intestine in healthy and gastroparetic subjects. Methods Data from 71 healthy and 42 gastroparetic subjects were analyzed. The number of contractions (Ct), area under the pressure curve and motility index (MI = Ln (Ct *sum amplitudes +1)) were analyzed for 60 min before gastric emptying of the capsule (GET), (gastric window) and after GET (small bowel window) and results between groups were compared with the Wilcoxon rank sum test. Key Results Significant differences were observed between healthy and gastroparetic subjects for Ct and MI (P < 0.05). Median values of the motility parameters in gastric window were Ct = 72, MI = 11.83 for healthy and Ct = 47, MI = 11.12 for gastroparetics. In the small bowel, median values were Ct = 144.5, MI = 12.78 for healthy and Ct = 93, MI = 12.12 for gastroparetics. Diabetic subjects with gastroparesis showed significantly lower Ct and MI compared with healthy subjects in both gastric and small bowel windows while idiopathic gastroparetic subjects did not show significant differences. Conclusions & Inferences The WMC is able to differentiate between healthy and gastroparetic subjects based on gastric and small bowel motility profiles.     

Variable abnormal physiological motility in the proximal upper gastrointestinal tract in gastroparesis

Background Traditional testing for gastroparesis with gastric emptying scintigraphy (GES) likely misses a subset of patients because of the heterogeneous nature of the disease. The primary aim of this study is to determine the prevalence of simultaneously measured transit and pressure abnormalities in patients with gastroparesis. The secondary aim is to assess diagnostic gain realized by measuring antroduodenal pressure and gastric transit with wireless motility capsule (WMC) compared to gastric transit measured by GES. Identification of abnormalities beyond gastric transit delay in gastroparesis may yield novel targets for pharmacological therapies. Methods Forty‐three subjects with symptoms of gastroparesis and previous abnormal GES within 2 years were enrolled in the study. Subjects underwent simultaneous GES and WMC to assess gastric transit. Gastric and small bowel pressure profiles were measured by WMC to determine the contribution of pressure to diagnostic gain realized with WMC. Key Results Fifty‐one percent of subjects had abnormal GES while 70% of subjects had either abnormal gastric emptying time (GET) or antroduodenal pressure. Gastric emptying time was abnormal in 60% of subjects while gastric or small bowel pressure was abnormal in 47% of subjects. The overall diagnostic gain of WMC compared to GES was 19% (P = 0.04). Seven percent of subjects had abnormal small bowel pressure profiles when both GES and GET were normal. Conclusions & Inferences (i) Gastroparesis is a heterogeneous disorder and testing only solid food emptying by scintigraphy may miss a significant amount of pathology. (ii) Measuring complementary aspects of gastric and small bowel function simultaneously results in greater detection of physiologic abnormalities that may underlie patient symptoms.     

Manometric responses of human duodenum during infusion of HCl,hyperosmolar saline,bile and oleic acid

Abstract Duodenal motor activity is incompletely understood. The purpose of this study was to define the contractile patterns of the duodenum that occur in response to rate controlled injection of various solutions. In nine healthy volunteers we placed a six channel perfused catheter, and recorded pressure activity in the antrum, pylorus and duodenum. Volumes of 10 and 20 mL of 0.9% NaCl, 100 mM HCl (pH 1), 5% NaCl (1711 mOsm/kg), human bile and iso-osmolar sodium oleate were randomly injected into the duodenum at 20 ml/min, starting IS min after phase III migratory motor complex (MMC). A 20 mL bolus of each solution caused more activity (P < 0.05) than a 10 mL bolus, but the motor pattern was similar. The control, 0.9% NaCl, produced occasional pressure waves, whereas bile and sodium oleate induced more (P < 0.05) activity which consisted of low amplitude, isolated or clusters (2–4 cycle/min) of non-propagating pressure waves that occurred at random sites. In three subjects, oleate produced isolated pyloric phasic contractions. In contrast, HCl and 5% NaCl induced high amplitude pressure waves that were seen either at a single channel or at multiple channels, occurring simultaneously. The motility index was also greater (P < 0.05) than that induced by other solutions. Additionally, within 2 min of infusion, a phase III MMC like pattern was observed in five of the nine subjects who received HCl and three of the nine who received 5% NaCl. A non-nutrient iso-osmolar solution induced occasional motor activity. HCl and hyperosmolar solutions induced more frequent and large amplitude, segmental contractions whereas lipid and bile induced fewer and smaller amplitude contractions. The volume, the pH, the osmolar and the nutrient make up of the infusate may each influence the duodenal motor responses.     

Gastric myoelectrical and antroduodenal motor activity in patients with achalasia

Achalasia is a primary motor disorder of the oesophagus, in which the myenteric plexus is involved. However, abnormalities in other parts of the digestive tract have also been described in achalasia. Whether gastric myoelectrical and duodenal motor activity in these patients is also affected is unknown. Therefore, interdigestive and postprandial gastric myoelectrical and antroduodenal motor activity were studied in 11 patients with achalasia, using electrogastrography (EGG) and stationary antroduodenal manometry.
Electrogastrographically, no differences were found in the gastric frequency, incidence of dysrhythmias and postprandial/fasting power ratio. In the interdigestive state a lower propagation velocity of phase III episodes was found in the achalasia patients, but other parameters were unaltered. Postprandially, no differences were found in the number of pressure waves, in the amplitude of pressure waves or in antro-duodenal coordination.
We conclude that gastric myoelectrical activity and antral motor activity in patients with achalasia is normal, suggesting an intact extrinsic and intrinsic neural innervation of the distal stomach. Although postprandial duodenal motility is normal, a lower propagation velocity of phase III suggests involvement of the small intestine in achalasia.     

Multiple rapid swallowing: a complementary test during standard oesophageal manometry

Abstract  Multiple rapid swallowing (MRS) stimulates neural inhibition resulting in abolition of contractions in the oesophageal body (OB) and complete lower oesophageal sphincter (LOS) relaxation which is followed by peristalsis and LOS contraction. The aim of this study was to evaluate the yield of MRS to detect abnormalities in inhibitory or excitatory oesophageal mechanisms in patients with oesophageal symptoms and either normal standard manometry or ineffective oesophageal motility (IOM). MRS (five water swallows, 2 mL, separated by 2–3 s) was evaluated in 23 healthy subjects, 109 symptomatic patients with normal standard sleeve manometry and in 48 patients with IOM. Healthy subjects had complete inhibition of OB motility during MRS and a strong motor response after MRS, i.e. amplitude of OB contractions in the oesophageal body and LOS tone being higher than after single swallows. Almost 70% of patients with oesophageal symptoms and normal manometry had abnormal MRS, mainly consistent on inability to increase amplitude of OB contractions after MRS. Nearly, half of the patients with IOM were able to normalize OB contractions after MRS. MRS is a simple complementary test that can be added to standard oesophageal manometry. Two-thirds of patients with normal manometry show abnormal MRS that could potentially underlie their symptoms. A normal response to MRS in patients with severe IOM might be used to predict response to prokinetic treatment.     

Swallows, oesophageal and gastric motility in normal subjects and in patients with gastro-oesophageal reflux disease: a 24-h pH-manometric study

Background: the motor aspects underlying gastro-oesophageal reflux disease (GORD) are still not completely clear. Aim: to evaluate the relationship between oesophageal and gastric motility in GORD patients. Patients: twelve patients with grade I–II oesophagitis, mean age 45 yr, and 10 healthy subjects, mean age 42 yr, were studied. Methods: a pH-manometry was performed to analyse oesophageal and gastric motility, swallows and oesophageal pH values for the whole 24-h period, and for the 2-min period before and after each reflux episode. Results: as compared to controls, GORD patients showed in the 24-h period, a greater number of swallows (P < 0.01) and a lower percentage of post deglutitive propagated oesophageal body waves (P < 0.05). The number of migrating motor complexes (MMC) was similar in the two groups, with a lower amplitude of phase III gastric waves in GORD. During MMC reflux episodes were seen only in GORD patients. After refluxes an increase in swallows, simultaneous and secondary oesophageal waves were detected in GORD patients, with a reduction of primary peristalsis. Isolated gastric contractions preceded reflux episodes more frequently in GORD patients than in controls. Conclusions: GORD patients showed an increase in swallows with altered post-deglutitive oesophageal motility and a reduced amplitude of gastric MMC. Moreover small contractions of gastric antrum are present before acid refluxes, suggesting a multifactorial pathogenesis of the disease.     

Adrenergic Control of Interdigestive and Digestive Motility via the Pyloric Region

This study examines the influence of an α-adrenergic blocking drug, phentolamine, on inter digestive and digestive motility when given intraarterially, close to the pylorus. In seven mongrel dogs four extraluminal bipolar platinum electrodes and four strain-gauge force transducers were placed at the antrum and proximal duodenum and three mini strain gauges and one electrode at the pyloric ring. After two migrating motor complexes (MMCs) were registered the drug was applied through a catheter inserted via the arteria gastroomentalis dextra to the pylorus, during phase I, the middle and end of phase II of the MMC, and 15 to 25 minutes after a meat meal. Local α-adrenergic blockade of the pylorus caused immediate conversion of phase I to phase II of the MMC, with significant prolongation of phase II, broadening of antral and pyloric contractions, and in some animals giant contractions with vomiting and retching. The pyloric motility index in phase III increased up to 22%. It prolonged phase II by 237%. Phentolamine after the meat meal caused an increase in motility index, mainly in the pylorus, while the increase in contraction frequency was less pronounced. The results indicate inhibitory adrenergic control of the interdigestive motor pattern and digestive motility in the pyloric region.     

Sham feeding disrupts phase III of the duodenal migrating motor complex in humans

The role of the vagus nerve in the control of the intestinal migrating motor complex (MMC) is unclear. This study aimed to evaluate the effect of physiological vagal stimulation with sham feeding on phase III of the MMC. Antroduodenal motility was recorded in six healthy volunteers. The first phase III was used as a control, and sham feeding was performed during the second phase III. The MMC was disrupted within 1.5 ± 0.4 min of sham feeding and its duration was shorter than the control phase III. Phase III propagation was inhibited in all subjects, most of them exhibiting no propagation beyond the third duodenal recording site. During sham feeding, the antrum exhibited transient phasic contractions in five out of six subjects. The duodenal motility index recorded for up to 30 min after the onset of the sham feeding was unchanged in five out of six subjects. We conclude that sham feeding consistently interrupted phase III of the duodenal MMC and induced antral contractions, but failed to provoke significant motor events in the duodenum.     

Oesophageal transport of solid dosage forms depends on body position, swallowing volume and pharyngeal propulsion velocity

Knowledge about transit of solid dosage forms (SDF) in the gastrointestinal tract is incomplete. Detection of magnetically marked capsules (MMC) via superconducting quantum interference device (SQUID) allows monitoring of oesophageal transport of SDF with high tempospatial resolution. The aim of the study was to investigate the influence of body position, volume at swallowing, and oesophageal motility on orogastric transport of SDF. In 360 measurements we determined tempospatial characteristics of orogastric transit of SDFs by a SQUID device in six volunteers. They swallowed MMCs with various amounts of water in upright and supine position with and without simultaneous oesophageal manometry. Orogastric transit time, oesophageal transport velocity and rate of oesophageal retention of SDF depend on swallowing volume and body position at all experimental conditions. At 50 mL water bolus and in upright position, the retention rate depends on the pharyngeal propulsion velocity, and the transport velocity of MMCs in the oesophageal body are faster than the propulsive oesophageal contractions. Body position, swallowing volume and pharyngeal propulsion velocity markedly influence the oesophageal transport of SDF. They should be taken in upright body position with at least 50 mL of water to minimize entrapment in the oesophagus.     

Motility of the oesophagus and small bowel in adults treated for Hirschsprung’s disease during early childhood

Background Dysmotility of the upper gastrointestinal (GI) tract has been reported in children with Hirschsprung’s disease (HD). In the present study, motility of the oesophagus and the small bowel was studied in adults treated for HD during early childhood to elucidate whether there are alterations in motility of the upper GI tract in this patient group. [Correction added after online publication 15 Sep: The preceding sentence has been rephrased for better clarity.] Methods Ambulatory small bowel manometry with recording sites in duodenum/jejunum was performed in 16 adult patients with surgically treated HD and 17 healthy controls. In addition, oesophageal manometry was performed with station pull‐through technique. Key Results The essential patterns of small bowel motility were recognized in all patients and controls. During fasting, phase III of the migrating motor complex (MMC) was more prominent in patients with HD than in controls when accounting for duration and propagation velocity (P = 0.006). Phase I of the MMC was of shorter duration (P = 0.008), and phase II tended to be of longer duration (P = 0.05) in the patients. During daytime fasting, propagated clustered contractions (PCCs) were more frequent in the patients (P = 0.01). Postprandially, the patients demonstrated a higher contractile frequency (P = 0.02), a shorter duration of contractions (P = 0.008) and more frequent PCCs (P < 0.001). The patients had normal oesophageal motility. Conclusions & Inferences This study demonstrates that adult patients with HD have preserved essential patterns of oesophageal and small bowel motility. However, abnormalities mainly characterized by increased contractile activity of the small bowel during fasting and postprandially are evident. These findings indicate alterations in neuronal control of motility and persistent involvement of the upper GI tract in this disease.     

High-resolution analysis of the duodenal interdigestive phase III in humans

To study the spatial organization of the propagating pressure waves of duodenal phase III, we performed fasting antroduodenal high-resolution manometry with a 16-channel catheter in 12 healthy subjects. The phase III pressure waves diverged in an anterograde and retrograde direction from the start site of each pressure wave. The pressure waves maintained this configuration as the activity front moved distally in the duodenum. The start site of the pressure waves moved gradually to a point approximately 12 cm (median) distal to the pylorus and remained at this point for about 40% of the phase III time before moving further distally. The length of retrograde pressure wave propagation increased to 6 cm (median) as the pressure wave origin moved aborally to a point 10-14 cm distal to the pylorus, and then decreased when the origin of pressure waves reached the distal end of the duodenum. Bidirectional pressure waves dominated in both retrograde and anterograde activity fronts. Three pressure-wave mechanisms behind the duodenal phase IV were observed. Isolated pyloric pressure waves were absent during late duodenal phase III retroperistalsis. Thus, a number of new features of the duodenal phase III-related motility were observed using high-temporospatial resolution recordings.     

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.