Bowel preparation affects the amplitude and spatiotemporal organization of colonic propagating sequences

Hyperactive Distal Colonic Motility and Recovery Patterns Following Right Colectomy: A High-Resolution Manometry Study

BACKGROUND

Postoperative ileus results in morbidity, prolonged hospitalization, and increased health care expenditure. However, the underlying abnormalities in motility remain poorly understood. Recent high-resolution manometry studies demonstrated that the distal colon becomes hyperactive with a cyclic motor pattern postoperatively, but they did not track this activity beyond 16 hours after surgery.

OBJECTIVE

This study used high-resolution manometry to evaluate distal colonic motility during the first 4 days after right-sided colectomy.

DESIGN

An observational study of perioperative high-resolution colonic manometry using a 36-sensor catheter with 1-cm resolution.

SETTING

A single tertiary hospital.

PATIENTS

Adult patients undergoing elective laparoscopic or open right-sided colonic resection.

MAIN OUTCOME MEASURES

Occurrence of distal colonic motor patterns during the perioperative period, defined according to a published classification system. Clinical markers of gut recovery included time to first stool, oral diet, and prolonged postoperative ileus.

RESULTS

Seven patients underwent perioperative manometry recordings. Hyperactive cyclic motor patterns emerged intraoperatively and peaked in the first 12 hours postoperatively, occupying 81.8% ± 3.9% of the recording. This gradually returned to normal during the first 4 days, reaching 19.0% ± 4.4% ( p = 0.002). No patient had a bowel movement before this hyperactivity resolved. High-amplitude propagating sequences were absent in early postoperative recordings, and their return temporally correlated with the passage of stool. Abnormal high-amplitude repetitive 0.5 to 1 cycle per minute activity was observed in the left colon of 1 patient with prolonged ileus.

LIMITATIONS

The invasive nature of recordings limited this study to a small sample size.

CONCLUSIONS

Cyclic motor patterns are markedly hyperactive in the distal colon after right-sided colectomy and resolve during the first 4 postoperative days. High-amplitude propagating sequences are inhibited by surgery and gradually recover. Bowel function may not return until these changes resolve. Other abnormal repetitive hyperactive patterns could contribute to the development of prolonged ileus. See Video Abstract at http://links.lww.com/DCR/B967 .

MOTILIDAD HIPERACTIVA DEL COLON DISTAL Y PATRONES DE RECUPERACIN DESPUS DE COLECTOMA DERECHA UN ESTUDIO DE MANOMETRA DE ALTA RESOLUCIN

ANTECEDENTES:El íleo post-operatorio produce una morbilidad significativa, una hospitalización prolongada y un aumento del gasto sanitario. Sin embargo, las anomalías subyacentes en la motilidad siguen siendo poco conocidas. Estudios recientes de manometría de alta resolución demostraron que el colon distal se vuelve hiperactivo con un patrón motor cíclico en el post-operatorio, pero no registraron esta actividad más allá de las 16 horas posteriores a la cirugía.OBJETIVO:Utilizar la manometría de alta resolución para evaluar la motilidad del colon distal durante los primeros cuatro días después de la colectomía del lado derecho.DISEÑO:Estudio observacional de pacientes sometidos a manometría colónica perioperatoria de alta resolución mediante catéter de 36 sensores con 1 cm de resolución.AJUSTE:Un solo hospital terciario.PACIENTES:Pacientes adultos sometidos a resección laparoscópica o abierta de colon del lado derecho de forma electiva.PRINCIPALES MEDIDAS DE RESULTADO:AAparición de patrones motores del colon distal durante el período perioperatorio, definidos según un sistema de clasificación publicado. Los marcadores clínicos de recuperación intestinal incluyeron, tiempo hasta la primera evacuación, dieta oral e íleo posoperatorio prolongado.RESULTADOS:Siete pacientes fueron sometidos a registros de manometría perioperatoria. Los patrones motores cíclicos hiperactivos emergieron intraoperatoriamente y alcanzaron su punto máximo en las primeras 12 horas post-operatorias, ocupando 81,8 ± 3,9% del registro. Esto volvió gradualmente a la normalidad durante los primeros cuatro días, alcanzando el 19,0 ± 4,4% (p = 0,002). Ningún paciente tuvo una evacuación intestinal antes de que se resolviera esta hiperactividad. Las secuencias de propagación de alta amplitud estaban ausentes en las grabaciones post-operatorias tempranas y su retorno se correlacionó temporalmente con el paso de las heces. Se observó actividad anormal de alta amplitud repetitiva de 0,5-1 ciclo / minuto en el colon izquierdo de un paciente con íleo prolongado.LIMITACIONES:La naturaleza invasiva de las grabaciones limitó este estudio a un tamaño de muestra pequeño.CONCLUSIONES:Los patrones motores cíclicos son marcadamente hiperactivos en el colon distal después de la colectomía del lado derecho y se resuelven gradualmente durante los primeros cuatro días posoperatorios. Las secuencias de propagación de gran amplitud se inhiben mediante cirugía y se recuperan gradualmente. Es posible que la función intestinal no regrese hasta que estos cambios se resuelvan. Otros patrones hiperactivos repetitivos anormales podrían contribuir al desarrollo de íleo prolongado. Consulte Video Resumen en http://links.lww.com/DCR/B967 . (Traducción-Dr. Mauricio Santamaria ).

Faecal incontinence is associated with an impaired rectosigmoid brake and improved by sacral neuromodulation

BACKGROUND

The rectosigmoid brake, characterised by retrograde cyclic motor patterns on high-resolution colonic manometry, has been postulated as a contributor to the maintenance of bowel continence. Sacral neuromodulation (SNM) is an effective therapy for faecal incontinence, but its mechanism of action is unclear. This study aims to investigate the colonic motility patterns in the distal colon of patients with faecal incontinence, and how these are modulated by SNM.

METHODS

A high-resolution fibreoptic colonic manometry catheter, containing 36 sensors spaced at 1-cm intervals, was positioned in patients with faecal incontinence undergoing stage 1 SNM. One hour of pre- and post meal recordings were obtained followed by pre- and post meal recordings with suprasensory SNM. A 700-kcal meal was given. Data were analysed to identify propagating contractions.

RESULTS

Fifteen patients with faecal incontinence were analysed. Patients had an abnormal meal response (fewer retrograde propagating contractions compared to controls; p = 0.027) and failed to show a post meal increase in propagating contractions (mean 17 ± 6/h premeal vs. 22 ± 9/h post meal, p = 0.438). Compared to baseline, SNM significantly increased the number of retrograde propagating contractions in the distal colon (8 ± 3/h premeal vs. 14 ± 3/h premeal with SNM, p = 0.028). Consuming a meal did not further increase the number of propagating contractions beyond the baseline upregulating effect of SNM.

CONCLUSION

The rectosigmoid brake was suppressed in this cohort of patients with faecal incontinence. SNM may exert a therapeutic effect by modulating this rectosigmoid brake.

Gastrocolonic Response

PURPOSE OF REVIEW

The gastrocolonic response (GCR), is a physiologic increase in motor activity of the colon, which usually occurs within minutes following meal ingestion. Over the years several triggers that provoke GCR were recognized including gastric dilation, caloric intake, and fat component of the meal. The response is mediated by the vagal nerve and neurohumoral mechanisms, and it can be modified by several pharmacological factors. Assessment of GCR is part of high-resolution colonic manometry studies, performed in patients with suspected colonic dysmotility. This review highlights the physiologic basis of GCR as well as its clinical and diagnostic features and implementation in variable pathological conditions and clinical practice.

RECENT FINDINGS

GCR has a role in patients with constipation, diabetes, dumping syndrome, bowel hyper and hypomotility and irritable bowel syndrome. Novel sensory triggers for GCR were recently recognized. GCR is a physiological response which is evaluated during colonic manometry studies. Abnormal GCR is a marker of an underlying pathology, which can provide a potential target for treatment.

Bio-impedance method to monitor colon motility response to direct distal colon stimulation in anesthetized pigs

Electrical stimulation has been demonstrated as an alternative approach to alleviate intractable colonic motor disorders, whose effectiveness can be evaluated through colonic motility assessment. Various methods have been proposed to monitor the colonic motility and while each has contributed towards better understanding of colon motility, a significant limitation has been the spatial and temporal low-resolution colon motility data acquisition and analysis. This paper presents the study of employing bio-impedance characterization to monitor colonic motor activity. Direct distal colon stimulation was undertaken in anesthetized pigs to validate the bio-impedance scheme simultaneous with luminal manometry monitoring. The results indicated that the significant decreases of bio-impedance corresponded to strong colonic contraction in response to the electrical stimulation in the distal colon. The magnitude/power of the dominant frequencies of phasic colonic contractions identified at baseline (in the range 2-3 cycles per minute (cpm)) were increased after the stimulation. In addition, positive correlations have been found between bio-impedance and manometry. The proposed bio-impedance-based method can be a viable candidate for monitoring colonic motor pattern with high spatial and temporal resolution. The presented technique can be integrated into a closed-loop therapeutic device in order to optimize its stimulation protocol in real-time.

1907-2020: more than one century of colonic mass movements in humans

Motility of the large bowel may be grossly subdivided in two types of contractile activity: low-amplitude single or cyclic propagated waves and high-amplitude propagated activity. The latter is mainly apt to shift relatively large amounts of colonic contents, and it is related to defecation. The main component of this propagated activity is represented by the radiologically identified mass movements that have a manometric equivalent known as high-amplitude propagated contractions (HAPC). The present article reviews origins and characterization of HAPC in the time course of colonic motility investigations, and correlates it with technological advancements in recent years, putting into perspective the future possible options to better detect and investigate these important physiological events.

Development and feasibility of an ambulatory acquisition system for fiber-optic high-resolution colonic manometry

BACKGROUND

High-resolution colonic manometry is an emerging technique that has provided new insights into the pathophysiology of functional colorectal diseases. Prior studies have been limited by bulky, non-ambulatory acquisition systems, which have prevented mobilization during prolonged recordings.

METHODS

A novel ambulatory acquisition system for fiber-optic high-resolution colonic manometry was developed. Benchtop validation against a standard non-ambulatory system was performed using standardized calibration metrics. Clinical feasibility studies were conducted in three patients undergoing right hemicolectomy.

RESULTS

Pressure profiles obtained from benchtop testing were near-identical using the ambulatory and the non-ambulatory systems. Clinical studies successfully demonstrated ambulatory data capture with patients freely mobilizing postoperatively during continuous recordings of >60 hours. The occurrence (P = .56), amplitude (P = .65), velocity (P = .10), and extent (P = .12) of colonic motor patterns were similar to those obtained in non-ambulatory studies.

CONCLUSIONS

A novel ambulatory system for high-resolution colonic manometry has been developed and validated. This technique will facilitate prolonged ambulatory recordings of colonic motor activity, assisting with investigations into the role of colonic motility in disease states.

First translational consensus on terminology and definitions of colonic motility in animals and humans studied by manometric and other techniques

Alterations in colonic motility are implicated in the pathophysiology of bowel disorders, but high-resolution manometry of human colonic motor function has revealed that our knowledge of normal motor patterns is limited. Furthermore, various terminologies and definitions have been used to describe colonic motor patterns in children, adults and animals. An example is the distinction between the high-amplitude propagating contractions in humans and giant contractions in animals. Harmonized terminology and definitions are required that are applicable to the study of colonic motility performed by basic scientists and clinicians, as well as adult and paediatric gastroenterologists. As clinical studies increasingly require adequate animal models to develop and test new therapies, there is a need for rational use of terminology to describe those motor patterns that are equivalent between animals and humans. This Consensus Statement provides the first harmonized interpretation of commonly used terminology to describe colonic motor function and delineates possible similarities between motor patterns observed in animal models and humans in vitro (ex vivo) and in vivo. The consolidated terminology can be an impetus for new research that will considerably improve our understanding of colonic motor function and will facilitate the development and testing of new therapies for colonic motility disorders.

Spatio-temporal motility MRI analysis of the stomach and colon

BACKGROUND

MRI is increasingly used to objectively assess gastrointestinal motility. However, motility metrics often do not offer insights into the nature of contractile action. This study introduces a systematic method of making spatio-temporal measurements of contractions, based on changes in bowel lumen diameter.

METHODS

Two heterogeneous cohorts of subjects were selected displaying gastric (n = 15) and colonic motility (n = 20) on which to test the spatio-temporal motility MRI (STMM) technique. STMM involved delineating the bowel lumen along with inner and outer bowel wall along a section of the gastrointestinal tract. A series of diameter measurements were made automatically across the central axis of the lumen. Measurements were automatically propagated through the time series using a previously validated algorithm. Contractions were quantitatively summarized with two methods measuring (a) normalized contraction plot (NCP) and (b) combined velocity distance (CVD) both of which can be visualized as spatio-temporal motility maps. Both metrics were correlated against subjective visual scoring systems.

KEY RESULTS

Good correlation was seen between reader scores and both motility metrics (NCP, R = 0.85, P < 0.001, CVD, R = 0.93, R < 0.001) in the gastric data. Good correlation was also seen between the reader scores and the two metrics in the colonic data (NCP, R = 0.82, P < 0.001, CVD, R = 0.78, R < 0.001).

CONCLUSIONS AND INFERENCES

Spatio-temporal motility MRI analysis of the stomach and colon correlates well with reader scores in a range of datasets and provides both a quantitative and qualitative means of assessing contractile activity in the gastrointestinal tract.

Characterization of Simultaneous Pressure Waves as Biomarkers for Colonic Motility Assessed by High-Resolution Colonic Manometry

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.

Colonic motor response to wakening is blunted in slow transit constipation as detected by wireless motility capsule

Background

Chronic constipation may be categorized as normal transit (NTC), slow transit (STC), or outlet obstruction. Colonic wake response is a relative increase in colonic motility upon awakening. Colonic manometry studies have demonstrated attenuated wake response in STC. We sought to evaluate wake response among healthy (H), NTC, and STC patients using wireless motility capsule (WMC).

Methods

A retrospective study of WMC data from a multicenter clinical trial and a tertiary gastroenterology clinic was performed. WMC motility parameters of contraction frequency (Ct) and area under the contraction curve (AUC) were analyzed in 20-min windows 1-h before and after awakening. T-tests compared parameters between H, NTC, and STC. Linear regression analysis was performed to determine if outlet obstruction confounded data. A receiver operating characteristic curve demonstrated optimal Ct cut-offs to define blunted wake response.

Results

A total of 62 H, 53 NTC and 75 STC subjects were analyzed. At 20, 40, and 60 min after awakening, STC subjects had significantly lower mean Ct when compared to H (p < 0.001) and NTC (p < 0.01). Linear regression demonstrated that outlet obstruction was not associated with a decreased wake response (β = 3.94, (CI −3.12–1.00), P = 0.27). Defined at the Ct threshold of 64 at 20-min post-wake, blunted wake response sensitivity was 84% and specificity was 32% for chronic constipation.

Conclusion

Findings of an impaired wake response in subjects with STC and not NTC adds further evidence to neuronal dysfunction as an etiology of STC, and identifies a possible temporal target for pharmacologic intervention.

Prucalopride induces high-amplitude propagating contractions in the colon of patients with chronic constipation: a randomized study

BACKGROUND

This study compared prucalopride, a selective, prokinetic, 5-HT4 receptor agonist, with polyethylene glycol 3350 + electrolytes (PEG3350), an osmotic laxative, on colonic motility parameters, primarily high-amplitude propagating contractions (HAPCs) in patients with chronic constipation.

METHODS

This randomized, cross-over, reader-blinded study was conducted at a single site in the USA. The study was open to men and women aged 18-75 years who met study inclusion criteria. Colonic manometry catheters were inserted the day before investigation. On the investigation days, patients received oral 2 mg prucalopride or 2 × 13.8 g PEG3350 in solution. The primary endpoint was HAPC count (threshold: mean amplitude ≥100 mmHg, propagation ≥20 cm [HAPC1 ]) in the 12 h after treatment administration. Analyses were also conducted at two co-primary thresholds: mean amplitude ≥75 mmHg, propagation ≥20 cm (HAPC2 ); and mean amplitude ≥75 mmHg, propagation ≥10 cm (HAPC3 ). Secondary endpoints included HAPC area under the curve (AUC), contraction force, amplitude, duration, and propagation velocity.

KEY RESULTS

Thirteen women were enrolled, with 12 completing the study. Significantly more HAPC1 (8.7 ± 2.06 vs 2.9 ± 2.06; p = 0.012) and HAPC2 (9.0 ± 2.11 vs 3.3 ± 2.11; p = 0.017) were observed in the 12-h periods with prucalopride than with PEG3350. Prucalopride significantly increased mean propagation distance and velocity (HAPC2 ) and mean AUC, force, and amplitude (HAPC3 ) compared with PEG3350. Adverse events were mild or moderate.

CONCLUSIONS & INFERENCES

Prucalopride was superior to PEG3350 in inducing HAPCs in patients with chronic constipation. ClinicalTrials.gov number NCT01707667.

Colonic migrating motor complexes, high amplitude propagating contractions, neural reflexes and the importance of neuronal and mucosal serotonin

The colonic migrating motor complex (CMMC) is a critical neurally mediated rhythmic propulsive contraction observed in the large intestine of many mammals. It seems to be equivalent to the high amplitude propagating contractions (HAPCs) in humans. This review focuses on the probable neural mechanisms involved in producing the CMMC or HAPC, their likely dependence on mucosal and neuronal serotonin and pacemaker insterstitial cells of Cajal networks and how intrinsic neural reflexes affect them. Discussed is the possibility that myenteric 5-hydroxytryptamine (5-HT) neurons are not only involved in tonic inhibition of the colon, but are also involved in generating the CMMC and modulation of the entire enteric nervous system, including coupling motility to secretion and blood flow. Mucosal 5-HT appears to be important for the initiation and effective propagation of CMMCs, although this mechanism is a longstanding controversy since the 1950s, which we will address. We argue that the slow apparent propagation of the CMMC/HAPC down the colon is unlikely to result from a slowly conducting wave front of neural activity, but more likely because of an interaction between ascending excitatory and descending (serotonergic) inhibitory neural pathways interacting both within the myenteric plexus and at the level of the muscle. That is, CMMC/HAPC propagation appears to be similar to esophageal peristalsis. The suppression of inhibitory (neuronal nitric oxide synthase) motor neurons and mucosal 5-HT release by an upregulation of prostaglandins has important implications in a number of gastrointestinal disorders, especially slow transit constipation.

Quantification of in vivo colonic motor patterns in healthy humans before and after a meal revealed by high-resolution fiber-optic manometry

BACKGROUND

Until recently, investigations of the normal patterns of motility of the healthy human colon have been limited by the resolution of in vivo recording techniques.

METHODS

We have used a new, high-resolution fiber-optic manometry system (72 sensors at 1-cm intervals) to record motor activity from colon in 10 healthy human subjects.

KEY RESULTS

In the fasted colon, on the basis of rate and extent of propagation, four types of propagating motor pattern could be identified: (i) cyclic motor patterns (at 2-6/min); (ii) short single motor patterns; (iii) long single motor patterns; and (iv) occasional retrograde, slow motor patterns. For the most part, the cyclic and short single motor patterns propagated in a retrograde direction. Following a 700 kCal meal, a fifth motor pattern appeared; high-amplitude propagating sequences (HAPS) and there was large increase in retrograde cyclic motor patterns (5.6 ± 5.4/2 h vs 34.7 + 19.8/2 h; p < 0.001). The duration and amplitude of individual pressure events were significantly correlated. Discriminant and multivariate analysis of duration, gradient, and amplitude of the pressure events that made up propagating motor patterns distinguished clearly two types of pressure events: those belonging to HAPS and those belonging to all other propagating motor patterns.

CONCLUSIONS & INFERENCES

This work provides the first comprehensive description of colonic motor patterns recorded by high-resolution manometry and demonstrates an abundance of retrograde propagating motor patterns. The propagating motor patterns appear to be generated by two independent sources, potentially indicating their neurogenic or myogenic origin.

Stimulation of colonic motility by oral PEG electrolyte bowel preparation assessed by MRI: comparison of split vs single dose

BACKGROUND

Most methods of assessing colonic motility are poorly acceptable to patients. Magnetic resonance imaging (MRI) can monitor gastrointestinal motility and fluid distributions. We predicted that a dose of oral polyethylene glycol (PEG) and electrolyte solution would increase ileo-colonic inflow and stimulate colonic motility. We aimed to investigate the colonic response to distension by oral PEG electrolyte in healthy volunteers (HVs) and to evaluate the effect of single 2 L vs split (2 × 1 L) dosing.

METHODS

Twelve HVs received a split dose (1 L the evening before and 1 L on the study day) and another 12 HVs a single dose (2 L on the main study day) of PEG electrolyte. They underwent MRI scans, completed symptom questionnaires, and provided stool samples. Outcomes included small bowel water content, ascending colon motility index, and regional colonic volumes.

KEY RESULTS

Small bowel water content increased fourfold from baseline after ingesting both split (p = 0.0010) and single dose (p = 0.0005). The total colonic volume increase from baseline was smaller for the split dose at 35 ± 8% than for the single dose at 102 ± 27%, p = 0.0332. The ascending colon motility index after treatment was twofold higher for the single dose group (p = 0.0103).

CONCLUSIONS & INFERENCES

Ingestion of 1 and 2 L PEG electrolyte solution caused a rapid increase in the small bowel and colonic volumes and a robust rise in colonic motility. The increase in both volumes and motility was dose dependent. Such a challenge, being well-tolerated, could be a useful way of assessing colonic motility in future studies.

How to perform and assess colonic manometry and barostat study in chronic constipation

Management of chronic constipation with refractory symptoms can be challenging. Although new drugs and behavioral treatments have improved outcome, when they fail, there is little guidance on what to do next. At this juncture, typically most doctors may refer for surgical intervention although total colectomy is associated with morbidity including complications such as recurrent bacterial overgrowth. Recently, colonic manometry with sensory/tone/compliance assessment with a barostat study has been shown to be useful. Technical challenges aside, adequate preparation, and appropriate equipment and knowledge of colonic physiology are keys for a successful procedure. The test itself appears to be safe with little complications. Currently, colonic manometry is usually performed with a 6–8 solid state or water-perfused sensor probe, although high-resolution fiber-optic colonic manometry with better spatiotemporal resolutions may become available in the near future. For a test that has evolved over 3 decades, normal physiology and abnormal findings for common phenotypes of chronic constipation, especially slow transit constipation, have been well characterized only recently largely through the advent of prolonged 24-hour ambulatory colonic manometry studies. Even though the test has been largely restricted to specialized laboratories at the moment, emerging new technologies and indications may facilitate its wider use in the near future.

Low-resolution colonic manometry leads to a gross misinterpretation of the frequency and polarity of propagating sequences: Initial results from fiber-optic high-resolution manometry studies

BACKGROUND

High-resolution manometry catheters are now being used to record colonic motility. The aim of this study was to determine the influence of pressure sensor spacing on our ability to identify colonic propagating sequences (PS).

METHODS

Fiber-optic catheters containing 72-90 sensors spaced at 1 cm intervals were placed colonoscopically to the cecum in 11 patients with proven slow transit constipation, 11 patients with neurogenic fecal incontinence and nine healthy subjects. A 2 h section of trace from each subject was analyzed. Using the 1 cm spaced data as the gold standard, each data set was then sub-sampled, by dropping channels from the data set to simulate sensor spacing of 10, 7, 5, 3, and 2 cm. In blinded fashion, antegrade and retrograde PS were quantified at each test sensor spacing. The data were compared to the PSs identified in the corresponding gold standard data set.

KEY RESULTS

In all subject groups as sensor spacing increased; (i) the frequency of identified antegrade and retrograde PSs decreased (P < 0.0001); (ii) the ratio of antegrade to retrograde PSs increased (P < 0.0001); and (iii) the number of incorrectly labeled PSs increased (P < 0.003).

CONCLUSIONS & INFERENCES

Doubling the sensor spacing from 1 to 2 cm nearly halves the number of PSs detected. Tripling the sensor spacing from 1 to 3 cm resulted in a 30% chance of incorrectly labeling PSs. Closely spaced pressure recording sites (<2 cm) are mandatory to avoid gross misrepresentation of the frequency, morphology, and directionality of colonic propagating sequences.

The effect of sacral nerve stimulation on distal colonic motility in patients with faecal incontinence

BACKGROUND

Sacral nerve stimulation (SNS) is an effective treatment for neurogenic faecal incontinence (FI). However, the clinical improvement that patients experience cannot be explained adequately by changes in anorectal function. The aim of this study was to examine the effect of SNS on colonic propagating sequences (PSs) in patients with FI in whom urgency and incontinence was the predominant symptom.

METHODS

In patients with FI a high-resolution fibre-optic manometry catheter, containing 90 sensors spaced at 1-cm intervals, was positioned colonoscopically and clipped to the caecum. A unipolar or quadripolar tined electrode was implanted into the S3 sacral nerve foramen. Colonic manometry was evaluated in a double-blind randomized crossover trial, using true suprasensory stimulation or sham stimulation. Each stimulation period, lasting 2 h, was preceded by a 2-h basal manometric recording.

RESULTS

All 11 patients studied showed a colonic response to SNS. In ten patients there was a significant increase in the frequency of retrograde PSs throughout the colon during true stimulation compared with sham stimulation (P = 0·014). In one outlier, with baseline retrograde PS frequency nine times that of the nearest patient, a reduction in retrograde PS frequency was recorded. Compared with sham stimulation, SNS had no effect on the frequency of antegrade PSs or high-amplitude PSs.

CONCLUSION

SNS modulates colonic motility in patients with faecal urge incontinence. These data suggest that SNS may improve continence and urgency through alteration of colonic motility, particularly by increasing retrograde PSs in the left colon.

Classification of normal and abnormal colonic motility based on cross-correlations of pancolonic manometry data

BACKGROUND

Manual analysis of data acquired from manometric studies of colonic motility is laborious, subject to laboratory bias and not specific enough to differentiate all patients from control subjects. Utilizing a cross-correlation technique, we have developed an automated analysis technique that can reliably differentiate the motor patterns of patients with slow transit constipation (STC) from those recorded in healthy controls.

METHODS

Pancolonic manometric data were recorded from 17 patients with STC and 14 healthy controls. The automated analysis involved calculation of an indicator value derived from cross-correlations calculated between adjacent recording sites in a manometric trace. The automated technique was conducted on blinded real data sets (observed) and then to determine the likelihood of positive indicator values occurring by chance, the channel number within each individual data set were randomized (expected) and reanalyzed.

KEY RESULTS

In controls, the observed indicator value (3.2 ± 1.4) was significantly greater than that predicted by chance (0.8 ± 1.5; P < 0.0001). In patients, the observed indicator value (-2.7 ± 1.8) did not differ from that predicted by chance (-3.5 ± 1.6; P = 0.1). The indicator value for controls differed significantly from that of patients (P < 0.0001), with all individual patients falling outside of the range of indicator values for controls.

CONCLUSIONS & INFERENCES

Automated analysis of colonic manometry data using cross-correlation separated all patients from controls. This automated technique indicates that the contractile motor patterns in STC patients differ from those recorded in healthy controls. The analytical technique may represent a means for defining subtypes of constipation.

The effect of luminal content and rate of occlusion on the interpretation of colonic manometry

BACKGROUND

Manometry is commonly used for diagnosis of esophageal and anorectal motility disorders. In the colon, manometry is a useful tool, but clinical application remains uncertain. This uncertainty is partly based on the belief that manometry cannot reliably detect non-occluding colonic contractions and, therefore, cannot identify reliable markers of dysmotility. This study tests the ability of manometry to record pressure signals in response to non-lumen-occluding changes in diameter, at different rates of wall movement and with content of different viscosities.

METHODS

A numerical model was built to investigate pressure changes caused by localized, non-lumen-occluding reductions in diameter, similar to those caused by contraction of the gut wall. A mechanical model, consisting of a sealed pressure vessel which could produce localized reductions in luminal diameter, was used to validate the model using luminal segments formed from; (i) natural latex; and (ii) sections of rabbit proximal colon. Fluids with viscosities ranging from 1 to 6800 mPa s(-1) and luminal contraction rates over the range 5-20 mmHg s(-1) were studied.

KEY RESULTS

Manometry recorded non-occluding reductions in diameter, provided that they occurred with sufficiently viscous content. The measured signal was linearly dependent on the rate of reduction in luminal diameter and also increased with increasing viscosity of content (R(2) = 0.62 and 0.96 for 880 and 1760 mPa s(-1), respectively).

CONCLUSIONS & INFERENCES

Manometry reliably registers non-occluding contractions in the presence of viscous content, and is therefore a viable tool for measuring colonic motility. Interpretation of colonic manometric data, and definitions based on manometric results, must consider the viscosity of luminal content.

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.

Temporal relationships between wall motion, intraluminal pressure, and flow in the isolated rabbit small intestine

Intraluminal manometry is a tool commonly used to record motility in the human digestive tract. The recorded signal results from a combination of factors, including the hydrodynamic pressure transmitted through the intestinal contents due to contraction of the gut wall and the force of the gut wall acting on the sensors in regions of a luminal occlusion. However, the actual relationships between small bowel wall contraction, the measured intraluminal pressure, and the resultant flow have not been directly addressed. Video recording and high-resolution fiber-optic manometry were used to create spatiotemporal video maps of diameter and intraluminal pressure from isolated segments of rabbit small intestine. In the unstimulated gut, longitudinal muscle contractions were the only detectable motor pattern; circular muscle contractions were elicited by distension or erythromycin (1 μM). Longitudinal muscle contractions were not lumen-occlusive, although they caused measurable low-amplitude changes in pressure. Localized nonpropagating circular muscle contractions caused small localized, nonpropagating peaks of intraluminal pressure. Propagating contractions of circular muscle evoked larger, propagating pressure changes that were associated with outflow. Propagating circular muscle contractions often caused dilation of aboral receiving segments, corresponding to "common cavities"; these were propulsive, despite their low intraluminal pressure. The highest-amplitude pressure events were caused by lumen-occlusive circular muscle contractions that squeezed directly against the catheter. These data allow us to define the complex relationships between wall motion, intraluminal pressure, and flow. A strong correlation between circular and longitudinal muscle contraction and intraluminal pressure was demonstrated. Common-cavity pressure events, caused by propulsion of content by circular muscle contractions into a receptive segment, were often of low amplitude but were highly propulsive. Studies of wall motion in isolated preparations, combined with manometry, can assist in interpretation of pressure recordings in vivo.

Pancolonic spatiotemporal mapping reveals regional deficiencies in, and disorganization of colonic propagating pressure waves in severe constipation

BACKGROUND

The morphology, motor responses and spatiotemporal organization among colonic propagating sequences (PS) have never been defined throughout the entire colon of patients with slow transit constipation (STC). Utilizing the technique of spatiotemporal mapping, we aimed to demonstrate 'manometric signatures' that may serve as biomarkers of the disorder.

METHODS

In 14 female patients with scintigraphically confirmed STC, and eight healthy female controls, a silicone catheter with 16 recording sites spanning the colon at 7.5 cm intervals was positioned colonoscopically with the tip clipped to the cecum. Intraluminal pressures were recorded for 24 h.

KEY RESULTS

Pan-colonic, 24 h, spatiotemporal mapping identified for the first time in STC patients: a marked paucity of propagating pressure waves in the midcolon (P = 0.01), as a consequence of a significant (P < 0.0001) decrease in extent of propagation of PS originating in the proximal colon; an increase in frequency of retrograde PS in the proximal colon; a significant reduction in the spatiotemporal organization among PS (P < 0.001); absence of the normal nocturnal suppression of PS.

CONCLUSIONS & INFERENCES

Pancolonic, 24 h, spatiotemporal pressure mapping readily identifies characteristic disorganization among consecutive PS, regions of diminished activity and absent or deficient fundamental motor patterns and responses to physiological stimuli. These features are all likely to be important in the pathophysiology of slow transit constipation.

Paediatric and adult colonic manometry: A tool to help unravel the pathophysiology of constipation

Colonic motility subserves large bowel functions, including absorption, storage, propulsion and defaecation. Colonic motor dysfunction remains the leading hypothesis to explain symptom generation in chronic constipation, a heterogeneous condition which is extremely prevalent in the general population, and has huge socioeconomic impact and individual suffering. Physiological testing plays a crucial role in patient management, as it is now accepted that symptom-based assessment, although important, is unsatisfactory as the sole means of directing therapy. Colonic manometry provides a direct method for studying motor activities of the large bowel, and this review provides a contemporary understanding of how this technique has enhanced our knowledge of normal colonic motor physiology, as well as helping to elucidate pathophysiological mechanisms underlying constipation. Methodological approaches, including available catheter types, placement technique and recording protocols, are covered, along with a detailed description of recorded colonic motor activities. This review also critically examines the role of colonic manometry in current clinical practice, and how manometric assessment may aid diagnosis, classification and guide therapeutic intervention in the constipated individual. Most importantly, this review considers both adult and paediatric patients. Limitations of the procedure and a look to the future are also addressed.