Received: 22 April 2021 | Accepted: 17 July 2021 DOI: 10.1111/nmo.14240 ORIGINAL ARTICLE Propagation patterns of jejunal motor activity measured by high-­resolution water-­perfused manometry Luis Gerardo Alcala-­Gonzalez1,2 | Carolina Malagelada1,2 | Carmen Galan1,2 | Adoracion Nieto1,2 | Anna Accarino1,2 | Fernando Azpiroz1,2 1 Digestive System Research Unit, University Hospital Vall d'Hebron Abstract Barcelona, Centro de Investigación Background: The manometric diagnosis of severe intestinal dysmotility is performed Biomédica en Red de Enfermedades Hepáticas y Digestivas (Ciberehd), Spain at most institutions using catheters with 2–­8 sensors 5–­10 cm apart. The recent appli- 2 Department of Medicine, Universitat cation of high-­resolution manometry catheters with closely spaced sensors to other Autònoma de Barcelona, Barcelona, Spain gut segments has been highly successful. The objective of the present study was to Correspondence determine the feasibility of a jejunal high-­resolution manometry method and to carry Carolina Malagelada, Digestive System Research Unit, Hospital General Vall out a descriptive analysis of normal jejunal motor function. d'Hebron, 08035-­Barcelona, Spain. Methods: A 36-­channel high-­resolution water-­perfused manometry catheter (MMS-­ Email: cmalagelada@vhebron.net Laborie, Enschede, The Netherlands) was orally placed in the jejunum of 18 healthy Funding information subjects (10 men, eight women; 21–­38 age range). Intestinal motility was recorded Instituto de Salud Carlos III (PI17/01794, CM20/00182), Spanish Ministry of during 5 h, 3 during fasting, and 2 after a 450 kcal solid-­liquid meal. Analysis of motil- Economy and Competitiveness (SAF ity patterns was supported by computerized tools. 2016-­76648-­R); Societat Catalana de Digestologia (beca Iniciació recerca) Key Results: All healthy subjects except one showed at least one complete migrating motor complex during the 3 h fasting period. Phase III activity lasted 5 ± 1 min and mi- grated aborally at a velocity of 7 ± 3 cm/min. High-­resolution spatial analysis showed that during phase III each individual contraction propagated rapidly (75 ± 37 cm/min) over a 32 ± 10 cm segment of the jejunum. During phase II, most contractile activity corresponded to propagated contractile events which increased in frequency from early to late phase II (0.5 ± 0.9 vs 2.5 ± 1.3 events/10 min, respectively; p < 0.001). After meal ingestion, non-­propagated activity increased, whereas propagated events were less frequent than during late phase II. Conclusions & Inferences: Jejunal motility analysis with high-­resolution manometry identifies propagated contractile patterns which are not apparent with conventional manometric catheters. KEYWORDS high-­resolution intestinal manometry, intestinal motility, postprandial motility, propagated contractions Alcala-­G onzalez and Malagelada share first authorship. This is an open access article under the terms of the Creat​ive Commo​ns Attri​butio​n-­NonCo​mmerc​ial-­NoDerivs License, which permits use and distribution in any medium, provided the original work is properly cited, the use is non-­commercial and no modifications or adaptations are made. © 2021 The Authors. Neurogastroenterology & Motility published by John Wiley & Sons Ltd. Neurogastroenterology & Motility. 2021;33:e14240.  wileyonlinelibrary.com/journal/nmo | 1 of 8 https://doi.org/10.1111/nmo.14240 2 of 8 | ALCALA-­GONZALEZ et al. 1 | I NTRO D U C TI O N Key points Intestinal manometry is the current gold standard test for the diag- • High-­resolution manometry provides a new insight into nosis of intestinal motility disorders, but still relies on the methodol- the propagation patterns of jejunal contractile events. ogy developed 40 years ago using manometric catheters with few • The different phases of the fasting and postprandial pe- (2–­8), widely spaced (5–­10 cm) recording sites.1,2 riods are characterized by a specific balance of propa- High-­resolution manometry involves multiple and closely spaced gated and non-­propagated contractile activity. recording sites covering a relatively long segment of the gut.3 This • High-­resolution manometry enhances the evaluation methodology is particularly useful for the analysis of propagation of jejunal motility, but its clinical value remains to be patterns of motor activity.4 Indeed, high-­resolution manometry has established. become the gold standard for the evaluation of esophageal motor function.5 Interesting data have been produced by exploratory stud- ies in the proximal intestine,6–­9 but unfortunately, the application of high-­resolution manometry for the evaluation of jejunal motility has 2.2 | Participants been limited by the lack of commercially available high-­resolution catheters long enough to cover the jejunum. Motor activity of the Eighteen healthy, non-­obese subjects without a history of gastro- digestive tract can be recorded using solid-­state or water-­perfused intestinal symptoms were recruited by public advertising. Exclusion systems. Solid-­state catheters incorporate intraluminal pressure sen- criteria were chronic health conditions, use of medications (except sors; these catheters may experience shifts in basal pressure during sporadic use of NSAIDs and antihistaminics), alcohol abuse, and prolonged studies, as required for evaluation of jejunal activity, are use of recreational drugs. Absence of current digestive symptoms relatively fragile considering the sharp bends of the small intestine, was verified using a standard abdominal symptom questionnaire and furthermore, are expensive. With multilumen water-­perfused (no symptom >2 on a 0–­10 scale). Psychological and eating disor- catheters, intraluminal pressures are transmitted from intraluminal ders were excluded using the following tests: Hospital Anxiety and side holes via water-­filled lines to external pressure transducers; Depression scale, Dutch Eating Behavior Questionnaire (Emotional perfusion catheters are more robust and considerably less expensive eating, External eating, Restrained eating), and Physical anhedonia than solid state. The accuracy of the recordings depends on the bal- scale. ance between the compliance of the lines and the perfusion rate. We used a water-­perfused system with a perfusion rate that provided accurate detection of pressure waves (phasic jejunal contractions) 2.3 | Manometric equipment and a total water load manageable for the duration of the studies. The aims of the present study were as follows: (a) to determine A customized 36-­channel perfusion high-­resolution catheter was the feasibility of a high-­resolution manometry method to evaluate designed to measure jejunal motility (Mui Scientific). The catheter the activity of the jejunum; and (b) to carry out a descriptive anal- was made of silicone and had an external diameter of 4.7 mm, 36 ysis of normal jejunal motor function with particular focus on two lumens of 0.4 mm for pressure recording and one central lumen of aspects: the organization of fasting phase III activity, and the dif- 1.5 mm for guidewire placement. The first two perfusion side holes ferences between fasting phase II and the postprandial pattern. To (recording sites) were located 58 and 48 cm from the tip of the these aims, we designed a high-­resolution manometry technology to catheter to register antral and duodenal contractions; the follow- measure jejunal motility by means of a 36-­channel perfusion cathe- ing 34 side holes, starting at 38 cm from the tip, were separated by ter with 1-­cm spaced side holes. 1 cm (4–­38 cm from the tip) to measure jejunal contractile activity. Radio-­opaque markers were located before the first and third most proximal side holes to facilitate fluoroscopic localization. The tip of 2 | M ATE R I A L S A N D M E TH O DS the catheter incorporated a small weight (three 5 × 2 mm tungsten pellets) to facilitate progression of the catheter through the stom- 2.1 | Study design ach. The catheter was connected to a low-­compliance manometric system (Solar GI HRM manometry system, MMS-­L aborie), and each Unicentric, prospective, pilot study in healthy subjects recording the channel was perfused with distilled water. Antral and duodenal re- jejunal motor activity during fasting and after a standard meal by cording sites served for final positioning of the catheter after intuba- high-­resolution manometry. The study protocol was approved by tion under fluoroscopic control. the Ethics Committee of the University Hospital Vall d'Hebron, and The standard perfusion rate of the equipment is 0.15 ml/min all participants gave their written informed consent before enroll- which implicates a total water load of 1620 ml during the study. To ment. The study protocol was registered with the Clini​calTr​ials.gov attempt a reduction of the water load, a series of preliminary stud- (ID: NCT04764019). All co-­authors had access to the study data and ies were performed correlating the perfusion rate and the pressure reviewed and approved the final manuscript. rise in response to occlusion of the side holes. Perfusion rates of ALCALA-­GONZALEZ et al. | 3 of 8 0.075, 0.1125, and 0.15 ml/min were tested; with each perfusion AUC was automatically calculated by the system integrating all pres- rate, three series of five consecutive 20-­ s occlusions were per- sure values above the 10 th percentile cut-­off level every min and ex- formed. Compared to the 0.15 ml/min perfusion rate, the 0.075 and pressed as mmHg*min; hence, the area under the curve is a motility 0.1125 ml/min perfusion rates reduced pressures at 20-­s occlusion index accounting for the number and amplitude of contractions. by 49 ± 3 and 24 ± 1%, respectively; the same relation was observed Propagated events were visually identified when the pressure at different occlusion times. Since lower flow rates impaired pres- contours of individual contractions overlapped between at least 10 sure recordings, we finally established 0.15 ml/min flow rate per consecutive sensors. Their velocity of propagation was measured as channel to be used. the length of propagation (distance between the first and last sensor detecting each propagated event) divided by the duration of prop- agation (time interval between the onset of the contraction at the 2.4 | Manometry procedure first and last sensor). Non-­propagated or shortly propagated irreg- ular activity was measured by computerized analysis in the interim Studies were conducted at the Vall d'Hebron GI Motility Unit in the between propagated events during early phase II, late phase II, early morning, after an overnight fast. The manometric system was first cali- postprandial, and late postprandial periods. brated by connecting the catheter to the perfusion pump and baseline values were adjusted. Then, the catheter, with a metallic guidewire in the central lumen to facilitate localization, was introduced trans- 2.6 | Statistical analysis nasally and placed into the small bowel under fluoroscopic control. Subjects were then conducted to a quiet room where the manometric Statistical analysis was performed with GraphPad Prism 9. Mean catheter was connected to the recording system. Fasting intestinal values (±SD) or median and 5th–­95th percentile of the parameters motor activity was measured for 3 h in supine position and then a measured were calculated. Normality of data distribution was evalu- 450 kcal solid-­liquid test meal was ingested in bed with the trunk at ated by the Kolmogorov–­Smirnov test. Comparisons of parametric, an angle of 45° to the horizontal. After meal ingestion, the study was normally distributed data were made by Student's t test, paired continued in supine position for a 2 -­h postprandial recording period. tests for intragroup comparisons, and unpaired tests for inter- group comparisons; otherwise, the Wilcoxon signed-­rank test was used for paired data within groups, and the Mann–­Whitney U test 2.5 | Analysis of manometric recordings for unpaired data between groups. Continuous variables were cor- related using Pearson's R. One-­way ANOVA was used for multiple Studies were analyzed both visually and using the MMS Database comparisons; when the ANOVA was significant, post hoc compari- Software v9.5h (MMS-­L aborie) by two physicians (CM and LA). sons were performed applying the Bonferroni multiple comparison Phases of the MMC were detected visually following standard correction procedure. Differences were considered significant at a criteria as follows: Phase III activity defined as regular contractile p value <0.05. activity of more than 10 mmHg at a frequency of 10–­12 contrac- tions per minute during at least 2 min; Phase I activity, defined as the period of motor quiescence after phase III and followed by phase II; 3 | R E S U LT S phase II was considered to begin when the first propagated contrac- tion of more than 10 mmHg amplitude was detected after phase I, 3.1 | Demographics and study flow and to end when phase III activity began. Baseline pressure was automatically determined every minute of Eight women and 10 men, 21–­38 years range with body mass index recording using the 10th percentile level. Contractile events were between 18.5 and 30 kg/m2 participated in the study. Jejunal intuba- predefined as an increase of pressure exceeding baseline pressure by tion was achieved in all participants in 86 ± 28 min. All participants more than 10 mmHg, lasting more than 2 s and <10 s. Computerized tolerated the procedure, completed the study, and were included for analysis was used to measure the number, frequency, and amplitude analysis. Micturition episodes occurred 1–­3 times per study (mean of phasic pressure waves (contractions) in fasting and fed periods. 1.8 ± 0.9). Artifacts, defined as simultaneous pressure rises occurring at all re- cording sites with similar amplitude and identical duration, were au- tomatically excluded. Micturition episodes were identified during the 3.2 | Fasting activity recordings and also excluded from the measurements. Parameters in 10-­min periods in the early and late phase II (just after phase I In eight subjects two or more phase III fronts were observed, and and before phase III, respectively) and early and late postprandial in them, total duration of the MMC was 89 ± 38 min (range 44–­ period (beginning and end of postprandial recording, respectively) 155 min), including a phase of quiescence (phase I), a phase of in- were measured. In each channel, the area under the curve (AUC) termittent, irregular activity (phase II) and a phase of continuous, was measured in the fasting and postprandial recording periods. The rhythmic activity (phase III). 4 of 8 | ALCALA-­GONZALEZ et al. (A) (B) (C) phase III contraction activated 2.8±1.2 cm segment 32±10 cm quiescence 1.5±0.8 cm F I G U R E 1 Jejunal phase III activity. (A) Example of high-­resolution manometry (7 min recording) showing phase III activity. (B) Expanded tracing. (C) Schematic representation of jejunal segment activated during phase III. Note, migration of phase III activity front at 7 ± 3 cm/min (yellow arrow) and propagation of individual contractions at 75 ± 37 cm/min (red arrow) from top to bottom of the entire activated segment 3.2.1 | Phase III velocity (cm/min) × duration (min), was 32 ± 10 cm (range 11–­37 cm; Figure 1). In 12 phases III, the length of the activated segment ex- Phase III activity fronts were observed 1–­3 times per subject in ceeded the 33 cm recording span; in the other 13 phases III, the ac- all subjects but one (total 25 phase III fronts in 17 subjects; mean tivated segment was entirely visible and in them, the length of the 1.5 ± 0.7 fronts/subject). Based on the antral recording site, it was segment directly measured by the number of recording sites acti- detected that 75% of the phase III activity fronts originated in the vated, exhibited a close correlation with the length calculated by the antrum. The duration of phase III activity (5 ± 1 min; range 2–­8 min) mathematical function (R = 0.856; p < 0.001). was longer at the distal recording sites (mean of 5.2 ± 1.5 min Jejunal phase III activity was characterized by continuous phasic over the 10 proximal sites vs 5.6 ± 1.6 min over the 10 distal sites; activity at a rhythm of 11 ± 1 contractions/min (Table 1), and the p = 0.029). Phase III fronts migrated from the most proximal record- frequency was similar at the proximal and distal recording sites. At ing sites in caudad direction at a mean velocity of 6.6 ± 2.8 cm/min each recording site, the individual contractions had an average du- and the velocity decreased distally (mean of 7.9 ± 3.7 min over the 10 ration of 3.4 ± 0.5 s and were simultaneously recorded over several proximal sites, and 6.0 ± 3.0 min over the 10 distal sites; p = 0.008). contiguous recording sites covering an extension of 2.8 ± 1.2 cm of The length of the jejunal segment simultaneously generating phase intestine. Contractions were separated by a gap of 2.1 ± 0.3 s and III activity, calculated by the function: length (cm) = migration the length of the quiescent jejunal sections between contractions ALCALA-­GONZALEZ et al. | 5 of 8 TA B L E 1 Jejunal motility normal range values in the fasting and Most contractile activity during phase II corresponded to prop- postprandial periods agated contractile events which increased in frequency from early 5th–­95th to late phase II (0.5 ± 0.9 vs 2.5 ± 1.3 events/10 min, respectively; Mean ± SD percentile p < 0.001). Most events (79%) initiated at the proximal recording Phase I sites and propagated at 80 ± 33 cm/min throughout the 34 jejunal Frequency, contractions/min 0.4 ± 0.1 0.2–­0.6 recording sites, the rest originated at different levels and migrated Contraction amplitude, mmHg 14.5 ± 3.4 12.0–­18.9 over 22 ± 5 cm (Figure 2). Retrograde propagation was exceptional AUC, mmHg*min 94 ± 5 67–­123 (2 ± 4% of events per subject). The number of contractions in these Phase II propagated events ranged between 1 and 5, similarly in early and Early phase II late phase II (p = 0.176). Single-­contraction events (34%) propagated faster than multiple contraction events (106 ± 32 vs 68 ± 25 cm/ Frequency, contractions/min 0.9 ± 0.4 0.3–­1.8 min, respectively; p < 0.001). The proportion of single vs multiple Contraction amplitude, mmHg 14.1 ± 6.8 5.7–­23.2 contraction events and their velocity of propagation did not change AUC, mmHg*min 121 ± 43 83–­197 from early to late the phase II. No rhythm in the sequence of propa- Late phase II gated events was detected. Frequency, contractions/min 2.1 ± 0.5 1.3–­3.0 In-­between these propagated events, contractile activity was Contraction amplitude, mmHg 20.7 ± 3.2 16.2–­26.4 scarce and corresponded to phasic, low-­amplitude, non-­propagated, AUC, mmHg*min 178 ± 38 129–­243 or shortly propagated contractions (Figure 3); to note, the number Phase III of contractions in these interim periods corresponded to a relatively Frequency, contractions/min 11.0 ± 0.8 10.2–­12.0 small proportion (26 ± 13%) of the total contractions during phase II, Contraction amplitude, mmHg 24.0 ± 3.6 17.3–­29.3 including propagated events. AUC, mmHg*min 548 ± 101 405–­733 Postprandial period Early postprandial 3.2.3 | Phase I Frequency, contractions/min 3.9 ± 1.5 2.1–­7.9 Phase I lasted 12 ± 5 min (range 5–­21 min) and was characterized by Contraction amplitude, mmHg 22.4 ± 2.8 18.2–­29.3 practically absent contractile activity (0.4 ± 0.1 contractions/min; AUC, mmHg*min 270 ± 105 182–­4 49 Table 1). Late postprandial Frequency, contractions/min 3.4 ± 1.1 1.8–­5.9 Contraction amplitude, mmHg 20.7 ± 3.0 16.8–­27.2 3.3 | Postprandial activity AUC, mmHg*min 233 ± 75 165–­374 After meal ingestion, intestinal contractility increased and remained stable in frequency and amplitude throughout the 2-­h postpran- was 1.5 ± 0.8 cm. Hence, the area of jejunum activated during phase dial recording period (AUC 270 ± 105 mmHg*min in the early vs III (32 ± 10 cm), generated 7.8 ± 3.0 contracted sections of intes- 233 ± 75 in the late postprandial period; p = 0.094). The AUC of tine of 2.8 cm separated by corresponding 1.5 cm sections of non-­ the postprandial period was consistently higher than during fasting contracted intestine (Figure 1). High-­resolution analysis also showed phase II (p < 0.001 vs both early and late phase II; Table 1). that the individual contractions conforming phase III propagated The increase in contractile activity was due to an increase in non-­ over the entire segment of activated intestine (from top to bottom), propagated or shortly propagated irregular activity which was more traveling rapidly at 75 ± 37 cm/min. The propagation velocity of the intense than during phase II (3.1 ± 1.6 vs 1.1 ± 0.4 contractions/min; individual contractions correlated with the migration velocity of the p < 0.001; Figure 2). phase III activity front, that is, when the phase III migrated faster, By contrast, propagated events were less frequent than during late the propagation velocity of the individual contractions was quicker phase II (Figure 3). The proportion of single-­contraction propagated (R = 0.76, p < 0.001). events was reduced compared to phase II (16% vs 34%; p = 0.001) and remained stable throughout the postprandial period. No rhythm in the sequence of these propagated events was detected. 3.2.2 | Phase II The mean duration of phase II was 72 ± 36 min (31–­137 min range). 3.4 | Effect of sex and body weight Contractile activity was irregular, but, a consistent increase over time from early to late phase II was observed in all subjects (AUC No significant differences were found when comparing motility pa- 121 ± 43 vs 178 ± 38 mmHg*min, respectively; p < 0.001; Table 1). rameters between men and women, except the velocity of phase III 6 of 8 | ALCALA-­GONZALEZ et al. (A) Fasng phase II (B) Postprandial F I G U R E 2 Fasting late phase II and postprandial high-­resolution manometry recordings (10 min) in the same subject. Note, different contribution of propagated and non-­propagated activity with increased non-­propagated activity and reduced propagated events in the postprandial period as compared to fasting phase II migration, which was slower in women (5.6 ± 1.8 vs 8.9 ± 3.6 cm/ The muscle cells within the intestinal wall generate continuous min, p = 0.017). No correlations between body mass index and the rhythmic oscillations (8–­12 cycles/min) of their membrane poten- motility parameters measured were detected. tial called slow waves. When membrane depolarization of the slow wave overcomes a certain threshold, spiking activity triggers pha- sic contractions of the smooth muscle. Intestinal motor function 4 | DISCUSSION is orchestrated by the interstitial cells of Cajal, also called pace- maker cells, which are electrically coupled to the smooth muscle Our study shows that high-­resolution manometry identifies two dis- cells through gap junctions forming an extensive electrical syncy- tinct motor components in the jejunum: non-­propagated and propa- tium that controls the propagation of contractions.10,11 Our data gated activity. Two aspects should be highlighted in this regard: the show that during phase III a relatively long segment of jejunum organization of fasting phase III fronts, and the striking differences becomes activated; the rhythm, propagation length, and velocity between fasting phase II activity and the postprandial pattern. of the individual contractions during phase III indicate that every ALCALA-­GONZALEZ et al. | 7 of 8 6 propagated events / 10 min preliminary studies, we determined the perfusion rate to be fasting phase II postprandial used, but still the system damps the recording of pressure peaks. Comparisons with conventional low-­ compliance or solid-­ s tate equipments can be figured out based on phase III activity, which is decreased by approximately 2–­5 mmHg by our system. 21–­23 During the 5 h recording, a relatively high water load flows from the per- fused channels into the intestine, calling for bladder emptying during the study. The span covered by the catheter (33 cm) was too 0 short to measure the length of the jejunal segment simultaneously 0 7 generating phase III: 50% of phases III exceeded 33 cm and a for- non-propagated activity, contractions / min mula had to be used to estimate the phase III span. Furthermore, F I G U R E 3 Individual data correlating propagated events and the acquisition of multiple data requires automated analysis. With non-­propagated activity. Note, discrimination between fasting late the current tools, we focused on relatively long-­distance propa- phase II and postprandial activity by high-­resolution manometry gated activity, but the analytical paradigms can be further devel- oped and upgraded for a more precise definition of non-­propagated slow wave reaches the depolarization threshold and generates and shortly propagated activity. propagated contractions running from top to bottom of the acti- The relevance of high-­ resolution manometry for the clinical vated segment. evaluation of small bowel motor function in patients with suspected In contrast to the uniformity of propagated activity during phase dysmotility remains to be established, but the sensitivity of the tech- III, high-­resolution manometry identified during phase II continu- nique in the detection of propagation patterns of contractile activity ous non-­propagated activity with interspersed propagated events. may prove valuable for diagnostic purposes. Propagated events were characterized by fronts of 1–­5 powerful contractions rapidly propagating over long segments of the jeju- AC K N OW L E D G E M E N T S num, and accounted for the major part of the activity, while non-­ This work was supported by the Instituto de Salud Carlos III and propagated activity was relatively scarce and weak. High-­resolution co-­f inanced by the European Union (FEDER/FSE) [PI17/01794]; manometry after meal ingestion identified a distinctly different Spanish Ministry of Economy and Competitiveness (Dirección postprandial motor pattern, in which non-­propagated (or shortly General de Investigación Científica y Técnica) [SAF 2016-­76648-­R]; propagated) contractile activity became more prominent, with Ciberehd is funded by the Instituto de Salud Carlos III. LA was more frequent and stronger contractions, while propagated events supported by scholarships from the Instituto de Salud Carlos III decreased. (CM20/00182) and the Societat Catalana de Digestologia (beca Classical studies in dogs correlating intestinal motor patterns Iniciació recerca). with flow of contents help to interpret our results.12–­14 Indeed, flow of contents was maximal during fasting phase III, with peristaltic C O N FL I C T O F I N T E R E S T contractions squeezing the activated segment of jejunum, but still No conflicts of interest. quite active during phase II, supporting the concept of the house- keeper role of fasting activity, which is concordant with the predom- ORCID inant propagated activity detected by our study during fasting.15,16 Luis Gerardo Alcala-­Gonzalez https://orcid. Conceivably, the prominent non-­propagated or shortly propagated org/0000-0003-3247-1539 activity in the postprandial period is related to mixing and stirring of Carolina Malagelada https://orcid.org/0000-0001-7097-1492 contents, while sparse propagated events contributed to spreading Fernando Azpiroz https://orcid.org/0000-0002-7327-960X of chime recruiting more distal areas of the intestine in the digestive process.17 REFERENCES Our study shows that small bowel high-­resolution manometry is 1. Stanghellini V, Camilleri M, Malagelada JR. Chronic idiopathic feasible. The superiority of multiple, closely spaced sensors in the intestinal pseudo-­ obstruction: clinical and intestinal manomet- ric findings. Gut. 1987;28(1):5–­12. doi:https://doi.org/10.1136/ evaluation of propagated activity has been previously described gut.28.1.5 both in the small bowel and colonic studies.18–­20 The catheter de- 2. Summers RW, Anuras S, Green J. 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