Intraluminal micromanometry: an evaluation of the dynamic performance of micro-extrusions and sleeve sensors

Utilizing intrabolus pressure and esophagogastric junction pressure to predict transit in patients with Dysphagia

Background/Aims

High-resolution manometry (HRM), with a greatly increased number of recording sites and decreased spacing between sites, allows evaluation of the dynamic simultaneous relationship between intrabolus pressure (IBP) and esophagogastric junction (EGJ) relaxation pressure. We hypothesized that bolus transit may occur when IBP overcomes integrated relaxation pressure (IRP) and analyzed the relationships between peristalsis pattern and the discrepancy between IBP and IRP in patients with dysphagia.

Methods

Twenty-two dysphagia patients with normal EGJ relaxation were examined with a 36-channel HRM assembly. Each of the 10 examinations was performed with 20 and 30 mmHg pressure topography isobaric contours, and findings were categorized based on the Chicago classification. We analyzed the relationships between peristalsis pattern and the discrepancy between IBP and IRP.

Results

Twenty-two patients were classified by the Chicago classification: 1 patient with normal EGJ relaxation and normal peristalsis, 8 patients with intermittent hypotensive peristalsis and 13 patients with frequent hypotensive peristalsis. A total of 220 individual swallows were analyzed. There were no statistically significant relationships between peristalsis pattern and the discrepancy between IBP and IRP on the 20 or 30 mmHg isobaric contours.

Conclusions

Peristalsis pattern was not associated with bolus transit in patients with dysphagia. However, further controlled studies are needed to evaluate the relationship between bolus transit and peristalsis pattern using HRM with impedance.

Myth: gastroesophageal reflux is a pathological entity in the preterm infant

There is concern about possible consequences of gastroesophageal reflux (GER) in preterm infants. GER is perceived to be a frequent condition in these infants, often causing an exhaustive investigation and expensive therapy. We review current evidence for and against an association between GER and apnea, failure to thrive, wheezing and respiratory diseases. Although there are some limitations to the methodologies currently used for detecting GER, there is clearly a lack of unequivocal evidence supporting a causal relationship between GER and its assumed consequences, particularly in preterm infants. Despite physiologic data that stimulation of laryngeal efferents by GER may induce apnea, there is little evidence for a causal relationship between GER and apnea. Studies on preterm infants with failure to thrive have also not demonstrated an association between the latter and GER in most cases, and there is equally little evidence for a casual relationship with respiratory problems. Therefore, we believe that GER in preterm infants is only rarely associated with serious consequences and existing evidence does not support the widespread use of anti-reflux medications for treatment of these signs in this age group. An improvement of methods to identify the few preterm infants at risk for developing serious consequences of GER is urgently needed.

Pediatric esophageal high-resolution manometry: utility of a standardized protocol and size-adjusted pressure topography parameters

OBJECTIVES

Esophageal high-resolution manometry (EHRM) has evolved rapidly from a research tool to a routine investigation in adult clinical practice. This study proposes and evaluates a standardized EHRM protocol for use in pediatric clinical practice.

METHODS

Thirty pediatric patients underwent unsedated EHRM. Indications for EHRM were dysphagia, feeding difficulty, or pre-fundoplication assessment. Two 20-channel customized water-perfused silicone catheters, with an outside diameter of 3.8 mm (MuiScientific, Ontario, CA), were used. The catheters had one distal gastric channel, five channels 0.5 cm apart for the e-sleeve, and 14 proximal channels either 1 cm (for children <5 years) or 2 cm apart (for children >5 years). Single wet swallows, multiple rapid swallows (MRS), and solid swallows were systematically studied.

RESULTS

The median age was 10 years (range 6 months-15 years). The esophageal motor findings were normal peristalsis (n=15), peristaltic dysfunction (n=12), achalasia (n=3), and spasm on consumption of solid food (n=2). The distal contractile integral adjusted for esophageal length (DCIa) of patients with peristaltic dysfunction was significantly lower than that of patients without peristaltic dysfunction (P<0.001). On MRS, aperistalsis with lack of esophagogastric junction (EGJ) relaxation was observed in patients with achalasia, and aperistalsis with complete EGJ relaxation was observed in patients with severe peristaltic dysfunction. On consumption of solid food, esophageal spasm associated with bolus impaction was observed in two patients.

CONCLUSIONS

This study provides objective information with regard to topography pressure parameters in esophageal motility disorders of childhood while using a standardized EHRM protocol. The new DCIa variable may be useful for the assessment of patients with peristaltic dysfunction.

Landmarks in the understanding and treatment of reflux disease

The last 50 years have seen a transformation in the understanding and treatment of reflux disease. The development and wide use of flexible endoscopy and progressively more sophisticated approaches to measurement of pathophysiological factors have been major drivers of advances. The recognition and progressive elucidation of the mechanical events that comprise the transient lower esophageal sphincter relaxation and how they lead to reflux provide a novel and firm foundation for tailoring therapies that act directly to reduce occurrence of reflux episodes, either surgically or pharmacologically. Novel GABA(B) agonist drugs have been shown to inhibit transient relaxations and are currently being evaluated in clinical trials on patients with reflux disease. Better understanding has extended to recognition of the extraordinarily high prevalence of reflux disease and of the ability of proton pump inhibitor drugs to deliver major benefits to a high proportion of patients with reflux disease. The life of the Gastroenterological Society of Australia has spanned the period of these major advances. A large number of the members of the Society and their associates have contributed substantially to these advances.

Gastrointestinal motility testing

Gastrointestinal motility and the effects on luminal contents that are brought about by it can be studied in several ways. In clinical practice, manometry remains one of the most important investigational techniques, in particular for oesophageal and anorectal disorders. Radiographic examination of bolus transit through the gastrointestinal tract also continues to be a valuable tool. Scintigraphy still is the gold standard for assessment of gastric emptying, but (13)(C) breath tests are an alternative. Many other techniques are used mainly in the context of scientific research but some of these may become incorporated in the diagnostic armamentarium.

In-vivo demonstration of a high resolution optical fiber manometry catheter for diagnosis of gastrointestinal motility disorders

Fiber optic catheters for the diagnosis of gastrointestinal motility disorders are demonstrated in-vitro and in-vivo. Single element catheters have been verified against existing solid state catheters and a multi-element catheter has been demonstrated for localized and full esophageal monitoring. The multi-element catheter consists of a series of closely spaced pressure sensors that pick up the peristaltic wave traveling along the gastrointestinal (GI) tract. The sensors are spaced on a 10 mm pitch allowing a full interpolated image of intraluminal pressure to be generated. Details are given of in-vivo trials of a 32-element catheter in the human oesophagus and the suitability of similar catheters for clinical evaluation in other regions of the human digestive tract is discussed. The fiber optic catheter is significantly smaller and more flexible than similar commercially available devices making intubation easier and improving patient tolerance during diagnostic procedures.

Esophageal motility testing: impedance-based transit measurement and high-resolution manometry

Esophageal function tests are widely used, not only to obtain insight into esophageal physiology and pathophysiology in a research setting, but also to diagnose esophageal motor disorders in patients with symptoms such as dysphagia and chest pain. While esophageal function testing has long been considered almost synonymous with manometry, recently new techniques such as impedance measurement and high-resolution manometry have emerged. With impedance monitoring the transit of a bolus through the esophagus can be studied without the use of ionizing radiation. High-resolution manometry offers a highly detailed and comprehensive view of esophageal pressure patterns. Multichannel high resolution manometry with color plotting facilitates positioning of the catheter and interpretation of the tracings. In this article the development, clinical usefulness, and indications of these new tests are discussed.

Determinants of postprandial flow across the human ileocaecal junction: a combined manometric and scintigraphic study

The relationships between ileocolonic motor patterns and flow have not been defined in humans. Utilizing simultaneous ileocolonic manometry and scintiscanning, we aimed to examine this relationship and test the hypotheses that ileal propagating sequences (PSs) underlie caecal filling, that caecal filling is a stimulus for proximal colonic PSs and that the ileocolonic junction (ICJ) regulates flow between the small and large bowel. In six healthy volunteers, a 5-m-long nasocolonic manometry catheter was positioned such that 16 recording sites, spaced at 7.5-cm intervals, spanned the ileum and proximal colon. Subjects were positioned under a gamma camera 30 MBq of (99m)Tc sulphur colloid was instilled, 22.5 cm proximal to the ICJ. Isotopic images were recorded (10 s per frame) and synchronized with the manometric trace. We identified 171 ileal PSs, 47 caecal PSs and 117 discrete episodes of caecal filling. Of the 117 episodes of caecal filling, 72% were associated temporally with ileal PSs. Conversely, 87% of ileal PSs were associated with caecal filling. Of the PSs originating in the caecum, 90% were temporally associated with caecal filling. We conclude that ileal PSs are highly propulsive and are the major determinant of episodic caecal filling and that caecal filling may be a major stimulus for caecal propagating sequences.

Sleeve sphincter of Oddi (SO) manometry: a new method for characterizing the motility of the sphincter of Oddi

BACKGROUND/PURPOSE

Perfused multilumen sphincter of Oddi (SO) manometry is accepted as the gold standard for diagnosis of SO dysfunction. However, this technique is associated with a relatively high incidence of post-procedure acute pancreatitis. In addition, triple-lumen manometry recordings may be difficult to interpret, as movement may produce artifacts. We have refined the development of a sleeve sensor for human SO manometry. This assembly aims to overcome the above limitations. In this study the accuracy of sleeve SO manometry (SOM) has been evaluated and compared with standard triple-lumen perfused SOM.

METHODS

Patients undergoing SO manometric studies consented to having both standard triple-lumen and sleeve SOM. A total of 32 paired studies were performed in 29 patients. Diagnosis was made only from standard triple-lumen SOM and the patient treated accordingly. For each study, SO basal pressure, contraction, amplitude, and frequency were recorded.

RESULTS

There was no statistically significant difference in the recordings of SO basal pressure, contraction, amplitude, and frequency between the two techniques. A strong correlation was demonstrated between SO basal pressure determined with the two catheters. The accuracy of sleeve SOM is comparable to standard triple-lumen SOM, with less movement artifact. One patient developed mild post-manometric pancreatitis.

CONCLUSIONS

The sleeve catheter records SO pressures with comparable values to standard triple-lumen SOM. The sleeve assembly potentially can replace the use of the perfused triple-lumen catheter for the objective diagnosis of SO dysfunction.

Diagnostic evaluation of dysphagia

Taking a careful history is vital for the evaluation of dysphagia. The history will yield the likely underlying pathophysiologic process and anatomic site of the problem in most patients, and is crucial for determining whether subsequently detected radiographic or endoscopic 'anomalies' are relevant or incidental. Although the symptoms of pharyngeal dysphagia can be multiple and varied, the typical features of neurogenic pharyngeal dysphagia are highly specific, and can accurately distinguish pharyngeal from esophageal disorders. The history will also dictate whether the next diagnostic procedure should be endoscopy, a barium swallow or esophageal manometry. In some difficult cases, all three diagnostic techniques may need to be performed to establish an accurate diagnosis. Stroke is the most common cause of pharyngeal dysphagia. A videoradiographic swallow study is vital in such cases to determine the extent and timing of aspiration and the severity and mechanics of dysfunction as a prelude to therapy.

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

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

High-resolution manometry

Recently, high-resolution oesophageal manometry was added to the armamentarium of researchers and gastroenterologists. Current studies suggest that the yield of high-resolution oesophageal manometry is higher than that of conventional pull-through manometry and is at least comparable to that of sleeve sensor manometry. Probably the most important advantage of solid-state high-resolution manometry is that it makes oesophageal manometry faster and easier to perform. Topographic plotting of high-resolution manometry signals facilitates their interpretation. It is concluded that high-resolution manometry is a promising technique for the evaluation of oesophageal motor function. Further studies will have to determine whether high-resolution manometry is superior to conventional manometry in the diagnostic work-up of patients with oesophageal symptoms.

High-resolution manometry of the esophagus: more than a colorful view on esophageal motility?

Since the introduction of pressure measurement of the esophagus, there has been a stepwise improvement in manometric techniques and the recognition of esophageal manometry as a useful tool to evaluate esophageal function in clinical practice. The newest development in this field is high-resolution manometry of the esophagus. In this review, we will briefly discuss the indications for esophageal manometry and we will focus on the development of the technique of high-resolution manometry and the new insights that were obtained by using this emerging tool. We conclude that high-resolution esophageal manometry with spatiotemporal plotting of signals is a valuable research tool. Clinically, the solid-state high-resolution technique is attractive because it makes it easy to perform a high-quality manometric test. However, future studies will have to determine whether the yield of the technique is higher than that of conventional manometry.

Development of esophageal peristalsis in preterm and term neonates

BACKGROUND & AIMS

High-resolution manometry demonstrates a chain of 3 sequential pressure segments that represent esophageal peristalsis in children and adults. We performed high-resolution manometry in preterm and term neonates to determine the ontogenesis of esophageal motility with regard to this segmental architecture.

METHODS

Sixteen preterm (gestational age 32.9 +/- 2.6 weeks at examination) and 14 term neonates (38.9 +/- 1.6 weeks) underwent manometry with a 9-lumen perfused catheter having recording side holes spaced at 1-cm intervals. Pressure responses to swallows were evaluated for the presence of peristaltic segments on isobaric contour maps by an investigator who was blinded to gestational age.

RESULTS

The second segment was well developed in > or =50% of swallows in all preterm and term neonates. In contrast, the first segment was present in > or =50% of swallows in only 2 preterm neonates (12.5%) and 8 term neonates (57.1%; P < .05 for each compared with second segment) with identical findings for the third segment (12.5% preterm and 57.1% term neonates; P < .05 for each). Completed peristalses with intact segmental contraction sequences throughout the esophageal body were present in 26% +/- 6% of swallows in preterm neonates vs 55% +/- 9% in term neonates (P = .01).

CONCLUSIONS

The second pressure segment in the midesophagus (proximal smooth-muscle region) is well developed before term. Presence of other segments significantly improves at term, but peristalsis remains incomplete in nearly half of swallows. Control mechanisms for both striated- and smooth-muscle esophageal regions are incompletely developed in neonates, the outcome of which could participate in infant reflux disease.

Sacral nerve stimulation induces pan-colonic propagating pressure waves and increases defecation frequency in patients with slow-transit constipation

OBJECTIVE

Colonic propagating sequences are important for normal colonic transit and defecation. The frequency of these motor patterns is reduced in slow-transit constipation. Sacral nerve stimulation (SNS) is a useful treatment for fecal and urinary incontinence. A high proportion of these patients have also reported altered bowel function. The effects of SNS on colonic propagating sequences in constipation are unknown. Our aims were to evaluate the effect of SNS on colonic pressure patterns and evaluate its therapeutic potential in severe constipation.

METHOD

In eight patients with scintigraphically confirmed slow-transit constipation, a manometry catheter (16 recording sites at 7.5 cm intervals) was positioned colonoscopically and the tip fixed in the caecum. Temporary electrodes (Medtronic) were implanted in the S2 and S3 sacral nerve foramina under general anaesthesia. In the fasted state, 14 Hz stimulation was administered and four sets of parameters (pulse width 300 or 400 micros; S2 and S3) were tested in four 2-h epochs, in random order, over 2 days. Patients were then discharged home with the sacral wires in situ and a 3-week trial stimulation commenced during which patients completed a daily stool diary.

RESULTS

When compared with basal activity, electrical stimulation to S3 significantly increased pan-colonic antegrade propagating sequence (PS) frequency (5.4 +/- 4.2 vs 11.3 +/- 6.6 PS/h; P=0.01). Stimulation at S2 significantly increased retrograde PSs (basal 2.6 +/- 1.8 vs SNS 5.6 +/- 4.8 PS/h; P=0.03). During the subsequent three-week trial (continuous stimulation), six of eight reported increased bowel frequency with a reduction in laxative usage.

CONCLUSION

These data demonstrate that SNS induces pan-colonic propagating pressure waves and therefore shows promise as a potential therapy for severe refractory constipation.

Removal of tonic nitrergic inhibition is a potent stimulus for human proximal colonic propagating sequences

Propagating sequences (PS) are important in colonic propulsion and defecation, yet the triggers of these motor patterns are not understood. Nonadrenergic noncholinergic neurones are believed to modulate smooth muscle in the gastrointestinal tract via the ubiquitous inhibitory neurotransmitter nitric oxide (NO). In the mouse colon periods of quiescence correlate with an increase in the release of NO. We investigated the colonic response to NO synthase inhibition in the conscious human subject. Intravenous infusion of saline or N(G)-monomethyl-L-arginine (L-NMMA; 3 or 6 mg kg(-1) h(-1)) occurred in random order in six healthy volunteers in whom a 5 m long nasocolonic manometry catheter was positioned such that 16 recording sites, at 7.5-cm intervals, spanned the terminal ileum and colon. L-NMMA infusion at 3 mg kg(-1) h(-1), but not 6 mg kg(-1) h(-1) significantly (P = 0.02) increased proximal colonic PS frequency (2.0 +/- 1.9 vs 11.7 +/- 7.0 PS h(-1)) and non-propagating motor activity (5,296 +/- 2,750 vs 6,362 +/- 1,275 mmHg s). We conclude that blockade of NO synthesis has a stimulatory effect on the frequency of proximal colonic PS. This suggests removal of tonic nitrergic inhibition of the colon might be a physiological stimulus for propagating activity.

Impaired proximal colonic motor response to rectal mechanical and chemical stimulation in obstructed defecation

PURPOSE

Both motor and sensory dysfunction have been implicated in the pathogenesis of obstructed defecation. We have found that despite preservation of a defecatory urge, patients with obstructed defecation have lost the normal predefecatory augmentation in frequency and amplitude of colonic propagating pressure waves. This observation might be explainable by either altered rectal sensory thresholds or by dysfunction in the colonic motor apparatus. By measuring rectal sensory thresholds and proximal colonic motor responses to rectal mechanical and chemical stimuli, we tested the hypotheses that central perception of rectal stimuli is enhanced and that the proximal colonic motor response to rectal stimulation is attenuated.

METHODS

In seven patients with obstructed defecation and ten healthy volunteers we measured proximal colonic motor responses and sensory thresholds in response to both rectal balloon distention and rectal instillation of chenodeoxycholic acid.

RESULTS

In controls, but not in patients, rectal mechanical distention significantly reduced and chemical stimulation significantly increased the frequency of proximal colonic propagating sequences (P = 0.01). There was no significant difference in rectal sensory thresholds between patients and controls. Prior instillation of chenodeoxycholic acid significantly reduced (P < 0.03) maximum tolerated balloon volume and defecatory urge volume to comparable degree in both patients and controls.

CONCLUSIONS

In obstructed defecation, 1) the normal rectocolonic pathways mediating stimulation-induced proximal colonic propagating pressure waves are nonfunctioning, and. 2) central perception of these rectal stimuli is normal.

Insulin modulates duodenal vagal afferents basal activity

Hyperglycemia markedly modifies gastro-duodenal motility. The question was raised whether hyperinsulinaemia, which is usually concomitant to hyperglycemia, could be the factor responsible for this effect through alteration of gastro-duodenal sensitivity. Indeed, vagal receptors are directly activated by insulin in lambs. However, insulin action significantly differs in ruminants and non-ruminants. The aim of our study was therefore to check (i) if insulin per se was able to modulate basal and distension induced discharges of duodenal vagal afferents in a monogatric animal model and (ii) if its action was direct or indirect through changes in gut compliance. Fourteen duodenal mechanoreceptors were studied in anaesthetized curarized pigs using the "single-fiber" method performed on the left cervical vagus. The characteristics of the vagal receptors were studied before (Control), and after (i) local insulin infusion in the gastroepiploic artery (IA), (ii) IV insulin perfusion inducing systemic hypoglycemia (IV), and (iii) during an euglycemic hyperinsulinemic clamp (EH). Basal recording, isobaric and isovolumetric distensions were performed in all experimental conditions. Basal discharge was significantly increased during IA (5.8+/-0.28 spikes/5 s), IV (6.6+/-0.30 spikes/5 s) and EH (5.7+/-0.25 spikes/5 s) compared to Control (4.4+/-0.27 spikes/5 s, p<0.05). Responses during isobaric and isovolumetric distensions were identical irrespective of the experimental condition. Gut compliance and intraluminal pressure during basal recording were not modified (p>0.05). In conclusion, insulin increased duodenal vagal mechanoreceptors basal activity but did not modulate the mechanosensitivity of the vagal units. Insulin-induced increase in basal discharge rate was due to hyperinsulinemia per se since it persisted during the euglycemic hyperinsulinemic clamp.

Sleeve sensor versus high-resolution manometry for the detection of transient lower esophageal sphincter relaxations

Transient lower esophageal sphincter relaxations (TLESRs) are the most important mechanism by which gastroesophageal reflux occurs, and sleeve sensor manometry is the gold standard for detection of TLESRs. The aim of this study was to evaluate manometry with closely spaced sideholes (high-resolution manometry) for the detection of TLESRs as an alternative. In 12 patients with gastroesophageal reflux disease, a 90-min postprandial manometry was performed by using a catheter incorporating both a sleeve sensor and closely spaced sideholes in the esophagogastric junction. TLESRs recorded with both techniques were scored. Reflux during TLESRs was detected by using manometry (common cavity), intraluminal impedance, and pH monitoring. A total of 145 TLESRs were detected by using both techniques, 117 with high-resolution manometry and 108 with sleeve sensor manometry [not significant (NS)]. Manometric signs of reflux during TLESRs detected with high-resolution and sleeve sensor manometry were found in 62.4 and 56.5%, NS, respectively, versus 38.5 and 35.2%, NS on pH-metry and 70.1 and 60.2%, NS on impedance monitoring. TLESRs recognized only with high-resolution manometry were more often accompanied by reflux, as detected with manometry (59.5%) and impedance monitoring (67.6%), than TLESRs recognized only with sleeve sensor manometry (32.1 and 28.6%). High-resolution manometry is at least as accurate as sleeve sensor manometry for the detection of TLESRs.

Abnormal predefecatory colonic motor patterns define constipation in obstructed defecation

BACKGROUND & AIMS

The pathophysiology of constipation in the syndrome of obstructed defecation is unknown. Using 24-hour pancolonic manometric recordings of the unprepared colon to record basal pressures and spontaneous defecation episodes, we tested the hypothesis that the frequency, timing, or spatial distribution of propagating colonic pressure waves is abnormal in patients with obstructed defecation.

METHODS

In 11 patients with obstructed defecation and 16 healthy controls, pressures were recorded using a nasocolonic catheter that was positioned such that 16 recording sites spanned the unprepared colon at 7.5-cm intervals.

RESULTS

The overall frequency of propagating sequences (PS) in the colon did not differ between patients and controls. When compared with controls, patients had a significant increase in the frequency of retrograde and antegrade PS (P < 0.05) in the left colon and a significant reduction in the amplitude of propagating pressure waves throughout the entire colon (P < 0.03). Defecation occurred in 6 of 11 patients and 9 of 16 controls. In the 15 minutes before defecation, controls showed a highly significant increase in frequency (P = 0.001) and amplitude (P = 0.01) of PS. In contrast, patients did not demonstrate this or the typical spatiotemporal organization of PS normally observed before expulsion of stool.

CONCLUSIONS

Patients with obstructed defecation lack the normal predefecatory augmentation in frequency and amplitude of propagating pressure waves and lack the normal stereotypic spatiotemporal patterning of colonic pressure waves that would normally culminate in effective expulsion of stool.

Gastroesophageal reflux: a critical review of its role in preterm infants

There is widespread concern about gastroesophageal reflux (GER) in preterm infants. This article reviews the evidence for this concern. GER is common in infants, which is related to their large fluid intake (corresponding to 14 L/day in an adult) and supine body position, resulting in the gastroesophageal junction's being constantly "under water." pH monitoring, the standard for reflux detection, is of limited use in preterm infants whose gastric pH is >4 for 90% of the time. New methods such as the multiple intraluminal impedance technique and micromanometric catheters may be promising alternatives but require careful evaluation before applying them to clinical practice. A critical review of the evidence for potential sequelae of GER in preterm infants shows that 1) apnea is unrelated to GER in most infants, 2) failure to thrive practically does not occur with GER, and 3) a relationship between GER and chronic airway problems has not yet been confirmed in preterm infants. Thus, there is currently insufficient evidence to justify the apparently widespread practice of treating GER in infants with symptoms such as recurrent apnea or regurgitation or of prolonging their hospital stay, unless there is unequivocal evidence of complications, eg, recurrent aspiration or cyanosis during vomiting. Objective criteria that help to identify those presumably few infants who do require treatment for GER disease are urgently needed.

Pathophysiological mechanisms of gastroesophageal reflux disease in children

Gastroesophageal reflux (GER) is an extremely common pediatric problem, but only in the past few years have we developed a better understanding of its pathophysiology. This is related to the wider use of investigative tools such as flexible endoscopy, 24-hour pH monitoring, and more recently, micromanometric methods and noninvasive breath tests, which have been particularly useful in infants. This paper reviews our current understanding of the esophageal and gastric mechanisms contributing to the pathophysiology of GER. In this context, we also highlight areas where new therapeutic approaches may be beneficial.

Fully automated analysis of colonic manometry recordings

The purpose of this study was to develop a computer program for fully automated analysis of all presently known motor patterns in human colonic motility recordings. Colonic pressure recordings obtained from 24 healthy volunteers were used. Algorithms were developed for the detection and numerical analysis of five types of pressure waves: antegrade, retrograde, simultaneous, high-amplitude and isolated pressure waves. Furthermore, periodical motor activity was quantified. Validation was performed by comparison with visual analysis by two experienced observers. Patterns recorded during day- and night-time were compared using multiple-factor analysis of variance with Bonferroni correction. Automated analysis correlated well with visual peak detection (r = 0.98, P <0.01) and detection of antegrade pressure waves (r = 0.98, P <0.01). Most motor patterns showed a diurnal variation. During the night, prevalences of antegrade (938 vs 455; P <0.05), retrograde (112 vs 81; P <0.05), high-amplitude (12.9 vs 1.3; P <0.05), isolated pressure waves (1114 vs 765; P <0.05), and periodic motor activity were decreased (7.33 vs 4.47%; P <0.05). However, when expressed as percentage of absolute numbers of pressure waves, prevalences remained constant. In conclusion, fully automated analysis of all hitherto described colonic motility patterns is feasible. During the night, overall wave prevalences markedly decreased, but the distribution over the various motor patterns was preserved.

The effect of baclofen on gastro-oesophageal reflux, lower oesophageal sphincter function and reflux symptoms in patients with reflux disease

BACKGROUND

Baclofen decreases gastro-oesophageal reflux episodes in healthy subjects by reducing the incidence of transient lower oesophageal sphincter relaxations.

AIM

To investigate the effect of baclofen on reflux symptoms, oesophageal pH and lower oesophageal sphincter manometry in patients with gastro-oesophageal reflux disease.

METHODS

A double-blind, placebo-controlled, two-way crossover design was used to study the effect of baclofen on heartburn and regurgitation 3 h after a provocation test meal in 37 patients with gastro-oesophageal reflux disease. Additionally, in 20 of these patients, the effect of baclofen on oesophageal pH, transient lower oesophageal sphincter relaxations and basal lower oesophageal sphincter pressure was studied.

RESULTS

Baclofen significantly decreased the acid reflux time and the incidence of gastro-oesophageal reflux episodes (8.3 +/- 8.8% vs. 12.4 +/- 12.0%, P = 0.03 and 10.9 +/- 7.3 per 3 h vs. 18.7 +/- 12.4 per 3 h). The incidence of transient lower oesophageal sphincter relaxations was significantly lower with baclofen than with placebo (15.1 +/- 6.4 per 3 h vs. 22.8 +/- 5.4 per 3 h, P < 0.0001). Lower oesophageal sphincter pressure and the percentage of transient lower oesophageal sphincter relaxations associated with reflux were not affected by baclofen. No significant effect on symptom scores was observed.

CONCLUSIONS

Baclofen decreases post-prandial acid reflux in patients with gastro-oesophageal reflux disease by reducing the incidence of transient lower oesophageal sphincter relaxations. No effect of a single dose of baclofen on reflux symptoms could be demonstrated in this 3-h post-prandial study.

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.

The proximal colonic motor response to rectal mechanical and chemical stimulation

We aimed to determine whether rectal distension and/or infusion of bile acids stimulates propagating or nonpropagating activity in the unprepared proximal colon in 10 healthy volunteers using a nasocolonic manometric catheter (16 recording sites at 7.5-cm spacing). Sensory thresholds and proximal colonic motor responses were assessed following rectal distension by balloon inflation and rectal instillation of chenodeoxycholic acid. Maximum tolerated balloon volume and the volume that stimulated a desire to defecate were both significantly (P < 0.01) reduced after rectal chenodeoxycholic acid. The frequency of colonic propagating pressure wave sequences decreased significantly in response to initial balloon inflations (P < 0.05), but the frequency doubled after subsequent chenodeoxycholic acid infusion (P < 0.002). Nonpropagating activity decreased after balloon inflation, was not influenced by acid infusion, and demonstrated a further decrease in response to repeat balloon inflation. We concluded that rectal chenodeoxycholic acid in physiological concentrations is a potent stimulus for propagating pressure waves arising in the proximal colon and reduces rectal sensory thresholds. Rectal distension inhibits all colonic motor activity.

Space-time pressure structure of pharyngo-esophageal segment during swallowing

We applied high-resolution manometry with spatiotemporal data interpolation and simultaneous videofluoroscopy to normal pharyngeal swallows to correlate specific features in the space-time intraluminal pressure structure with physiological events and normal deglutitive transsphincteric bolus flow to define normal biomechanical properties of the pharyngo-esophageal (PE) segment. Pressures were recorded by microperfused catheter, and the two-dimensional space-time data sets were plotted as isocontours. On these were superimposed bolus trajectories, anatomic segment movements, and hyo-laryngeal trajectories from concurrent videofluoroscopy. Correlation of the highly reproducible space-time-pressure structure with radiographic images confirmed that primary deglutitive PE segment functions (pressure profile, laryngeal elevation, axial sphincter motion, timing of relaxation, contraction) are accurately discernible from single isocontour pressure visualization. Pressure during bolus flow was highly dependent on axial location within PE segment and time instant. The intrabolus pressure domain, corresponding to the space-time region between bolus head and tail trajectories, demonstrated significant bolus volume dependence. High-resolution manometry accurately, comprehensively, and highly reproducibly depicts the PE segment space-time-pressure structure and specific physiological events related to upper esophageal sphincter opening and transsphincteric flow during normal swallowing. Intrabolus pressure variations are highly dependent on position within the PE segment and time.

Small intestinal motor patterns in critically ill patients after major abdominal surgery

OBJECTIVES

In patients who have had major surgery or trauma, early enteral feeding is safer and more effective than parenteral or nasogastric feeding but is frequently associated with diarrhea. Limited recordings have shown that the patterning of duodenal interdigestive motor activity is frequently abnormal after surgery or in patients who are critically ill. The aims of this study were to evaluate the effects of major abdominal surgery on small intestinal motility, and to elucidate the motor patterns that occur postoperatively in critically ill patients in response to enteral feeding.

METHODS

The effects of elective aortic aneurysm repair on small intestinal motility were studied in 11 patients aged 63-77 yr. A 3.5-mm diameter multilumen extrusion was used to monitor pressures at 12 points, distributed between the antrum and 100 cm distal to the pylorus. An additional lumen allowed enteral feeding into the duodenum. Recordings commenced immediately postoperatively and continued for up to 4 days. Data are given as means and SEMs.

RESULTS

Bursts (frequency > 10/min) of small intestinal pressure waves that resembled phase III interdigestive motor activity occurred in all patients immediately after surgery. During mechanical ventilation, the timing of bursts along the segment evaluated was frequently abnormal for true interdigestive phase III activity, with simultaneous onset in multiple channels (46%), multiple or distal origins (8%), or retrograde migration (20%). When patients were not being ventilated, the migration pattern of the bursts was more typical of interdigestive phase III activity. The interval between bursts was unusually short for interdigestive motor activity, although it increased from 30+/-12 min on day 1 to 41+/-18 min on day 3 (p < 0.05). A phase II pattern of pressure waves was virtually absent in all patients on all study days. In six patients who received postoperative enteral nutrition, the bursts of pressure waves were not abolished by feeding, contrary to normal phase III activity.

CONCLUSIONS

Small intestinal pressure wave bursts are seen immediately after elective aortic aneurysm repair, but the migration of these bursts is frequently abnormal for phase III interdigestive activity. Duodenal nutrient delivery did not interrupt the occurrence of these bursts. Persistence of pressure wave bursts in this setting may be important in the delivery of enteral nutrition.

Prolonged multi-point recording of colonic manometry in the unprepared human colon: providing insight into potentially relevant pressure wave parameters

OBJECTIVES

To determine the feasibility of and derive normative data for prolonged, 24-h, multipoint, closely spaced, water perfused manometry of the unprepared human colon.

METHODS

In 14 healthy volunteers, 24-h recordings were made using a water perfused, balloon-tipped, 17 lumen catheter which was passed pernasally and positioned so that 16 recording sites spanned the colon at 7.5 cm intervals from cecum to rectum. The area under the pressure curve and propagating pressure wave parameters were quantified for the 16 regions. High amplitude propagating sequences were defined as were rectal motor complexes.

RESULTS

Nasocolonic recording was well tolerated and achievable. Propagation sequences, including high amplitude propagating sequences, originated in the cecum (0.32 +/- 0.05/h) more frequently than in other regions and the extent of propagation correlated significantly with proximity of the site of sequence origin to the cecum (p < 0.001). Propagation velocity of propagating sequences was greater than high amplitude propagating sequences (p = 0.0002) and region-dependent, unlike high amplitude propagating sequences (p < 0.01). The frequency of propagating sequences did not increase after the meal, but frequency of high amplitude propagating sequences was increased significantly by the meal (p < 0.01). Rectal motor complexes were seen throughout the colon with no apparent periodicity.

CONCLUSIONS

Prolonged, multipoint, perfusion manometry of the unprepared colon provides improved spatial resolution of colonic motor patterns and confirms the diurnal and regional variations in propagating pressure waves detected in the prepared colon. The study demonstrates differences between high amplitude propagating sequences and propagating sequence parameters that may have functional significance; and also, that the rectal motor complex is a ubiquitous pan colonic motor pattern.

Desensitization of ileal vagal receptors by short-chain fatty acids in pigs

Coloileal reflux episodes trigger specialized ileal motor activities and inhibit gastric motility in pigs. The initiation of these events requires the detection by the distal ileum of the invading colonic contents that differ from the ileal chyme primarily in short-chain fatty acid (SCFA) concentrations. In addition to the already described humoral pathway, this detection might also involve ileal vagal afferents. Sensitivity to SCFA of 12 ileal vagal units was investigated in anesthetized pigs with single-unit recording at the left cervical vagus. SCFA mixtures (0.35, 0.7, and 1.4 mol/l) containing acetic, propionic, and butyric acids in proportions identical to that in the porcine cecocolon were compared with isotonic and hypertonic saline. All units behaved as slowly adapting mechanoreceptors (half-adaptation time = 35.4 +/- 15.89 s), and their sensitivity to local mechanical probing was suppressed by local anesthesia; 7 units significantly decreased their spontaneous firing with 0.7 and 1.4 but not 0.35 mol/l SCFA infusion compared with hypertonic or isotonic saline. Similarly, the response induced by distension in the same seven units was reduced (5 neurons) or abolished (2 neurons) after infusion of 0.7 (22.8 +/- 2.39 impulses/s) and 1.4 (30.3 +/- 2.12 impulses/s) mol/l SCFA solutions compared with isotonic saline (38.6 +/- 4.09 impulses/s). These differences in discharge were not the result of changes in ileal compliance, which remained constant after SCFA. In conclusion, SCFA, at concentrations near those found during coloileal reflux episodes, reduced or abolished mechanical sensitivity of ileal vagal afferents.

Prolonged recording of oesophageal and lower oesophageal sphincter pressure using a portable water-perfused manometric system

The aim of our study was to investigate the recording fidelity of a water-perfused micromanometric catheter with incorporated sleeve combined with a newly developed portable water-perfused manometric system for pharyngeal, oesophageal and lower oesophageal sphincter (LOS) pressure recording. The system's performance was assessed in prolonged recordings in ambulant gastro-oesophageal reflux disease (GORD) patients. Eighty 24-h studies in GORD patients, carried out with the perfused portable manometric system, were evaluated. Twelve of these recordings were analysed in detail in order to compare oesophageal and LOS motor patterns with those described previously. Paired 2-h manometric recordings of the pharynx, oesophagus, LOS and stomach, using the new system and a conventional perfused stationary manometric system, were performed in eight healthy subjects. With the portable manometric system oesophageal contractions, transient LOS relaxations, swallow-associated prolonged LOS relaxations and LOS pressures were recorded with equal fidelity to the conventional manometric system. Recordings obtained with the portable system showed meal-related and diurnal variations in oesophageal and LOS variables that were similar to these found in studies using conventional equipment. The new manometric system, consisting of a perfused micromanometric catheter with incorporated sleeve and a portable perfusion system, enables prolonged studies on oesophageal and LOS motor patterns in ambulant subjects.

Evaluation of miniature manometric techniques for the measurement of esophageal body pressure waves

BACKGROUND AND AIMS

Perfused miniature manometric assemblies with lumina of 0.4-0.5 mm i.d. have been developed. Reduced luminal size offers the advantages of reduced assembly bulk and increased assembly complexity with greater numbers of lumina and lower manometric infusion volumes because of a slower perfusion rate. This study investigated the recording fidelity of miniature manometric assemblies in the measurement of esophageal peristalsis.

METHODS

Four miniature manometric assemblies, each containing manometric lumina of either 0.4 or 0.5 mm i.d., were evaluated at 100 and 180 cm lengths. The fidelity of miniature manometric luminal recordings were evaluated in vivo during esophageal peristalsis by using a simultaneous comparison with the standard lumina and an intraluminal strain gauge.

RESULTS

During esophageal peristalsis, miniature manometric lumina recorded the peak amplitude of pressure waves, with an accuracy at perfusion rates of 0.04 mL/min (0.4 mm, i.d.) and 0.15 mL/min (0.5 mm, i.d.).

CONCLUSION

Miniature manometric assemblies of lengths that are practical for use in humans are suitable for recording esophageal peristalsis.

Evaluation of multiple-point measurement of sphincter of Oddi motility in the Australian brush-tailed possum

Manometric assembly diameter is a major limitation on the number of perfused manometric recording points for recordings from the sphincter of Oddi (SO). We evaluated novel polyimide manometric assemblies whereby four recording channels were incorporated in an overall assembly diameter of 0.8 mm. Over the very low range of perfusion rates tested (0.005-0.04 ml/min), the assemblies had pressure offsets attributable to water perfusion from 2 to 23 mmHg and pressure rise rates from 20 to 163 mmHg/s. In six anesthetized Australian brush-tailed possums, manometric recordings from the SO showed a significant reduction in the recorded peak amplitude of pressure waves with perfusion rates below 0.02 ml/min. The pressure profile of the sphincter was found to be asymmetric, and phasic wave propagation patterns were complex (antegrade 35.6%, "mixed" 64.4%). In conclusion, accurate multipoint SO manometry in the possum can be performed with micromanometric assemblies at very low perfusion rates to give a more complete understanding of SO mechanics. These methods are also potentially applicable to perfusion manometry in other small laboratory animals such as mice.

Reflux in children

Gastro-oesophageal reflux (GOR) is an extremely common paediatric problem that often runs a harmless and self-limited course. Physiological GOR however can lead to marked parental anxiety, many unnecessary investigations and often unwarranted and potentially harmful therapeutic interventions. Our ability to better define GOR and gastro-oesophageal reflux disease (GORD) has improved in the past 15 years with a better understanding of the pathophysiology in infants and children due to the development and wider use of flexible endoscopy, 24-hour oesophageal pH monitoring and, more recently, the use of micromanometric methods for studying oesophageal motility. This will be further enhanced in the future with the development of non-invasive breath testing to study gastrointestinal motility and the use of electrical impedance to study fluid movement. Our therapeutic interventions have also improved particularly in the areas of acid suppression, improved surgical techniques and most recently laparoscopic fundoplication. This chapter reviews these advances in the paediatric area especially with regard to pathophysiology, diagnostic testing and therapeutic intervention.

Spatial and temporal organization of pressure patterns throughout the unprepared colon during spontaneous defecation

OBJECTIVE

The aim of this study was to examine colonic motor events associated with spontaneous defecation in the entire unprepared human colon under physiological conditions.

METHODS

In 13 healthy volunteers a perfused, balloon-tipped, 17-lumen catheter (outer diameter, 3.5 mm; intersidehole spacing, 7.5 cm) was passed pernasally and positioned in the distal unprepared colon.

RESULTS

In the hour before spontaneous defecation, there was an increase in propagating sequence frequency (p = 0.04) and nonpropagating activity when compared to basal conditions (p < 0.0001). During this hour the spatial and temporal relationships among propagating sequences demonstrated a biphasic pattern. Both the early (proximal) and late (distal) colonic phases involved the whole colon and were characterized by respective antegrade and retrograde migration of site-of-origin of arrays of propagating sequences. There was a negative correlation between propagating sequence amplitude and the time interval from propagating sequence to stool expulsion (p = 0.008).

CONCLUSIONS

The colonic motor correlate of defecation is the colonic propagating sequence, the frequency and amplitude of which begin to increase as early as 1 h before stool expulsion. During the preexpulsive phase, the spatial and temporal relationship among the sites of origin of individual propagating sequences demonstrate a stereotypic anal followed by orad migration, which raises the possibility of control by long colocolonic pathways.

The effect of motilin agonist ABT-229 on gastro-oesophageal reflux, oesophageal motility and lower oesophageal sphincter characteristics in GERD patients

BACKGROUND

ABT-229, a motilin agonist without antibacterial activity, has been shown to enhance both lower oesophageal sphincter pressure in cats and gastric emptying in humans.

AIM

To investigate the effect of oral treatment with ABT-229 10 mg b.d., ABT-229 5 mg b. d. and cisapride 10 mg q.d.s. on gastro-oesophageal reflux, lower oesophageal sphincter pressure, transient lower oesophageal sphincter relaxations and symptoms in GERD patients.

METHODS

Twenty-four GERD patients completed the study. A randomized, double-blind, placebo-controlled, three-period incomplete crossover design was used with three dosing periods of 7 days. All patients received ABT-229 10 mg b.d. and placebo during two of the three periods. In the remaining period 12 patients were given ABT-229 5 mg b.d. and 12 received cisapride 10 mg q.d.s. Ambulatory 24 h recordings of oesophageal pH and pharyngeal, oesophageal, lower oesophageal sphincter and gastric pressures were performed on day 7 using an assembly incorporating a Dent sleeve connected to a portable water-perfused manometric system.

RESULTS

Oesophageal acid exposure was not affected by ABT-229 or cisapride, but the incidence of reflux episodes was reduced by cisapride. None of the drugs affected oesophageal motility, lower oesophageal sphincter pressure or the incidence of transient lower oesophageal sphincter relaxations. Both ABT-229 10 mg b.d. and cisapride reduced the severity of daytime heartburn.

CONCLUSION

The value of ABT-229 in the treatment of GERD appears to be limited.

Mechanism of gastroesophageal reflux in premature infants with chronic lung disease

BACKGROUND/PURPOSE

The aim of this study was to characterize the motor events responsible for gastroesophageal reflux (GER) and esophageal acid clearance in a cohort of preterm infants with chronic lung disease (CLD).

METHODS

Esophageal motility was recorded for 2 to 3 hours postprandially in 14 preterm infants with mild-moderate or moderate-severe CLD at 33 to 39 weeks postmenstrual age using a sleeve-side hole micromanometric assembly into which a pH probe had been installed.

RESULTS

Twenty-six acid GER episodes were recorded by pH probe. Of these, 22 (85%) were associated with transient lower esophageal sphincter (LES) relaxation. Transient LES relaxations were significantly longer in duration than single swallows (13.7 seconds v 4.6 seconds, P < .001) and had lower nadir pressures (1.1 mm Hg v 2.5 mm Hg, P < .001). During periods of esophageal acidification (pH below 4), peristaltic esophageal body pressure wave sequences cleared acid refluxate more effectively than nonperistaltic pressure wave sequences.

CONCLUSIONS

In preterm infants with CLD, transient LES relaxations are the predominant mechanism underlying GER, and esophageal clearance mechanisms are fully functional, which is similar to that seen in healthy preterm infants.

Measurement of upper esophageal sphincter tone and relaxation during swallowing in premature infants

Upper esophageal sphincter (UES) motor function has not been previously evaluated in premature infants. The motor patterns associated with tonic activity and swallow-related relaxation of the UES were recorded for 1 h after completion of gavage feeding in 11 healthy preterm neonates (postmenstrual age 33-37 wk) with a micromanometric assembly, which included a sleeve sensor specifically adapted for UES recordings. A clearly defined UES high-pressure zone was observed in all premature infants studied. Resting UES pressure ranged from 2.3 to 26.2 mmHg and was higher during periods of irritability and apparent discomfort. During dry swallows, UES pressure relaxed from a resting pressure of 28.2 +/- 4.0 mmHg to a nadir of 1.1 +/- 3.3 mmHg. The mean UES relaxation interval (the time from relaxation onset to relaxation offset) was 0. 31 +/- 0.11 s. We conclude that in premature infants >/=33 wk postmenstrual age the motor mechanisms regulating UES resting pressure and the onset of UES relaxation are well developed.

Lower esophageal sphincter position in premature infants cannot be correctly estimated with current formulas

OBJECTIVES

Strobel's formula (Esophageal length = 5 + 0.252 x Height) is frequently used as a guide for determining the distance from the nares to the lower esophageal sphincter (LES) in term infants. The aim of this study was to examine this relationship in premature infants.

STUDY DESIGN

The distance from nares to LES was manometrically determined in 156 premature infants (26-40 weeks' postmenstrual age; body weights of 610-3050 g). The ability of body weight, height (body length), head circumference, and postmenstrual age to predict the manometrically determined LES position was evaluated with linear and non-linear regression analyses.

RESULTS

Body weight and body length were the most predictive of distance from nares to LES (r(2) = 0.848 and 0.802, respectively). These relationships were non-linear and, in the case of body length, deviated substantially from Strobel's model.

CONCLUSIONS

In premature neonates, a different formula is needed for prediction of the distance between nares and LES than that applied to term infants and children.

Characterization of esophageal body and lower esophageal sphincter motor function in the very premature neonate

OBJECTIVES

To characterize esophageal body and lower esophageal sphincter (LES) motor function in very premature infants.

STUDY DESIGN

Esophageal manometry was performed in 12 very premature infants of 26 to 33 weeks' postmenstrual age (PMA) (body weights of 610-1360 g). Esophageal motor patterns were recorded for 30 minutes with a perfused micromanometric sleeve assembly (outer diameter, 2.0 mm).

RESULTS

Esophageal pressure waves triggered by dry swallows were predominantly (84%) peristaltic in propagation sequence. All infants showed tonic LES contraction; the mean resting LES pressure (LESP) for individual infants ranged from 5.0 +/- 4.1 mm Hg to 20.0 +/- 4.8 mm Hg. In all infants the LES relaxed (duration, 5.8 +/- 3.0 seconds; nadir pressure, 1.8 +/- 2.6 mm Hg) in response to pharyngeal swallows. Transient LES relaxations (TLESRs) (duration, 21.7 +/- 8.7 seconds; nadir pressure, 0.1 +/- 1.8 mm Hg) occurred on average 2.6 +/- 1.6 times per study; 86% of these relaxations triggered esophageal body common cavity events known to be associated with gastroesophageal reflux.

CONCLUSIONS

Esophageal motor function is well developed in very premature infants. Our data also suggest that TLESR is the predominant mechanism of reflux in these babies.

Lower esophageal sphincter relaxation characteristics using a sleeve sensor in clinical manometry

OBJECTIVE

We undertook this study to determine the characteristics of swallow-induced lower esophageal sphincter (LES) relaxation in the setting of clinical manometry using a standardized methodology.

METHODS

We reviewed 170 manometric recordings performed using a perfused manometric assembly with a sleeve sensor and a computer polygraph. Patients were categorized as patient controls, gastroesophageal reflux disease (GERD), diffuse esophageal spasm (DES), or achalasia. Tracing were semiautomatically analyzed for basal LES pressure, LES pressure during deglutitive relaxation (relaxation LES pressure), duration of LES relaxation, timing of LES relaxation, and the success rate of primary peristalsis.

RESULTS

Forty-six patient controls, 93 with GERD, five with DES, and 26 with achalasia were identified. GERD and achalasia patients had lower or higher basal LES pressures than patient controls, respectively. Compared with patient controls, achalasia patients had higher relaxation LES pressures, lower percent LES relaxation, and shorter durations of LES relaxation. The best single measure for distinguishing achalasia was the relaxation LES pressure; using the 95th percentile value of patient controls (12 mm Hg) as the upper limit of normal, its sensitivity and positive predictive value for the diagnosis of achalasia were 92% and 88%, respectively. Coupled with the finding of aperistalsis, a relaxation LES pressure > or = 10 mm Hg achieved 100% sensitivity and positive predictive value among these patients.

CONCLUSIONS

Sleeve sensor recording is a practical method for clinical manometry that reliably records LES relaxation characteristics and is amenable to both a standardized manometry protocol and a semiautomated analysis routine. Relaxation LES pressure has a high diagnostic value for achalasia.

Mechanisms of gastroesophageal reflux in healthy premature infants

OBJECTIVES

The aim of this study was to characterize the motor events responsible for gastroesophageal reflux (GER) and esophageal acid clearance in a cohort of healthy preterm infants.

STUDY DESIGN

Esophageal motility was recorded for 2 to 3 hours after a feeding in 24 preterm infants, 31 to 38 weeks' postmenstrual age, by using a sleeveside hole micromanometric assembly incorporating a pH probe.

RESULTS

Sixty acid GER episodes were recorded by pH probe, and 133 non-acid GER episodes were recorded manometrically by the presence of esophageal common cavities. Of the 193 GER episodes, 159 (82%) were associated with transient lower esophageal sphincter relaxation (TLESR). TLESRs were significantly longer in duration than single swallows (15.1 seconds vs 5.6 seconds, P < .001) and had lower nadir pressures (0.8 mm Hg vs 2.3 mm Hg, P < .001). A total of 3216 esophageal body pressure waves were analyzed; 70% of swallow-induced pressure waves were peristaltic in sequence compared with 5% of swallow-unrelated pressure waves. During periods of esophageal acidification (pH below 4), peristaltic esophageal body pressure wave sequences cleared acid refluxate more effectively than nonperistaltic pressure wave sequences.

CONCLUSIONS

In healthy preterm infants, TLESRs are the predominant mechanism underlying GER, and esophageal clearance mechanisms are well developed by at least 31 weeks' postmenstrual age.

Measurement of gastrointestinal motility in the GI laboratory

Current tests of gastric and small intestinal motor function provide relevant physiological information, but their clinical utility is controversial. This article reviews the current procedures, indications, significance, pitfalls, and guidelines for gastrointestinal motility measurements by scintigraphy, gastroduodenojejunal manometry, and surface electrogastrography in humans. Methods included review of literature and discussions in closed and open fora among investigators, including presentations for peer review at focused (Iowa City American Motility Society Symposium, December 1995) and national meetings (American Gastroenterological Association, May 1996, and American Motility Society, September 1996). The current tests are generally complementary; scintigraphy is typically the first test in the evaluation of gastric motor function and often confirms the clinical suspicion of dysmotility. Manometry identifies patterns suggestive of myopathy, neuropathy, or obstruction but may be most helpful when it shows entirely normal findings, because manometry helps in part to exclude dysmotility as a cause of symptoms. Electrogastrography may identify dysrhythmias or failure of signal power to increase postprandially; rhythm abnormalities may be independent of impaired emptying among dyspeptic patients. The best validated and clinically most significant results pertain to transit tests; manometry may contribute importantly to the diagnostic process; and the significance of electrogastrography remains to be fully elucidated.

A comparison of micromanometric and standard manometric techniques for recording of oesophageal motility

Perfused micromanometric assemblies with an outer diameter of 2 mm or less have been developed for use in premature infants and small laboratory animals. Such assemblies offer advantages with regard to subject comfort and low perfusion rates that make them attractive for use in adults. The aim of this study was to investigate the recording fidelity of micromanometric assemblies in the measurement of oesophageal peristalsis in adults. Two micromanometric assemblies with an outer diameter of 1.8-2.0 mm and a length suitable for use in adults (165 cm), and containing micromanometric lumina of 0.28-0.35 mm i.d. and a standard lumen of 0.6-0.75 mm i.d. were evaluated. Each assembly was tested by measurement of pressure rise rate in response to sudden occlusion, and in vivo during oesophageal peristalsis by simultaneous comparison with an intraluminal strain gauge. At perfusion rates of 0.01-0.15 mL min-1 microlumina achieved pressure rise rates of 21-430 mmHg sec-1 that were comparable to 37-390 mmHg sec-1 for the standard lumina perfused at 0.15-0.6 mL min-1. During oesophageal peristalsis, micromanometric lumina recorded the occurrence and timing of all pressure waves accurately when compared with standard lumina and the microtransducer. However, microlumina under-recorded pressure wave amplitude to varying degrees dependent upon perfusion rate although the performance of microlumina could be improved to that of the standard lumen by shortening their length to 70 cm. Micromanometric assemblies are suitable for recording oesophageal peristalsis in adults although there is some impairment of absolute manometric fidelity. Fidelity can be improved by minimizing total assembly length.

A novel portable perfused manometric system for recording of small intestinal motility

The development of solid-state catheters with miniature pressure transducers and portable dataloggers with a large memory capacity has allowed recording of gastrointestinal motility in ambulant subjects. Developments in silicone rubber extrusion technology made it possible to build a perfused manometric system, using a perfused manometric assembly requiring a low volume of perfusate. In the present study the feasibility of recording and automated analysis of small intestinal motility using a perfused multiple lumen manometric system was evaluated in seven healthy volunteers. Pressures were recorded from 12 sideholes arranged in four clusters spaced at 10-cm intervals from the catheter tip. Each channel was perfused at 0.15 mL min-1 with degassed water by a portable, low-compliance, perfusion pump. The 12 sidehole recording channels were connected to external transducers mounted on a belt. Pressure data were stored in two dataloggers. Motility was recorded in the sitting (30 min), and supine (30 min) position, during walking (30 min) and postprandially (90 min). Using purpose-built software baseline variations were corrected for and manometric variables (number of pressure waves, mean amplitude and motility index) calculated. Bench testing of the manometric assembly showed a median baseline pressure offset of 4.2 kPa (range 3.7-10.1) and upon occlusion a rise rate of 27.8 kPa sec-1 (range 19.7-30.8). Changes in body position affected baseline pressures so that compared to the supine position changes in baseline pressure varied between 1.5 +/- 0.7 kPa and 1.9 +/- 0.6 kPa during sitting (P < 0.02), and between 1.7 +/- 0.7 kPa and 1.5 +/- 0.9 kPa during walking (P < 0.03). Manometric recordings obtained during the fasting period showed an increase in small intestinal motor activity during walking. In the postprandial period no differences in motility variables were observed within one cluster and in time. Recording of small intestinal motility with a multiple-channel silicone rubber manometric assembly with a portable perfusion system is a feasible technique which is relatively inexpensive. Computer-assisted data processing allows for adequate elimination of artefacts and automated numerical analysis.