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Keywords:

  • bolus transport;
  • esophagus;
  • high-resolution manometry (HRM);
  • stasis;
  • videofluoroscopy

Abstract

  1. Top of page
  2. Abstract
  3. Introduction
  4. Materials and methods
  5. Results
  6. Discussion
  7. Funding
  8. Disclosure
  9. Author contribution
  10. References

Background  Non-obstructive dysphagia patients prove to be a difficult category for clinical management. Esophageal high-resolution manometry (HRM) is a novel method, used to analyze dysphagia. However, it is not yet clear how findings on HRM relate to bolus transport through the esophagus.

Methods  Twenty healthy volunteers and 20 patients with dysphagia underwent HRM and videofluoroscopy in a supine position. Each subject swallowed five liquid and five solid barium boluses. Esophageal contraction parameters and bolus transport were evaluated with HRM and concurrent videofluoroscopy.

Key Results  Stasis of liquid and solid barium boluses occurred in patients and in healthy volunteers in 64% and 41% and in 84% and 82% of the swallows, respectively. Overall, 70% of the liquid and 72% of the solid bolus swallows were followed by a peristaltic contraction, the difference not being statistically significant. Statistically significant associations were found for transition zone length of liquid and solid boluses, and for DCI and distal contraction amplitudes for liquid stasis. No correlation was found between the degree of stasis and other manometric parameters.

Conclusions & Inferences  Stasis of both liquid and solid boluses occurs frequently in patients and in controls and can be regarded as physiological. Motility patterns can predict the effectiveness of bolus transit and level of stasis to some degree but the relationship between esophageal motility and transit is complex and far from perfect. Esophageal manometry is therefore currently deemed unfit to be used for the prediction of bolus transit, and should rather be used for the identification of treatable esophageal motility disorders.


Abbreviations:
CDP

contractile deceleration point

CFV

contractile front velocity

DCI

distal contractile integral

DL

distal contractile latency

EGJ

esophagogastric junction

HRM

high-resolution manometry

IBP

intrabolus pressure

IRP

integrated relaxation pressure

LES

lower esophageal sphincter

TZ

transition zone

Introduction

  1. Top of page
  2. Abstract
  3. Introduction
  4. Materials and methods
  5. Results
  6. Discussion
  7. Funding
  8. Disclosure
  9. Author contribution
  10. References

Patients suffering from dysphagia with negative endoscopic findings prove to be a difficult category for clinical management, after achalasia and eosinophilic esophagitis have been excluded. Since its introduction in the 1950s, esophageal manometry has been the mainstay in the evaluation of these patients, as with this method one can measure pressure patterns that drive bolus transport. The underlying idea to do so is that ineffective or abnormal motility is the cause of bolus stasis and is resulting in symptoms of dysphagia.

However, the relation between findings on manometry and symptoms does not always seem clear. Bolus transport results form a close interplay between pressures, neuronal control, and contraction waves that serve to propel the bolus further down to the stomach. Recent studies have discovered the presence of a transition zone, which is a zone of diminished peristalsis at approximately one-third of the length of the esophagus, and is thought to represent a change in neural sensory afferent innervation and efferent motor control.1 If contraction waves proximal and distal to the transition zone are uncoordinated, bolus stasis may occur.2 In addition, inadequate inhibition preceding muscle contraction may also play a role in failed bolus transport.3 Although our understanding increases, the complexity of the underlying mechanisms that cause bolus transport have still to be elucidated fully.

With conventional manometry, pressures are usually measured at 5-cm intervals in the esophagus and its sphincters. High-resolution manometry (HRM) is a relatively new tool in the evaluation of esophageal motility and can be regarded as a technical improvement over conventional manometry. High-resolution manometry offers the possibility of studying peristalsis at 1-cm intervals in the entire esophagus. The obtained data sets can be represented as either conventional manometric line plots or as spatiotemporal plots (i.e., contour or color plots) to aid in the interpretation of the results.

It has been suggested that HRM improves understanding of the pathophysiologic mechanism underlying dysphagia.4–6 In particular, HRM might be useful by allowing the detection of pressure patterns that might cause stasis of the swallowed bolus. In fact, new paradigms have been developed to aid in the interpretation whether bolus clearance has occurred.7 These parameters prove to be reproducible.8 Until now, however, the gold standard for measurement of bolus transit in the esophagus has been videofluoroscopy.9–12

In this study we therefore use concurrent videofluoroscopy and HRM to investigate the relationship between transit of swallowed liquid and solid boluses and the esophageal pressure patterns.

Materials and methods

  1. Top of page
  2. Abstract
  3. Introduction
  4. Materials and methods
  5. Results
  6. Discussion
  7. Funding
  8. Disclosure
  9. Author contribution
  10. References

Subjects

Twenty healthy volunteers (9 males, 11 females, mean age 45 years, range 25–64 years) and twenty patients suffering from dysphagia (9 males, 11 females, mean age 56 years, range 27–73 years) were included in this study.

The patients were recruited from the outpatient GI clinic at the University Medical Center Utrecht or referred from regional hospitals. All patients had dysphagia as main symptom and had undergone upper endoscopy to exclude intraluminal causes of their complaints. In all cases, esophageal biopsies had been taken to exclude eosinophilic esophagitis. Conventional manometry was done before to exclude the presence of achalasia. Their medical history did not include previous GI tract surgery. The healthy volunteers were devoid of gastrointestinal symptoms or history of upper gastrointestinal tract surgery, and were without medication.

Informed written consent was obtained before the start of the study and the protocol was approved by the Medical Ethics Committee of the University Medical Center Utrecht.

Esophageal high-resolution manometry

The participants were not allowed to take any medication, smoke, or drink alcoholic beverages the day before and on the day of the measurements. Drugs known to affect esophageal motility were discontinued until after the measurements. After a 6-h fast, a 36-channel solid-state catheter (Unisensor AG, Attikon, Switzerland) was placed transnasally. The catheter was positioned with its 36 channels straddling the esophagus and its sphincters. The catheter was fixed in place by taping it to the nose. Thereafter, participants were placed in supine position. The participants were asked to collect 5 mL of barium in their mouth, which was injected by syringe, and take a single swallow of the collected material on command. This was repeated for a total of five times separated by 30-s intervals.

This was followed by a total of five single swallows of 1 cm3 cubes, composed of a barium and gelatine mixture, together with 5 mL water. Chewing of the cubes was not allowed. The cubes are made from 100 mL liquid barium mixed with 20 g of gelatine (Dr. Oetker GmbH, A-9500, Villach, Austria) and 200 mL water. Gelatine was made flexible in lukewarm water, after which it was transferred into a bowl containing 100 mL liquid barium sulphate and mixed together. After cooling, 1 cm3 cubes were cut. The cubicles were freshly prepared before every measurement. The barium sulphate was obtained from the pharmacy. All participants were asked if they perceived dysphagia after each single swallow of either liquid or solid boluses.

If the liquid barium or the barium solids were not cleared after one swallow, participants were asked to take a dry swallow. If that did not result in clearance, 5-mL swallows of water were offered until clearance was achieved on videofluoroscopic imaging.

Videofluoroscopy

Videofluoroscopy was performed concurrently with HRM with continuous imaging. Patients were placed in a supine position, and a fluoroscope (Easy Diagnost; Philips Medical Systems, Best, The Netherlands) was positioned over the chest area, shielding other parts of the body as much as possible. Recording was started each time the subject was instructed to swallow a bolus. Pressure data were digitized at a sampling frequency of 25 Hz and processed using dedicated software [Medical Measurement Systems (MMS), Enschede, The Netherlands], and installed on a personal computer containing a data acquisition card (PCI-6023E; National Instruments Corporation, Austin, TX, USA). An image acquisition card (PCI-1411; National Instruments Corporation) linked to the videofluoroscope enabled concurrent videofluoroscopy and manometry recording.

All barium swallows were ranked according to a 7-grade Likert scale as previously described by Fox et al.4 in order to grade barium clearance: (i) successful bolus transport; (ii) successful bolus clearance, minor abnormality; (iii) bolus escape, with clearance; (iv) bolus escape, delayed clearance; (v) pendular bolus movement, with clearance; (vi) pendular bolus movement, no clearance; (vii) complete failure of transport. In a binomial analysis, bolus transit was considered effective when the stasis score was ≤2 and considered as failed or stasis when the stasis score was ≥3. In addition, when a bolus was graded 3 or more, the anatomical level of stasis was noted. Stasis was called proximal if the bolus did not reach the aortic arch, whereas stasis was called mid-esophageal if the bolus stasis occurred between the level of the aortic arch and the heart contour. Stasis was called distal when the bolus stasis occurred distal to the heart contour.

Data analysis

Data were analyzed using dedicated software (MMS, Enschede, The Netherlands). Previously established criteria were used to characterize esophageal motility using pressure topography parameters, also known as the Chicago Classification.6,13–15 Measurements of lower esophageal sphincter (LES) relaxation pressure, resting pressure, and length, as well as upper esophageal sphincter (UES) pressures were facilitated by automated analysis software, referenced to gastric pressure and atmospheric pressure, respectively. Hereby, the upper limit of the LES was measured at inspiration, and the lower limit of the LES was measured at expiration. The transition zone was defined as the segment between the demarcation at the end of the proximal esophageal segment and the beginning of the distal esophageal segment in the 30-mmHg isobaric contour. Distal and proximal contraction amplitudes were measured at 5 and 15 cm above the LES, respectively. The contractile front velocity (CFV) was defined as the slope of the line connecting the points on the 30-mmHg isobaric contour at the proximal and the distal margin of the distal esophageal segment and was considered normal when <7.5 cm s−1.16 Distal contractile latency (DL) was defined as the interval between UES relaxation and the contractile deceleration point (CDP: the inflection point along the 30 mmHg isobaric contour where propagation velocity slows demarcating the tubular oesophagus from the phrenic ampulla) and was considered normal when >4.5 s.17 Distal contractile integral (DCI) quantifies the contractile activity in a space-time box by multiplying the length of the smooth muscle esophagus by the duration of propagation of the contractile wave front, and the mean pressure in the entire box excluding pressures below 20 mmHg. The DCI was considered normal when below 5000 mmHg s cm.6 Integrated relaxation pressure (IRP4) represents the lowest 4-s cumulative pressure values for the deglutitive time period through the anatomic zone defining the EGJ and was considered normal below 15 mmHg.18 Intrabolus pressure (IBP) was measured between the peristaltic wavefront and the EGJ, and was considered normal when below 15 mmHg.6 In addition, making use of the conventional line tracings, LES resting pressure was measured at end-expiration, referenced to intragastric pressure, and was considered normal if between 5 and 32 mmHg.14 Lower esophageal sphincter relaxation pressure was defined as the minimum pressure reached during relaxation after a swallow, similar to the technique used in conventional tracing analysis, and was considered normal when below 10 mmHg (<1.4 kPa).14

Peristalsis was considered normal when the following criteria were met: TZ < 3 cm, CFV < 7.5 cm s−1, IRP4 < 15 mmHg, IBP < 15 mmHg, DCI < 5000.6 Hypotensive peristalsis was defined as a normal appearing wavefront propagation with a > 3 cm defect in the 30-mmHg isobaric contour distal to the TZ.6 Hypertensive peristalsis was defined as a normal appearing wavefront propagation with a DCI > 5000.6

In the analysis of swallows with a peristaltic pattern, all contractions with a CFV < 7.5 cm s−1 were included, independent of contraction amplitude and sphincter relaxation.

Statistical analysis and presentation of data

For comparison of means of parametric data the independent samples t-test was used and for non-parametric data the Wilcoxon signed rank test was used. Fisher exact test was used for analysis of categorical data. Correlation was studied using the Spearman test. Data is presented as mean ± SEM or median [interquartile range].

Results

  1. Top of page
  2. Abstract
  3. Introduction
  4. Materials and methods
  5. Results
  6. Discussion
  7. Funding
  8. Disclosure
  9. Author contribution
  10. References

In this study, 20 patients and 20 controls were included. Of the patients, eight patients were classified as normal, one patient as having absent peristalsis, six patients as having EGJ outflow obstruction, two patients as having distal esophageal spasm, two patients as having weak peristalsis with large peristaltic defects, one patient as having nutcracker. Of the healthy controls, 13 were classified as normal, three were classified as having frequent failed peristalsis, and four as having weak peristalsis with small peristaltic defects.

Relationship between contraction pattern and bolus transit

In total, we successfully recorded 200 liquid barium swallows and 193 solid barium swallows.

Seventy percent of the liquid bolus swallows and 71.5% of the solid bolus swallows was peristaltic, the difference not being statistically significant (Table 1). There were no differences in proportion of simultaneous contractions, hypertensive peristaltic contractions, hypotensive peristaltic and absent contractions between liquid and solid bolus swallows (Table 1). An abnormal LES relaxation was seen equally often with liquid bolus swallows as with solid bolus swallows (Table 1).

Table 1.   Characteristics of esophageal contractions, LES relaxation and bolus stasis (healthy subjects and patients with dysphagia combined)
 % of all swallowsStasis score% Stasis (score ≥3)
LiquidSolidLiquidSolidLiquidSolid
  1. # < 0.05 vs other contractions; *< 0.05 vs liquid. LES, lower esophageal sphincter.

All swallows100.0100.03 [2–6]6 [5–6]*52.583.4*
Peristaltic7071.52 [1–4]#6 [3–6]#*33.6#76.8#*
Not peristaltic3028.56 [5–6]6 [6–6]*66.4100.0*
Normotensive peristalsis48.751.32 [1–2]#6 [2–6]#*21.1#72.7#*
Simultaneous9.710.96 [4–6]#6 [6–6]*94.7#76.2
Hypertensive5.16.22.5 [1–4]6 [1.5–7]*50.075.0
Hypotensive19.014.54 [2–5.5]6 [5–6]*59.582.1*
Absent21.514.56 [6–7]#6 [6–7]#94.1#100.0#
Normal LES relaxation6769.42 [2–6]6 [5–6]*48.580.6*
Abnormal LES relaxation3330.64 [1–6]6 [6–6]*60.689.8*

Liquid bolus swallows with a peristaltic pattern had a significantly lower stasis score and a lower proportion of stasis (stasis score ≤2) than swallows without a peristaltic pattern (Table 1). Swallows with normotensive peristalsis had a lower stasis score and a lower proportion of stasis than swallows with other contraction patterns while swallows with simultaneous or absent contractions had a significantly higher stasis score and were more often accompanied by stasis than other swallows (Table 1).

Solid bolus swallows with a peristaltic pattern had a significantly lower stasis score and a lower proportion of stasis than swallows with no peristaltic pattern, in fact all swallows without a peristaltic pattern showed incomplete bolus clearance (Table 1). Solid bolus swallows with normotensive peristalsis had a lower stasis score and a lower proportion of stasis than other solid bolus swallows while swallows with absent contractions had a significantly higher stasis score and were always accompanied by stasis (Table 1). Also, incomplete LES relaxation was associated with a higher stasis score and with a higher proportion of stasis.

Median stasis score was significantly lower with liquid bolus swallows than with solid bolus swallows (Table 1). Also, 52.5% of the liquid boluses were incompletely cleared vs 83.4% of the solid boluses, whereby clearance is thus significantly more often incomplete with solid boluses (Table 1).

Both for contractions with a peristaltic pattern as for contractions without a peristaltic pattern bolus stasis scores were lower for liquid boluses than for solid boluses. More specified, liquid swallows with normotensive peristaltic, simultaneous, hypertensive peristaltic or hypotensive peristaltic contraction all had a lower stasis score than solid swallows with these contraction patterns. In addition, both normal and abnormal LES relaxations are accompanied by a lower stasis score and a lower proportion of stasis for liquid than for solid bolus transit.

During liquid bolus swallows with stasis, the transition zone was significantly longer compared to swallows with normal clearance (Table 2). The DCI and pressure amplitude of peristaltic contractions at 5 cm above the LES were significantly lower in liquid bolus swallows with stasis (Table 2). Intrabolus pressure and IRP4 did not significantly differ between swallows with stasis and swallows without stasis. With increasing length of transition zone, increasingly higher stasis scores for liquid swallows were found (Fig. 1). For DCI and distal contraction amplitude, a negative relationship with stasis scores for liquids was found (Figs 2 and 3).

Table 2.   Characteristics of all peristaltic contractions (healthy subjects and patients)
 LiquidSolid
No stasis (score <3)Stasis (score ≥3)No stasis (score <3)Stasis (score ≥3)
  1. *< 0.05 vs no stasis; no differences found between liquid and solid bolus. DCI, distal contractile integral; IBP, intrabolus pressure; IRP4, integrated relaxation pressure; Distal Amp, distal esophageal contraction amplitude; Prox Amp, proximal esophageal contraction amplitude. Please note that all parameters except IRP4 were calculated for peristaltic contractions only.

Length of transition zone (cm)3.5 ± 0.25.0 ± 0.5*2.7 ± 0.43.7 ± 0.3
DCI (mmHg*s*cm)1311.6 ± 107.4753.5 ± 106.4*1534.1 ± 211.01134.3 ± 83.8
IBP (mmHg)9.3 ± 0.511.1 ± 1.28.4 ± 0.99.4 ± 0.6
IRP4 (mmHg)12.9 ± 1.011.8 ± 1.29.3 ± 1.312.6 ± 0.9
Distal Amp (mmHg)89.8 ± 5.351.6 ± 5.2*98.8 ± 8.879.2 ± 4.6
Prox Amp (mmHg)39.1 ± 3.027.9 ± 3.639.8 ± 4.341.8 ± 3.0
Distal Latency (s)6.9 ± 1.46.4 ± 3.06.9 ± 1.76.2 ± 1.7
image

Figure 1.  Transition zone (TZ) length vs stasis score for liquids and solids. With increasing TZ length, the stasis scores increase, the relationship being significant for liquid swallows.

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image

Figure 2.  Distal contraction amplitude vs stasis score for liquids and solids. With decreasing amplitudes stasis scores were higher, the inverse relationship being significant for liquid swallows.

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image

Figure 3.  DCI vs stasis score for liquids and solids. With decreasing DCI the stasis scores are higher, the inverse relationship being significant for liquid swallows. DCI, distal contractile integral.

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For solid bolus swallows, there were no differences in pressure amplitudes, DCI, IBP, and IRP4 between swallows with stasis and without stasis. For peristaltic contractions, no differences were found in contraction parameters between solid and liquid bolus swallows. No difference was found in IRP4 between liquid and solid bolus swallows.

In general, correlation between contraction parameters and stasis score was poor (Table 3). Significant correlations were found for DCI and distal contraction amplitude for stasis of liquid bolus swallows and a tendency to statistical significance was observed for correlation between stasis and transition zone length (Fig. 4A). For solid bolus swallows, only transition zone length was significantly correlated to stasis score (Fig. 4B). None of the relationships was very strong with low Rho values for all parameters. Of interest, no correlation was found between stasis score and IRP4, not for solid bolus swallows and not for liquid bolus swallows. Differences between the above mentioned parameters were not significantly different between solid and liquid bolus swallows.

Table 3.   Correlation between manometric parameters and stasis (in all subjects)
 LiquidSolid
Spearman RhoP-valueSpearman RhoP-value
  1. DCI, distal contractile integral; IBP, intrabolus pressure; IRP4, integrated relaxation pressure; Distal Amp, distal esophageal contraction amplitude; Prox Amp, proximal esophageal contraction amplitude.

Length of transition zone (cm)0.150.060.170.03
DCI (mmHg s cm)−0.180.02−0.10.17
IBP (mmHg)0.100.200.120.12
IRP4 (mmHg)−0.030.650.090.23
Distal Amp (mmHg)−0.033<0.01−0.120.11
Prox Amp (mmHg)−0.150.06−0.010.99
Distal Latency (s)−0.180.09−0.130.10
image

Figure 4.  Correlation between transition zone and liquid (A) and solid (B) stasis scores. There is a tendency to statistical significance between TZ length and liquid stasis score (Spearman R = 0.15, = 0.06), whereas statistical significance was found for solid stasis score (Spearman R = 0.17, = 0.03).

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Relationship between contraction pattern and anatomical level of stasis

Stasis of solid boluses was significantly more often seen in the proximal esophagus compared to liquid bolus swallows. When stasis occurred during liquid bolus swallows with a peristaltic pattern, it most frequently occurred in the mid or distal esophagus while when stasis occurred during swallows without a peristaltic pattern mostly the bolus did not reach the distal esophagus and stasis was seen in the proximal or mid esophagus (Table 4). A similar effect was observed for solid bolus swallows (Table 4). For liquid bolus swallows, the anatomical level at which stasis occurred with hypertensive peristaltic contractions most often was in the distal esophagus, while stasis with absent peristalsis was most often seen in the proximal esophagus (Table 4). For solid swallows, significantly more proximal stasis was seen with simultaneous contractions and absent peristalsis compared to other contraction patterns.

Table 4.   Anatomical level of stasis (in all subjects)
 LiquidSolid
ProximalMidDistal ProximalMidDistal  
  1. # < 0.05 vs other contractions; *< 0.05 vs liquid. LES, lower esophageal sphincter.

All swallows24.559.216.3 53.438.58.1 *
Peristaltic7.060.532.6#35.851.912.3#*
Not peristaltic38.258.23.643.66.450.0*
Normotensive peristalsis10.563.226.3 33.350.016.7# 
Simultaneous25.062.512.5 81.318.80.0#*
Hypertensive12.537.550.0#44.455.60.0 *
Hypotensive5.065.030.0#42.353.83.8 *
Absent37.562.50.0#89.310.70.0#*
Normal LES relaxation25.465.19.5#50.039.810.2#*
Abnormal LES relaxation22.948.628.660.435.83.8*

Comparison patients vs controls

In patients 64.0% of the liquid bolus swallows was incompletely cleared vs 41% in controls (Table 5A). The stasis score after liquid bolus swallows was significantly higher in patients than in controls (Table 5A).

Table 5.   Patients vs controls
 % of totalStasis score% stasis (score ≥3)
PatientControlPatientControlPatientControl
  1. LES, lower esophageal sphincter.

  2. # < 0.05 vs other contractions; *< 0.05 vs patients.

(A) Liquid swallows
 All swallows100.0100.04 [2–6]2 [1–5]*64.041.0*
 Peristaltic66.084.02 [2–4]2 [1–2]*45.520.2
 Not peristaltic34.026.06 [5–6]6 [5–6]100.092.3
 Normotensive peristalsis45.355.62 [1–3]1.5 [1–2]30.214.0
 Simultaneous18.91.1*6 [4–6]2 [2–2]100.00.0
 Hypertensive10.50.0*2.5 [1–4] 50.0 
 Hypotensive13.726.76 [4–6]2 [1–4]*84.645.8*
 Absent11.022.77 [6–7]6 [5.5–6]*100.0100.0
 Normal LES relaxation57.077.0*2 [2–6]2 [2–6]49.148.1
 Abnormal LES relaxation43.023.0*4 [4–6]1 [1–2]*83.717.4*
(B) Solid swallows
 All swallows100.0100.06 [5–6]6 [5–6]84.282.7
 Peristaltic67.475.56 [3–6]6 [4–6]76.677.0
 Not peristaltic32.624.56 [6–6]6 [6–7]100.0100.0
 Normotensive peristalsis53.352.06 [1–6]#6 [2–6]72.9#72.5#
 Simultaneous13.34.1*6 [6–6]6 [6–6]100.0100.0
 Hypertensive12.21.0*6 [3–7]1 [1–1]81.80.0
 Hypotensive5.623.5*6 [5–6]6 [5–6]100.078.3
 Absent10.619.47 [6–7]#6 [6–7]100.0100.0#
 Normal LES relaxation58.979.6*6 [3–6]#6 [6–6]73.285.9
 Abnormal LES relaxation41.120.4*6 [6–6]6 [4–7]94.980.0

In patients, a lower proportion of the contractions after liquid bolus swallows showed a peristaltic pattern compared to controls. Also, more simultaneous contractions (18.9%vs 1.0%) and hypertensive peristalsis (10.5%vs 0.0%) were seen in patients while absent peristalsis was frequently seen in both patients and controls (11.0%vs 22.7%). Abnormal LES relaxation was more often seen in patients.

Both in patients and controls a very high proportion of solid bolus swallows was not cleared at once (Table 5B). The stasis scores were high in both patients and controls and these were not significantly different between these groups.

With solid bolus swallows, peristaltic contractions were seen in 67.4% of the swallows in patients and 75.5% of the swallows in controls. Normal LES relaxation was significantly more often seen in controls than in patients. With solid bolus swallows, more hypertensive peristalsis and simultaneous contractions were seen in patients while more hypotensive peristalsis was seen in controls. Also, with solid bolus swallows normal LES relaxation was more often seen in controls.

Discussion

  1. Top of page
  2. Abstract
  3. Introduction
  4. Materials and methods
  5. Results
  6. Discussion
  7. Funding
  8. Disclosure
  9. Author contribution
  10. References

In this study we used combined HRM and videofluoroscopy to study the relationship between esophageal pressure patterns and bolus clearance of liquid barium sulphate swallows and solid barium gelatin cube swallows. Perhaps the most striking observation in this study is that stasis occurs very frequently after both liquid and solid bolus swallows, not only in patients but also in controls. Our data further show that even in case of normal peristalsis incomplete liquid bolus clearance occurs frequently and complete transit of a solid bolus is infrequent in both patients and controls. Apparently, it is physiological that multiple swallows are required to clear a bolus. The fact that the barium suspension we used is more viscous than water probably explains why we found a relatively high prevalence of abnormal peristalsis in controls. The observation that often multiple swallows are required to reach complete clearance is in line with previous publications showing that only after the fourth swallow the esophagus is entirely cleared from a liquid barium bolus.19 However, for routine motility tests performed in the clinical motility lab single water swallows are most commonly used as they provide a reproducible pattern. One should bear in mind however, that single water swallows are not ideal to simulate the physiological situation of eating.

Because our aim was to study the relationship between manometric patterns and esophageal bolus transit we wished to minimize the effect of other factors such as gravity. Therefore, we performed this study in a supine position. This probably may also have resulted in a higher prevalence of stasis than we would have observed in an upright position.19

Both for liquid and solid boluses the contraction pattern that is initiated by a swallow is an important factor that determines whether a bolus is transported successfully through the esophagus. When a peristaltic contraction pattern was present, the likelihood of stasis was much lower than when esophageal contractions were simultaneous or absent. Furthermore, shorter transition zone, higher DCI and higher distal contraction amplitude were associated with successful bolus transit. One can thus conclude that manometric findings (including impedance manometry) can to some extent predict successful bolus transit, as also previously reported by several others.4,20–23 However, there is substantial overlap between contraction parameters of swallows with and swallows without stasis and the correlation between stasis scores and manometric parameters is even weak to non-existent. This makes that one should be very cautious to interpret manometry results, as they can only predict transit to a certain degree.

Stasis was much more often observed with solid boluses than with liquid boluses, while the proportion of contractions with a peristaltic pattern is similar between liquid and solid bolus swallows. Moreover, the proportion of normal and abnormal LES relaxation is not very different between liquid and solid bolus transit while much more stasis occurs with solid boluses. This indicates that factors other than contraction pattern and LES relaxation determine the difference in bolus transit pattern for solids and liquids. These factors, such as bolus shape, surface and consistency, and which cannot be measured with manometry, thus play an important role in the effectiveness of bolus transport for solids.

Most often stasis of solid boluses occurred in the proximal esophagus while stasis of liquid boluses occurred predominantly at the mid-esophageal level. Besides the consistency of the medium the nature of the esophageal contraction determines if and at what level stasis will occur. When stasis of a liquid bolus occurs during a peristaltic wave, stasis most often occurs at the mid and distal esophagus. When stasis occurs when the contraction is not peristaltic, stasis usually occurs at the proximal esophagus and the bolus will not even reach the mid esophagus. For solid boluses, simultaneous and absent contractions almost always lead to stasis in the proximal esophagus, probably because there is hardly any transit with these contraction patterns after the bolus has entered the esophagus.

Of note, LES relaxation does not seem to be a major factor in determining bolus stasis. This is likely to be due to the observation that stasis most often occurs in the proximal and mid esophagus and the bolus often does not reach the distal esophagus due to failed or incomplete peristalsis. Indeed, as reported previously, LES abnormalities can be overcome by normal peristaltic esophageal body contractions.23

Usually, when the relationship between esophageal motility and bolus transit is described, one assumes that ineffective contractions are responsible for bolus stasis. However, it has been described that stasis of a bolus at a certain level in the esophagus results in abnormal contractions further distally.19 Stasis is not only caused by ineffective contractions but also results in it. The view that bolus stasis is always caused by abnormal peristalsis is thus an oversimplification of the complex relationship between wall tension and muscle contraction that eventually results in peristalsis. This is also illustrated by the observation that motility with liquid bolus swallows differs from motility seen with solid bolus swallows. Perhaps esophageal wall distension is a contributing factor in symptom generation.

In conclusion, this study shows that stasis of swallowed boluses is common, even in healthy subjects. Motility patterns can predict the effectiveness of bolus transit and level of stasis to some degree but the relationship between esophageal motility and transit is complex and far from perfect. Esophageal manometry is therefore currently deemed unfit to be used for the prediction of bolus transit, and should rather be used for the identification of treatable esophageal motility disorders.

Funding

  1. Top of page
  2. Abstract
  3. Introduction
  4. Materials and methods
  5. Results
  6. Discussion
  7. Funding
  8. Disclosure
  9. Author contribution
  10. References

AB, JO and AS have no funding interests to declare. AJB has served as a consultant to Janssen–Cilag, AstraZeneca and Movetis and is supported by The Netherlands Organization for Scientific Research. He has received speaker fees from MMS International. PS has served as a consultant to Janssen–Cilag and has received unrestricted grants from AstraZeneca, Nycomed and Janssen–Cilag, The Netherlands. The sponsors did not have a role in the design and conduct of the study; collection, management, analysis, and interpretation of the data; and preparation, review, or approval of the paper.

Author contribution

  1. Top of page
  2. Abstract
  3. Introduction
  4. Materials and methods
  5. Results
  6. Discussion
  7. Funding
  8. Disclosure
  9. Author contribution
  10. References

AB, AJB, PS and AS were responsible for study concept and design, revision and drafting the paper, analysis and interpretation of data, and statistical analysis; JO was responsible for acquisition of data; AB had access to all of the data and takes responsibility for the integrity of the data and accuracy of the analysis. He is the guarantor of the article.

References

  1. Top of page
  2. Abstract
  3. Introduction
  4. Materials and methods
  5. Results
  6. Discussion
  7. Funding
  8. Disclosure
  9. Author contribution
  10. References