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Keywords:

  • body position;
  • oesophago-gastric junction;
  • oesophageal high resolution manometry

Abstract

  1. Top of page
  2. Abstract
  3. Introduction
  4. Methods
  5. Results
  6. Discussion
  7. References

Background  Oesophageal motility classification using high resolution manometry (HRM) has been established in the supine position. Nevertheless, examination in the sitting position is more physiological. Our aim was to determine if body position modifies oesophago-gastric junction (OGJ) morphology and oesophageal motility.

Methods  A total of 100 patients (47 males, mean age 51 years) were included in this study. The oesophageal HRM protocol included examination in supine and sitting positions. Recordings were reviewed by two different operators. Amplitude, duration, velocity, Distal Contractile Integral (DCI) and Pressurization Front Velocity of oesophageal waves induced by swallowing were recorded.

Key Results  The lower oesophageal sphincter resting pressure was not significantly changed by body position. The sitting position modified the OGJ classification in 12 patients. The inter-observer agreement to classify OGJ was moderate (kappa = 0.54 and 0.46, in the supine and sitting positions respectively) while it was good to diagnose motility disorders (kappa = 0.72 and 0.83). The percentage of normal waves was lower in the sitting position in comparison with the supine position (56%vs 67%, < 0.01). The DCI was also lower in the sitting position (1125 mmHg.s.cm vs 1639, < 0.01) as well as the amplitude of oesophageal waves. Finally the diagnosis was concordant in both positions in 72 patients.

Conclusions & Inferences  Body position can affect OGJ morphology and oesophageal motility assessment by HRM in some patients. Normal values in the sitting position should thus be determined. Inter-observer variation for the proposed classification of OGJ morphology must also be taken into account.


Introduction

  1. Top of page
  2. Abstract
  3. Introduction
  4. Methods
  5. Results
  6. Discussion
  7. References

High resolution manometry (HRM) with topographic plots for assessment of oesophageal motor function was first described by Clouse and Staiano in the 1990s.1 An entire pressure profile from the pharynx to the stomach can be studied simultaneously using this technique. Thus, motility of the whole oesophagus can be recorded at the same time. The transition zone between striated and smooth muscle and segmental motility abnormalities are easily identified. Moreover, the three-dimensional spatiotemporal representation of pressure variations facilitates analysis of oesophageal contractions.2

The oesophago-gastric junction (OGJ) morphology can also be assessed accurately thanks to closely spaced pressure sensors. The relative positions of the lower oesophageal sphincter (LOS) and the crural diaphragm (CD) are easy to identify.3 The separation by more than 2 cm of these two OGJ components indicates a hiatal hernia.3

Thus oesophageal HRM cannot only improve the diagnosis of oesophageal motility disorders4,5 but also the evaluation of OGJ.

Based on the pressure topography characteristics, a new classification of oesophageal motility disorders has been proposed by Pandolfino et al.6,7 Analysis of oesophageal motility is performed in supine position. Nevertheless, examination could be more physiological in upright or sitting positions and can be easily realized with solid-state sensors HRM.

Body position affects normal distal oesophageal peristalsis and LOS pressure. Previous studies using conventional manometry showed that amplitude wave contractions and LOS tone are lower in upright than in recumbent positions.8,9 The same has been described with HRM in healthy volunteers.10 Therefore, the diagnosis of oesophageal motility disorders based on amplitude pressure could be affected by body position. Moreover, to our knowledge the effect of position on OGJ morphology has not yet been studied with HRM.

Our aim was to determine if body position modified OGJ morphology and the diagnosis of oesophageal motility disorders in patients.

Methods

  1. Top of page
  2. Abstract
  3. Introduction
  4. Methods
  5. Results
  6. Discussion
  7. References

Patients

Between October 2008 and March 2009, 115 consecutive patients (55 males, 60 females, mean age 50 years) were referred to our laboratory for oesophageal HRM.

Fifteen patients were excluded from the study because: (i) the examination was performed only in the supine position in six patients; (ii) impossibility to get the catheter tip through the OGJ in five patients (2 achalasia, 2 dysphagia after Nissen fundoplication, 1 dilated oesophagus after gastric banding); and (iii) incomplete protocol due to poor tolerance in four patients. Finally, the data were analysed in 100 patients (47 males). Patients’ characteristics are summarized in Table 1. With regard to clinical data, we only reported the main indication for the test, as our goal was to determine the reliability of manometry findings in supine and sitting positions.

Table 1.   Patients’ characteristics (= 100)
  1. BMI, body mass index.

Mean age (range) in years51 (14–86)
Sex (male/female)47/53
Mean BMI (range) in kg m−224.6 (16.8–37.5)
Indications for manometry
 Gastro-oesophageal reflux disease43
 Dysphagia32
 Thoracic pain10
 Systemic sclerosis7
 Systematic post-Nissen fundoplication evaluation5
 Postgastric banding dilated oesophagus2
 Aerophagia1
Previous surgical history (19%)
 Nissen fundoplication15
 Heller myotomy2
 Gastric banding2

HRM protocol

Manometric data were obtained using a solid-state manometry assembly with 36 circumferential sensors spaced at 1-cm intervals (Sierra Scientific Instruments Inc., Los Angeles, CA, USA). Studies were performed in the fasting state. The manometric probe was inserted transnasally in a supine patient and positioned to record from the hypopharynx to the stomach using at least three intragastric sensors. The catheter was fixed in place by taping it to the nose. The manometric protocol included a recording in both supine and sitting positions. The recording started in the left lateral supine position with a 30-s basal period without swallowing, followed by two deep breaths (to identify the diaphragm position), and five 5-mL water swallows. Then, the patient sat down and the same sequence was repeated. Finally, repeated swallowing in the sitting position was studied during free drinking of 100 mL of water. The patient was asked to drink as fast as possible 100 mL of water with a straw.

Data analysis

Manometric data were analysed using Mano View analysis software (Sierra Scientific Instruments Inc.).

Oesophago-gastric junction was classified as proposed by the Chicago group3 during a basal period of 30 s without swallowing in supine and sitting positions independently by two different operators (SR and FM). The two observers were blind to clinical presentation. Briefly OGJ type I was defined when separation of the highest pressure of LOS and CD was indiscernible or <1 cm, type II when LOS-CD separation was >1 cm and <2 cm and type III when LOS-CD separation was >2 cm. In case of disagreement, manometric recordings were reviewed by the two operators to obtain a consensus.

End expiratory OGJ tone was measured during the basal period without swallowing in supine and sitting positions. OGJ relaxation pressure was assessed using an automated measurement of the integrative relaxation pressure over a 4-s interval (4-s IRP) within the postdeglutitive period during five 5-mL water swallows in both positions and during free drinking. Oesophageal waves were analysed using automated analysis and systematically and independently reviewed by two operators (SR and FM). They were characterized with amplitude, duration, velocity, Distal Contractile Integral (DCI) and Pressurization Front Velocity (PFV). The oesophageal motility abnormalities were classified as proposed by a consensus of experts.7 Hypertensive peristalsis and spastic nutcracker were lumped together as well as intermittent and frequent hypotensive persitalsis. In case of disagreement, manometric recordings were reviewed by the two operators to obtain a consensus.

Statistical analysis

The agreement between the two observers to classify OGJ morphology and to diagnose oesophageal motility disorders was assessed using the kappa coefficient (95% CI).

The HRM results (OGJ tone, OGJ relaxation pressure, wave amplitude, duration and velocity, DCI, PFV) were expressed as a mean (SEM). Data in supine and sitting positions were compared using paired t-test. P-values <0.05 were considered as significant.

Results

  1. Top of page
  2. Abstract
  3. Introduction
  4. Methods
  5. Results
  6. Discussion
  7. References

Oesophago-gastric junction

The mean resting LOS pressure was not significantly changed by body position nor the mean residual LOS pressure (Table 2).

Table 2.   Manometric data according to body position
 Supine positionSitting positionP (supine vs sitting)Free drinkingP (sitting position vs free drinking)
  1. LOS, lower oesophageal sphincter; DCI, distal contractile integral; PFV, pressurization front velocity. *During 5-mL liquid swallow.

Basal LOS pressure (mmHg)8.1 (1.1)7.1 (1.2)0.31  
Residual LOS pressure (mmHg)*4.4 (0.6)4.8 (0.6)0.922.3 (0.7)<0.01
Wave amplitude (mmHg)*71 (4)60 (4)<0.0157 (6)0.17
Wave duration (s)*3.4 (0.1)3.2 (0.1)<0.013.5 (0.2)0.12
Wave velocity (cm s−1)*5.5 (0.4)6.0 (0.7)0.325.1 (0.9)0.79
DCI (mmHg.cm.s)*1639 (194)1126 (130)<0.011896 (443)0.11
PFV (cm s−1)*7.1 (1.7)6.1 (1.1)0.435.0 (0.7)0.73

Oesophago-gastric junction classification was discordant between the two operators in 26% of patients in the supine as well as in the sitting position. The inter-observer agreement was moderate in the supine position [kappa = 0.54 (0.40–0.69)] and in the sitting position [kappa = 0.46 (0.28–0.65)]. The inter-observer agreement was poorer for the 15 patients with previous Nissen fundoplication [kappa = 0.38 (−0.07–0.80) and 0.11 (−0.53–0.74) in supine and sitting positions respectively]. Finally, when OGJ was described in two groups (types I and II vs type III) the inter-observer agreement was slightly better [kappa = 0.58 (0.4–0.76) in the supine position and 0.61 (0.40–0.82) in the sitting position].

The OGJ consensus classification according to body position is reported in Table 3. Body position modified the OGJ morphology in 12 patients only: three patients with type II in the supine position were found type I in the sitting position, and nine patients with type III in the supine position were found type I in the sitting position (four cases) or type II (five cases).

Table 3.   Oesophago-gastric junction type according to body position
 Supine position
Type IType IIType IIITotal
Sitting position
 Type I653472
 Type II0358
 Type III002020
Total65629 

Body oesophageal motility

The mean percentage of normal waves (defined as an intact 30 mmHg isobaric contour)6 was lower in the sitting position in comparison with the supine position (56%vs 67%, = 0.0001). Moreover, postdeglutitive oesophageal contraction waves were more often absent in the sitting position (mean percentage of absent waves in the supine position 13%vs 20% in the sitting position, = 0.01).

As shown in Table 2, the DCI was lower in the sitting position as well as the mean distal amplitude of oesophageal waves. On the opposite, PFV remained unchanged as well as the velocity of oesophageal waves.

Free drinking

In sitting position, free drinking induced a deeper relaxation of LOS than 5-mL swallows (Table 3). The contraction wave following repeated swallowing was absent in 34 patients (12 patients with peristaltic dysfunction, 6 normal, 4 scleroderma, 4 achalasia, 4 spasms, 3 patients with hypotensive LOS, 1 aperistalsis). When the wave was present, the amplitude, velocity, duration, DCI and PFV were the same as after 5-mL water swallows in the sitting position.

Diagnosis of oesophageal motility disorders

The diagnosis of oesophageal motility disorders was concordant between the two operators in 79% of patients in the supine position and in 88% in the sitting position. The inter observer agreement was good in the supine position [kappa = 0.72 (0.60–0.82)] and very good in the sitting position [kappa = 0.83 (0.74–0.91)].

The diagnosis based on the expert consensus classification7 remained unchanged in both positions in 72 patients. Table 4 describes the diagnosis made according to body position.

Table 4.   Diagnosis according to expert consensus classification in supine and sitting position Thumbnail image of

In patients classified as normal in the supine position, wave amplitude, wave duration and DCI decreased in the sitting position [70(5) mmHg vs 86(5), < 0.01, 3.3(0.1) s vs 3.5(0.1), = 0.02 and 1199(128) mmHg.cm.s vs 1756(168), < 0.01, respectively]. In patients with hypotensive peristalsis in the supine position, we observed a decrease of the percentage of normal waves (35%vs 51%, < 0.01), wave amplitude 39 (3) mmHg vs 45(3), = 0.02) and DCI [511(68) mmHg.cm.s vs 756(84), < 0.01] in the sitting position. Patients with functional obstruction had a decreased wave amplitude in the sitting position [52(9) mmHg vs 69(11), < 0.01] and a decreased DCI [904(216) mmHg.cm.s vs 1531(310) = 0.02]. Finally, no significant change in manometric data was observed in patients diagnosed with achalasia, aperistalsis, distal oesophageal spasm or hypertensive peristalsis in supine position.

Discussion

  1. Top of page
  2. Abstract
  3. Introduction
  4. Methods
  5. Results
  6. Discussion
  7. References

Our study clearly demonstrates that body position affects the results of oesophageal HRM in some patients. Compared to the supine position, wave amplitude, duration and DCI were significantly decreased in the sitting position while LOS pressure was not modified. In our study inter-observer agreement for OGJ classification was moderate whereas it was good to diagnose motility disorders. With regard to the recently proposed consensus classification,7 body position must be taken into account: hypotensive peristalsis and aperistalsis were more frequently seen in the sitting position. Thus, normal values of oesophageal HRM should be determined in both sitting and supine positions.

The inter-observer discrepancy to classify OGJ may be due to OGJ mobility. Indeed intermittent spatial separation of diaphragm and LOS is frequent especially in patients with gastro-oesophageal reflux disease (GORD).11 We tried to limit this potential bias by having the two operators assessing OGJ morphology on the same 30 s windows. However, the inter-observer agreement was even worse in patients after fundoplication, a situation known to decrease OGJ instability.12 In these cases, the pressure topography of OGJ is altered by the constructed fundic wrap. This wrap elongates the subdiaphragmatic component of OGJ pressure 13 and can be mistaken with LOS or CD pressure.

Contrary to previous publications,8,14 body position did not modify LOS pressure in our series. This absence of decreased LOS resting pressure in the sitting position may be explained by the fact that the mean resting pressure in the supine position was low in our study (8.1 mmHg in our series vs 17.8 to 20.1 mmHg in Bernhard et al. series).14 We included a high proportion of patients with GORD (43%) whereas Bernhard et al. had only 22% of GORD patients.

As previously reported, body position affects motility disorder diagnosis.14 The use of supine normal values to interpret upright or sitting manometric studies would also result in diagnosing in excess peristaltic dysfunction. Indeed we observed like others8–10,15 that swallowing in sitting position was associated with lower contraction amplitude. As shown previously, the workload required for bolus transport is decreased in the sitting position:10,15,16 this should explain the decrease of wave amplitude and DCI we observed in the sitting position. Therefore, this decreased amplitude of contraction wave leads to overdiagnose hypotensive peristalsis in the sitting position if supine normal values are used. In our series the diagnosis of hypotensive peristalsis made in the sitting position represents the main cause of discrepancies [16 out of 28 (57%)] between both positions. Tutuian et al.9 observed in a series of 80 healthy volunteers, 34% of ineffective motility when interpretation of upright oesophageal manometry was based on supine values. Likewise, Bernhard et al.14 noted a lower proportion of patients with normal manometry and a higher proportion of ineffective oesophageal motility in upright position in comparison with recumbent position. With regard to the identification of hypotensive peristalsis depending on body position, our results confirm that the decrease in contraction amplitude induced by the sitting position must be taken into account.

Finally, five swallows in supine and sitting positions instead of 10 in both positions may be insufficient due to the intermittent nature of oesophageal motility and could explain some of the observed differences. For example, a case of achalasia in the supine position turned out in functional OGJ obstruction in the sitting position: contraction waves were absent in the first part of the examination in the supine position although they were present at the end of the examination in the sitting one. More swallows in the supine position may have modified the diagnosis. We had to choose between the repetitive and time-consuming performance of 20 swallows vs a more practical approach of 10 swallows: the latter approach was favoured in the absence of definite data in the literature.

Body position did not modify contraction velocity contrary to previous studies.8,10,17 The observed change of velocity was moderate and could depend on the location of the perfused catheters: propagation times were shorter in the upper oesophagus and longer in lower oesophagus in the upright position in the study of Kaye et al.17 More recent studies using solid-state sensors failed to demonstrate a significant influence of body position on wave velocity in healthy volunteers.15,18

In conclusion, HRM by allowing simple examination of oesophageal function in supine and upright positions may significantly improve the diagnosis yield of oesophageal manometry. However, the body position-induced change of OGJ morphology and oesophageal waves’ characteristics implies the establishment of normal values in upright and supine positions. A classification of oesophageal motility disorders taking into account both positions may be helpful.

References

  1. Top of page
  2. Abstract
  3. Introduction
  4. Methods
  5. Results
  6. Discussion
  7. References
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