Coordination Versus Pressure in Oesophageal Peristalsis
Condition: Gastroesophageal Reflux
MeSH terms: Gastroesophageal Reflux
Study type: Observational

Summary: 
      High Resolution Manometry (HRM) is a new advance in oesophageal measurement that permits the
      acquisition of pressure data through the entire length of the oesophagus over time via
      closely spaced sensors that continuously record the motor activity of the oesophagus. This
      allows not only contractile pressure to be measured, but also the coordination
      (proximal-distal) of contractions and the development of effective intra-bolus pressure (the
      force that drives bolus movement).

      The study hypothesis is that (1) there will be a progressive increase in peristaltic pressure
      and decrease in velocity as the subjects move from the upright, through the supine to the
      upside down position and (2) the increase in pressure will be most evident in the
      mid-oesophagus at the transition zone between the striated and the smooth muscle
      contractions.
    

Detailed description: 
      Introduction High Resolution Manometry (HRM) is an advance in oesophageal measurement that
      permits the acquisition of pressure data through the entire length of the oesophagus over
      time via closely spaced sensors that continuously record the motor activity of the
      oesophagus. This information can then be analysed either as conventional line plots or as a
      spatiotemporal plot, a compact, visually intuitive presentation of oesophageal pressure
      activity.1 This process has been quantified and verified in 75 normal volunteers.2 Increasing
      evidence suggests that HRM is a more sensitive and accurate means of assessing oesophageal
      function compared to conventional manometry.1 3 Compared to conventional manometry, HRM
      increases the accuracy with which the success of bolus transport can be predicted.1 This is
      important because oesophageal symptoms are more closely linked to impaired bolus transport
      than conventional pressure measurements per se.4

      The additional information provided by HRM and the presentation of data as a spatiotemporal
      plot enable investigators to study the pressure activity in the oesophagus during normal
      eating behaviour for the first time. This study will assess the effects of position, bolus
      volume and consistency (liquid, solid). In addition, pressure activity during a standardized
      test meal will be observed.

      Understanding the oesophageal response due to these 'physiologic challenges' is likely to be
      of clinical importance because most patients complain of swallowing problems, regurgitation
      or chest pain during such events and in the postprandial period. This is in contrast to
      standard manometry protocols that include the intake only of individual water, viscous fluid
      (e.g. yoghurt) or small, solid bolus swallows.

      Healthy controls will be studies to provide normal data. Patients referred for investigation
      of oesophageal symptoms will be studied to assess whether physiologic challenge increases the
      ability to differentiate this group from normal controls, explain patient symptoms and
      increase diagnostic yield.

      Effects of Position It is well known that transient lower oesophageal sphincter relaxations
      (TLOSRs) and reflux events are suppressed in the supine position in both healthy volunteers
      and in patients with mild-moderate reflux disease.7 The effects of position on oesophageal
      peristalsis and lower oesophageal sphincter pressure assessed by conventional manometry have
      been less consistent.

      Recently HRM and video-fluoroscopy has been applied to study the effect of position and bolus
      consistency on oesophageal function.8 No effect of position on LOS pressure was found in
      these thin, healthy volunteers. In contrast peristaltic pressure increased and velocity
      decreased as the subject moved from the upright to the supine position. Similarly,
      peristaltic pressure increased and velocity decreased progressively as the subject took dry,
      water and solid swallows.8 These observations confirm combined manometry and impedance
      studies that show oesophageal function is not stereotyped but responds to the workload
      required for bolus transport. 5 67

      Although findings are consistent for a given individual, variation in peristaltic contractile
      pressure is high and the correlation between peristaltic pressure and the success of bolus
      transport in healthy volunteers and patients is weak. Rather, preliminary observations by Fox
      et al. suggest that successful bolus transport, especially for solids, may depend more on
      effective coordination between proximal (striated) and mid-distal (smooth muscle)
      contractions than increased peristaltic pressure. In particular the prompt response of the
      mid-oesophageal segment appears to be linked to successful bolus transport through the
      oesophagus.8

      Swallowed material can be transported successfully through the oesophagus in the upside down
      position. With the use of HRM, a detailed analysis of oesophageal peristalsis and bolus
      transport from the pharynx to the stomach is possible. We propose to explore the effect of 3
      different positions (upright, supine and 60o head down) on the swallow of liquid and viscous
      material in healthy volunteers. Use of the extreme head down position provides a classical
      physiologic challenge that will highlight the oesophageal response to increased work against
      gravity.

      Further events that increase oesophageal workload include the rapid intake of large volumes
      of fluid (i.e. free drinking) and the intake of solid food (i.e. test meal). Following the
      studies of position on oesophageal function, we will then assess the effect of drinking a
      standardized fluid load by multiple repeated swallows and intake of a standardized test meal
      on oesophageal and lower oesophageal sphincter function. Observations will be continued for
      20minutes after ingestion to assess also oesophago-gastric function in the postprandial
      period.

      Study hypothesis The driving force developed by oesophageal motor function 'increases'
      progressively with workload (e.g. increasing inclination, solid food) in healthy volunteers.

      Hypothesis #1: This 'increase in driving force' will be more apparent and consistent as an
      increased in coordination of peristaltic contractions and development of intra-bolus pressure
      (i.e. endpoints assessed only by HRM) than effects on contractile pressure (i.e.; endpoints
      assessed also by conventional manometry).

      Repeated swallowing during drinking suppresses oesophageal contractility. Hypothesis #2:
      Intermittent, coordinated and powerful peristaltic waves will be observed during a test meal
      and failure of this activity will result in raised intra-bolus pressure and symptoms
      (dysphagia, regurgitation, chest pain).

      Hypothesis #3: Observations during and after a test meal will increase diagnostic yield for
      rumination and reflux related symptoms during stationary studies.
    

Observational model: Cohort
Time perspective: Prospective
Sampling method: Probability Sample
Study population: 
        Healthy controls and patients presenting with symptoms of reflux and endoscopy negative
        dysphagia
      
Keywords: Esophagus; Peristalsis; Contractile Pressure; Coordination of contraction; Bolus transport; Esophageal function