Oesophageal Physiology (pH and Manometry)

Oesophageal physiology studies are usually undertaken to assess the function of the oesophagus and to investigate symptoms of gastro-oesophageal reflux in patients being considered for surgical or endoscopic intervention. It is sometimes used to assess the swallow and to assess whether symptoms of reflux are due to excess acid reflux or oesophageal hypersensitivity.

 

This test usually constitutes two parts, an assessment of oesophageal function – how well the gullet (oesophagus) works as a swallowing tube. A  tube is passed through the nose, which can cause some discomfort, over the back of the throat and down the gullet. The tip then lies within the upper part of the stomach. This tube has a number of pressure sensors spread at intervals along its length. Patients are then requested to swallow a number of aliquots of water and or solid material. A physiologist then observes the pressure within each part of the gullet as the swallow progresses. Normal swallowing is seen as a wave of contraction from the top to the bottom of the gullet, with corresponding relaxation of the area just infront of the swallow. As patients swallow the upper and  lower oesophageal sphincters should relax at appropriate moments during the observation. This test is used to assess the efficacy of the swallow in those being considered for surgery, or endoscopic intervention. It can also be used to diagnose oesophageal motility disorders such as Achalasia.

 

The second part of the test involves assessment of the extent to which either reflux of acid, belching or erucation arise, it can also detect swallowing of air or fluids. Usually the second part involves removal of the initial tube and placement of a second tube through the nose, however an alternative known as a Bravo capsule, which can be placed endoscopically may be used instead in patients where passage of nasal tubes is contra-indicated or not tolerated. The second tube has several sensor which detect either acid or changes in impedance (the assessment of how well electric current flows through a substance), which enables the detection of fluid or gas travelling up or down the oesophagus. This small tube is connected to a small box to which the recordings are downloaded and stored, for later analysis by the physiologist. The tube usually remains in place for 24 hours, although on occasion this can be longer.

 

A Bravo capsule is a small device that is placed endoscopically (upper GI endocopy) in the lower oesophagus and secured to the oesophageal wall by the endoscopist. After a period of a few days it drops off and is passed in the stools. This capsule record episodes of reflux within the part of the oesophagus in which it is secured. It then transmits this information (Bluetooth) to a receiver, usually carried in a small bow by the patient. The data can then be analysed by the physiologist when the procedure is complete.