Technical recommendations for gastro-oesophageal reflux detection
| pH-metry |
| • The sensitivity of pH monitoring to detect individual reflux events can be increased by using an optimal sampling frequency of above 1 Hz. A sampling frequency lower than 1 Hz may not detect short lived reflux events. |
| • The specificity of pH monitoring can be increased by defining a required increment of pH drop and setting a recovery time for pH to return to a value greater than pH 4. |
| • Even optimised pH criteria will have a low sensitivity and specificity for recognition of superimposed acid reflux episodes. |
| Intraluminal impedance monitoring |
| • In adults, it is considered adequate to measure impedance from three adjacent electrodes placed at 2 cm intervals, with the most distal electrode positioned 1–2 cm above the proximal margin of the lower oesophageal sphincter. An optimal arrangement of electrodes should detect at least 90% of all reflux episodes. |
| • Impedance monitoring is the only recording method that can achieve high sensitivity for detection of all types of reflux episode. |
| • Basal intraluminal impedance is abnormally low in patients with oesophageal mucosal abnormalities such as Barrett’s columnar epithelium or oesophagitis. |
| Combined pH-metry and intraluminal impedance monitoring |
| • Combined impedance monitoring and pH monitoring provides a more accurate assessment of reflux than either method alone but the decision to add impedance monitoring should be determined by the primary aim of the particular investigation. |
| • Optimal pH criteria need to be developed for recognition of different types of reflux by evaluating concurrent impedance and pH recordings, as the two methods give complementary information. |
| Oesophageal bilirubin monitoring |
| • The term “oesophageal bilirubin monitoring” should be applied to the use of continuous measurement of bilirubin concentration for recognition of reflux of duodenal contents into the oesophagus. |
| • An individual duodenogastro-oesophageal reflux episode (DGOR) is defined as beginning when the bilirubin absorbance recorded by Bilitec is more than 0.14 and the DGOR episode is considered to be terminated when the absorbance value returns to less than 0.14. |
| • While bilirubin measurement adds valuable information on the chemical nature of refluxed material, the method has some shortcomings. It requires the use of a liquid diet and cannot detect, with accuracy, either the onset or frequency of DGOR episodes. |