Esophageal Manometry and pH-Impedance Studies in Gastro-Esophageal Reflux Disease
The first attempts at measuring the pH changes in Gastro-esophageal reflux disease (GORD) were made by Tuttle et al, who in 1960 used a glass pH electrode to demonstrate a gradual sloping gradient in the gastro-esophageal pH gradient in patients with esophagitis in contrast to a sharp one in normal subjects(1).Later, Johnson and DeMeester developed a dependable external electrode in 1974, successfully using it to measureesophageal pH changes for up to 24 hours(2). During the last decade, further studies demonstrated thatthe use of combined pH-impedance monitoring was more effective compared to pH monitoring alone in clinical practice.
Kronecker…show more content… Detection of periods of esophageal acidification allows for a direct diagnosis of episodes of gastro-esophageal reflux and quantification of the exposure of the distal esophagus to acid(2). For ambulatory monitoring, the basic equipment should include a data logger and an event marker to signal symptoms and other events during the period of recording. Reflux is defined as a drop in pH below 4. The number of episodes of reflux and the acid exposure time (the % of time with the pH <4) is recorded.The acid exposure time has been shown to positively correlate with the degree of mucosal damage. Although routine studies are performed with one distal pH sensor, experimental studies using multiple pH sensors allow evaluation of the proximal extent of the reflux(4). However, pH studies do not give a measurement of the volume of the reflux. Wireless pH monitoring using a capsule is a fairly recent advancement which is more tolerable to the patient, but is limited by cost.
Intraluminal Impedance Monitoring
Impedance monitoring includes the concurrent measurement of impedance from multiple intraluminal recording segments of an impedance catheter positioned within the esophageal body (5). The different patterns of electrical conductivity of gas, liquid or mixed content allows their distinction. It is also possible to distinguish between resting states, bolus transit, and wall contraction. The sequence of impedance changes allow