Dr John Pandolfino and colleagues from Illinois compared esophageal acid exposure data obtained during simultaneous esophageal pH studies.
The research team compared the use of the Bravo wireless and the Slimline catheter-Mark III Digitrapper pH systems.
The team reported that 25 asymptomatic subjects underwent endoscopy with endoclip placement at the squamocolumnar junction and manometry to localize the lower esophageal sphincter.
A Bravo capsule was placed 6 cm above the squamocolumnar junction and a Slimline catheter 5 cm above the lower esophageal sphincter and relative positions were checked fluoroscopically.
The researchers compared synchronized pH data by manual extraction into Excel spreadsheets and an in vivo pH reference was established with swallows of orange juice.
|Acid exposure time was greater with Slimline compared to Bravo systems|
|American Journal of Gastroenterology|
The team found that the median acid exposure time was greater with the Slimline compared to the Bravo system but electrode positions were similar.
The researchers noted that the dominant source of discrepancy between systems was an offset in recorded pH values around pH 4 as evidenced by the recorded values of the swallowed orange juice.
Bench-top testing suggested that this offset was attributable to the software designed to compensate for the difference in electrode recording characteristics between room and body temperature.
After adjusting the pH data sets to accurately reflect actual orange juice pH, the researchers observed that acid exposure between systems was similar.
Dr Pandolfino's team concludes, “The Slimline system on average over-recorded esophageal acid exposure compared to the Bravo system largely because of a flawed software scheme for electrode thermal calibration.”
“Accuracy of pH data sets from both systems can be improved by scrutiny for artifacts and use of an in vivo pH reference.”