Combining gastroesophagael reflux disease (GERD) tests allows strengths and weaknesses of each method to be identified in detecting reflux.
Dr Steven Shay and colleagues compared 2 methods that measure bolus volume to pH monitoring, which measures change in acid concentration of a refluxant.
The methods for measuring bolus volume of a refluxant included impedance monitoring and manometry.
The researchers studied 19 symptomatic gastroesophagal reflux disease patients and 10 normal volunteers before and after a meal.
All had 2-hour simultaneous manometry, pH, and impedance monitoring.
The team measured reflux by a fall in pH from above to below 4.
There were 973 reflux in all subjects, but only 19% were detected simultaneously by all 3 methods.
Impedance monitoring detected 96% of reflux's, 76% were detected by manometry, and 28% by pH probe.
Researchers found that impedance monitoring was the only method to detect 15% of reflux's, while detection only by pH probe or manometry was rare.
Most reflux's detected by impedance monitoring were detected simultaneously by manometry.
|Impedance monitoring detected 96% of reflux's vs 28% detected by pH probe|
|Difestive Diseases & Sciences|
The team noted that reflux's not detected by manometry were usually in blind spots either in the vulnerable period 2 to 3 sec after a swallow.
Reflux's during a posture change, or during a Valsalva were also not detected by manometry.
The researchers observed that most relux's detected by impedance monitoring were not detected by the pH probe.
Though most liquid reflux's fasting were detected by pH, the researchers found that most liquid postprandial reflux's were not.
The research team noted that this was due primarily to weakly acidic rather than superimposed acid reflux's.
Bolus clearing time by impedance monitoring and manometry was nearly identical.
In comparison, the team detected that acid clearing was 3-fold longer than bolus clearing by impedance monitoring or manometry.
Dr Shay's team conclude, “Impedance monitoring is better than manometry and pH monitoring in reflux detection before and after a meal, and manometry in determining reflux composition as liquid or gas.”
“The pH probe measures reflux acidity and acid clearing.”
“Simultaneous impedance and pH combines the two methods strengths, and is a powerful tool for reflux detection and characterization.”