Direct Comparison of Impedance, Manometry, and pH Probe in Detecting Reflux Before and After a Meal

P1: KEGsjny355-ddas-502901 DDAS.cls August 10, 2005 23:57Digestive Diseases and Sciences, Vol. 50, No. 9 (September 2005), pp. 15841590 ( C 2005)DOI: 10.1007/s10620-005-2901-5Direct Comparison of Impedance, Manometry,

and pH Probe in Detecting Reflux Before

and After a MealSTEVEN SHAY, MD, and JOEL RICHTER, MDCombining GERD tests allows strengths and weaknesses of each method to be identified in detecting

and characterizing reflux (RE). Aim of this study was to compare two methods that measure bolus

volume of a refluxant (impedance monitoring (Imp) and manometry (common cavity)) to pH monitoring which measures changes in acid concentration of a refluxant. Nineteen symptomatic GERD

patients and 10 normal volunteers were studied before and after a meal. All had 2-hr simultaneous

manometry, pH, and Imp (six sites: 3, 5, 7, 9, 15, 17 cm above LES). Reflux by pH was a fall

in pH from above to below 4. There were 973 REs in all subjects, but only 19% were detected

simultaneously by all three methods. Imp detected more REs (96%) than manometry (76%) or pH

probe (28%). Imp was the only method to detect 15% (144/973) of REs, while detection only by pH

probe (2%) or manometry (2%) was rare. Most REs detected by Imp were detected simultaneously

by manometry (75%,720/937). Those not detected by manometry were usually in blind spots either

in the vulnerable period 23 sec after a swallow, during a posture change, or during a Valsalva. Most

REs detected by Imp were not detected by the pH probe. Though most liquid REs fasting were

detected by pH, most liquid postprandial REs were not, due primarily to weakly acidic rather than

superimposed acid REs. Bolus clearing time by Imp and manometry was nearly identical, while acid

clearing was threefold longer than bolus clearing by Imp or manometry. In conclusion, impedance

monitoring is better than manometry and pH monitoring in RE detection before and after a meal,

and manometry in determining RE composition as liquid or gas. The pH probe measures RE acidity

and acid clearing. Simultaneous impedance and pH combines the two methods strengths, and is a

powerful tool for reflux detection and characterization.KEY WORDS: impedance monitoring; pH monitoring; esophageal manometry; GERD.or 1000 cc. (1) In contrast to the pH probe, manometry

and impedance monitoring detect reflux...