Analysis of pH dynamics in the distal esophagus utilizing
pH histograms and acid clearance values
Yasuhiro Watanabe, Takuji Todani, Akira Toki
Pediatr Surg Int 7: 345-350, 1992
Existing scoring systems for 24-h esophageal pH recordings
rely heavily on total duration of acid reflux; little is known or understood
of the significance of dynamic aspects of esophageal acid clearance. The
24-h pH profile and rate of acid clearance in the lower esophagus was analyzed
in children with clinical features of gastroesophageal reflux (GER) . Twenty-four-hour
histograms of pH and time were developed with whole-pH data obtained by
24-h pH monitoring, and values for acid clearance were calculated from actual
pH curves. The acid clearance value represented the average time in seconds
to recover I pH unit from the lowest pH to pH 4.0. Clearance values greater
than 100 s/pH were considered to be abnormal. Sixty-six recordings were
analyzed. Five types of pH profile were characterized: (1) a "normal"
pattern in which esophageal pH did not fall below pH 4.0 and the acid clearance
value was 67.9+-41.1 s/pH (mean +- SD); (2) a "long-tail" pattern
with a moderate number of reflux episodes and rapid acid clearance. The
mean acid clearance value was 78.1+-46.4 s/pH; (3) an "intermediate"
pattern with esophageal pH at or near 4.0 for prolonged periods where the
mean acid clearance value was significantly delayed (285.6+-109.8 s/pH);
(4) a "pseudo-GER" pattern with moderate reduction in pH during
reflux episodes, but with prolonged acid clearance. The mean acid clearance
value was 175.1+-93.0 s/pH; and (5) a "GER" pattern; this was
associated with either infrequent acid reflux and delayed acid clearance,
or frequent reflux episodes and rapid acid clearance. The mean acid clearance
value was 160.3+-113.6 s/pH. Dynamic analysis of acid clearance in the esophagus
may be useful therapeutically.
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