The Clinical Significance of a Prolonged Stable pH around
4.0 in 24-h pH Monitoring
Yasuhiro Watanabe and Anthony G. Catto-Smith
J Pediatr Gastroenterol Nutr 19: 50-57, 1994
from: Departments of General Surgery and Gastroenterology, Royal Children's
Hospital, Melbourne, Australia
Esophageal acidity may remain stable for long periods
at or near pH 4.0, potentially influencing the estimation of risk of esophagitis
in esophageal pH monitoring assessment. Our aim was to determine the frequency
and clinical significance of a prolonged stable pH around 4.0 (PSpH4) (pH
3.5-4.5) by retrospective examination of 503 pH records from children and
by analysis of clinical information, pH parameters , motility studies, and
esophageal biopsies. The frequency , duration, and proportion of total time
with PSpH4 were quantified, and the ratio of the time for which the pH was
<pH 4.0 during PSpH4 episodes to the total reflux time below pH 4.0 was
calculated [stable/reflux (S/R) rate]. One hundred fifty-eight PSpH4 episodes
were identified in 80 records. The average duration was 60 min and the S/R
rate was 30%. Sixty-one percent of PSpH4 episodes started in the postprandial
period (p < 0.05). Proportionally more episodes of PSpH4 occurred with
an increased total percentage reflux time (p < 0.01). In recordings with
PSpH4, the average number of reflux episodes remained normal, even when
the percentage reflux time was >=10%. No correlation was shown between
PSpH4 and esophageal dysmotility , esophagitis , cardiorespiratory symptoms,
or prematurity. PSpH4 did not occur in recordings obtained after fundoplication.
We conclude that PSpH4 is common and may result in an overestimation of
risk of esophagitis . Qualitative assessment of pH monitoring is necessary
along with conventional quantitative measurements.
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