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Updated: Jun 21, 2026
Simultaneous Laryngopharyngeal and Conventional Esophageal pH Monitoring
Published on: December 14, 2020
Technical limitations in detection of gastroesophageal reflux in neonates
Juliann M Di Fiore1, Marina Arko, Kim Churbock
1Division of Neonatology, Rainbow Babies and Children's Hospital, Cleveland, OH 44106, USA. jmd3@case.edu
Insights
Many acid reflux events are missed by multiple intraluminal impedance (MII) monitoring, especially in preterm infants. Delayed esophageal clearance may explain these pH-only reflux events.
Area of Science:
- Gastroenterology
- Pediatric Medicine
- Diagnostic Technology
Background:
- Acid reflux is a common concern in infants, particularly preterm infants.
- Multiple intraluminal impedance (MII) monitoring is a standard tool for detecting gastroesophageal reflux.
- pH monitoring complements MII but can detect events not identified by MII.
Purpose of the Study:
- To investigate the incidence of acid reflux events detected by pH monitoring but missed by MII.
- To explore the reasons for MII's failure to detect these pH-only events.
- To identify factors associated with these missed reflux events in infants.
Main Methods:
- Studied 80 preterm and 39 term infants with documented pH-only reflux events.
- Classified MII detection failures: scoring criteria, air bolus, artifact, or no impedance change.
- Analyzed events with no impedance change for indicators like low impedance or preceding reflux.
Main Results:
- 59% of pH-detected acid reflux events were not identified by MII.
- pH-only events were more frequent in preterm infants (54%) than term infants (42%).
- The majority of missed events (64%) showed no impedance change, often linked to transient refluxate or preceding events.
Conclusions:
- A significant proportion of acid reflux events are missed by MII, particularly in preterm infants.
- Delayed esophageal fluid clearance is hypothesized as the primary reason for these discrepancies.
- Findings highlight limitations of MII and suggest underlying physiological differences in immature infants.
Objective:
Characterize the incidence and possible etiologies of acid reflux events detected by pH and not identified by multiple intraluminal impedance (MII) monitoring.
Materials And Methods:
Acid reflux events detected by pH but not identified by MII (pH-only) were documented in 80 preterm and 39 term infants. Reasons for failure of MII to detect these events were classified as failure to meet MII scoring criteria, presence of an air bolus, technical artifact, and no change in impedance. Events with no change in impedance were stratified to low impedance throughout the study (possible esophageal inflammation), transient decrease in pre-event impedance (presence of refluxate), occurrence <30 seconds of a preceding event, and no explanation.
Results:
A total of 2572 events were detected by pH, with 59% of events not identified by MII. A higher incidence of pH-only events occurred in preterm versus term infants (54 +/- 27% versus 42 +/- 23%, P = .025, respectively). Thirteen percent of pH-only events were missed due to MII scoring criteria, 12% due to technical artifact, 11% due to an air bolus, and 64% had no change in impedance. Of the 978 events with no change in impedance, 154 were associated with low impedance throughout the study, 430 with a transient decrease in pre-event impedance, and 175 were preceded by a reflux episode within 30 seconds.
Conclusions:
There was a high incidence of acid reflux events detected by pH but not identified by MII. This occurred more often in the least mature infants, and we speculate that delayed esophageal fluid clearance is the major underlying mechanism.
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