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Simultaneous monitoring of gastric and oesophageal pH reveals limitations of conventional oesophageal pH monitoring in milk fed infants
  1. D J Mitchella,
  2. B G McClurea,
  3. T R J Tubmanb
  1. aThe Nuffield Department of Child Health, The Queen's University of Belfast, Institute of Clinical Science, Grosvenor Road, Belfast BT12 6BJ, UK, bJubilee Maternity Hospital, Lisburn Road, Belfast BT9 7AB, UK
  1. Dr D Mitchell, Regional Neonatal Intensive Care Unit, Royal Maternity Hospital, Grosvenor Road, Belfast BT12 6BA, UKdavidmitchell{at}


BACKGROUND Monitoring oesophageal pH conventionally detects “acid reflux” (pH less than 4). The pH of the gastric contents determines whether or not reflux can be detected.

AIM To monitor gastric and oesophageal pH simultaneously in order to determine the effect of milk feeds on gastric pH and how this would influence interpretation of the oesophageal pH record.

METHODS Milk fed infants for whom oesophageal pH monitoring was requested underwent simultaneous gastric and oesophageal pH monitoring using a dual channel pH probe.

RESULTS Twenty of 24 records were technically satisfactory. Mean reflux index was 1.0%, range 0.0–4.0%. Gastric pH was less than 4 for 24.5% (range 0.6–69.1%) of the total time. The average time the gastric pH was greater than 4 after feeds was 130 minutes (range 29–212 minutes). The corrected reflux index (limited to the time the gastric pH was less than 4) was 2.6% (range 0.0–11.0%).

CONCLUSION The pH of the gastric contents may be greater than 4 for prolonged intervals, during which oesophageal pH monitoring using current criteria cannot detect reflux nor correlate it with clinical events. A low reflux index may reflect prolonged buffering of gastric acidity rather than the absence of reflux.

  • gastro-oesophageal reflux
  • oesophageal pH monitoring
  • gastric pH

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