Acid oro-pharyngeal secretions can predict gastro-oesophageal reflux in preterm infants

Acid gastro-oesophageal reflux (GOR) is common in preterm infants but there is a lack of a non-invasive technique to establish the diagnosis. The aim of this study was to identify whether the presence of acid in oro-pharyngeal secretions (OPS) was a valid indicator of clinically significant acid GOR in preterm infants. A total of 23 infants with suspected GOR were studied with 24 h lower-oesophageal pH monitoring and during this period the OPS were tested for acid with litmus paper at 6 hourly intervals. Median (range) gestation was 28 weeks (24-31), birth weight 1023 g (480-1750) and age at study 34 days (11-76). Significant GOR was defined as a reflux index >5%. Of the investigated infants, 18 subjects (78%) had significant GOR. Of this group, 16 infants had acid in the OPS on at least one occasion. Five infants did not demonstrate significant GOR and in four of these acid was not detected in the OPS. Our data indicate that as a predictor for significant GOR, litmus-testing OPS for acid has a sensitivity of 89%, specificity of 80%, positive predictive value of 94% and a negative predictive value of 67%. The difference in the incidence of acid OPS between the GOR and the No GOR group was significant (P<0.03).

The presence of acid in the oropharyngeal secretions may help in the prediction of acid gastro-oesophageal reflux in preterm infants. The method is simple, inexpensive cheap and involves minimal disturbance. We suggest that it could aid clinical diagnosis and indicate a need for further investigation of gastro-oesophageal reflux.