Abbreviated oesophageal pH monitoring in infants.

The results of 24 h oesophageal pH monitoring, performed in 129 infants aged 6-10 weeks, were compared to those in the same patients after shorter periods (3, 6, 9 and 12 h). In the investigated population there was no significant difference between the reflux index (percentage of time with a pH < 4.0) after 12 or 24 h. Moreover, the correlation coefficient between the reflux index after 12 and 24 h was excellent (r 0.95). However, the intra-individual difference in reflux index after 12 and 24 h was 5% in 19% of the infants, and even exceeded 10% in more than 5% of the infants, making the interpretation of the results unreliable. Even in this particular population of infants in whom a 24-h period could be divided into almost identical periods (including a feeding and a sleeping period), 24-h registrations provided the most reliable results. However, if for some reason the investigation had to be interrupted after a minimum of 12 h, the risk for erroneous interpretation of the data appeared to be acceptable. The results of this study must not be extrapolated to older children.