PH monitoring in children.

Long-term oesophageal pH monitoring has become the preferred technique for detection and quantification of gastro-oesophageal reflux (GOR). The most obvious advantages of pH monitoring are the duration of the investigation, the possibility of being able to relate "events" (emesis, heartburn, apnoea) to pH changes (and to study "occult GOR"), the physiological conditions in which the data are recorded (sleep, work), and the possibility of repeating the investigation in treatment conditions. However, it has been reported that the accuracy of pH monitoring is no higher than 90%, because the intermittent presence of acid in the oesophagus is only one of the various abnormalities in the syndrome of GOR. A tremendous number of technique- (pH monitoring system, type of electrode, location of the electrode) and patient-related factors influence pH data. Age, position (both for adults and for infants), duration of the investigation (day/night), feeding and drugs are patient-related factors. Finally, the question arises (which is still unanswered) whether the indication for pH monitoring should be considered in the interpretation of the data: are the same criteria valid for GOR in children presenting with emesis and oesophagitis as for children with GOR resulting in chronic respiratory disease or "near-miss sudden infant death syndrome".