Do normal results of pH measurement allow to exclude the esophageal origin of the chest pain ?
G. Vantrappen (Leuven)
It is generally agreed that chest pain of esophageal origin may be due to at least two different mechanisms i.e. gastroesophageal reflux and esophageal motility disorders. Recent evidence suggests that, in addition, chest pain of esophageal origin may also be due to irritability of the esophagus. The latter group of patients
experience pain which is sometimes related to reflux without motility disorders and at other times to motility disorders without reflux.
Twenty-four hour pH-measurement can be analysed in two different ways. Quantitative analysis is based on measurement of various quantitative parameters including the number of pH drops below a certain level (usually pH 4), the total duration of acid exposure and the number of longlasting pH drops (≥ 5 min). Frequently, these parameters are calculated separately for the day and night periods (upright and supine position). When one or several parameters exceed the mean thus 2 SD, the result of pH-metry is considered to be abnormal and the patient is said to have pathological reflux. It should be noted that, although the reflux pattern is fairly reproducible in any one patient, there is great interindividual variability. Therefore, it is difficult to define the limits of normality.
Another way of analysing pH-measurements is to correlate symptoms, such as chest pain, with reflux episodes. When chest pain coincides in time with a reflux episode, and it can be shown by statistical evaluation that this simultaneous occurrence is not due to chance, it is concluded that the pain is related to the reflux episode. There is no doubt that such a qualitative analysis allows in some patients to identify gastroesophageal reflux as the cause of the chest pain, although the quantitative analysis of reflux parameters is strictly normal.