Background: Nocturnal acid breakthrough (NAB) is defined as gastric pH below 4 over 60 consecutive minutes at night-time in subjects who take proton pump inhibitors twice daily. The link between NAB and gastroesophageal reflux (GER) episodes has not been investigated using combined multichannel intraluminal impedance and pH-metry (MII-pH).
Aims and methods: The aim was to investigate the relationship between NAB and GER by means of MII and gastroesophageal pH-metry. We reanalyzed MII-pH recordings obtained in patients on twice-daily proton pump inhibitors.
Results: Overall 15 eligible recordings were reanalyzed in detail (7 males, 8 females; age 59 +/- 10 years, range 36-68 years). NAB was detected in 7/15 (46%) recordings with one NAB in 4 subjects and two 2 NABs in 3 subjects. In 6 of the cases with NAB, reflux symptoms were reported at night, but in no case did these occur in association with NAB. Patients with NAB reported significantly more typical than atypical symptoms (77 times vs. 47 times), whereas patients without NAB reported fewer typical than atypical symptoms (48 times vs. 60; p = 0.011). Over the total 24-hour period, acid reflux was more frequent (9 +/- 11 times) in patients with NAB than in patients without NAB (1 +/- 0.5 times; p = 0.04). Weakly acid reflux also occurred more frequently (15 +/- 9 times) in subjects with NAB than in subjects without NAB (6 +/- 4 times; p = 0.02). Weakly alkaline reflux occurred in equal frequencies in subjects with and without NAB (2 +/- 4, 0 +/- 0.4, respectively). Esophageal acid exposure in the upright position was not different between subjects with NAB and subjects without NAB, but subjects with NAB presented a higher recumbent esophageal acid exposure than subjects without NAB (2.0 +/- 2.4 vs. 0%, respectively).
Conclusion: Esophageal acid exposure is not increased during NAB episodes. However, over a period of 24 h, patients with NAB presented with increased gastroesophageal reflux. Although NAB and GER are not strongly associated, symptoms of patients with and without NAB are different.