Nocturnal acid breakthrough: clinical significance and correlation with esophageal acid exposure

OBJECTIVES

Previous studies suggest that the addition of H2 receptor antagonist (H2RA) therapy is more effective than proton pump inhibitor (PPI) therapy alone in reducing nocturnal acid breakthrough (NAB). However, the clinical significance of NAB with respect to esophageal acid control has not been investigated. The aim of this study was to evaluate prospectively the degree of upright and supine esophageal and gastric acid suppression using various PPI regimens in comparison to the addition of an H2RA at bedtime.

METHODS

A total of 22 subjects (13 with gastroesophageal reflux disease and nine who served as control subjects) were prospectively evaluated by serial combined esophageal and gastric 24-h pH monitoring. Studies were performed at baseline off antireflux medical therapy and subsequent to completion of the following four drug regimens: 1) omeprazole 20 mg b.i.d. for 2 wk; 2) omeprazole 20 mg b.i.d. plus ranitidine 300 mg HS for 4 wk; 3) omeprazole 20 mg QAM and QHS for 2 wk; and 4) omeprazole 20 mg every 8 h for 2 wk. A dual pH probe was placed 5 cm above and 10 cm below the manometrically defined LES for a minimum of 18 h. Median total, upright, and supine pH values were compared among treatment regimens. All subjects underwent Helicobacter pylori serology testing.

RESULTS

A total of 17 men and eight women (mean age 37 yr +/- 2.4 yr, range 22-71 yr) were enrolled in the study. Total, upright, and supine median percentage of the time that gastric pH was <4 were significantly less than baseline values in all treatment regimens. Although patients treated with Q8 h omeprazole had significantly (p < 0.01) more gastric acid suppression, there was a high degree of overlap among regimens. Treatment regimens resulted in NAB elimination of 9-41%. However, no single treatment regimen resulted in more significant NAB suppression than the others. Despite continued NAB with all treatment regimens, esophageal acid reflux (90%) and patient symptoms (100%) were well controlled. In addition, there were no differences in the esophageal median percentage of time that pH was <4 for any treatment regimen.

CONCLUSIONS

NAB is an isolated gastric phenomenon that is poorly controlled even with most aggressive acid suppressive therapy. Esophageal acid suppression and symptom control are not dependent on the degree of NAB elimination.