Prolonged intraesophageal pH monitoring with 16-hr overnight recording. Comparison with "24-hr" analysis.

UNLABELLED: From studies in 43 patients (17 male, 26 female, mean age 51 years), we compared the analysis of the routine complete "24-hr" ambulatory esophageal pH monitoring study to that of the 16-hr overnight interval (4:00 PM to 8:00 AM). The latter included a major meal with an upright postprandial period and a recumbent period. All patients were monitored for at least 20 hr (median = 22.6 hr). The percent distal esophageal pH less than 4.0 and number of reflux episodes were measured for the total, upright, and recumbent periods of both the 16-hr and "24-hr" monitoring times. Significant (P less than 0.001) positive correlations were found for all comparisons between the two monitoring periods including percent time of pH less than 4.0 (total: r = 0.98; upright: r = 0.96) and number of episodes (totals r = 0.97; upright: r = 0.93). Patients were separated into normal and abnormal refluxers based on results of "24-hr" monitoring (pH below 4.0 greater than 4.2% total time; greater than 6.0% upright; greater than 1.2% recumbent). Based on this, sensitivity and specificity for 16-hr monitoring were as follows: total study: 86% and 95%; upright: 80% and 91%; recumbent: 100% for both.
CONCLUSIONS: (1) a 16-hr overnight pH monitoring period can provide a reliable representation of "24-hr" distal esophageal acid exposure, (2) this shorter monitoring may improve patient acceptability and compliance, and (3) the symptom index was changed in 26.3% of patients using the 16-hr evaluation.