Characterisation of Patients With Supine Nighttime Reflux

Observations Made With Prolonged Wireless Oesophageal pH Monitoring

Renske A. B. Oude Nijhuis; Rami Sweis; Humayra Abdul-Razakq; Jeroen M. Schuitenmaker; Terry Wong; Radu-Ionut Rusu; Jac. Oors; Andreas J. P. M. Smout; Albert J. Bredenoord


Aliment Pharmacol Ther. 2021;54(2):144-152. 

In This Article

Abstract and Introduction


Background: Although nighttime reflux symptoms are common, the presence of nocturnal reflux is seldom confirmed with a standard 24 hours pH study.

Aim: To study patients with supine nighttime reflux symptoms using prolonged wireless pH monitoring.

Methods: In this retrospective study, patients with typical acid reflux symptoms were studied using 96-h pH monitoring. Patients with nighttime reflux symptoms were compared to those without. Night-to-night variability and diagnostic accuracy of 24-, 48- and 72-hours pH studies compared to the 96-hours "gold standard" were evaluated.

Results: Of the 105 included patients (61.9% females; mean age 46.8 ± 14.4 years), 86 (81.9%) reported nighttime reflux symptoms, of which 67.4% had pathological supine nocturnal acid exposure in at least one night. There was high variance in night-to-night acid exposure (94% [IQR0–144]), which was larger than the variance in upright acid exposure (58% [IQR32–88]; P < 0.001). When analysing the first 24 hours of the pH study, 32% of patients were diagnosed with pathological supine nighttime acid exposure versus 51% of patients based upon the 96-hours pH-test. The diagnostic accuracy and yield improved with study duration (P < 0.001). Reflux episodes with a lower nadir pH or longer acid clearance time were more prone to provoke nightly symptoms.

Conclusions: The majority of patients with nocturnal reflux symptoms had pathological acid exposure in at least one night of the prolonged pH recording. A high night-to-night variability in acid exposure reduces the clinical value and diagnostic yield of pH monitoring limited to 24 hours. Prolonged testing is a more appropriate diagnostic tool for patients with nocturnal reflux symptoms.


Nighttime reflux symptoms are common in the general population; it has been estimated that approximately 50% of individuals who suffer from generalised reflux symptoms, also experience nighttime symptoms, disturbing sleep and daytime functioning.[1–3] Conversely, poor sleep quality and arousal from sleep have been shown to evoke reflux as well, underlining the complex relationship between sleep and reflux.[4,5] Although the last years' progress has been made in our understanding of the pathogenesis of nocturnal reflux, several questions remain unanswered and patients with nocturnal reflux symptoms are still an underreported group in the current literature.[2,4,6]

In patients with nighttime reflux symptoms referred for ambulatory pH monitoring, the diagnosis of nocturnal reflux is seldom confirmed. One could argue, however, that a traditional 24-hour catheter-based system is not the appropriate diagnostic tool to identify nocturnal reflux. Gastro-oesophageal reflux occurs multiple times during the day, also in healthy subjects.[7,8] In patients with gastroesophageal reflux disease (GERD), the incidence of daytime reflux episodes is often increased and this usually causes multiple symptoms during the day. Nighttime reflux occurs less frequently, both in healthy asymptomatic subjects and in patients.[6,8,9] However, when nocturnal reflux does occur, these episodes are commonly associated with prolonged oesophageal acid exposure due to reduced acid clearing mechanisms at night, frequently resulting in mucosal damage such as reflux oesophagitis and severe symptoms leading to sleep arousal, poor sleep quality and excessive heartburn.[10] In other words, although a single nocturnal reflux episode can alter the clinical diagnosis of a 24-hour study, the likelihood of detecting it is low, which may result in a falsely negative study report in a substantial subset of patients. In addition, the very nature of catheter-based pH systems influences comfort and sleeping behaviour, which minimises the occurrence of nocturnal reflux.[11] We hypothesise that patients with nocturnal reflux symptoms may benefit from prolonged pH monitoring because of improved sensitivity. Wireless pH study uses a radio-telemetric capsule temporarily attached to the oesophageal mucosa. It allows for a prolonged recording and has been shown to be generally better tolerated by patients, thereby increasing sensitivity for detecting reflux events.[12–15] Intuitively, it is presumed that this improved sensitivity extends to nocturnal reflux. In this study, we aimed to explore this concept. Our primary objective was to evaluate the added diagnostic value and reproducibility of prolonged pH testing for the presence of nocturnal reflux. Our second objective was to study patients with nocturnal reflux, specifically prevalence, clinical characteristics and symptom perception.