![]() These 82 subjects were invited for a second visit in 2013, of which 71 (87 %) participated. Of the 455 participants in ECRHS III in Iceland, 82 had symptoms suggestive of nGER. A subgroup also underwent a 24 h oesophageal pH-impedance measurement, the results of which have been reported elsewhere. All participants reported their medications, including proton pump inhibitors (PPI), and if they used them on a regular basis or as needed. They participated in a structured interview, answered questionnaires including the Epworth sleepiness scale, underwent spirometry, measurements of height and weight, gave blood samples, and underwent a home polygraphic study. Among the 522 subjects contacted in Iceland for ECHRS III, a total of 455 participated, or 87 % of those invited. The study participants in ECRHS in Iceland were first studied in 1990, re-studied in 2000, and for the third time in 2012, when the participants were aged 40–65 years. This study is based on a 20 years prospective, population-based cohort study in Reykjavik, Iceland, the European Community Respiratory Health Survey (ECRHS, see ). We also hypothesized that SDB might affect the association between nGER and respiratory disorders. We used various exhaled biomarkers to study if the two above mentioned mechanisms explained the association between nGER and respiratory disorders, and if the two mechanisms had different symptom profiles. Our aim was to comprehensively investigate the association between nGER and respiratory symptoms, exacerbations of respiratory symptoms, lung function and SDB. Further studies on the pathogenesis will increase our understanding of the interactions between nGER, SDB and respiratory symptoms, which will ultimately lead to a more appropriate treatment of these patients. For instance, pepsin has been described as a marker of aspiration, and neuroinflammatory markers such as neurokinin A and substance P associated with a vagal reflex. Studies on respiratory biomarkers in GER suggest these two mechanisms are probably associated with different extra-oesophageal manifestations. One involves micro-aspiration of gastric fluids into the lungs causing irritation and inflammation, while the second involves bronchoconstriction caused by a vagal reflex induced by acidic reflux to the distal oesophagus. Two different pathophysiological mechanisms have been proposed for the GER-induced respiratory symptoms and diseases. However, obesity is a significant confounder as it increases the risk of both SDB and nGER. Conversely, persistent nGER seems to be a risk factor for developing symptoms of SDB. The strain on the gastroesophageal junction by increased respiratory effort in SDB is hypothesized to lead to nGER. Sleep-disordered breathing (SDB) and nGER are also closely linked. However, it is not fully known how GER patients with asthma symptoms differ from other asthma patients, and what the pathogenic mechanisms are. Gastroesophageal reflux (GER), and especially nocturnal GER (nGER), is associated with many symptoms from the respiratory tract, often asthma symptoms. Biomarker measurements in EBC, PEx and serum indicate that micro-aspiration and neurogenic inflammation are plausible mechanisms. Also, nGER is associated with increased respiratory effort during sleep. In a general population sample, nGER is associated with symptoms of asthma and bronchitis, as well as exacerbations of respiratory symptoms. ![]() Albumin and surfactant protein A in PEx were lower among nGER subjects. Objectively measured snoring was more common among subjects with nGER than controls (snores per hour of sleep, median (IQR): 177 (79–281) vs 67 (32–182), p = 0.004). ResultsĪsthma and bronchitis symptoms were more common among nGER subjects than controls (54 % vs 29 %, p = 0.01 and 60 % vs 26 %, p < 0.01, respectively), as were exacerbations of respiratory symptoms (19 % vs 5 %, p = 0.04). An exacerbation of respiratory symptoms was defined as an episode of markedly worse respiratory symptoms in the previous 12 months. Participants in the European Community Respiratory Health Survey III in Iceland with nGER symptoms ( n = 48) and age and gender matched controls ( n = 42) were studied by questionnaires, exhaled breath condensate (EBC), particles in exhaled air (PEx) measurements, and a home polygraphic study. ![]() We aimed to investigate the association between nGER and respiratory symptoms, exacerbations of respiratory symptoms, SDB and airway inflammation. Nocturnal gastroesophageal reflux (nGER) is associated with respiratory symptoms and sleep-disordered breathing (SDB), but the pathogenesis is unclear. ![]()
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