title: Nocturnal weakly acidic reflux promotes aspiration of bile acids in lung transplant recipients.
abstract: BACKGROUND
  Gastroesophageal reflux (GER) and aspiration of bile acids have been implicated as non-alloimmune risk factors for the development of bronchiolitis obliterans syndrome (BOS) after lung transplantation. The aim of our study was to investigate the association between GER and gastric aspiration of bile acids and to establish which reflux characteristics may promote aspiration of bile acids into the lungs and may feature as a potential diagnostic tool in identifying lung transplantation (LTx) patients at risk for aspiration.
  
  
  METHODS
  Twenty-four stable LTx recipients were studied 1 year after transplantation. All patients underwent 24-hour ambulatory impedance-pH recording for the detection of acid (pH <4) and weakly acidic (pH 4 to 7) reflux. On the same day, bronchoalveolar lavage fluid (BALF) was collected and then analyzed for the presence of bile acids (Bioquant enzymatic assay).
  
  
  RESULTS
  Increased GER was detected in 13 patients, of whom 9 had increased acid reflux and 4 had exclusively increased weakly acidic reflux. Sixteen patients had detectable bile acids in the BALF (0.6 [0.4 to 1.5] micromol/liter). The 24-hour esophageal volume exposure was significantly increased in patients with bile acids compared to patients without bile acids in the BALF. Acid exposure and the number of reflux events (total, acid and weakly acidic) were unrelated to the presence of bile acids in the BALF. However, both nocturnal volume exposure and the number of nocturnal weakly acidic reflux events were significantly higher in patients with bile acids in the BALF.
  
  
  CONCLUSIONS
  Weakly acidic reflux events, especially during the night, are associated with the aspiration of bile acids in LTx recipients and may therefore feature as a potential risk factor for the development of BOS.
authors.affiliation: Centre for Gastroenterological Research, Katholieke Universiteit Leuven, Leuven, Belgium.
authors.forename: Kathleen
authors.initials: K
authors.lastname: Blondeau
authors.forename: Veerle
authors.initials: V
authors.lastname: Mertens
authors.forename: Bart A
authors.initials: BA
authors.lastname: Vanaudenaerde
authors.forename: Geert M
authors.initials: GM
authors.lastname: Verleden
authors.forename: Dirk E
authors.initials: DE
authors.lastname: Van Raemdonck
authors.forename: Daniel
authors.initials: D
authors.lastname: Sifrim
authors.forename: Lieven J
authors.initials: LJ
authors.lastname: Dupont
mesh_terms: D000280:Administration, Inhalation; D000328:Adult; D000368:Aged; D001647:Bile Acids and Salts / Q000008:administration & dosage* / Q000009:adverse effects / Q000378:metabolism; D001989:Bronchiolitis Obliterans / Q000453:epidemiology; D005260:Female; D005764:Gastroesophageal Reflux / Q000453:epidemiology* / Q000503:physiopathology; D006801:Humans; D006863:Hydrogen-Ion Concentration; D016040:Lung Transplantation / Q000009:adverse effects*; D008297:Male; D008875:Middle Aged; D029424:Pulmonary Disease, Chronic Obstructive / Q000601:surgery*; D012307:Risk Factors; D013997:Time Factors; D055815:Young Adult
chemical_list: D001647:Bile Acids and Salts