title: Severe gastroesophageal reflux is associated with reduced carbon monoxide diffusing capacity.
abstract: OBJECTIVE
  To assess whether severe gastroesophageal reflux (GER) is associated with abnormalities in lung function including measures of lung volume and gas diffusion.
  
  
  METHODS
  Data from 147 patients with obesity (body mass index [BMI] range, 31.7 to 70 kg/m(2)) who presented for obesity surgery was analyzed retrospectively. A questionnaire was completed preoperatively that included a history of GER, frequency and severity of symptoms, investigations, and medications used. A history of lung disease, sleep-disordered breathing, and smoking also was obtained. A physician who was blinded to lung function graded GER severity prospectively by the results of pH monitoring and/or gastroscopy, and medication use. Spirometry, lung volumes, and gas transfer were measured preoperatively.
  
  
  RESULTS
  Patients with severe GER had reduced levels of the diffusing capacity of the lung for carbon monoxide (DLCO) [21.1 mL/min/mm Hg; 95% confidence interval (CI), 18.9 to 23.2], as measured by CO transfer, compared with those patients without GER (26.3 mL/min/mm Hg; 95% CI, 24.4 to 28.2; p = 0.001). This remained significant after adjusting for age, gender, BMI, and smoking history. Gas transfer corrected for lung volume also was reduced in the group with severe GER (4.6 mL/min/mm Hg per L; 95% CI, 4.3 to 4.9) compared to the group without GER (5.3 mL/min/mm Hg per L; 95% CI, 5.1 to 5.5; p = 0.001). There was no significant difference in other measures of lung function.
  
  
  CONCLUSIONS
  Severe GER is associated with an impairment of gas exchange. This may be due to microaspiration of gastric acid or fluid into the airways.
authors.affiliation: Institute for Breathing and Sleep, Austin and Repatriation Medical Centre, Heidelberg, VIC, Australia. lindams@bigpond.com
authors.forename: Linda M
authors.initials: LM
authors.lastname: Schachter
authors.forename: John
authors.initials: J
authors.lastname: Dixon
authors.forename: Robert J
authors.initials: RJ
authors.lastname: Pierce
authors.forename: Paul
authors.initials: P
authors.lastname: O'Brien
mesh_terms: D000328:Adult; D002248:Carbon Monoxide / Q000378:metabolism*; D005260:Female; D005764:Gastroesophageal Reflux / Q000209:etiology / Q000503:physiopathology*; D006801:Humans; D008297:Male; D009765:Obesity / Q000503:physiopathology; D011653:Pulmonary Diffusing Capacity / Q000502:physiology*; D011659:Pulmonary Gas Exchange / Q000502:physiology; D012129:Respiratory Function Tests; D012189:Retrospective Studies
chemical_list: D002248:Carbon Monoxide