AGA Abstracts parameters were dichotomized, IPF was associated with increased abnormal distal nonacid reflux (57.9% vs. 26.3%, p=0.03). Trends in increased abnormal proximal bolus reflux (21.1% vs. 5.3%) and abnormal distal bolus reflux (31.6% vs. 15.8%) in IPF compared to NF were also observed but did not reach statistical significance. Conclusion: Increased reflux parameters on pre-lung transplant MII-pH were observed in IPF patients compared to NF patients with similar pulmonary function. IPF patients also had significantly more abnormal nonacid reflux compared to NF subjects. Our results suggest that microaspiration likely plays a role in chronic inflammation and fibrosis in IPF patients. The majority of IPF patients had abnormal nonacid reflux, which may explain the inconsistent response to acid suppression. Anti-reflux therapy such as fundoplication may provide more clinical benefit compared to anti-secretory medications in these patients. Tu1854 Patients With Dental Erosions Have Significant Silent Gastroesophageal Reflux As Quantified by Multichannel Intraluminal Impedance and pH-Monitoring Clive H. Wilder-Smith, Andrea Materna, Adrian Lussi INTRODUCTION: Silent, i.e. asymptomatic acidic distal gastroesophageal reflux (GERD) is common in patients with advanced dental erosions (1). Proximal esophageal and weakly acidic reflux have not been quantified in these patients, but are probably of major importance in the pathophysiology of GERD-associated dental erosions. The aim of this study was to for the first time characterize reflux using multichannel intraluminal impedance and pH- monitoring (MII-pH). AIMS&METHODS: Successive patients presenting to the University of Bern Dental Clinic 2010-2013 with at least medium dental erosions (Lussi erosion index >1 or BEWE score >8), without symptoms of reflux (less than once per week) and without GERD treatment were referred for upper endoscopy and esophageal 24-hour MII-pH after exclusion of extrinsic and non-reflux causes of dental erosions. The numbers of acidic (pH<4) and weakly acidic (pH 4-7) reflux episodes, the % time with pH<4 and <5.5 and the percentage of proximal esophageal reflux episodes below a pH-threshold of 4 are reported. RESULTS: 404 successive patients (276 males, mean age (range) 35yr (8-74) with advanced dental erosions (mean (95%CI) BEWE 13 (12.3-13.7)) were studied. In the distal esophagus the mean % time with pH<4 was 11.0 (9.2-12.8)(normal upper limit 4.3%) and with pH<5.5 was 34.4 (31.7-37.2). The mean DeMeester score was 44.1 (15.5-72.7). The mean numbers of acidic and weakly acidic reflux episodes were 46 (32-55)(normal upper limit <50 episodes) and 32 (27-37)(normal upper limit <33 episodes), resp.. 19% (15-23) of acidic reflux episodes reached the proximal esophagus. Hiatal hernia was present in 21% and GERD symptoms <1/week in 25% of patients. CONCLUSION: In patients presenting to a tertiary care dental clinic with advanced dental erosions the duration of reflux is markedly increased compared to normal values, while typical GERD symptoms are rare. Both the duration and the proximal extent of reflux are often considered to be associated with increased GERD symptoms. Therefore, the reason for the development of dental erosions in the absence of typical GERD symptoms despite increased reflux needs to be explored further. (1) Wilder- Smith CH et al. Gastroenterology 2012;142:411 Tu1855 Correlation of Externally Applied Cricoid Pressure With Luminal Upper Esophageal Sphincter Pressure Augmentation; Effect of Posture and Technique Arash Babaei, Hongmei Jiao, Ling Mei, Mark Kern, Reza Shaker Background: External cricoid pressure application has been proposed as a method of supporting upper esophageal sphincter (UES) pressure barrier and preventing esophagopha- ryngeal reflux episodes. However, correlation of luminal UES pressure and external cricoid pressure has not been systematically studied. Aim: To determine the relationship between the luminal UES pressure and the externally applied cricoid pressure. Methods: Eight healthy and seven patients with supra-esophageal GERD (Age 59±21) were studied. External cricoid pressure was applied over a thin air-filled bulb connected to an External Pressure Sensor™ (Somna Therapeutics, Glendale, WI). Intra-luminal UES pressure was measured using a solid-state circumferential sensor manometry catheter (Given Imaging, Duluth, GA). Cricoid pressure was applied perpendicularly (x3) in both upright and supine posture in two fashions: a) Manual pressure application for 10seconds (typically three respiratory cycles) and b) using the Reza Band™ "UES assist device" (Somna Therapeutics, Glendale, WI). We tested 10, 20, 30, 40, 50 mmHg cricoid pressures. UES pressure was measured utilizing electronic sleeve as average end-expiratory UES pressure and average overall UES pressure over three respiratory cycles. Luminal UES pressure increase across external pressure levels are presented as mean ± SD. Comparisons were made using analysis of variance and linear regression. Variability was measured using coefficient of variation. Results:The average neck circumfer- ence and cricoid-sternal notch distance was 37.4±2.6cm and 4.1±0.5cm respectively. All participants tolerated the cricoid pressure. Baseline average end-expiratory and overall UES pressure were 27±15 mmHg and 34±17 mmHg respectively. Increasing externally applied cricoid pressure resulted in graded luminal UES pressure increase by both manual and UES assist device. Participant's posture did not have a significant effect. UES assist device resulted in higher luminal UES pressure compared to manual pressure application (Fig 1, p<0.001). Externally applied manual and UES assist device cricoid pressure techniques were both significantly correlated to luminal UES pressure augmentation (Fig 2, p<0.001). Intra-subject and inter-subject coefficient of variation of UES pressure augmentation was 26-48% in manual and 15-33% in UES assist device pressure application techniques. Conclusions: There is a significant correlation between externally applied cricoid pressure and intralumi- nally recorded UES pressure augmentation irrespective of technique and posture. On average intraluminal pressure augmentation is 6±5 mmHg less than externally applied cricoid pres- sure. This difference needs to be taken into account when deciding on desired amount of UES pressure augmentation to prevent pharyngeal reflux. S-856 AGA Abstracts Tu1856 Obstructive Sleep Apnea Syndrome and Gastroesophageal Reflux Disease: Is It All About Obesity and Gender? Ozen K. Basoglu, Rukiye Vardar, Mehmet S. Tasbakan, Zeynep Z. Ucar, Sibel Ayik, Timur Kose, Serhat Bor BACKGROUND: It is claimed that gastroesophageal reflux disease (GERD) increases in patients with obstructive sleep apnea syndrome (OSAS). However prospective and compara- tive studies are limited and contradictory. We aimed to evaluate the prevalence of GERD symptoms on patients with OSAS in a large cohort. METHODS: We recruited 1209 patients scheduled to polysomnography at three hospitals. All patients were filled out the validated GERD questionnaire with 54 questions on the day of tests, demographic, anthropometric characteristics, upper gastrointestinal symptoms, medications, habits were recorded. 105 patients were excluded. Results were analyzed according to OSAS classifications compared to primary snoring as controls and laboratory results. "Frequent symptoms" defined as a major symptom (heartburn and/or regurgitation) occurring at least once a week or more (GERD). "Occasional symptoms" defined as an episode of one of the major symptoms occurring less than once a week within the past 12 months. RESULTS: The prevalence of GERD was 38.0% in total, 45.2% for women and 34.9% for men (p=0.006). 32.5% of subjects had occasional symptoms. Only 29.5% of subjects were not defining any GERD symptoms within a period of one year. If patients divided to four groups according to the severity of OSAS and primary snoring no difference was shown; 32.0% in the primary snoring to 38.8% in the most severe OSAS (p=0.405). Extraesophageal symptoms were very common in severe OSAS patients (50.4%) compared to primary snoring (13.4%) and mild- to-moderate OSAS (18.1%). Women were significantly more obese compared to male. A significant difference observed according to BMI; the prevalence of GERD was 26.8% in patients with BMI<25 (n=71), 36.2% BMI 25-34.9 (n=698), 45.7 BMI>35 (n=335) (p= 0.002). The prevalence of GERD increased with BMI starting from 27.1% (BMI≤35) to 37.4% (BMI>35) in male and 25% to 52.3% in female. No difference was shown in the prevalence of GERD in patients with primary snoring and OSAS groups. A large neck