AGA Abstracts All values in mean (standard error of mean), P significant , 0.05 Tu1197 A Subgroup of Achalasia Patients With Manometrically Normal LES Relaxation Can Be Identified by Measurements of Esophagogastric Junction Distensibility Fraukje A. Ponds, Albert J. Bredenoord, Boudewijn F. Kessing, Wout O. Rohof, Andreas J. Smout Background: Esophageal manometry is the gold standard for diagnosing achalasia. Typical findings are absent peristalsis and incomplete relaxation of the LES (integrated relaxation pressure (IRP) .15 mmHg). However, in a subgroup of patients with typical symptoms of achalasia, stasis on barium esophagogram and absent peristalsis on manometry, LES relaxation is not impaired. The aim of our study was to further characterize these patients using distensibility measurements of the esophagogastric junction (EGJ) and to study the effect of treatment. Methods: Consecutive patients with typical symptoms of achalasia, no abnor- malities on upper endoscopy, significant stasis on barium esophagogram, absent peristalsis but normal IRP were included. Distensibility of the EGJ was measured using impedance planimetry (EndoFLIP). Distensibility was defined as the minimal cross-sectional area (CSA) of the EGJ divided by balloon pressure at volumes of 20, 30, 40 and 50 ml (mm2/mmHg) and was compared to previously established data of 15 healthy controls. The cut-off for normality was determined at the lower 90th percentile of the EGJ distensibility at 50 ml in these controls. Symptom severity was assessed using the Eckardt score, a score ,4 was considered as treatment success. Measurements of EGJ distensibility and Eckardt score were repeated .3 months after treatment. Results: We included 9 patients (5 male; age 21-59 years) with typical symptoms of achalasia, Eckardt score 6 (5-7) (median (IQR)). On esopha- geal manometry failed contractions were observed in 5 patients, panesophageal pressurization in 3 patients and spastic contractions in 1 patient. The median IRP was 9.3 mmHg (3.7- 12), baseline LES pressure was 8.6 mmHg (4.5-11.9). Distensibility of the EGJ was signifi- cantly reduced in patients compared to controls at all balloon volumes: 20 ml (1.97 ± 0.16 vs 2.46 ± 0.54 mm2/mmHg, P ,.05 (mean ± SEM)), 30 ml (1.81 ± 0.08 vs 2.67 ± 0.36 mm2/mmHg, P ,.0001), 40 ml (1.08 ± 0.12 vs 5.02 ± 0.58 mm2/mmHg, P ,.0001) and 50 ml (1.08 ± 0.11 vs 6.28 ± 0.65 mm2/mmHg, P ,.0001). All patients exhibited EGJ distensibility below the cut-off value set for normality (2.9 mm2/mmHg). Treatment was performed in 6 patients (4 pneumodilation, 2 Heller myotomy). Post-treatment, in all of these patients symptomatic improvement was seen (Eckardt 2 (1-2)) and a substantial increase in EGJ distensibility, to a value within the normal range (5.32 ± 0.9 mm2/mmHg) was observed. Conclusions: A subgroup of patients with typical symptoms of achalasia, significant esophageal stasis, absent peristalsis but no impaired LES relaxation on esophageal manometry can have impaired EGJ distensibility at impedance planimetry. These patients can be regarded as having achalasia and respond favorably to achalasia treatment. Tu1198 Effect of Aging on Lower Esophageal Sphincter Relaxation, Peristaltic Integrity and Esophageal Flow Resistance Charles Cock, Stamatiki Kritas, Carly M. Burgstad, Laura Besanko, Alison K. Thompson, Richard Heddle, Robert J. Fraser, Nathalie Rommel, Taher Omari BACKGROUND: Incomplete lower esophageal sphincter (LES) relaxation and increase in isobaric contour defect (IC defect) length are associated with decreased esophageal clearance 1 . Esophageal automated impedance manometry (AIM) analysis has recently been validated to measure esophageal pressure/flow variables in patients with post-operative dysphagia 2 and non-obstructive dysphagia 3 . Aging appears to be associated with decreased LES relaxation 4 . AIM: To examine the effect of age on LES relaxation, IC defect and esophageal flow resistance using AIM analysis. METHOD: 57 participants were studied in four age groups: 20-39 (n= 15); 40-59 (n=15); 60-79 (n=17) and 80 plus (n=10) years. All subjects scored zero on a validated esophageal dysphagia scale. Recording of swallowing of standardized liquid and viscous bolus (5x 5ml and 10ml) was performed in the upright position by solid-state manometry-impedance catheter (OD 3.2mm, 25 pressure at 1cm, 12 impedance at 2cm) for the distal esophageal segment and LES. Swallows were analyzed using esophageal AIMplot S-788 AGA Abstracts software to determine pressure flow variables as well as HRM metrics (Chicago criteria). AIMplot measured peak pressure (Pp); pressure at nadir impedance (PNadImp); impedance at peak pressure (ZPp); intrabolus pressure (IBP); intrabolus pressure slope (IBPslope); time from nadir impedance to peak pressure (TNadimp_PP) and total 20mmHg IC defect size. Integrated relaxation pressure in 4sec (IRP4) was determined for the LES. Standard Chicago metrics were assessed. Pressure flow index was determined through the formula PFI = (IBP * IBP_slope)/TNadImp_PP 3 . Impedance nadir to peak ratio was determined (ZNPR = Nad- Imp/ZPp) as a marker of ineffective bolus transport. Grouped variables were compared using ANOVA (Kruskal Wallis) and Mann-Whitney test. A P ,0.05 was considered significant. RESULTS: LES IRP4 values for viscous boluses increased progressively with age (Figure: p= 0.018). There was a significant increase in IBP slope (p=0.001) and TNadimp_PP (p=0.002) with advancing age. The average IC defect size was increased in 80+ vs. 60-79 yrs (p ,0.05) and more patients aged 80+ yrs had weak esophageal peristalsis (as indicated by peristaltic defect . 2cm) despite not reporting symptoms (p ,0.001 vs. all age groups). AIM indicators of dysphagia, PFI (p=0.009) and ZNPR (p ,0.001) increased progressively with age. There was good correlation (r = 0.494) between IC defect size and ZNPR. CONCLUSIONS: Aged individuals have a progressive increase in AIM derived indicators of increased resistance to bolus flow and poor esophageal clearance, despite not reporting symptoms. This appears to be driven by an increase in IRP4 and IC defect size. 1 Bulsiewicz et al. Am J Gastroenterol 2009; 2 Myers et al. Neurogastroenterol Motil 2012; 3 Nguyen et al. Neurogastroenterol Motil 2012; 4 Besanko et al. World J Gastroenterol 2011. Tu1199 Hyperactive Upper Esophageal Sphincter and Esophageal Reflexes in Chronic Lung Disease of Infants: Potential Mechanism for Pulmonary Symptoms Sudarshan R. Jadcherla, Kathryn Hasenstab, Chin Yee Chan, Rebecca K. Moore, Robert G. Castile, Reza Shaker BACKGROUND: Airway protective mechanisms activated during bolus transit through the pharynx and esophagus are largely understudied in chronic lung disease of infancy (CLDI). The relevance for such protection is vital during anterograde transit such as swallowing or during retrograde transit as in gastro-esophago-pharyngeal reflux events. Infants with CLDI experience coughing, bronchospasms, respiratory rhythm disturbances, dysphagia and related consequences. AIMS: Our aim was to test the hypothesis that compared to controls, airway protective reflexes during esophageal stimulation are inadequately developed in infants with CLDI. METHODS: 17 infants with CLDI (born at 26.0 ± 0.6 wks gestational age, studied at 42.3 ± 1.1 wks post-menstrual age) were examined using pharyngo-esophageal manometry methods and a specially designed manometry catheter with upper esophageal sphincter (UES) and lower esophageal sphincter (LES) sleeves, 5 side ports and a mid- esophageal provocation port to infuse stimuli and investigated esophageal motility reflex changes. Concurrent dual band respiratory inductance plethysmography and nasal air flow thermistor were also applied to assess respiratory phases and tidal ventilation. Ten control infants (born at 33.8 ± 1.1 wks gestational age, studied at 39.71 ± 0.9 wks post-menstrual age) who did not have lung disease were also evaluated. The provocation protocol included graded infusion volumes of air, water and apple juice. Overall, 993 infusions were adminis- tered. The sensory-motor characteristics of the UES and esophageal body reflex responses were evaluated. Comparisons were made between infants with CLDI vs. controls. Statistical analysis was performed using mixed models. Data are presented as mean ± SE, or as percentage. RESULTS: Aero-digestive support of infants with CLDI included ventilation for 49.9 ± 12.4 days, nasal CPAP for 31.6 ± 6.6 days, supplemental oxygen for 59.8 ± 9.3 days, gavage-feeding for 64.8 ± 11.9 days, gavage and oral feeding for 53.6 ± 6.8 days, and oral feeding for 20.1 ± 6.8 days until discharge. Characteristics of UES contractile reflex and peristaltic reflexes including deglutition response and secondary peristalsis were studied (Table 1). There were both initial responses and subsequent continuing responses until respiratory normalcy was restored. CONCLUSIONS: Despite similar resting UES and LES pressures, infants with CLDI have significantly increased magnitude and frequency UES contractile reflexes, more rapid LES relaxation and esophageal peristaltic responses compared to control infants. Distinct delays in esophageal clearance mechanisms were also evident. These findings implicate Vagal neuropathy and hyperactivity of the sensory-motor apparatus within the esophagus of infants with CLDI. *Supported in part by PPG-PO1 DK 068051 (Jadcherla/Shaker) Table 1. Characteristics of UES and Esophageal Peristaltic Reflexes