P-BN40 Fundoplication following lung transplant: A retrospective cohort analysis

Background Gastroesophageal reflux disease (GORD) in patients receiving a lung transplant has been associated with worsened graft function and decreased survival. This analysis aimed to identify whether fundoplication following lung transplant can improve graft function and overall survival. Methods patients undergoing lung transplantation between January 1993 and January 2020 were included. Data on oesophageal pH, manometry testing, post-transplant lung function testing and overall survival were collected. Cox-regression testing was used to analyse associations between oesophageal manometry and pH testing, fundoplication and overall survival. Results Of 345 patients who underwent a lung transplant, 20 patients also received fundoplication. 84 patients received oesopageal pH and manometry testing. Abnormal manometry was recorded in 41 patients. Average Demeester score was 28.45 for patients not receiving fundoplication and 37.28 for those receiving fundoplication. Average pre-operative reflux time was 8.6% for those not receiving fundoplication and 10.3% for those receiving fundoplication. Of 20 fundoplications, 4 were carried out within 1 year of transplant and 12 within 2 years. 1 patient had a post-operative complication following fundoplication. 13 of 20 patients had a positive response to fundoplication, defined as a less than 10% decrease in FEV1 lung function at 2 years. Receiving fundoplication was associated with better overall survival (p = 0.024) as was total reflux time <7% (p = 0.21). Conclusions Fundoplication is a safe operation after lung transplant with good outcomes. Fundoplication was associated with better overall survival on cox-regression analysis.

169 THE RELATIONSHIPS BETWEEN SYMPTOMS, REFLUX PH VALUES, AND EXTENT OF REFLUX IN PATIENTS WITH P-CAB-RESISTANT NERD

In patients with proton pump inhibitor-resistant non erosive reflux disease (NERD) having symptoms associated with liquid reflux, there are reports that reflux symptoms are more likely to be caused by the proximal extent of the reflux and reflux where pH <5. The objective of this study was to investigate the relationships between symptoms, reflux pH values, and the extent of reflux in patients with potassium-competitive acid blocker (P-CAB)-resistant NERD. Methods The subjects were 20 patients with P-CAB-resistant NERD whose symptoms did not improve even after administration of P-CAB (vonoprazan 20 mg/day) for 2–4 weeks. Their symptom index was positive for liquid reflux in impedance–pH monitoring. We investigated reflux pH values in symptomatic and asymptomatic reflux events, proportion of symptomatic reflux events according to the reflux pH value (pH <5 or ≥ 5), proportion of symptomatic reflux events at each impedance site, and proportion of symptomatic reflux events at each impedance site according to the reflux pH value (pH <5 or ≥ 5). Results About 60% of the symptomatic reflux events were caused by reflux with pH ≥5 in patients with P-CAB-resistant NERD. The median reflux pH value for total reflux events was 5.3 and that for symptomatic reflux events was 5.2. The proportion of symptomatic reflux events caused by reflux with pH <5 was significantly higher than that caused by reflux with pH ≥5. Symptomatic reflux events for reflux with pH <5 are more likely to be caused by proximal extent. There was no difference in the proportion of symptomatic reflux events for reflux with pH ≥5 at each reflux extent site. Conclusion In patients with P-CAB-resistant NERD, their symptoms were often caused by reflux with pH ≥5. A difference in the relationship between the reflux extent site and appearance of symptoms was observed according to the reflux pH value.

Magnetic Sphincter Augmentation for Hiatus Hernia and De Novo Gerd after Sleeve Gastrectomy

Laparoscopic sleeve gastrectomy (LSG) has become the most popular bariatric surgical procedure owing to its safety, reproducibility and effectiveness. However, gastroesophageal reflux disease (GERD) with or without hiatal hernia is diagnosed at an alarming rate after LSG. Revisional surgery and conversion to Roux-en-Y gastric bypass (RYGB) does not guarantee total reflux control and is associated with morbidity. Magnetic sphincter augmentation (MSA) combined with crural repair is an alternative therapeutic option as a concurrent or remedial procedure in LSG, but current clinical evidence is still limited.

Oesophageal pH-Impedance for the Diagnosis of Gastro-Oesophageal Reflux Disease: Validation of General Population Reference Values in Children with Chronic Neurological Impairments

Diagnosis of gastro-oesophageal reflux disease (GORD) in children with chronic neurological impairment (NI) remains a clinical challenge. The study aimed to validate the relevance of the reference values used to assess gastro-oesophageal reflux (GOR) in children with NI and to determine the optimal cut-off level of the pH-impedance parameter with the best predictive value for outcomes associated with endoscopic assessments of the oesophagus. Sixty-seven children (32 male, 35 female; age: interquartile range, 5 years 6 months–14 years 10 months; median, 11 years 3 months) with NI were prospectively recruited for the study. The exclusion criteria were previous fundoplication and lack of consent for the study. All patients underwent evaluations for GOR disease, including pH-impedance and gastroscopy. Based on endoscopy, oesophagitis was diagnosed in 22/67 children (32.8%); 9/67 (13.4%) were classified as having Hetzel–Dent grade III or IV. GOR was present in 18/67 children (26.9%), as determined by pH-impedance. Patients with endoscopic lesions had a significantly higher number of total reflux (p = 0.0404) and acidic episodes (p = 0.0219). The total number of reflux episodes, with a cut-off level of 44 episodes, was the pH-impedance parameter most strongly predictive of the presence of lesions in gastroscopy (specificity: 50%, sensitivity: 73%). These findings suggest that endoscopic lesions may be present in children with chronic NI with a low number of GOR episodes, as recorded by pH-impedance. The use of standardised reference norms determined for the general population may underestimate GOR episodes in this group of patients.

The Relationship Between Gastroesophageal Reflux Disease and Laryngopharyngeal Reflux Based on pH Monitoring

Objectives: Many studies on the relationship between gastroesophageal reflux disease (GERD) and laryngopharyngeal reflux (LPR) were based on symptoms, but there are few research on it using reflux monitoring. This study was designed to investigate the relationship between GERD and LPR based on pH monitoring. Methods: All patients were scheduled for esophageal manometry and pH monitoring sequentially. They were stratified into 4 groups as no reflux disease, isolated GERD, isolated LPR (iLPR), and GERD combined with LPR (GERD&LPR) according to pH monitoring. Results: The incidence of LPR in GERD was 46.3%, while the probability of combining GERD in LPR was 52.7%. The reflux profile in the laryngopharynx showed a significant difference in the total reflux time (17.82 ± 18.4 vs 9.62 ± 9.58, P = .023) and the percentage of total reflux time (1.31% ± 1.37% vs 0.71% ± .0.73%, P = .023) between the GERD&LPR and iLPR groups. Conclusion: Laryngopharyngeal reflux can be combined with GERD or it can exist as an independent diagnosis. In patients with GERD&LPR, the total reflux time and the percentage of reflux time in the laryngopharynx are higher than those in the iLPR group. Reflux episodes in the laryngopharynx of patients with GERD&LPR may be derived from GERD.

Post-reflux swallow-induced peristaltic wave (PSPW): physiology, triggering factors and role in reflux clearance in healthy subjects

Background and aims The underlying physiology of post-reflux swallow-induced peristaltic wave (PSPW) is unclear. We aimed to: 1) calculate the probability of a random association between reflux and PSPW; 2) characterize factors that could underlie triggering of PSPW and 3) assess the chemical clearance effect of PSPW in healthy asymptomatic subjects. Methods A total of 251 impedance–pH tracings from healthy asymptomatic subjects were analysed. Twenty consecutive tracings from this pool with 20–40 reflux episodes/24 h and a PSPW index higher than 50% were separately analyzed to evaluate the probability of a random association between reflux and PSPW. The characteristics of reflux episodes followed by a PSPW were compared with those not associated with PSPW. Results A mean time interval of 29.3 s between a reflux episode and the first swallow captured 71% of total reflux episodes, and 67% of accompanying swallows were non-random. Compared to reflux without PSPW, reflux episodes with PSPW were more frequently acidic (P = 0.048), mixed with gas (P < 0.0001), of high proximal extent (P < 0.0001), while awake (P < 0.0001), and with shorter chemical clearance time (P = 0.040). High proximal extent, gas presence and occurring while awake were independent factors associated with PSPW (P < 0.0001). Conclusion Using a time window between reflux and PSPW of around 30 s, the probability of a chance association is around 30%. Reflux episodes with high proximal extent, containing gas and occurring while awake are important factors associated with PSPW in healthy subjects. Reflux episodes with PSPW have a shorter chemical clearance time.

Modeling and Simulation of Flow and Uranium Isotopes Separation in Gas Centrifuges Using Implicit Coupled Density-Based Solver in OpenFOAM

The performance of a gas centrifuge that is used for isotopes separation is dependent on the gas flow inside it. In this study, for modeling the UF6 gas flow, an Implicit Coupled Density-Based (ICDB) solver, was developed in OpenFOAM. To validate the ICDB solver, the gas flow within the rotor in total reflux state was compared with the analytical solution obtained by Onsager model and the numerical solution obtained by the Fluent software. The results showed that the ICDB solver had acceptable accuracy and validity. Also the computational efficiency of Roe, AUSM (Advection Upstream Splitting Method) and AUSM+ up schemes were compared. The results showed AUSM+ up scheme is efficient. Then, the uranium isotopes separation in a gas centrifuge was simulated. It was revealed that all gas flow characteristics including velocity, pressure, temperature and axial mass flux, as well as uranium isotope separation parameters including separation power and separation coefficients could well be predicted.

Greenhouse gas emissions reduction by process intensification: Reactive distillation column with side decanter

Direct hydration of cyclohexene to produce cyclohexanol is the industrial process with a lower raw material cost but with a quite expensive process. Large energy consumption is consequence of large cyclohexene recycle related with its unfavourable chemical equilibrium. This study corroborates that the Asahi process is a good candidate for intensification avoiding the cyclohexene recycle. Rigorous simulation shows that a single reactive distillation column, with a side decanter, operated at total reflux, allows overcoming the chemical equilibrium limitations as the product is continuously collected by the column bottoms and the heat of reaction is directly used to separate the product by distillation. The novel process is studied and compared to the classical Asahi process. An energy comparison with the available processes proposed in the literature is performed. Therefore, achieving more energy-efficient processes leads to lowering their environmental impact, thus decreasing the carbon dioxide emissions. Applying the proposed methodology for cyclohexanol production, more than 67,000 t CO2/y emissions can be avoided compared to the nowadays used classical process, thus the potential savings applying process intensification to the chemical industry are very large and worth further investigation.