Impedance has traditionally been employed in esophageal disease as a means to assess bolus flow and reflux episodes. Recent and ongoing research has provided new and novel applications for this technology. Measurement of esophageal mucosal impedance, via either multichannel intraluminal impedance catheters or specially designed endoscopically deployed impedance catheters, provides a marker of mucosal integrity. Mucosal impedance has been shown to segregate gastroesophageal reflux disease (GERD) and eosinophilic esophagitis from non-GERD controls and may play a role in predicting response to reflux intervention. More data are needed with regard to other esophageal subgroups, outcome studies, and functional disease. Our paper reviews the history of impedance in esophageal disease, the means of assessing baseline and mucosal impedance, data with regard to the newly developed mucosal impedance probes, the clinical utility of mucosal impedance in specific clinical conditions, and limitations in our existing knowledge, along with suggestions for future studies.

Gastroesophageal reflux disease (GERD) is prevalent and may be associated with both esophageal and extraesophageal syndromes, which include various pulmonary conditions. GERD may lead to pulmonary complications through the "reflux" (aspiration) or "reflex" (refluxate-triggered, vagally mediated airway spasm) mechanisms. While GERD may cause or worsen pulmonary disorders, changes in respiratory mechanics due to lung disease may also increase reflux. Typical esophageal symptoms are frequently absent and objective assessment with reflux monitoring is often needed for diagnosis. Impedance monitoring should be considered in addition to traditional pH study due to the involvement of both acidic and weakly acidic/nonacidic reflux. Antireflux therapy may improve outcomes of some pulmonary complications of GERD, although careful selection of a candidate is paramount to successful outcomes. Further research is needed to identify the optimal testing strategy and patient phenotypes that would benefit from antireflux therapy to improve pulmonary outcomes.

Esophageal dysphagia is a common symptom in adults. Fluoroscopic contrast studies, endoscopy, and esophageal manometry have been used in the diagnosis of esophageal dysphagia for many years. The diagnostic yield has been improved with new test protocols that highlight abnormal bolus transit in the esophagus and outflow obstruction, as well as new high-definition and high-resolution technical advances in equipment. Functional luminal impedance planimetry and the addition of impedance to high-resolution esophageal manometry have also allowed the assessment of new parameters to better understand esophageal structure and function. In this concise review, we describe the role and utility of various diagnostic modalities in the assessment of patients with esophageal dysphagia.

GOAL: The goal of this study was to assess the relationship between pretransplant measures of reflux and longer-term outcomes of chronic allograft rejection in lung transplant recipients.

BACKGROUND: Bronchiolitis obliterans syndrome (BOS) is a primary measure of morbidity and mortality following lung transplantation, and a manifestation of chronic lung allograft dysfunction (CLAD). Acid reflux has been associated with early allograft injury through a proposed mechanism of aspiration and activation of the inflammatory cascade, but its association with chronic rejection is unclear.

STUDY: This was a retrospective cohort study of lung transplant recipients undergoing impedance-pH testing off proton pump inhibitor from 2007 to 2016. Patients with pretransplant antireflux surgery were excluded. Time-to-event analysis using the Cox proportional hazards model was applied to assess the relationship between pretransplant reflux measures and the development of BOS, defined histologically and clinically. A secondary analysis was completed using CLAD as the outcome variable.

RESULTS: Fifty-one subjects (59% men, mean age: 56, mean follow-up: 2.2 y) met inclusion criteria for the study. The BOS endpoint was reached in 13 subjects (28%). In time-to-event analyses, BOS was associated with increased acid exposure, defined as >4.2% of time with pH<4 [hazard ratio (HR): 4.18; 95% confidence interval (CI): 1.31-13.4; P=0.01], and elevated DeMeester score >14.7 (HR: 3.08; 95% CI: 1.02-9.26; P=0.04), with confirmation from Kaplan-Meier analyses. The secondary analysis demonstrated a similar association between increased acid exposure and CLAD (HR: 3.28; 95% CI: 1.09-9.88; P=0.03), which persisted on multivariate models.

CONCLUSION: Increased acid exposure on pretransplant reflux testing was associated with the development of BOS and CLAD, both measures of chronic allograft rejection, after lung transplantation, and may provide clinically relevant information to improve lung allograft survival through aggressive reflux management.

BACKGROUND/AIMS: Peroral endoscopic myotomy (POEM) has recently come to the forefront in the management of achalasia. We aimed to analyze the efficacy and safety of the use of electrocautery enhanced scissors (EES) for POEM.

METHODS: This retrospective cohort study prospectively collected the data of all adult patients (aged ≥18 years) with normal foregut anatomy who underwent POEM using EES. The patients' baseline characteristics and procedure details (time, tunnel length, myotomy length, depth, and location) were recorded. The primary outcome was clinical success (3-month post-procedure Eckardt score of ≤3). The secondary outcomes were technical success and adverse events. A paired Student's t-test was performed.

RESULTS: Fifteen patients were included in this study. The technical success rate of myotomy using EES was 100%. Fellows participated in the myotomy in all cases. The clinical success rate was 93.3% (14/15). The mean pre-Eckardt score was 5.4±2.5, while the mean post-Eckardt score was 1.3±1.3, which indicated a significant improvement (p≤0.0001). The most common treatment-related adverse events were post-procedure pain (4, 26.7%) and symptomatic reflux disease (4, 26.7%).

CONCLUSION: In the largest series to date on the use of EES in POEM, we demonstrated that this technique has both technical and clinical efficacy as well as an excellent safety profile.

INTRODUCTION: Although coronavirus disease (COVID-19) has been associated with gastrointestinal manifestations, its effect on the pancreas remains unclear. We aimed to assess the frequency and characteristics of hyperlipasemia in patients with COVID-19.

METHODS: A retrospective cohort study of hospitalized patients across 6 US centers with COVID-19.

RESULTS: Of 71 patients, 9 (12.1%) developed hyperlipasemia, with 2 (2.8%) greater than 3 times upper limit of normal. No patient developed acute pancreatitis. Hyperlipasemia was not associated with poor outcomes or symptoms.

DISCUSSION: Although a mild elevation in serum lipase was observed in some patients with COVID-19, clinical acute pancreatitis was not seen.

BACKGROUND: The 2019 novel coronavirus disease (COVID-19) has created unprecedented medical challenges. There remains a need for validated risk prediction models to assess short-term mortality risk among hospitalized patients with COVID-19. The objective of this study was to develop and validate a 7-day and 14-day mortality risk prediction model for patients hospitalized with COVID-19.

METHODS: We performed a multicenter retrospective cohort study with a separate multicenter cohort for external validation using two hospitals in New York, NY, and 9 hospitals in Massachusetts, respectively. A total of 664 patients in NY and 265 patients with COVID-19 in Massachusetts, hospitalized from March to April 2020.

RESULTS: We developed a risk model consisting of patient age, hypoxia severity, mean arterial pressure and presence of kidney dysfunction at hospital presentation. Multivariable regression model was based on risk factors selected from univariable and Chi-squared automatic interaction detection analyses. Validation was by receiver operating characteristic curve (discrimination) and Hosmer-Lemeshow goodness of fit (GOF) test (calibration). In internal cross-validation, prediction of 7-day mortality had an AUC of 0.86 (95%CI 0.74-0.98; GOF p = 0.744); while 14-day had an AUC of 0.83 (95%CI 0.69-0.97; GOF p = 0.588). External validation was achieved using 265 patients from an outside cohort and confirmed 7- and 14-day mortality prediction performance with an AUC of 0.85 (95%CI 0.78-0.92; GOF p = 0.340) and 0.83 (95%CI 0.76-0.89; GOF p = 0.471) respectively, along with excellent calibration. Retrospective data collection, short follow-up time, and development in COVID-19 epicenter may limit model generalizability.

CONCLUSIONS: The COVID-AID risk tool is a well-calibrated model that demonstrates accuracy in the prediction of both 7-day and 14-day mortality risk among patients hospitalized with COVID-19. This prediction score could assist with resource utilization, patient and caregiver education, and provide a risk stratification instrument for future research trials.

Liver injury has been described with COVID-19, and early reports suggested 2%-11% of patients had chronic liver disease (CLD). In this multicentre retrospective study, we evaluated hospitalized adults with laboratory-confirmed COVID-19 and the impact of CLD on relevant clinical outcomes. Of 363 patients included, 19% had CLD, including 15.2% with NAFLD. Patients with CLD had longer length of stay. After controlling for age, gender, obesity, cardiac diseases, hypertension, hyperlipidaemia, diabetes and pulmonary disorders, CLD and NAFLD were independently associated with ICU admission ([aOR 1.77, 95% CI 1.03-3.04] and [aOR 2.30, 95% CI 1.27-4.17]) and mechanical ventilation ([aOR 2.08, 95% CI 1.20-3.60] and [aOR 2.15, 95% CI 1.18-3.91]). Presence of cirrhosis was an independent predictor of mortality (aOR 12.5, 95% CI 2.16-72.5). Overall, nearly one-fifth of hospitalized COVID-19 patients had CLD, which was associated with more critical illness. Future studies are needed to identify interventions to improve clinical outcomes.

BACKGROUND: Weight regain (WR) after gastric bypass is thought to be multifactorial in etiology with behavioral, neurohormonal, and anatomic features playing a role. A significant proportion of patients complain of dysphagia after Roux-en-Y gastric bypass (RYGB) and may have difficulty tolerating solid foods. Our observations suggest that this subgroup of patients compensate for esophageal symptoms by increasing their intake of calorie-dense liquid and soft foods, which can precipitate WR.

OBJECTIVES: We hypothesize that dysphagia predisposes to greater WR than seen in individuals without swallowing symptoms.

SETTING: Single tertiary care referral center.

METHODS: This was a matched-cohort study analysis of prospectively collected data on RYGB patients. All individuals who underwent high-resolution manometry after RYGB were enrolled. Controls were identified via a retrospective analysis of a prospective institutional database. Patients who developed dysphagia were matched with controls, from a subset of 450 eligible controls. Each patient with dysphagia was matched with 4 control patients based on age, body mass index, and time since surgery. WR was defined as an increase of ≥15% from nadir. Χ2 and t test (or Wilcoxon rank sum, if applicable) were used for bivariable analysis. Multiple logistic and linear regression were used for multivariable calculations.

RESULTS: Forty-nine patients with dysphagia were included. After matching, there were 196 RYGB controls that did not have swallowing or esophageal symptoms. Controls had similar baseline demographic characteristics and initial weight loss compared with dysphagia cases. WR was common in both groups; however, total WR in those with dysphagia was greater than controls (15.7 versus 11.4 kg, respectively; P = .02). In addition, percent WR in those with dysphagia exceeded that seen in controls (mean 37% versus 25%, P = .003), and more individuals regained 15% of nadir weight (55% of dysphagia cases versus 38% of controls, P = .03) when adjusting for baseline body mass index, age at surgery, and race. Dietary histories suggested that, among those with dysphagia, patients with partial or complete conversion to soft or liquid calories had greater WR than those who adhered to the solid food diet.

CONCLUSIONS: Dysphagia is a risk factor for WR post-RYGB. This is likely due to increased intake of soft or liquid foods that are tolerable in these patients but lead to a positive energy balance and accelerated WR. More than half of patients with dysphagia after RYGB regain significant weight. Screening for and aggressively managing dysphagia in patients before or after RYGB may be warranted to prevent significant WR.