Changes in esophageal contractile and barrier function in lung transplant recipients

Gastroesophageal reflux is a well-studied risk factor for chronic lung allograft dysfunction in lung transplant recipients. Despite increasing evidence of esophageal dysmotility in lung transplant recipients, the relationship between esophageal contractility, esophageal barrier function, and reflux events has yet to be elucidated. We aimed to assess for changes in esophageal function before and after lung transplant using esophageal manometry, pH-impedance testing, and characterization of esophageal barrier function. We also performed correlational analyses aimed at further characterizing the observed changes in contractility and acid exposure time and identified potential driving factors for the observed relationships.

A retrospective review of medical records was performed for 36 patients who received a lung transplant (LTx) at an academic medical center in the United States between January 1, 2017 and July 23, 2019 who had undergone both pre and post-transplant high-resolution esophageal manometry and esophageal pH impedance studies. We further isolated 29 patients who did not receive narcotics within 30 days of their manometry and pH test. All manometry studies and esophageal pH impedance studies were read in a blinded manner after randomization. Reflux parameters, esophageal contractility metrics, and acute rejection scores were compared using non-parametric methods (Wilcoxon signed-rank test and the Exact McNemar's test).

We found no significant characteristic differences between our original cohort and our narcotics-excluded cohort. In our narcotics-excluded cohort, we found improvement in gastroesophageal reflux after lung transplant as evident by a decrease in distal AET. We found a significant increase in esophageal contractility post-lung transplantation when compared to pre-transplantation (p = 0.01). We also noted a significant decrease in the transdiaphragmatic pressure gradient (TPG) and mean upper esophageal sphincter (UES) pressure post-transplant. Driving factor analysis revealed that post-transplant distal contractile integral (DCI) was negatively correlated with distal acid exposure time (AET) (p = 0.041).

Our study demonstrated increased contractility after lung transplantation without a significant effect on GERD, possibly due to the observed inverse relationship between distal contractile integral and acid exposure time. Additionally, our study demonstrated a significant increase in esophagogastric junction barrier function and a significant decrease in upper esophageal barrier function which has not been shown in previous studies to our knowledge. Future studies are needed to evaluate the impact of these changes on allograft function.