Relevance of GERD in lung transplant patients

Airway pepsinogen A4 identifies lung transplant recipients with microaspiration and predicts chronic lung allograft dysfunction

BACKGROUND

Aspiration is a known risk factor for adverse outcomes post-lung transplantation. Airway bile acids are the gold-standard biomarker of aspiration; however, they are released into the duodenum and likely reflect concurrent gastrointestinal dysmotility. Previous studies investigating total airway pepsin have found conflicting results on its relationship with adverse outcomes post-lung transplantation. These studies measured total pepsin and pepsinogen in the airways. Certain pepsinogens are constitutively expressed in the lungs, while others, such as pepsinogen A4 (PGA4), are not. We sought to evaluate the utility of measuring airway PGA4 as a biomarker of aspiration and predictor of adverse outcomes in lung transplant recipients (LTRs) early post-transplant.

METHODS

Expression of PGA4 was compared to other pepsinogens in lung tissue. Total pepsin and PGA4 were measured in large airway bronchial washings and compared to preexisting markers of aspiration. Two independent cohorts of LTRs were used to assess the relationship between airway PGA4 and chronic lung allograft dysfunction (CLAD). Changes to airway PGA4 after antireflux surgery were assessed in a third cohort of LTRs.

RESULTS

PGA4 was expressed in healthy human stomach but not lung. Airway PGA4, but not total pepsin, was associated with aspiration. Airway PGA4 was associated with an increased risk of CLAD in two independent cohorts of LTRs. Antireflux surgery was associated with reduced airway PGA4.

CONCLUSIONS

Airway PGA4 is a marker of aspiration that predicts CLAD in LTRs. Measuring PGA4 at surveillance bronchoscopies can help triage high-risk LTRs for anti-reflux surgery.

Tolerability and Feasibility of the Upper Esophageal Sphincter Assist Device in Preventing Acute and Chronic Allograft Rejection Among Lung Transplant Recipients

GOALS

We aimed to evaluate a novel upper esophageal sphincter (UES) assist device loaner program for the prevention of acute cellular rejection and chronic lung allograft dysfunction among lung transplant (LTx) recipients.

BACKGROUND

Laryngopharyngeal reflux can lead to chronic microaspiration and LTx rejection. The UES assist device applies external pressure at the level of UES to decrease reflux.

STUDY

We prospectively enrolled and issued UES assist devices to consecutive transplant patients referred for gastrointestinal motility testing from 2016 to 2020. Device tolerability was defined by successful utilization as a bridge to ambulatory pH monitoring and/or antireflux procedure, or as permanent therapy. Incidence of rejection was analyzed before, during, and after device implementation.

RESULTS

Twenty-six participants were issued devices (15 pathologic, 5 physiological, 6 unknown reflux status), none of whom developed acute rejection episodes or chronic lung allograft dysfunction while using the device. Thirteen adopted the device promptly after transplantation (mean 1.7 mo) and remained free of rejection episodes over a mean 24.7 months of follow-up. Among those with pathologic reflux, lag time to device adoption strongly correlated with the development of rejection ( r =0.8, P =0.0006). There was no such correlation among those with physiological reflux. Five developed acute rejection after device return.

CONCLUSIONS

The device was tolerated by a majority of LTx patients and appears feasible as a barrier measure in the prevention of rejection. Delayed treatment of laryngopharyngeal reflux may lead to early allograft failure; therefore, the UES assist device should be given important consideration in transplant protection.

Triaging donor lungs based on a microaspiration signature that predicts adverse recipient outcome

BACKGROUND

Aspiration is a relative contraindication to accepting donor lungs for transplant and is currently assessed by visual inspection of the airways via bronchoscopy. However, this method is limited as it does not assess for microaspiration. Bile acids measured in large airway bronchial wash (LABW) samples have been shown to be a marker of aspiration in lung transplant recipients. Herein, we investigate the utility of measuring total bile acids (TBA) in donor LABW to predict performance of donor lungs and recipient outcomes.

METHODS

TBA was measured in 605 consecutive lung donors at the Toronto Lung Transplant Program. TBA levels were compared in donor lungs deemed unsuitable for transplant, requiring further assessment on ex vivo lung perfusion (EVLP), and those suitable for direct transplantation using Mann-Whitney-U tests. Relationships between LABW TBA concentrations and recipient outcomes were evaluated using multivariable Cox-PH models and log-rank analysis.

RESULTS

Donor TBA was highest in lungs deemed unsuitable for transplant and correlated with clinical assessment of aspiration. LABW TBA concentration correlated with calcium, decreased pH, and increased pro-inflammatory mediators in EVLP perfusate. TBA cut-off of 1245 nM was able to differentiate donor lungs directly declined from those suitable for direct transplantation with a 91% specificity (AUROC: 73%). High donor TBA status was associated with the increased rate of primary graft dysfunction, longer time to extubation, and shorter time to chronic lung allograft dysfunction.

CONCLUSIONS

In a large retrospective cohort, we observed that donor LABW TBA was associated with suitability of donor lungs for transplant, performance of the organ on EVLP, and adverse recipient outcomes.

Treatment of Gastroesophageal Reflux Disease After Lung Transplant Using Radiofrequency Ablation to the Lower Esophageal Sphincter (Stretta Procedure)

BACKGROUND

Gastroesophageal reflux disease (GERD) is associated with chronic lung allograft dysfunction after lung transplant. Treating GERD after lung transplant has been shown to improve lung allograft function. This case series describes the efficacy of the Stretta procedure to control GERD after lung transplant at our institution.

METHODS

Eleven patients underwent the Stretta procedure at our institution for GERD after lung transplant during the years 2016-2017. Pre- and post-Stretta reflux parameters were gathered. Pulmonary function was followed up until subsequent fundoplication surgery, death, or end of study observation.

RESULTS

Reflux on esophagram was noted in 9 patients before Stretta and 8 patients after Stretta. The median number of acid reflux events was 31.5 vs. 26 after Stretta (P = .95), and median percent time in reflux was 17.7% before vs. 14.5% after Stretta (P = .76). Median DeMeester score before Stretta was 65.5 (range: 33.2-169.8) vs. 42.5 (range: 19.2-109.8) after the procedure (P = .14). Median lower esophageal resting pressure was 20.7 mm Hg (n = 7) compared to 25.9 mm Hg (n = 9) on post-Stretta follow-up (P = .99). Median FEV₁% predicted was 84% (41-97%) before compared to 71% (23-108%) at 1 year after the procedure (P = .14). Seven patients required fundoplication surgery for continued reflux. All patients were on triple immunosuppression, most commonly prednisone, tacrolimus, and mycophenolate (n = 9).

DISCUSSION

The Stretta procedure did not provide expected results at our institution after lung transplant surgery. Based on our limited series, we do not recommend routine use of the Stretta procedure for management of GERD in lung transplant patients.

Impact of vagus nerve integrity testing on surgical management in patients with previous operations with potential risk of vagal injury

BACKGROUND

Thoracic and foregut operations can cause vagal nerve injury resulting in delayed gastric emptying or gastroparesis. However, the cause of gastroparesis in these patients is not always from a vagal injury. We hypothesize that vagal nerve integrity (VNI) testing may better define who has vagal nerve dysfunction. This information may change subsequent operations. The aim of this study was to evaluate the impact of VNI testing in patients with prior thoracic or gastric surgery.

METHODS

From January 2014 to December 2017, patients who had previous operations with the potential risk of vagal injury and had VNI testing were reviewed. Excluded patients were those with no plan for a second operation or the second operation was only for gastroparesis. The main outcome was the percentage of operations altered due to the results of VNI testing.

RESULTS

Twelve patients (eight females) were included. Ages ranged from 37 to 77 years. VNI results were compatible with vagal injury in eight patients (67%). VNI test results altered subsequent operative plans in 41.7% (5/12). Pyloroplasty was done in addition to fundoplication in two patients. Plans for hiatal hernia repair with or without redo-fundoplication in three patients were changed by an additional pyloroplasty in one patient and partial gastrectomy with Roux-en-Y reconstruction in two patients. All patients who had secondary surgery had resolution of symptoms and improvement in objective testing.

CONCLUSION

The addition of VNI testing in patients with a previous potential risk of vagal nerve injury may help the surgeon select the appropriate secondary operation.

Risks associated with lung transplantation in cystic fibrosis patients

INTRODUCTION

Survival after lung transplantation lags behind outcomes of other solid organ transplants, and complications from lung transplant are the second most common cause of death in cystic fibrosis. Evolving surgical techniques, therapeutics, and perioperative management have improved short-term survival after lung transplantation, yet have not translated into significant improvement in long-term mortality. Areas covered: We review risk factors for poor long-term outcomes among patients with cystic fibrosis undergoing lung transplantation to highlight areas for improvement. This includes reasons for organ dysfunction, complications of immunosuppression, further exacerbation of extrapulmonary complications of cystic fibrosis, and quality of life. A literature search was performed using PubMed-indexed journals. Expert commentary: There are multiple medical and socioeconomic barriers that threaten long-term survival following lung transplant for patients with cystic fibrosis. An understanding of the causes of each could elucidate treatment options. There is a lack of prospective, multicenter, randomized control trials due to cost, complexity, and feasibility. Ongoing prospective studies should be reserved for the most promising interventions identified in retrospective studies in order to improve long-term outcomes.

Practical guidelines: lung transplantation in patients with cystic fibrosis

There are no European recommendations on issues specifically related to lung transplantation (LTX) in cystic fibrosis (CF). The main goal of this paper is to provide CF care team members with clinically relevant CF-specific information on all aspects of LTX, highlighting areas of consensus and controversy throughout Europe. Bilateral lung transplantation has been shown to be an important therapeutic option for end-stage CF pulmonary disease. Transplant function and patient survival after transplantation are better than in most other indications for this procedure. Attention though has to be paid to pretransplant morbidity, time for referral, evaluation, indication, and contraindication in children and in adults. This review makes extensive use of specific evidence in the field of lung transplantation in CF patients and addresses all issues of practical importance. The requirements of pre-, peri-, and postoperative management are discussed in detail including bridging to transplant and postoperative complications, immune suppression, chronic allograft dysfunction, infection, and malignancies being the most important. Among the contributors to this guiding information are 19 members of the ECORN-CF project and other experts. The document is endorsed by the European Cystic Fibrosis Society and sponsored by the Christiane Herzog Foundation.

An important role for autoimmunity in the immunopathogenesis of chronic allograft rejection

Organ transplantation is the treatment of choice for patients with end-stage organ dysfunction. In spite of advances in understanding of donor and recipient physiology, organ preservation, operative techniques and immunosuppression, long-term graft survival still remains a major problem primarily due to chronic rejection. Alloimmune responses to mismatched major histocompatibility antigens have been implicated as an important factor leading to rejection. However, there is increasing evidence pointing towards cross-talk between the alloimmune and autoimmune responses creating a local inflammatory milieu, which eventually leads to fibrosis and occlusion of the lumen in the transplanted organ i.e. chronic rejection. In this review, we will discuss recent studies and emerging concepts for the interdependence of alloimmune and autoimmune responses in the immunopathogenesis of chronic allograft rejection. The role of autoimmunity in the development of chronic rejection is an intriguing and exciting area of research in the field of solid-organ transplantation with a significant potential to develop novel therapeutic strategies towards preventing chronic allograft rejection.