Non-acidic supraesophageal reflux associated with diffuse alveolar damage and allograft dysfunction after lung transplantation: a case report

Role of gastroesophageal reflux disease in lung transplantation

Lung transplantation is one of the highest risk solid organ transplant modalities. Recent studies have demonstrated a relationship between gastroesophageal reflux disease (GERD) and lung transplant outcomes, including acute and chronic rejection. The aim of this review is to discuss the pathophysiology, evaluation, and management of GERD in lung transplantation, as informed by the most recent publications in the field. The pathophysiology of reflux-induced lung injury includes the effects of aspiration and local immunomodulation in the development of pulmonary decline and histologic rejection, as reflective of allograft injury. Modalities of reflux and esophageal assessment, including ambulatory pH testing, impedance, and esophageal manometry, are discussed, as well as timing of these evaluations relative to transplantation. Finally, antireflux treatments are reviewed, including medical acid suppression and surgical fundoplication, as well as the safety, efficacy, and timing of such treatments relative to transplantation. Our review of the data supports an association between GERD and allograft injury, encouraging a strategy of early diagnosis and aggressive reflux management in lung transplant recipients to improve transplant outcomes. Further studies are needed to explore additional objective measures of reflux and aspiration, better compare medical and surgical antireflux treatment options, extend follow-up times to capture longer-term clinical outcomes, and investigate newer interventions including minimally invasive surgery and advanced endoscopic techniques.

How useful is antireflux surgery in lung transplant patients with gastroesophageal reflux?

BACKGROUND AND OBJECTIVE

Respiratory function deteriorates over time after lung transplant. Reflux disease with pulmonary complications is a possible cause of this decline. This case series we aim to assess whether respiratory function improves after Nissen fundoplication in lung transplant patients and if surgery reduces gastroesophageal reflux disease (GERD) symptoms and use of proton pump inhibitors (PPIs).

MATERIALS AND METHODS

A retrospective case series of lung transplant patients with reflux disease and Nissen fundoplication. Clinical symptoms, pH-metry data, use of PPIs were recorded before the procedure and up to 18 months postoperatively. The FEV1 values before and after Nissen fundoplication were recorded at 3 monthly intervals. Patients' satisfaction scores were recorded before operation and postoperatively.

RESULTS

A total of 64 lung transplant patients were selected. After Nissen fundoplication, the pH studies were done on 26 patients. The mean overall acid exposure fraction was 1.03% (P<0.05). FEV1 declined for 6 months postoperatively and then gradually improved. The comparison of FEV1 at 3 months preoperatively to 3 months postoperatively showed no significant difference (P=0.067) as well as at 6 months. A significant improvement in clinical GERD symptoms was achieved after antireflux surgery; however, the patients remained receiving PPIs.

CONCLUSIONS

NF has been established as a safe operation for lung transplant patients. Late Nissen fundoplication did not improve lung function significantly amongst lung transplanted patients; however, patients with symptomatic GERD may have benefited from Nissen fundoplication in terms of symptom relief. A multicenter randomized control trial is needed to assess the effect of early unselected reflux control on respiratory function and graft survival.

Bronchiolitis Obliterans Syndrome and Chronic Lung Allograft Dysfunction: Evolving Concepts and Nomenclature

Bronchiolitis obliterans syndrome (BOS) eventually occurs in the majority of lung transplant recipients who survive beyond 1 year, can greatly impair quality of life, and is, directly or indirectly, the major cause of delayed allograft dysfunction and recipient death. A number of associated events or conditions are strongly associated with the risk for developing BOS; these include acute rejection, gastroesophageal reflux, infections, and autoimmune reactions that can occur in the setting of alloimmune responses to the lung allograft as recipients are given intense immunosuppression to prevent allograft rejection. The term chronic lung allograft dysfunction (CLAD) is being increasingly used to refer to recipients with late allograft dysfunction that meets the spirometric criteria for the diagnosis of BOS, but clinicians should recognize that such dysfunction can occur for a variety of reasons other than BOS. The recently identified entity of restrictive allograft syndrome, which is now recognized as a relatively distinct phenotype of CLAD, has features that differentiate it from classic obstructive BOS. A number of other entities that can also significantly affect allograft function must also be considered when significant allograft dysfunction is encountered following lung transplantation.

Effect of different pH criteria on dual-sensor pH monitoring in the evaluation of supraesophageal gastric reflux in children

BACKGROUND AND AIM

Existing tests for supraesophageal gastric reflux (SEGR) that focus on pH drops <4 in the proximal esophagus have had limited sensitivity and specificity. The aim of the present study was to evaluate the effect of newly proposed pH criteria on SEGR detection.

PATIENTS AND METHODS

Twenty-four-hour dual-sensor pH tracings of 32 patients were reviewed. Proximal esophageal pH data were evaluated according to the conventional definition of pH drop <4 and 2 proposed definitions: pH drop <5.5 while upright and <5.0 while supine and pH drop of >10% from a running baseline. For each potential SEGR event, the preceding 1-minute window was examined for corresponding distal acid reflux.

RESULTS

Of the 542 distal acid reflux events detected, 200 were associated with a proximal pH drop <4; this number increased to 295 using the definition of proximal pH drop <5.5 (upright)/<5.0 (supine) and 301 using the definition of proximal pH drop >10%. A proportion of proximal events, however, was not associated with distal acid reflux: 21 of 200 (10.5%) proximal pH <4 events, 119 of 414 (29%) proximal pH <5.5 (upright)/<5.0 (supine) events, and 272 of 573 (47%) proximal pH drop >10% events lacked a preceding or simultaneous drop in distal pH <4.

CONCLUSIONS

Although the use of more liberal pH criteria increased the diagnostic yield for SEGR events with dual-sensor monitoring, a significant proportion of proximal pH events did not correlate with distal acid reflux. These events could represent either false-positive measurements or association with weakly acid reflux.

Relevance of GERD in lung transplant patients

Lung transplantation has become a valuable treatment for end-stage pulmonary disorders in an attempt to improve quality of life and extend survival. Development of chronic rejection, also known as bronchiolitis obliterans syndrome (BOS), is responsible for the vast majority of deaths after lung transplantation. Up to 50% of lung transplant patients develop BOS within the first 5 years after transplantation. A high prevalence of gastroesophageal reflux and aspiration of gastric components has been described after lung transplantation. Reflux and aspiration have been implicated in the development of BOS and antireflux surgery has been proposed; however, the causal relationship with BOS and the impact of reflux in lung transplantation survival needs to be further elucidated.

Gastroesophageal reflux and altered motility in lung transplant rejection

BACKGROUND

Lung transplantation has become an effective therapeutic option for selected patients with end stage lung disease. Long-term survival is limited by chronic rejection manifest as bronchiolitis obliterans syndrome (BOS). The aspiration of gastric contents has been implicated as a causative or additive factor leading to BOS. Gastroesophageal reflux (GER) and altered foregut motility are common both before and after lung transplantation. Further, the normal defense mechanisms against reflux are impaired in the allograft. Recent studies using biomarkers of aspiration have added to previous association studies to provide a growing body of evidence supporting the link between rejection and GER. Further, the addition of high-resolution manometry (HRM) and impedance technology to characterize bolus transit and the presence and extent of reflux regardless of pH might better identify at-risk patients. Although additional prospective studies are needed, fundoplication appears useful in the prevention or treatment of post-transplant BOS.

PURPOSE

This review will highlight the existing literature on the relationship of gastroesophageal reflux and altered motility to lung transplant rejection, particularly BOS. The article will conclude with a discussion of the evaluation and management of patients undergoing lung transplantation at our center.

Gastroesophageal reflux in bronchiolitis obliterans syndrome: a new perspective

BACKGROUND

Long-term survival after lung transplantation (LTx) is limited largely by bronchiolitis obliterans syndrome (BOS). Gastroesophageal reflux disease (GERD) is proposed as a risk factor for BOS development. This study investigates the relationship between BOS and GERD measured by esophageal impedance.

METHODS

After the initiation of routine screening for GERD, 59 LTx recipients underwent ambulatory esophageal impedance monitoring. Exposure to acid reflux and non-acid liquid reflux was recorded. Clinical outcomes were reviewed to analyze any effect of reflux on the time to development of BOS.

RESULTS

Thirty-seven (65%) had abnormal acid reflux and 16 (27%) had abnormal non-acid reflux. There was no relationship between acid reflux and BOS. The hazard ratio (HR) for development of BOS in the presence of abnormal non-acid reflux was 2.8 (p = 0.043). The HR for development of BOS increased to 3.6 (p = 0.022) when the number of acute rejection episodes was also taken into account.

CONCLUSIONS

GERD is prevalent in LTx recipients and may represent a modifiable risk factor for BOS. This study found non-acid reflux, measured by esophageal impedance to be associated with the development of BOS. Prospective studies are now required to investigate a causal association between GERD and the development of BOS and to establish the role of surgery for GERD in preventing progression to BOS. The methods used to identify GERD in future studies may be important.

Nocturnal weakly acidic reflux promotes aspiration of bile acids in lung transplant recipients

BACKGROUND

Gastroesophageal reflux (GER) and aspiration of bile acids have been implicated as non-alloimmune risk factors for the development of bronchiolitis obliterans syndrome (BOS) after lung transplantation. The aim of our study was to investigate the association between GER and gastric aspiration of bile acids and to establish which reflux characteristics may promote aspiration of bile acids into the lungs and may feature as a potential diagnostic tool in identifying lung transplantation (LTx) patients at risk for aspiration.

METHODS

Twenty-four stable LTx recipients were studied 1 year after transplantation. All patients underwent 24-hour ambulatory impedance-pH recording for the detection of acid (pH <4) and weakly acidic (pH 4 to 7) reflux. On the same day, bronchoalveolar lavage fluid (BALF) was collected and then analyzed for the presence of bile acids (Bioquant enzymatic assay).

RESULTS

Increased GER was detected in 13 patients, of whom 9 had increased acid reflux and 4 had exclusively increased weakly acidic reflux. Sixteen patients had detectable bile acids in the BALF (0.6 [0.4 to 1.5] micromol/liter). The 24-hour esophageal volume exposure was significantly increased in patients with bile acids compared to patients without bile acids in the BALF. Acid exposure and the number of reflux events (total, acid and weakly acidic) were unrelated to the presence of bile acids in the BALF. However, both nocturnal volume exposure and the number of nocturnal weakly acidic reflux events were significantly higher in patients with bile acids in the BALF.

CONCLUSIONS

Weakly acidic reflux events, especially during the night, are associated with the aspiration of bile acids in LTx recipients and may therefore feature as a potential risk factor for the development of BOS.