Management of microaspiration and gastrointestinal dysfunction after lung transplantation: A narrative review

Chronic Lung Allograft Dysfunction (CLAD) is the leading cause of late morbidity and mortality following lung transplantation. Increasing evidence implicates microaspiration, often secondary to gastroesophageal reflux disease (GERD) and gastrointestinal (GI) dysfunction, as a critical non-alloimmune driver of CLAD. However, its often silent presentation, diagnostic complexity, and heterogeneous management contribute to persistent knowledge and treatment gaps.

This narrative review synthesizes recent literature on the pathophysiology, diagnosis, and clinical impact of microaspiration and GI dysfunction in lung transplant recipients. We focus on emerging biomarkers (e.g., conjugated bile acids and pepsinogen A4), diagnostic modalities, and both medical and surgical treatment strategies aimed at mitigating aspiration-induced graft injury.

Microaspiration leads to epithelial damage, surfactant disruption, immune activation, and microbial dysbiosis, collectively promoting allograft dysfunction. Conjugated bile acids in large airway bronchial wash fluid and pepsinogen A4 have shown superior specificity as aspiration biomarkers compared to pepsin alone. Gastrointestinal disorders, such as GERD, gastroparesis, and esophageal dysmotility, frequently co-exist post-transplant and contribute to aspiration risk. Pharmacologic interventions provide limited benefit, while anti-reflux surgery significantly improves graft outcomes, particularly when performed early. Conservative measures such as head-of-bed elevation also reduce reflux burden and may complement therapeutic strategies.

Microaspiration is a modifiable and underrecognized contributor to allograft injury. Integration of aspiration biomarkers, early reflux evaluation, and personalized stepwise management, including surgical intervention when indicated, may improve long-term transplant outcomes. This review provides clinicians with a structured framework for diagnosis and management of microaspiration-related injury in lung transplantation.