Airway blood flow changes after lung transplantation

Background: Lung transplantation is a therapeutic option for the treatment of end-stage parenchymal and vascular lung diseases. Long-term survival of transplant patients, however, remains disappointing because of severe complications, such as infections and rejections affecting function of lung allografts. Since vasculature typically participates in tissue inflammation, airway infections and allograft rejections are expected to influence airway blood flow in these patients. Airway blood flow measurement, therefore might be important to detect early signs of these complications. Objective: The purpose of the study was to determine airway blood flow levels in lung transplant patients. Methods: Ten lung transplant patients (1 month to 15 years after transplantation, without bronchial artery revascularization) and 10 healthy non-smoker volunteers participated in the study. Airway mucosal blood flow (Q aw ) was measured using a soluble, inert gas uptake method. Results: In our measurements, average Q aw level was about 90% higher in lung transplant patients than in healthy controls (64.8 ± 3.8 vs. 33.9 ± 3.8 μl/ml/min; p aw level in case of allograft rejection, and regional heterogeneity of airway blood flow in case of recent lung transplantation. Conclusions: Our results demonstrate that lung transplantation is associated with an increase in Q aw , a heretofore unknown relationship of lung transplantation and the vasculature in the airway mucosa. We propose that Q aw measurements, by incorporating into the posttransplant surveillance protocol, might have diagnostic and prognostic roles in lung transplant recipients with airway infection or allograft rejections.