Simulation of lung function evolution after heart-lung transplantation using a numerical model.

Area of Science:

• Pulmonary Medicine
• Computational Biology
• Biomedical Engineering

Background:

• Heart-lung transplantation (HLT) can lead to altered lung function, manifesting as unusual maximum expiratory flow-volume (MEFV) curve configurations.
• Postoperative MEFV curves often display a peak, plateau, and sudden drop (knee), differing from typical expiratory flow patterns.

Purpose of the Study:

• To investigate the relationship between MEFV curve changes and airway mechanics alterations after HLT using a computational model.
• To test hypotheses regarding lung denervation and airway obstruction, specifically bronchiolitis obliterans, as causes for the observed MEFV curve patterns.

Main Methods:

• Development and application of a morphometry-based computational model for human expiratory flow.
• Computer simulations to analyze the effects of lung denervation and airway obstruction on MEFV curve configuration.
• Comparison of simulated MEFV curves with measured postoperative patient data.

Main Results:

• Simulated MEFV curves closely matched the observed postoperative plateau-knee patterns.
• The model confirmed that flow limitation in early airway generations, combined with increased peripheral airway resistance, causes plateau shortening.
• Lung denervation was identified as a potential cause for increased expiratory flows in the latter part of expiration.

Conclusions:

• The plateau-knee configuration of the MEFV curve in HLT patients can be attributed to specific airway mechanical changes, including peripheral airway obstruction and denervation.
• The study highlights that airways larger than transitional and respiratory bronchioles can be involved in pulmonary function decline.
• The computational model is a reliable tool for evaluating heterogeneous lung periphery changes in HLT recipients.