A Computational Fluid Dynamics Analysis of BiPAP Pressure Settings on Airway Biomechanics Using a CT-Based Respiratory Tract Model.

Central and Obstructive Sleep Apnea (CSA and OSA), Chronic Obstructive Pulmonary Disease (COPD), and Obesity Hypoventilation Syndrome (OHS) disrupt breathing patterns, posing significant health risks and reducing the quality of life. Bilevel Positive Airway Pressure (BiPAP) therapy offers adjustable inhalation and exhalation pressures, potentially enhancing treatment adaptability for the above diseases. This is the first-ever study that employs Computational Fluid Dynamics (CFD) to examine the biomechanical impacts of BiPAP under four settings: Inspiratory Positive Airway Pressure (IPAP)/Expiratory Positive Airway Pressure (EPAP) of 12/8, 16/6, and 18/8 cmH₂O, compared to a without-BiPAP scenario of zero-gauge pressure. Utilizing a computed-tomography-based respiratory tract model from the nasal cavity extending to the 13th generation, we analyzed parameters such as static pressure, shear stress, and airway wall normal force across different airway regions. Our results indicate that BiPAP, particularly at higher IPAP settings, effectively increases static pressure, thereby improving airway patency and potentially reducing the risk of airway collapse in both CSA and OSA. Lower EPAP, on the other hand, helps reduce the work of breathing during exhalation, which is particularly useful for patients who have difficulty exhaling against higher pressures or need to exhale CO₂ more effectively. This comparative analysis confirms that BiPAP not only maintains open airways but does so with an adjustable approach that can be used for the specific needs of patients with various respiratory dysfunctions, thereby offering a versatile and effective treatment option.