Computational airflow analysis before and after maxillomandibular advancement surgery

BackgroundThe purpose of this study was to analyze pharyngeal airflow using computational fluid dynamics (CFD) in obstructive sleep apnea (OSA) patients before and after maxillomandibular advancement (MMA).MethodsDigitized pharyngeal airway models of 19 obstructive sleep apnea patients were generated from cone beam computed tomography scans presurgery and an average of 18.3 ± 17.3 days postsurgery. CFD was used to simulate and characterize pharyngeal airflow, which was assumed to be turbulent at an inspiration rate of 340 mL/s. Standard steady-state numerical formulation were used for airflow simulations.ResultsMean pressure drop during inspiration was significantly reduced from 34.82 ± 65.65 Pa presurgery to 3.06 ± 3.96 Pa postsurgery. Mean maximum airflow velocity along the airway was also significantly reduced from 11.14 ± 8.49 m/s presurgery to 4.09 ± 3.07 m/s postsurgery. There was a significant increase in mean airway volume of 66.8% postsurgery. There was a 75% mean reduction in airway resistance postsurgery. There was a decrease in the pressure gradient and total pressure drop postsurgery for all 19 patients. There was a statistically significant moderate, negative correlation between the change in airway resistance and the change in airway volume postsurgery. No correlation was found between skeletal advancement and airway volume or airway resistance.ConclusionsA decrease in relative pressure implies less effort required for maintaining constant pharyngeal airflow according to CFD analyses on airways of OSA patients after MMA surgery.