Fluid dynamic assessment of tracheal flow in infants with congenital tracheal stenosis before and after surgery

Tracheal flow in infants with congenital tracheal stenosis (CTS) was numerically investigated using subject-specific airway models before and after reconstructive surgery. We quantified tracheal flow based on airway resistance during inhalation, and compared it between controls and patients before and after surgery. The airway resistance in each subject was assessed using geometrical parameters of the trachea: the minimum cross-sectional area A_min, the minimum cross-sectional area normalized by the standard deviation of the cross-sectional area A_min/σ_A, the area ratio of the minimum and maximum cross-sectional area A_min/A_max, and ratio of the normalized standard deviation of cross-sectional area to the mean cross-sectional area σ_A/A_mean. Our numerical results demonstrated that such geometrical parameters could be used to assess the severity of CTS. Since subjects can be more clearly categorized as controls and most preoperative patients in terms of the airway resistance, a simulation using subject-specific airway models can lead us to a precise understanding of tracheal flow, and also provide knowledge about therapeutic decision. Our numerical results also demonstrated that significant surgical expansion of cross-sectional area did not help recover tracheal flow because of expansion loss. These results will be helpful not only when making therapeutic decisions about surgery but also when assessing quality of life in postoperative patients.