Computational fluid dynamics assessment of upper airway morphology and flow dynamics in infants with Robin sequence treated with the Stanford Orthodontic Airway Plate

Infants with Robin sequence (RS) may develop upper airway obstruction (UAO) due to glossoptosis. The Stanford orthodontic airway plate (SOAP) improves the obstructive apnoea–hypopnoea index (OAHI), but treatment-related airway changes are difficult to quantify. We used computational fluid dynamics (CFD) to assess pre- and post-treatment CT scans from eight infants with RS. Unsteady Reynolds-averaged Navier–Stokes simulations with the SST k–ω model were performed to evaluate paired changes and associations with ΔOAHI. After treatment, airflow became more uniform and peak local breathing resistance decreased (Wilcoxon p = 0.016). Pearson analysis showed the strongest association with ΔOAHI for local breathing resistance (r = 0.847, p = 0.008), followed by narrowing gradient (r = 0.775, p = 0.024). Minimum cross-sectional area was not significantly associated (r = −0.233, p = 0.579). Spearman analysis showed consistent directions for local breathing resistance and narrowing gradient, although associations were weaker; velocity showed a strong rank-based association (ρ = 0.810, p = 0.022). Integrating airway morphology with CFD-derived flow metrics may enable quantitative assessment of UAO in infants with RS. Local breathing resistance and narrowing gradient may complement UAO assessment and warrant validation in larger cohorts.