BACKGROUND AND OBJECTIVE: Chronic rhinosinusitis (CRS) is a prevalent inflammatory condition that substantially affects patients' quality of life. Functional endoscopic sinus surgery (FESS) is commonly performed in cases where medical therapy fails. Effective post-operative drug delivery is crucial for improving outcomes. This study uses computational fluid dynamics (CFD) to compare nebulisation and nasal irrigation (bottle wash) in post-operative sinonasal models and to evaluate how anatomical alterations affect drug deposition across various paranasal sinuses. METHODS: Eight post-FESS models were generated from the CT scans of a 29-year-old female CRS patient. These models included variations in maxillary ostium sizes, both with and without partial middle turbinectomy. Using 3D Slicer®, images were segmented, and Ansys SpaceClaim® prepared the final geometries. CFD simulations then examined drug delivery efficiency for both nebulisation and nasal irrigation. RESULTS: Nebulisation faces considerable challenges due to sinus complexity
however, surgical modifications improved nebuliser deposition in the maxillary and sphenoid sinuses. In contrast, nasal irrigation showed higher efficiency in delivering drugs to the frontal sinuses. The residual liquid layer on sinus walls after irrigation significantly impacts comparative evaluations of these methods. CONCLUSIONS: These findings emphasise the importance of adapting drug delivery strategies to specific surgical and anatomical factors. Tailored post-operative protocols may enhance outcomes in CRS, potentially improving patient comfort and compliance, and reducing recurrence rates. Further investigations are warranted to precisely quantify the liquid layer thickness remaining after irrigation, particularly as head movements can result in medication flowing back from sinuses into the nasal cavity.