Yash J. Avashia, MD
Duke University, Division of Plastic and Reconstruction Surgery, Division of Otolaryngology, Head and Neck Surgery
Summary: Three common options for midvault reconstruction include primary repair of upper lateral cartilages to the dorsal aspect of the septum, spreader grafts, and spreader flaps. This study is a cadaveric study seeking to describe the functional changes to nasal airway after the different midvault reconstruction techniques.Core: Medical Knowledge, Patient CareCadaveric StudyLearning Objectives: N/AStudy: 1. To quantify nasal airflow dynamics and airway size in cadavers both before and after dorsal hump reduction and midvault reconstruction using spreader grafts. 2. To compare changes in CFD computed values for both spreader flaps and spreader grafts at CFD identified sites of greatest nasal obstruction.Design: This is a cadaveric study seeking to quantify and compare the functional changes after midvault reconstruction with spreader grafts and spreader flaps. Preoperative and postoperative digital nasal models were created from the high-resolution, fine-cut, computed tomographic (CT) imaging after each intervention.We used computational fluid dynamic techniques to calculate nasal resistance, nasal airflow, and nasal airflow partitioning for each intervention.Method: Ten unenbalmed cadaver heads were prepared in standard fashion. Three sequential surgical maneuvers were performed on each cadaver. High resolution CT scans were obtained after each technique (1) Soft Tissue Elevation [Control]; (2) Dorsal Hump Reduction and Spreader Flap [Experimental Group 1]; (3) Spreader Graft [Experimental Group 2]. Computational Fluid Dynamics (CFD) was used to analyze both pre- and post-operative CT scans. Implementation of CFD modeling involve (1) 3D reconstruction of nasal cavity from radiographic images; (2) generation of volume mesh elements in the computational domain to discretize the nasal airspace; (3) simulation of airflow by numerically solving discretized equations governing fluid flow. Endpoints of CFD includedNasal airflow, nasal resistance, and partitioning of airflow.Results: Using the soft-tissue elevation model as baseline, computational fluid dynamic analysis predicted that both spreader grafts and spreader flaps as techniques for midvault reconstruction improved nasal airflow and partitioning while reducing nasal resistance. Airflow resistance was shown to decrease for the spreader graft group (0.011 Pa.s/ml) compared to the baseline soft tissue elevation (0.014 Pa.s/ml) group, however this was not seen in the spreader flap (0.015 Pa.s/ml) group consistently. There were no significant alterations in airflow partitioning between spreader grafts and spreader flaps.Conclusion: Our cadaveric study suggests that spreader grafts provide a greater functional improvement in nasal airway obstruction compared to spreader flaps while both preserve airflow partitioning between each side.