Physical and Computational Modeling of Ventilation of the Maxillary Sinus

Abstract

Objective. Sinus ventilation is often associated with sinusitis, a common condition causing significant pain and reduced quality of life. Clinical implications of the diverse anatomy of ostia connecting sinus to nose and the efficacy of surgical intervention in chronic sinusitis are poorly understood. This study aimed to measure sinus ventilation and explore variables in physical and mathematical models. Study Design. γ-Scintigraphy of krypton 81m (81mKr) was carried out in a stylized physical model of a human maxillary sinus. Computational simulations matched this model for validation and extrapolated to combinations of variables not possible experimentally for evaluation of transport mechanisms. Setting. Research laboratory in Department of Aeronautics. Imperial College London, and Department of Nuclear Medicine, Hammersmith Hospital, London. Methods. 81mKr distribution was measured with both single- and double-ostia sinuses. Computational simulations matched and extended the physical measurements and enabled separate identification and evaluation of transport mechanisms. Results. The presence of an additional ostium resulted in a 50-fold increase in the effective volume flow rate of gas replacement in the sinus. In the case of a single ostium, doubling the ostial diameter doubled the effective volume flow rate of gas exchange. Conclusion. γ-Scintigraphy of 81mKr enables quantitative assessment of effective volume flow rate in physical model sinuses. These flow rates obtained experimentally for single- and double-ostium sinuses match the computational predictions of matching geometries. The increased ventilation seen with an additional ostium or increased ostial diameters may not be clinically beneficial, because it could reduce nitric oxide concentration in the sinus.