In-silico investigation of airflow and micro-particle deposition in human nasal airway pre- and post-virtual transnasal sphenoidotomy surgery.

Sphenoid sinus, located posterior to the nasal cavity, is difficult to reach for a surgery. Several operation procedures are available for sphenoidotomy, including endoscopic surgeries. Although the endoscopic sinus surgery is minimally invasive with low post-operative side effects, further optimization is required. Transnasal sphenoidotomy is a low invasive alternative to transethmoidal sphenoidotomy, but it still needs to be studied to understand its effects on the airflow pattern and the particle deposition. In this work, we simulated airflow and the micro-particle deposition in the nasal airway of a middle-aged man to investigate the change in particle deposition in the sphenoid sinus after virtual transnasal sphenoidotomy surgery. The results demonstrated that after transnasal sphenoidotomy, particle deposition in the targeted sphenoid sinus was an order of magnitude lower than that observed after virtual transethmoidal sphenoidotomy surgery. In addition, the diameter of the particles for the peak deposition fraction in the targeted sinus was shifted to smaller diameters after the transnasal sphenoidotomy surgery compared with that in the post-transethmoidal condition. These results suggest that the endoscopic transnasal sphenoidotomy can be a better procedure for sphenoid surgeries as it decreases the chance of bacterial contaminations and consequently lowers the surgical side effects and recovery time.

Numerical simulation of airflow and micro-particle deposition in human nasal airway pre- and post-virtual sphenoidotomy surgery.

In the present study, the effects of endoscopic sphenoidotomy surgery on the flow patterns and deposition of micro-particles in the human nasal airway and sphenoid sinus were investigated. A realistic model of a human nasal passage including nasal cavity and paranasal sinuses was constructed using a series of CT scan images of a healthy subject. Then, a virtual sphenoidotomy by endoscopic sinus surgery was performed in the left nasal passage and sphenoid sinus. Transient airflow patterns pre- and post-surgery during a full breathing cycle (inhalation and exhalation) were simulated numerically under cyclic flow condition. The Lagrangian approach was used for evaluating the transport and deposition of inhaled micro-particles. An unsteady particle tracking was performed for the inhalation phase of the breathing cycle for the case that particles were continuously entering into the nasal airway. The total deposition pattern and sphenoid deposition fraction of micro-particles were evaluated and compared for pre- and post-surgery cases. The presented results show that sphenoidotomy increased the airflow into the sphenoid sinus, which led to increased deposition of micro-particles in this region. Particles up to 25 µm were able to penetrate into the sphenoid in the post-operation case, and the highest deposition in the sphenoid for the resting breathing rate occurred for 10 µm particles at about 1.5%.