New CFD tools to evaluate nasal airflow

Abstract

Computational fluid dynamics (CFD) is a mathematical tool to analyse airflow. As currently CFD is not a usual tool for rhinologists, a group of engineers in collaboration with experts in Rhinology have developed a very intuitive CFD software. The program MECOMLAND only required snapshots from the patient's cross-sectional (tomographic) images, being the output those results originated by CFD, such as airflow distributions, velocity profiles, pressure, temperature, or wall shear stress. This is useful complementary information to cover diagnosis, prognosis, or follow-up of nasal pathologies based on quantitative magnitudes linked to airflow. In addition, the user-friendly environment NOSELAND helps the medical assessment significantly in the post-processing phase with dynamic reports using a 3D endoscopic view. Specialists in Rhinology have been asked for a more intuitive, simple, powerful CFD software to offer more quality and precision in their work to evaluate the nasal airflow. We present MECOMLAND and NOSELAND which have all the expected characteristics to fulfil this demand and offer a proper assessment with the maximum of quality plus safety for the patient. These programs represent a non-invasive, low-cost (as the CT scan is already performed in every patient) alternative for the functional study of the difficult rhinologic case. To validate the software, we studied two groups of patients from the Ear Nose Throat clinic, a first group with normal noses and a second group presenting septal deviations. Wall shear stresses are lower in the cases of normal noses in comparison with those for septal deviation. Besides, velocity field distributions, pressure drop between nasopharynx and the ambient, and flow rates in each nostril were different among the nasal cavities in the two groups. These software modules open up a promising future to simulate the nasal airflow behaviour in virtual surgery intervention scenarios under different pressure or temperature conditions to understand the effects on nasal airflow.

Three-dimensional modeling and automatic analysis of the human nasal cavity and paranasal sinuses using the computational fluid dynamics method

“…The results of these studies performed on small groups of patients suggest the usefulness of this approach for the 35 14 49 397,273 795,414 2 a 30 10 40 157,998 316,416 3 b 13 3 16 987,349 1,795,234 4 b 15 2 17 997,316 1,726,033 5 5 2 7 813, assessment of airflow within the nasal cavity and paranasal sinuses [16,[19][20][21][24][25][26][27][28][29]. The discussed methodology enables simulation of airflow and prediction/simulation of airflow changes in patients after nasal and paranasal sinus surgeries, for both children and adults [17,30,31]. Unfortunately, no randomized clinical trials on large groups of patients were published so far.…”

Nasal surgery handled by CFD tools

“…Simulations were performed using the new CFD tool MECOLAND @ , which was specifically developed to study nasal airflow patterns . This software has 3 different modules: Segmentation module.…”

“…Finally, it is noteworthy that a typical simulation on the order of 10 million cells took less than 6 hours using a computer with an Intel@ Core™ i7‐2700K CPU with 4 cores at 3.5 GHz. Postprocessing module. MECOLAND @ has its own postprocessor that allows flow visualizations and analysis of different flow characteristics (see Burgos et al for further details).…”

“…c. Postprocessing module. MECOLAND @ has its own postprocessor that allows flow visualizations and analysis of different flow characteristics (see Burgos et al 20 for further details).…”

Rhinomanometry Versus Computational Fluid Dynamics: Correlated, but Different Techniques

“…16–18 Therefore, CFD-based virtual surgery planning has the potential to improve surgical outcomes for NAO patients. 18–22…”