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ObjectivesAdenotonsillectomy (AT) is commonly used to treat upper airway obstruction in children, but selection of patients who will benefit most from AT is challenging. The need for diagnostic evaluation tools without sedation, radiation, or high costs has motivated the development of long-range optical coherence tomography (LR-OCT), providing real-time cross-sectional airway imaging during endoscopy. Since the endoscope channel location is not tracked in conventional LR-OCT, airway curvature must be estimated and may affect predicted airway resistance. The study objective was to assess effects of three realistic airway curvatures on predicted airway resistance using computational fluid dynamics (CFD) in LR-OCT reconstructions of the upper airways of pediatric patients, before and after AT.MethodsEight subjects (five males, three females, aged 4-9 years) were imaged using LR-OCT before and after AT during sedated endoscopy. Three-dimensional (3D) airway reconstructions included three airway curvatures. Steady-state, inspiratory airflow simulations were conducted under laminar conditions, along with turbulent simulations for one subject using the k-ω turbulence model. Airway resistance (pressure drop/flow) was compared using two-tailed Wilcoxon signed rank tests.ResultsRegardless of the airway curvatures, CFD findings corroborate a surgical end-goal with computed post-operative airway resistance significantly less than pre-operative (P  0.25). Resistances computed using turbulent simulations differed from laminar results by less than ∼5%.ConclusionsThe results suggest that reconstruction of the upper airways from LR-OCT imaging data may not need to account for airway curvature to be predictive of surgical effects on airway resistance. Lasers Surg. Med. 51:150-160, 2019. © 2018 Wiley Periodicals, Inc.

Objective: Mucosal decongestion with nasal sprays is a common treatment for nasal airway obstruction. However, the impact of mucosal decongestion on nasal aerodynamics and the physiological mechanism of nasal airflow sensation are incompletely understood. The objective of this study is to compare nasal airflow patterns in nasal airway obstruction (NAO) patients with and without mucosal decongestion and nondecongested healthy subjects. Study Design: Cross‐sectional study of a convenience sample. Setting: Academic tertiary medical center. Methods: Forty‐five subjects were studied (15 nondecongested healthy subjects, 15 nondecongested NAO patients, and 15 decongested NAO patients). Three‐dimensional models of the nasal anatomy were created from computed tomography scans. Steady‐state simulations of airflow and heat transfer were conducted at 15 L/min inhalation rate using computational fluid dynamics. Results: In the narrow side of the nose, unilateral nasal resistance was similar in decongested NAO patients and nondecongested healthy subjects, but substantially higher in nondecongested NAO patients. The vertical airflow distribution within the nasal cavity (inferior vs middle vs superior) was also similar in decongested NAO patients and nondecongested healthy subjects, but nondecongested NAO patients had substantially less middle airflow. Mucosal cooling, quantified by the surface area where heat flux exceeds 50 W/m2, was significantly higher in decongested NAO patients than in nondecongested NAO patients. Conclusion: This pilot study suggests that mucosal decongestion improves objective measures of nasal airflow, which is consistent with improved subjective sensation of nasal patency after decongestion. [ABSTRACT FROM AUTHOR]

Virtual surgery planning based on computational fluid dynamics (CFD) simulations has the potential to improve surgical outcomes for nasal airway obstruction patients, but the benefits of virtual surgery planning must outweigh the risks of radiation exposure. Cone beam computed tomography (CT) scans represent an attractive imaging modality for virtual surgery planning due to lower costs and lower radiation exposures compared with conventional CT scans. However, to minimize the radiation exposure, the cone beam CT sinusitis protocol sometimes images only the nasal cavity, excluding the nasopharynx. The goal of this study was to develop an idealized nasopharynx geometry for accurate representation of outlet boundary conditions when the nasopharynx geometry is unavailable. Anatomically accurate models of the nasopharynx created from 30 CT scans were intersected with planes rotated at different angles to obtain an average geometry. Cross sections of the idealized nasopharynx were approximated as ellipses with cross-sectional areas and aspect ratios equal to the average in the actual patient-specific models. CFD simulations were performed to investigate whether nasal airflow patterns were affected when the CT-based nasopharynx was replaced by the idealized nasopharynx in 10 nasal airway obstruction patients. Despite the simple form of the idealized geometry, all biophysical variables (nasal resistance, airflow rate, and heat fluxes) were very similar in the idealized vs patient-specific models. The results confirmed the expectation that the nasopharynx geometry has a minimal effect in the nasal airflow patterns during inspiration. The idealized nasopharynx geometry will be useful in future CFD studies of nasal airflow based on medical images that exclude the nasopharynx. [ABSTRACT FROM AUTHOR]

Introduction The nasal cycle represents a significant challenge when comparing pre- and post-surgery objective measures of nasal airflow. Methods Computational fluid dynamics (CFD) simulations of nasal airflow were conducted in 12 nasal airway obstruction patients showing significant nasal cycling between pre- and post-surgery computed tomography scans. To correct for the nasal cycle, mid-cycle models were created virtually. Subjective scores of nasal patency were obtained via the Nasal Obstruction Symptom Evaluation (NOSE) and unilateral visual analog scale (VAS). Results The correlation between objective and subjective measures of nasal patency increased after correcting for the nasal cycle. In contrast to biophysical variables in individual patients, cohort averages were not significantly affected by the nasal cycle correction. Conclusions The ability to correct for the confounding effect of the nasal cycle is a key element that future virtual surgery planning software for nasal airway obstruction will need to account for when using anatomic models based on single instantaneous imaging. [ABSTRACT FROM AUTHOR]

Background: Nasal airway obstruction (NAO) is a common health condition impacting mood, energy, recreation, sleep, and overall quality of life. Nasal surgery often addresses NAO but the results are sometimes unsatisfactory. Evaluating surgical treatment efficacy could be improved if objective tests were available that correlated with patient-reported measures of symptoms. The goal of this study was to develop methods for comparing nasal resistance computed by computational fluid dynamics (CFD) models with patient-reported symptoms of NAO using early data from a 4-year prospective study. Methods: Computed tomography (CT) scans and patient-reported scores from the Nasal Obstruction Symptom Evaluation (NOSE) scale and a visual analog scale (VAS) measuring unilateral airflow sensation were obtained pre- and postoperatively in two NAO patients showing no significant mucosal asymmetry who were successfully treated with functional nasal surgery, including septoplasty. Pre- and postsurgery CFD models were created from the CT scans. Numerical simulation of steady-state inspiratory airflow was used to calculate bilateral and unilateral CFD-derived nasal resistance (CFD-NR). Results: In both subjects, NOSE and VAS scores improved after surgery, bilateral CFD-NR decreased, and unilateral CFD-NR decreased on the affected side. In addition, NOSE and VAS scores tracked with unilateral CFD-NR on the affected side. Conclusion: These preliminary results suggest a possible correlation between unilateral NR and patient-reported symptoms and imply that analysis of unilateral obstruction should focus on the affected side. A formal investigation of unilateral CFD-NR and patient-reported symptoms in a series of NAO patients is needed to determine if these variables are correlated. [ABSTRACT FROM AUTHOR]

Objective. To study the effects of nasal deformity on aerosol penetration past the nasal valve (NV) for varying particle sizes using sprays or nebulizers.Study Design. Computed mathematical nasal airway model.Setting. Department computer lab.Subjects and Methods. Particle deposition was analyzed using a computational fluid dynamics model of the human nose with leftward septal deviation and compensatory right inferior turbinate hypertrophy. Sprays were simulated for 10 µm, 20 µm, 50 µm, or particle sizes following a Rosin Rammler particle size distribution (10-110 µm), at speeds of 1, 3, or 10 meters per second. Nebulization was simulated for 1, 3.2, 6.42, or 10 µm particles. Steady state inspiratory airflow was simulated at 15.7 liters per minute.Results. Sprays predicted higher NV penetration on the right side for particle sizes >10 µm, with comparable penetration on both sides at 10 µm. Nearly 100% deposited in the nasal passages for all spray characteristics. Nebulizer predictions showed nearly 100% of particles <6.42 µm and more than 50% of 6.42 µm bypassing both sides of the nose without depositing. Of the nebulized particles that deposited, penetration was higher on the right at 10 µm, with comparable penetration on both sides at 6.42 µm. Spray penetration was highest at 10 µm, with more than 96% penetrating on both sides at 1 and 3 meters per second. Nebulization penetration was also highest at 10 µm (40% on the left, >90% on the right).Conclusion. In the presence of a septal deviation, sprays or nebulizers containing 10-µm particles may have good penetration beyond the NV. Nebulized particles <10 µm are likely to be respirable. Additionally, spray speeds above 3 meters per second may limit penetration. [ABSTRACT FROM AUTHOR]

The outcomes of aesthetic and functional nasal surgery are difficult to assess objectively because of the intricate balance between nasal form and function. Despite historical emphasis on patient-reported subjective measures, objective measures are gaining importance in both research and the current outcomes-driven health care environment. Objective measures currently available have several shortcomings that limit their routine clinical use. In particular, the low correlation between objective and subjective measures poses a major challenge. However, advances in computer, imaging, and bioengineering technology are now setting the stage for the development of innovative objective assessment tools for nasal surgery that can potentially address some of the current limitations. Assessment of nasal form after aesthetic surgery is evolving from two-dimensional analysis to more sophisticated three-dimensional analysis. Similarly, assessment of nasal function is evolving with the introduction of computational fluid dynamics techniques, which allow for a detailed description of the biophysics of nasal airflow. In this article, we present an overview of objective measures in both aesthetic and functional nasal surgery and discuss future trends and applications that have the potential to change the way we assess nasal form and function. [ABSTRACT FROM AUTHOR]

Background: Septal deviation is an extremely common anatomic variation in healthy adults. However, there are no standard criteria to determine when a deviated septum is clinically relevant. Presently, selection of patients for septoplasty is based on mostly clinical examination, which is prone to observer bias and may lead to unsuccessful treatment. The objective of this article is twofold. First, we investigate whether the location of a septal deviation within the nasal passages affects nasal resistance. Second, we test whether computer simulations are consistent with rhinomanometry studies in predicting that anterior septal deviations increase nasal resistance more than posterior deviations. Methods: A three-dimensional computational model of a healthy nose was created from computed tomography scans. Geometry-deforming software was used to produce models with septal deviations. Computational fluid dynamics techniques were used to simulate nasal airflow and compute nasal resistance. Results: Our results revealed that the posterior nasal cavity can accommodate significant septal deviations without a substantial increase in airway resistance. In contrast, a deviation in the nasal valve region more than doubled nasal resistance. These findings are in good agreement with the rhinomanometry literature and with the observation that patients with anterior septal deviations benefit the most from septoplasty. Conclusion: In the model, anterior septal deviations increased nasal resistance more than posterior deviations. This suggests, in agreement with the literature, that other causes of nasal obstruction (dysfunction of the nasal valve, allergy, etc.) should be carefully considered in patients with posterior septal deviations because such deviations may not affect nasal resistance. This study illustrates how computational modeling and virtual manipulation of the nasal geometry are useful to investigate nasal physiology. [ABSTRACT FROM AUTHOR]

Background: Quantitative methods for comparing intranasal drug delivery efficiencies pre- and postoperatively have not been fully utilized. The objective of this study is to use computational fluid dynamics techniques to evaluate aqueous nasal spray penetration efficiencies before and after surgical correction of intranasal anatomic deformities. Methods: Ten three-dimensional models of the nasal cavities were created from pre- and postoperative computed tomography scans in 5 subjects. Spray simulations were conducted using a particle size distribution ranging from 10 μm to 110 μm, a spray speed of 3 m/second, plume angle of 68 degrees, and with steady state, resting inspiratory airflow present. Two different nozzle positions were compared. Statistical analysis was conducted using Student t test for matched pairs. Results: On the obstructed side, posterior particle deposition after surgery increased by 118% and was statistically significant ( p = 0.036), while anterior particle deposition decreased by 13% and was also statistically significant ( p = 0.020). The fraction of particles that bypassed the airways either pre- or postoperatively was less than 5%. Posterior particle deposition differences between obstructed and contralateral sides of the airways were 113% and 30% for pre- and postsurgery, respectively. Results showed that nozzle positions can influence spray delivery. Conclusion: Simulations predicted that surgical correction of nasal anatomic deformities can improve spray penetration to areas where medications can have greater effect. Particle deposition patterns between both sides of the airways are more evenly distributed after surgery. These findings suggest that correcting anatomic deformities may improve intranasal medication delivery. For enhanced particle penetration, patients with nasal deformities may explore different nozzle positions. © 2013 ARS-AAOA, LLC. [ABSTRACT FROM AUTHOR]