Characterizing airflow profile in the postoperative maxillary sinus by using computational fluid dynamics modeling: A pilot study

Nasal Airflow Dynamics following LeFort I Advancement in Cleft Nasal Deformities: A Retrospective Preliminary Study

Unilateral cleft lip and palate (UCLP) nasal deformity impacts airflow patterns and pressure distribution, leading to nasal breathing difficulties. This study aims to create an integrated approach using computer-aided design (CAD) and computational fluid dynamics (CFD) to simulate airway function and assess outcomes in nasal deformities associated with unilateral cleft lip and palate (UCLP) after LeFort I osteotomy advancement. Significant alterations were observed in nasal geometry, airflow velocity, pressure dynamics, volumetric flow rate, and nasal resistance postoperatively, indicating improved nasal airflow. The cross-sectional area increased by 26.6%, airflow rate by 6.53%, and nasal resistance decreased by 6.23%. The study offers quantitative insights into the functional impacts of such surgical interventions, contributing to a deeper understanding of UCLP nasal deformity treatment and providing objective metrics for assessing surgical outcome.

Intranasal Spray Characteristics for Best Drug Delivery in Patients With Chronic Rhinosinusitis

OBJECTIVES

To determine parameter combinations for effective drug delivery of intranasal spray steroids to the ostiomeatal complex (OMC) and maxillary sinus (MS) in patients with chronic rhinosinusitis (CRS).

METHODS

Each patient's sinonasal cavity was reconstructed from computed tomography scans. Intranasal airflow and drug particle transport were simulated using computational fluid dynamic modeling. Airflow simulations were performed at 15 Pascal inhalation pressure. Intranasal spray particles of 1-100 μm were simulated at release speeds of 1, 5, and 10 m/s from 6 release locations (Bottom, Center, Top, Lateral, Lateral-Bottom, and Lateral-Top) at a nozzle insertion depth of 15 mm. Drug delivery simulations were performed in the head tilted forward position.

RESULTS

Maximal OMC deposition was 0.78%-12.44%, while maximal MS deposition was 0.02%-1.03% across all simulations. In general, particles between 6 and 10 μm had the best OMC (at 1 m/s particle velocity) and MS (at 10 m/s particle velocity) deposition. Particles ranging from 21 to 30 μm also had superior OMC deposition. The lateral and lateral-top spray release locations produced maximum OMC deposition, but no one release location demonstrated an increase in MS deposition.

CONCLUSION

This preliminary study suggests that it is challenging to determine a common set of intranasal spray parameter combinations for effective drug delivery to the OMC and MSs. Although drug particle size and spray particle velocity seem to impact particle deposition patterns, spray release location appears to vary with anatomical differences between subjects, particularly when the MS is the target location for particle deposition. Laryngoscope, 133:1036-1043, 2023.

Human maxillary sinus size, shape, and surface area: Implications for structural and functional hypotheses

OBJECTIVES

Although research into human maxillary sinus (MS) morphology has overwhelmingly focused on sinus volume, other aspects of morphology (e.g., overall shape, mucosal surface area) factor prominently in hypotheses regarding MS form and function. Here, we investigate MS volume in conjunction with measures of MS shape and surface area in a large, diverse sample of modern humans. We test whether variation in MS volume is associated with predictable changes in MS shape (i.e., allometry) and investigate the influence of MS size-shape scaling on mucosal surface area dynamics.

MATERIALS AND METHODS

Measures of MS volume and surface area were obtained from computed tomographic (CT) scans of 162 modern human crania from three ancestral backgrounds-Equatorial Africa, Europe, and East Asia. 3D coordinate landmarks and linear measurements were also collected. Multivariate analyses were employed to test for associations between MS volume and other morphological variables.

RESULTS

Significant associations between MS volume and 3D shape were identified both across and within the subsamples. Variation in MS volume was found to predominantly relate to differences in MS height and width dimensions relative to MS length. This pattern of allometric scaling was found to differentially influence total mucosal surface area and the SAV ratio.

CONCLUSION

This study suggests that variation in MS volume is disproportionately mediated by MS width and height dimensions. This finding has implications for hypotheses which structurally link MS morphology to craniofacial ontogeny and those which suggest that MS morphology may perform adaptive physiological functions.

A systematic analysis of surgical interventions for the airway in the mature unilateral cleft lip nasal deformity: a single case study

PURPOSE

Individuals with unilateral cleft lip nasal deformity (uCLND) often require rhinoplasty in adolescence to correct nasal obstruction. The intent of this study is to identify sites of greatest nasal obstruction and evaluate the effects of isolated and combinations of simulated surgical procedures on these sites using computational fluid dynamics (CFD).

METHODS

Computed tomography imaging of an adolescent subject with uCLND was converted to an anatomically accurate three-dimensional nasal airway model. Initial analysis was performed to identify anatomic sites of obstruction based on CFD computed resistance values. Virtual surgery procedures corresponding to common uCLND surgical interventions were simulated. Resulting airspace models were then analyzed after conducting airflow and heat transfer simulations.

RESULTS

The preoperative model had 21 obstructed sites with a nasal resistance of 0.075 Pa s/mL. Following simulated surgical procedures with functional interventions alone and in combinations, the three virtual surgery models with most improved nasal airflow were inferior turbinate reduction (ITR) with posterior septoplasty (resistance = 0.054 Pa s/ml, reduction in 14 of 21 obstructed sites), ITR with anterior septoplasty (resistance = 0.058 Pa s/ml, reduction in 8 of 21 obstructed sites), and ITR with both anterior and posterior septoplasty (resistance = 0.052 Pa s/ml, reduction in 17 of 21 obstructed sites).

CONCLUSION

This study introduces a new technique for analysis of the impact of different simulated surgical interventions on uCLND-induced nasal obstruction. In this subject, simulated septoplasty with ITR on the non-cleft side provided maximal relief of nasal obstruction. The proposed technique can be further studied for possible utility in analyzing potential surgical interventions for optimal relief of nasal obstruction in patients with uCLND.

Orally Inhaled Drug Particle Transport in Computerized Models of Laryngotracheal Stenosis

OBJECTIVE

Adjuvant management for laryngotracheal stenosis (LTS) may involve inhaled corticosteroids, but metered dose inhalers are designed for pulmonary drug delivery. Comprehensive analyses of drug particle deposition efficiency for orally inhaled corticosteroids in the stenosis of LTS subjects are lacking.

STUDY DESIGN

Descriptive research.

SETTING

Academic medical center.

METHODS

Anatomically realistic 3-dimensional reconstructions of the upper airway were created from computed tomography images of 4 LTS subjects-2 subglottic stenosis and 2 tracheal stenosis subjects. Computational fluid dynamics modeling was used to simulate airflow and drug particle transport in each airway. Three inhalation pressures were simulated, 10 Pa, 25 Pa, and 40 Pa. Drug particle transport was simulated for 100 to 950 nanoparticles and 1 to 50 micron-particles. Particles were released into the airway to mimic varying inhaler conditions with and without a spacer chamber.

RESULTS

Based on smallest to largest cross-sectional area ratio, the laryngotracheal stenotic segment shrunk by 57% and 47%, respectively, for subglottic stenosis models and by 53% for both tracheal stenosis models. Airflow resistance at the stenotic segment was lower in subglottic stenosis models than in tracheal stenosis models: 0.001 to 0.011 Pa.s/mL vs 0.024 to 0.082 Pa.s/mL. Drug depositions for micron-particles and nanoparticles at stenosis were 0.06% to 2.48% and 0.10% to 2.60% for subglottic stenosis and tracheal stenosis models, respectively. Particle sizes with highest stenotic deposition were 6 to 20 µm for subglottic stenosis models and 1 to 10 µm for tracheal stenosis models.

CONCLUSION

This study suggests that at most, 2.60% of inhaled drug particles deposit at the stenosis. Particle size ranges with highest stenotic deposition may not represent typical sizes emitted by inhalers.

An Overview of Computational Fluid Dynamics Preoperative Analysis of the Nasal Airway

Evaluation of the nasal airway is crucial for every patient with symptoms of nasal obstruction as well as for every patient with other nasal symptoms. This assessment of the nasal airway comprises clinical examination together with imaging studies, with the correlation between findings of this evaluation and symptoms reported by the patient being based on the experience of the surgeon. Measuring nasal airway resistance or nasal airflow can provide additional data regarding the nasal airway, but the benefit of these objective measurements is limited due to their lack of correlation with patient-reported evaluation of nasal breathing. Computational fluid dynamics (CFD) has emerged as a valuable tool to assess the nasal airway, as it provides objective measurements that correlate with patient-reported evaluation of nasal breathing. CFD is able to evaluate nasal airflow and measure variables such as heat transfer or nasal wall shear stress, which seem to reflect the activity of the nasal trigeminal sensitive endings that provide sensation of nasal breathing. Furthermore, CFD has the unique capacity of making airway analysis of virtual surgery, predicting airflow changes after trial virtual modifications of the nasal airway. Thereby, CFD can assist the surgeon in deciding surgery and selecting the surgical techniques that better address the features of each specific nose. CFD has thus become a trend in nasal airflow assessment, providing reliable results that have been validated for analyzing airflow in the human nasal cavity. All these features make CFD analysis a mainstay in the armamentarium of the nasal surgeon. CFD analysis may become the gold standard for preoperative assessment of the nasal airway.

Can computational fluid dynamic models help us in the treatment of chronic rhinosinusitis

PURPOSE OF REVIEW

The aim of this study was to review the recent literature (January 2017-July 2020) on computational fluid dynamics (CFD) studies relating to chronic rhinosinusitis (CRS), including airflow within the pre and postoperative sinonasal cavity, virtual surgery, topical drug and saline delivery (sprays, nebulizers and rinses) and olfaction.

RECENT FINDINGS

Novel CFD-specific parameters (heat flux and wall shear stress) are highly correlated with patient perception of nasal patency. Increased ostial size markedly improves sinus ventilation and drug delivery. New virtual surgery tools allow surgeons to optimize interventions. Sinus deposition of nasal sprays is more effective with smaller, low-inertia particles, outside of the range produced by many commercially available products. Saline irrigation effectiveness is improved using greater volume, with liquid entering sinuses via 'flooding' of ostia rather than direct jet entry.

SUMMARY

CFD has provided new insights into sinonasal airflow, air-conditioning function, the nasal cycle, novel measures of nasal patency and the impact of polyps and sinus surgery on olfaction. The deposition efficiency of topical medications on sinus mucosa can be markedly improved through parametric CFD experiments by optimising nasal spray particle size and velocity, nozzle angle and insertion location, while saline irrigation effectiveness can be optimized by modelling squeeze bottle volume and head position. More sophisticated CFD models (inhalation and exhalation, spray particle and saline irrigation) will increasingly provide translational benefits in the clinical management of CRS.

[Modification of the method for closing the defect of the medial wall of the maxillary sinus]

Pathological ventilation of the maxillary sinus (MS) is one of the risk factors for the formation of chronic maxillary sinusitis.

PURPOSE OF STUDY

Is to evaluate the effectiveness of the method of restoring the medial wall of the MS with an autograft - a quadrangular cartilage of the nasal septum using the butterfly technique (Patent Application No. 2018140468, priority of 11/19/2018).

MATERIAL AND METHODS

The study included patients who underwent septoplasty, endoscopic surgery on the MS with plasty of the medial wall of the MS (1st, main group, n=136), as well as patients who underwent surgery according to Caldwell-Luc with the formation of persistent nasoantral anastomosis in the lower nasal passage (2nd, control group, n=56). The criteria for the inclusion of patients in the study were as follows: the presence of MS fungal body; inverted papilloma with lesions of the MS; cysts and/or a foreign body of the MS with localization in the alveolar bay without involving the natural anastomosis in the pathological process; concomitant 3rd or 4th, or 5th or 6th types of curvature of the nasal septum according to R. Mladina (1987). An objective assessment of the condition of the patients was carried out using the SNOT-22 clinical questionnaire, and for analysis the state of aerodynamics of the nasal cavity and MS in patients of various groups after surgical treatment used the method of computational aerodynamics.

RESULTS

In patients with nasoantral ostium in the lower nasal meatus, the pathological maxillary sinus aeration one was observed. It is recommended to close the nasoantral ostium to prevent violations of the aerodynamics of the nasal cavity and the maxillary sinus during surgery through the lower nasal meatus.

CONCLUSION

Our proposed method for closing a defect in the lower nasal passage is effective. The autograft is well established, contributes to the speedy restoration of normal sinus aerodynamics.

Partial Preservation of the Inferior Turbinate in Endoscopic Medial Maxillectomy: A Computational Fluid Dynamics Study

Background

Endoscopic medial maxillectomy (EMM) is a workhorse for multiple sinonasal conditions. To reduce its burden on the sinonasal physiology, several modified EMM (M-EMM) have been proposed. Objective: In order to provide a theoretical basis for EMM and its modifications, this study introduces a computational fluid dynamics (CFD) model, based on a time-resolved direct numerical simulation, describing EMM and assessing the role of the M-EMM in preserving the overall fluid dynamics of the sinonasal cavities.

Methods

A normal sinonasal CT scan was converted into a geometrical model and used as a reference; 2 anatomies were then created by virtual surgery, mimicking EMM and M-EMM, with the latter sparing the anterior portion of inferior turbinate and medial maxillary sinus wall. The airflow was simulated in the models via the OpenFOAM CFD software and compared in terms of flow rate, mean and fluctuating velocity, vorticity, and turbulent structures.

Results

The analysis shows that EMM induces a massive flow rate increase in the operated side, which becomes less obvious in the M-EMM model. In contrast to M-EMM, EMM induces higher velocity fields that reach the maxillary sinus. Velocity and vorticity fluctuations are negligible in the baseline model, but become increasingly evident and widespread in the M-EMM and EMM models.

Conclusions

A significant disruption of the nasal fluid dynamics is observed in EMM, while M-EMM minimizes variations and reduces interference with nasal air conditioning. Our analysis provides insights into the pathophysiology of radical sinus surgery and provides a theoretical basis for the ability of M-EMM to reduce the temporary surgery-related changes on both healthy and operated sides.

The microbiome of the upper respiratory tract in health and disease

The human upper respiratory tract (URT) offers a variety of niches for microbial colonization. Local microbial communities are shaped by the different characteristics of the specific location within the URT, but also by the interaction with both external and intrinsic factors, such as ageing, diseases, immune responses, olfactory function, and lifestyle habits such as smoking. We summarize here the current knowledge about the URT microbiome in health and disease, discuss methodological issues, and consider the potential of the nasal microbiome to be used for medical diagnostics and as a target for therapy.

Review: The role of computational simulation in understanding the postoperative sinonasal environment

Nasal surgery improves symptoms in a majority of patients for whom medical treatment has failed. In rhinosinusitis patients, endoscopic sinus surgery aims to alleviate obstruction and re-establish mucociliary clearance. Surgery alters the structure-function relationship within the nasal passage, which is difficult to assess clinically. Computational modelling has been used to investigate this relationship by simulating air flow and environmental variables inside realistic three-dimensional models of the human nasal airway but many questions remain unanswered and need further investigation. The application of computational models to improve pre-surgical planning and post-surgical treatment may not be currently possible due to the absence of knowledge correlating the model-predicted parameters to physiological variables. Links between these parameters to patient outcomes are yet to be established. This article reviews the recent application of computational modelling to understand the nasal structure-function relationship following surgery in patients with sinusitis and nasal obstruction.

Review: The role of computational simulation in understanding the postoperative sinonasal environment

Nasal surgery improves symptoms in a majority of patients for whom medical treatment has failed. In rhinosinusitis patients, endoscopic sinus surgery aims to alleviate obstruction and re-establish mucociliary clearance. Surgery alters the structure-function relationship within the nasal passage, which is difficult to assess clinically. Computational modelling has been used to investigate this relationship by simulating air flow and environmental variables inside realistic three-dimensional models of the human nasal airway but many questions remain unanswered and need further investigation. The application of computational models to improve pre-surgical planning and post-surgical treatment may not be currently possible due to the absence of knowledge correlating the model-predicted parameters to physiological variables. Links between these parameters to patient outcomes are yet to be established. This article reviews the recent application of computational modelling to understand the nasal structure-function relationship following surgery in patients with sinusitis and nasal obstruction.

Computational Analysis of the Mature Unilateral Cleft Lip Nasal Deformity on Nasal Patency

Background

Nasal airway obstruction (NAO) due to nasal anatomic deformities is known to be more common among cleft patients than the general population, yet information is lacking regarding severity and variability of cleft-associated nasal obstruction relative to other conditions causing NAO. This preliminary study compares differences in NAO experienced by unilateral cleft lip nasal deformity (uCLND) subjects with noncleft subjects experiencing NAO.

Methods

Computational modeling techniques based on patient-specific computed tomography images were used to quantify the nasal airway anatomy and airflow dynamics in 21 subjects: 5 healthy normal subjects; 8 noncleft NAO subjects; and 8 uCLND subjects. Outcomes reported include Nasal Obstruction Symptom Evaluation (NOSE) scores, cross-sectional area, and nasal resistance.

Results

uCLND subjects had significantly larger cross-sectional area differences between the left and right nasal cavities at multiple cross sections compared with normal and NAO subjects. Median and interquartile range (IQR) NOSE scores between NAO and uCLND were 75 (IQR = 22.5) and 67.5 (IQR = 30), respectively. Airflow partition difference between both cavities were: median = 9.4%, IQR = 10.9% (normal); median = 31.9%, IQR = 25.0% (NAO); and median = 29.9%, IQR = 44.1% (uCLND). Median nasal resistance difference between left and right nasal cavities were 0.01 pa.s/ml (IQR = 0.03 pa.s/ml) for normal, 0.09 pa.s/ml (IQR = 0.16 pa.s/ml) for NAO and 0.08 pa.s/ml (IQR = 0.25 pa.s/ml) for uCLND subjects.

Conclusions

uCLND subjects demonstrated significant asymmetry between both sides of the nasal cavity. Furthermore, there exists substantial disproportionality in flow partition difference and resistance difference between cleft and noncleft sides among uCLND subjects, suggesting that both sides may be dysfunctional.

A hierarchical stepwise approach to evaluate nasal patency after virtual surgery for nasal airway obstruction

BACKGROUND

Despite advances in medicine and expenditures associated in treatment of nasal airway obstruction, 25-50% of patients undergoing nasal surgeries complain of persistent obstructive symptoms. Our objective is to develop a "stepwise virtual surgery" method that optimizes surgical outcomes for treatment of nasal airway obstruction.

METHODS

Pre-surgery radiographic images of two subjects with nasal airway obstruction were imported into Mimics imaging software package for three-dimension reconstruction of the airway. A hierarchical stepwise approach was used to create seven virtual surgery nasal models comprising individual (inferior turbinectomy or septoplasty) procedures and combined inferior turbinectomy and septoplasty procedures via digital modifications of each subject's pre-surgery nasal model. To evaluate the effects of these procedures on nasal patency, computational fluid dynamics modeling was used to perform steady-state laminar inspiratory airflow and heat transfer simulations in every model, at resting breathing. Airflow-related variables were calculated for virtual surgery models and compared with dataset containing results of healthy subjects with no symptoms of nasal obstruction.

FINDINGS

For Subject 1, nasal models with virtual septoplasty only and virtual septoplasty plus inferior turbinectomy on less obstructed side were within the healthy reference thresholds on both sides of the nasal cavity and across all three computed variables. For Subject 2, virtual septoplasty plus inferior turbinectomy on less obstructed side model produced the best result.

INTERPRETATION

The hierarchical stepwise approach implemented in this preliminary report demonstrates computational fluid dynamics modeling ability to evaluate the efficiency of different surgical procedures for nasal obstruction in restoring nasal patency to normative level.

Investigating the effects of laryngotracheal stenosis on upper airway aerodynamics

OBJECTIVE

Very little is known about the impact of laryngotracheal stenosis (LTS) on inspiratory airflow and resistance, especially in air hunger states. This study investigates the effect of LTS on airway resistance and volumetric flow across three different inspiratory pressures.

METHODS

Head-and-neck computed tomography scans of 11 subjects from 2010 to 2016 were collected. Three-dimensional reconstructions of the upper airway from the nostrils to carina, including the oral cavity, were created for one subject with a normal airway and for 10 patients with LTS. Airflow simulations were conducted using computational fluid dynamics modeling at three different inspiratory pressures (10, 25, 40 pascals [Pa]) for all subjects under two scenarios: 1) inspiration through nostrils only (MC), and 2) through both nostrils and mouth (MO).

RESULTS

Volumetric flows in the normal subject at the three inspiratory pressures were considerably higher (MC: 11.8-26.1 L/min; MO: 17.2-36.9 L/min) compared to those in LTS (MC: 2.86-6.75 L/min; MO: 4.11-9.00 L/min). Airway resistances in the normal subject were 0.051 to 0.092 pascal seconds per milliliter (Pa.s)/mL (MC) and 0.035-0.065 Pa.s/mL (MO), which were approximately tenfold lower than those of subjects with LTS: 0.39 to 0.89 Pa.s/mL (MC) and 0.45 to 0.84 Pa.s/mL (MO). Furthermore, subjects with glottic stenosis had the greatest resistance, whereas subjects with subglottic stenosis had the greatest variability in resistance. Subjects with tracheal stenosis had the lowest resistance.

CONCLUSION

This pilot study demonstrates that LTS increases resistance and decreases airflow. Mouth breathing significantly improved airflow and resistance but cannot completely compensate for the effects of stenosis. Furthermore, location of stenosis appears to modulate the effect of the stenosis on resistance differentially.

LEVEL OF EVIDENCE

NA. Laryngoscope, 128:E141-E149, 2018.

The impact of endoscopic sinus surgery on paranasal physiology in simulated sinus cavities

BACKGROUND

Surgery improves symptoms for the majority of chronic rhinosinusitis (CRS) patients; however, physiological changes in the sinus cavities remain poorly characterized. Direct measurement of changes in airflow, pressure, temperature, humidity, and intranasal spray distribution following surgery is technically challenging. Accordingly, we have used computational fluid dynamic modeling to quantify how these parameters change postoperatively.

METHODS

Computed tomography images from a normal control, a patient with CRS preoperatively and postoperatively, and a patient following an endoscopic Lothrop procedure (ELP) were used to create 4 three-dimensional models of the sinus cavities. Changes in physiologic parameters and topical drug distribution were modeled (inhaled air at 16°C and 10% humidity) at the maxillary ostium, frontal recess, and sphenoid ostium.

RESULTS

Large differences were seen between models. Following surgery, the maxillary ostia were found on average to be cooler (by 2.4°C), with an increased airflow (0.26 m/second; from 0 m/second), and a 9% reduction in absolute humidity. Sphenoid ostial parameters followed a similar trend. Significant changes in frontal recess physiology were seen following ELP in which the recess was 4.2°C cooler, had increased airflow (0.76 m/second) and a 17% reduction in absolute humidity. Topical drug distribution increased with surgery, particularly after ELP.

CONCLUSION

Surgery changes the geometry and physiology of the paranasal sinuses. These changes are likely to have an impact on wound healing, mucociliary function, and microbial ecology in postoperative cavities. Application of this model to further understand the effects of surgery may help to optimize surgical techniques and improve topical drug delivery.

Changes in the bacterial microbiome of patients with chronic rhinosinusitis after endoscopic sinus surgery

BACKGROUND

Endoscopic sinus surgery (ESS) improves symptoms for many chronic rhinosinusitis (CRS) patients by enlarging the size of sinus ostia, improving mucociliary clearance, and facilitating access for topical therapies. However, the effect of surgery on the sinonasal microbiota remains poorly understood. This study examined changes in bacterial communities in CRS patients before and after surgery.

METHODS

Swab samples were taken from the middle meatus of 23 patients undergoing ESS. Follow-up swabs were taken in clinic (mean 120 days postsurgery). Symptom scores and antibiotic use were recorded. Bacterial communities were characterized using 16s ribosomal RNA (rRNA) gene-targeted amplicon sequencing and bacterial abundance was measured using quantitative polymerase chain reaction (PCR). Coexisting asthma, aspirin sensitivity, antibiotic use, and presence of polyps were controlled for.

RESULTS

Unpredictable shifts in bacterial community composition were seen postoperatively. ESS was associated with increased bacterial richness. Many taxa had changes in average relative abundance and prevalence. Staphylococcus was the only dominant taxa to increase significantly in relative abundance (p = 0.002). Changes in bacterial communities were driven more by intersubject variability (p = 0.007) than other study factors. Finegoldia, a minority taxon, was associated with a reduction in abundance following ESS, increases in patients with higher symptoms scores, and reductions in patients with reduced total bacterial burden.

CONCLUSION

This study documented changes in bacterial composition and abundance in the middle meatus following ESS. The complexity of these changes reflects the variability between patients. Modern molecular techniques highlight the currently limited knowledge of the impact of therapies on the microbiology of CRS.

Characterizing human nasal airflow physiologic variables by nasal index

Although variations in nasal index (NI) have been reported to represent adaptation to climatic conditions, assessments of NI with airflow variables have not been rigorously investigated. This study uses computational fluid dynamics modeling to investigate the relationship between NI and airflow variables in 16 subjects with normal nasal anatomy. Airflow simulations were conducted under constant inspiratory pressure. Nasal resistance (NR) against NI showed weak association from nostrils to anterior inferior turbinate (R(2)=0.26) and nostril to choanae (R(2)=0.12). NI accounted for 38% and 41% of the respective variation in wall shear stress (WSS) and heat flux (HF) at the nasal vestibule, and 52% and 49% of variability in WSS and HF across the entire nose. HF and WSS had strong correlation with NI<80, and weakly correlated with NI>80; these differences in HF and WSS for NI<80 and NI>80 were not statistically significant. Results suggest strong relationship between NI and both WSS and HF but not NR, particularly in subjects with NI<80.