Comparison of Airflow Between Spreader Grafts and Butterfly Grafts Using Computational Flow Dynamics in a Cadaveric Model

Secondary Contouring for the Butterfly Graft: Improving Form and Preserving Function

OBJECTIVE

The butterfly graft (BFG) secondary contouring procedure addresses external nasal irregularities following the primary BFG surgery. We explore demographic factors associated with the desire for secondary contouring and assess patient-reported outcomes following the procedure.

METHODS

A retrospective analysis of 374 patients undergoing BFG between April 2020 and April 2023 identified 10 individuals electing for secondary contouring. Demographics, Nasal Obstruction Symptoms Evaluation (NOSE) scores, Rhinosinusitis Disability Index (RSDI), and decision regret scale (DRS) were collected and reported.

RESULTS

Secondary contouring rate was 2.7% of total cases. The majority of patients desiring BFG secondary contouring were white females (90%). NOSE scores significantly improved post-primary surgery (mean change: 51.7, SD: 14.01, p-value: <0.05). Although overall NOSE scores remained improved after secondary contouring (mean change: 47.2, SD: 18.84, p-value: <0.05) compared with their preoperative NOSE scores, one patient (10%) reported worse score after secondary contouring. Four patients (40%) reported worsening after secondary contouring compared with after initial BFG surgery. DRS indicated minimal regret from patients.

CONCLUSION

BFG secondary contouring is a valuable option for patients with external nasal complaints, providing improvements in nasal appearance and durable improvement in breathing outcomes. We emphasize the importance of patient counseling and appropriate patient selection. Our results suggest that patients should expect a slight worsening of NOSE scores following secondary contouring, but that significant worsening is a low risk.

LEVEL OF EVIDENCE

Level 4: Case series Laryngoscope, 2024.

Indications and Evolution of the Butterfly Graft in Nasal Valve Repair

Persistent nasal airway obstruction from inadequately addressed nasal valve compromise is common. Many techniques exist to perform nasal valve repair. Historically, spreader grafts are the most commonly used, despite a relative lack of evidence demonstrating its superiority over other methods. The butterfly graft is an alternative method of nasal valve repair and detailed surgical description from over 20 years of innovation follows in this section. There is growing evidence to suggest that the butterfly graft may be superior to spreader grafts with similar acceptability of the esthetic outcomes.

Functional and esthetic outcomes of functional rhinoplasty for internal nasal valve dysfunction in Asian patients

OBJECTIVE

This study aimed to use validated measures to evaluate the functional and esthetic outcomes in patients who underwent functional rhinoplasty for Internal Nasal Valve Dysfunction (INVD) in Korea.

METHODS

A retrospective review of consecutive patients who underwent functional rhinoplasty for INVD confirmed by endoscopic findings and the modified Cottle test between 2016 and 2018 was performed. Nasal obstruction was assessed with the Visual Analog Scale (VAS) and nasal obstruction symptom evaluation (NOSE) scale. Acoustic rhinometry was performed pre- and post-operatively. The Minimal Cross-Sectional Area (MCA) of the nose was measured. Objective assessment of the esthetic outcomes was performed with the Objective Rhinoplasty Outcome Score (OROS), which assesses tip rotation, projection, width, dorsal height, width, length, symmetry, and the overall result.

RESULTS

Fifty-seven patients (46 men and 11 women; mean age, 30.5 ± 12.3 years) who underwent functional rhinoplasty were included in this study. The VAS and NOSE scores indicated functional improvement in all cases (all p < 0.001). There were no significant between-group differences (VAS score, p = 0.274; NOSE score, p = 0.952). The objective functional outcomes evaluated using MCA on the concave (p = 0.478) and convex (p = 0.631) sides did not differ significantly pre- and post-operatively. The subjective evaluation of esthetic satisfaction revealed no between-group difference. Moreover, 31 out of 44 patients (70.5%) with static INVD and nine out of 14 patients (64.3%) with dynamic or combined INVD showed excellent outcomes. Regarding objective esthetic outcomes, scores for the eight factors were >3, and there was no significant difference between the two groups (all p > 0.05).

CONCLUSIONS

Functional rhinoplasty, including extracorporeal septoplasty and spreader grafting, may be a viable option for correcting INVD with functional and esthetic improvement. Dynamic INVD is less prevalent among Asians, and there was no significant difference in the surgical outcomes compared with those of static INVD.

LEVEL OF EVIDENCE

Level 4.

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.

Cadaveric Assessment of the Butterfly Graft in Rhinoplasty

INTRODUCTION

The rhinoplasty butterfly graft is used to improve the internal nasal valve (INV), but post-operative visibility remains a concern. Intraoperative techniques have developed to thin the graft with unknown effect on functionality.

OBJECTIVES

Improve understanding of how to modify the aesthetics of the butterfly graft without impacting patient outcomes. Determine how graft contouring affects its biomechanical properties.

METHODS

Cadaveric cartilage grafts were used to examine the biomechanics in its native state and with progressive thinning. The force needed to stabilize the INV in an unaltered state and the resistance force provided by native (original), partially thinned, and fully thinned cartilage grafts were recorded.

RESULTS

The mean thickness of grafts in their natural state was 1.64 mm, median 1.50 mm (SD 0.64 mm). The fully-thinned mean was 0.84 mm, median 0.8 mm (SD 0.18 mm). The mean force (N) of the native graft was 0.74 N and 0.60 N for fully thin (p = 0.016, 95%). The mean force (N) needed to stabilize the INV was 0.15 N (right) and 0.19 N (left).

CONCLUSION

Butterfly grafts can be thinned by approximately 50% of their original thickness and retain the strength to stabilize the INV.

LEVEL OF EVIDENCE

NA Laryngoscope, 134:1638-1641, 2024.

Updates in Butterfly Graft Technique

Nasal obstruction is a significant challenge greatly affecting individual quality of life. It is one of the most common presentations in the otolaryngology clinic, often persisting despite medical and, at times, surgical intervention. The butterfly graft has proven to be a veritable option addressing nasal valve collapse. Herein, we describe our most recent operative technique, highlight its application in ethnic rhinoplasty and revision cases, and discuss incorporation of dorsal preservation techniques in functional rhinoplasty.

Considerations for Optimal Grafting in Rhinoplasty

A wide variety of grafting materials and techniques can be used to create functional and aesthetic changes in rhinoplasty. Choosing the optimal grafting approach is critical to achieving an optimal patient outcome. We present a review of autografts, allografts, and alloplasts used in primary and revision rhinoplasty and discuss factors that impact graft choice. Autologous grafts serve as the pillar for grafting material in rhinoplasty given their reliable long-term outcomes, low rates of infection, resorption, and extrusion, and ability to provide structural scaffolding as well as contour. Cadaveric allografts can be utilized as a source of grafting material in certain clinical scenarios including revision rhinoplasty and have been shown to be equally safe and effective as autologous grafts while avoiding donor-site morbidity. Alloplasts can prove useful in rhinoplasty in cases of iatrogenic nasal deformities or revision cases. Careful consideration of clinical scenario, patient factors, and outcome goals is necessary to choose the appropriate grafting approach to address functional and cosmetic outcomes.

Casual Observers' Perception on the Aesthetics of the Butterfly Graft

OBJECTIVE

The butterfly graft is an effective technique for improving the internal nasal valve, however, there is hesitancy among surgeons due to possible aesthetic changes. This study aims to determine if average observers rated the post-operative appearance of the butterfly graft negatively.

METHODS

An online survey was distributed by social media to non-medical observers in which they rated either the pre-operative or post-operative appearance of 22 patients' noses (11 butterfly graft, 11 spreader graft). A heat map was used to determine if the supratip region was rated as the least aesthetically appealing. Post-operative ratings and heat maps of the butterfly graft patients were compared to pre-operative ratings as well as ratings of the spreader graft group.

RESULTS

226 observers responded. There was no difference in the pre-operative and post-operative rating of the butterfly graft group (58.27 vs. 58.00, p = 0.88) or the number of supratip regions selected as least attractive (165 vs. 169, p = 0.60). Similarly, there was no difference in post-operative ratings between the butterfly graft group and spreader graft group (58.00 vs. 58.21, p = 0.63) or in selection of the supratip as the least attractive region (169 vs. 172, p = 0.74).

CONCLUSION

The butterfly graft did not negatively affect observers' opinion of patients' noses.

LEVEL OF EVIDENCE

3 Laryngoscope, 133:2578-2583, 2023.

Gender Differences in Nasal Anatomy and Function Among Caucasians

Background: Anatomical variations influence nasal physiology, yet sex differences in physiology remains unclear. Objective: To investigate sex differences among Caucasians using computational fluid dynamics. Methods: Adult subjects were selected with normal nasal cone beam computed tomography (CBCT) images and Nasal Obstruction Symptom Evaluation scores ≤30. The CBCT images were used to create subject-specific airway models. Nasal surface area (SA) and volume were computed, and airflow and heat transfer were simulated. Results: The CBCT scans were taken from 23 females and 12 males. The SA and volume (males: mean = 25.0 cm3; females: mean = 19.5 cm3; p < 0.001; Cohen's d = 1.51) were significantly larger for males, but SA-to-volume ratio did not differ significantly. Although unilateral nasal resistance did not vary greatly, females had higher bilateral resistance (males: mean = 0.04 Pa.s/mL; females: mean = 0.05 Pa.s/mL; p = 0.044; Cohen's d = 0.37). Females had higher heat flux (males: mean = 158.5 W/m2; females: mean = 191.8 W/m2; p = 0.012; Cohen's d = 0.79), but males had larger SA where mucosal heat flux exceeds 50 W/m2. Conclusions: These findings suggest differences in normal nasal anatomy and physiology between Caucasian males and females, which may be useful when assessing sex-specific functional outcomes after nasal surgery.

Anatomic Optical Coherence Tomography (aOCT) for Evaluation of the Internal Nasal Valve

OBJECTIVES/HYPOTHESIS

To establish the utility of anatomic optical coherence tomography (aOCT) in evaluating internal nasal valve (INV).

STUDY DESIGN

Anatomic specimen imaging study.

METHODS

Fresh-harvested human specimen heads were evaluated using both computed tomography (CT) imaging as well as using aOCT. Scans were performed at three time points: 1) After septoplasty for cartilage harvest, 2) after placement of butterfly graft (BFG), and 3) after placement of bilateral spreader grafts (SG). Imaging data were then converted into 3D models of the nasal airway. CT- and aOCT-generated models were compared by both static volumetric analysis and computational fluid dynamics (CFD) to predict nasal resistance and pressure.

RESULTS

Scans using aOCT showed comparable results to CT in terms of volumetric parameters both before and after intervention. Analysis of aOCT data by CFD demonstrated decrease in pressure after SG or BFG intervention. No statistically significant difference was observed when comparing CT- and aOCT-generated calculations of pressure or resistance.

CONCLUSION

The INV can be imaged in a static fashion using aOCT technology. Advantages over traditional CT imaging include lack of exposure to radiation and rapid scan time. In addition, in-office use is possible as aOCT technology develops. Further investigation will be necessary to define the role of aOCT in the dynamic evaluation of this vital component of the nasal airway.

LEVEL OF EVIDENCE

3 Laryngoscope, 132:2148-2156, 2022.

Butterfly Graft Technique for Addressing the Internal Nasal Valve

Nasal airway obstruction is a common presenting complaint to otolaryngology clinics, with the internal valve a commonly implicated anatomic area of obstruction. The nasal butterfly graft is a robust technique to address this subsite with good reported functional and aesthetic outcomes in both primary and secondary rhinoplasty. We describe our approach to patient evaluation, surgical candidate selection, operative technique, and outcomes assessment for this technique.

Comparison of the Effect of Spreader and T-Splay Graft in Internal Nasal Valve Management

BACKGROUND

The midvalve area is one of the most important anatomical points in rhinoplasty procedures. An additional intervention may be required to ensure there is no narrowing in this region. For this reason, several different techniques are used. Spreader graft technique is the most common of all these methods. T-splay graft technique is an alternative method that can effectively widen the angle of the midvalve. The present study compares the anatomical and functional outcomes of these two methods.

METHODS

The study included 60 cases who presented to our clinic for rhinoplasty. The cases were evaluated demographically, anatomically, and functionally, and the acquired data were recorded. All cases were preoperatively administered the Visual Analogue Scale, the Nasal Obstruction Symptom Evaluation scale, and the modified Glatzel mirror test. By randomly selecting the cases, midvalve restoration was performed with a spreader graft in 30 cases and a T-splay graft in 30 cases.

RESULTS

A comparison of the Visual Analogue Scale, the Nasal Obstruction Symptom Evaluation scale, and the modified Glatzel mirror test scores revealed that the scores of both groups at postoperative months 3 and 6 were significantly different from the preoperative measurement values.

CONCLUSIONS

Although spreader graft technique is a very effective method in midvalve management, we believe that T-splay graft technique may also produce effective outcomes. In addition, the midvalve functions could be better simulated anatomically and functionally with T-splay graft technique. Therefore, we believe that T-splay graft technique is an alternative method that can be safely used in selected cases.

LEVEL OF EVIDENCE III

This journal requires that authors assign a level of evidence to each article. For a full description of these Evidence-Based Medicine ratings, please refer to the Table of Contents or the online Instructions to Authors www.springer.com/00266 .

An Alternative Method for Midvault Restoration: "T-Splay Graft"

BACKGROUND

The internal nasal valve is one of the highly important anatomical points in rhinoplasty procedures. As a key anatomical area, the anatomical and functional integrity of this region must be preserved or reconstructed during rhinoplasty procedures. Several techniques have been defined in the literature for midvault restoration, among which, the most common are spreader grafts and flaps. Both techniques achieve a natural and harmonic contour but may fail to provide the splay effect to the upper lateral cartilages in some cases. A new technique known as the "T-splay graft", to be used as an alternative approach in cases where there is a risk of midvault collapse, and in which the splay effect in the upper lateral cartilage is preferred to be augmented, is explained in the present study.

METHODS

In the present study, a septal tunnel is opened of sufficient size for the cartilage graft planned for placement, at the planned level of the septum, to expand the midvault region and create a splay effect. A bilateral pocket is created in the inferior mucosa of the upper lateral cartilages. The harvested cartilage graft is passed through the septum in the horizontal plane. The cartilage graft is inserted into the bilateral pockets so as way to create convexity to the dorsum.

RESULTS

As a result of the applied method, it was established that the internal nasal valve angle could be expanded to the desired extent and the dorsal aesthetic lines could be achieved in a normal anatomical structure.

CONCLUSIONS

This technique enables the lateral direction of the tension between the graft and the upper lateral cartilages, and the creation of a splay effect. As such, we believe that this method is a highly effective alternative for use in appropriate cases.

LEVEL OF EVIDENCE IV

This journal requires that authors assign a level of evidence to each article. For a full description of these Evidence-Based Medicine ratings, please refer to the Table of Contents or the online Instructions to Authors www.springer.com/00266 .

The Virtual Nose: Assessment of Static Nasal Airway Obstruction Using Computational Simulations and 3D-Printed Models

Background: The use of virtual noses to predict the outcome of surgery is of increasing interests, particularly, as detailed and objective pre- and postoperative assessments of nasal airway obstruction (NAO) are difficult to perform. The objective of this article is to validate predictions using virtual noses against their experimentally measured counterpart in rigid 3D-printed models. Methods: Virtual nose models, with and without NAO, were reconstructed from patients' cone beam computed tomography scans, and used to evaluate airflow characteristics through computational fluid dynamics simulations. Prototypes of the reconstructed models were 3D printed and instrumented experimentally for pressure measurements. Results: Correlation between the numerical predictions and experimental measurements was shown. Analysis of the flow field indicated that the NAO in the nasal valve increases significantly the wall pressure, shear stress, and incremental nasal resistance behind the obstruction. Conclusions: Airflow predictions in static virtual noses correlate well with detailed experimental measurements on 3D-printed replicas of patient airways.

Computational characterization of inhaled droplet transport to the nasopharynx

How human respiratory physiology and the transport phenomena associated with inhaled airflow in the upper airway proceed to impact transmission of SARS-CoV-2, leading to the initial infection, stays an open question. An answer can help determine the susceptibility of an individual on exposure to a COVID-2019 carrier and can also provide a preliminary projection of the still-unknown infectious dose for the disease. Computational fluid mechanics enabled tracking of respiratory transport in medical imaging-based anatomic domains shows that the regional deposition of virus-laden inhaled droplets at the initial nasopharyngeal infection site peaks for the droplet size range of approximately 2.5-19 [Formula: see text]. Through integrating the numerical findings on inhaled transmission with sputum assessment data from hospitalized COVID-19 patients and earlier measurements of ejecta size distribution generated during regular speech, this study further reveals that the number of virions that may go on to establish the SARS-CoV-2 infection in a subject could merely be in the order of hundreds.

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.

Computational technology for nasal cartilage-related clinical research and application

Surgeons need to understand the effects of the nasal cartilage on facial morphology, the function of both soft tissues and hard tissues and nasal function when performing nasal surgery. In nasal cartilage-related surgery, the main goals for clinical research should include clarification of surgical goals, rationalization of surgical methods, precision and personalization of surgical design and preparation and improved convenience of doctor-patient communication. Computational technology has become an effective way to achieve these goals. Advances in three-dimensional (3D) imaging technology will promote nasal cartilage-related applications, including research on computational modelling technology, computational simulation technology, virtual surgery planning and 3D printing technology. These technologies are destined to revolutionize nasal surgery further. In this review, we summarize the advantages, latest findings and application progress of various computational technologies used in clinical nasal cartilage-related work and research. The application prospects of each technique are also discussed.

Numerical evaluation of spray position for improved nasal drug delivery

Topical intra-nasal sprays are amongst the most commonly prescribed therapeutic options for sinonasal diseases in humans. However, inconsistency and ambiguity in instructions show a lack of definitive knowledge on best spray use techniques. In this study, we have identified a new usage strategy for nasal sprays available over-the-counter, that registers an average 8-fold improvement in topical delivery of drugs at diseased sites, when compared to prevalent spray techniques. The protocol involves re-orienting the spray axis to harness inertial motion of particulates and has been developed using computational fluid dynamics simulations of respiratory airflow and droplet transport in medical imaging-based digital models. Simulated dose in representative models is validated through in vitro spray measurements in 3D-printed anatomic replicas using the gamma scintigraphy technique. This work breaks new ground in proposing an alternative user-friendly strategy that can significantly enhance topical delivery inside human nose. While these findings can eventually translate into personalized spray usage instructions and hence merit a change in nasal standard-of-care, this study also demonstrates how relatively simple engineering analysis tools can revolutionize everyday healthcare. Finally, with respiratory mucosa as the initial coronavirus infection site, our findings are relevant to intra-nasal vaccines that are in-development, to mitigate the COVID-19 pandemic.

Nasal Airflow Changes With Bioabsorbable Implant, Butterfly, and Spreader Grafts

OBJECTIVES/HYPOTHESIS

Internal nasal valve compromise is a major cause of nasal obstruction, with a growing number of ways to treat this condition. In this study, we compared the effects of butterfly graft, spreader graft, and the bioabsorbable nasal implant on nasal airflow resistance.

STUDY DESIGN

Cadaver study.

METHODS

Computational fluid dynamics (CFD) simulations were completed from nine preoperative and postoperative cadaveric subjects. Each cadaveric head underwent placement of a bioabsorbable nasal implant (BNI) (Spirox Latera; Stryker ENT, Plymouth, MN), butterfly graft, or spreader graft. Pre- and postoperative computed tomography (CT) scans were used to generate three-dimensional models of the nasal airway used in steady-state CFD simulations of airflow and heat transfer during inspiration.

RESULTS

Butterfly graft placement resulted in a mean improvement in nasal airway resistance of 24.9% (±7.3), whereas BNI placement resulted in a 6.7% (±1.2) improvement, and spreader graft placement also resulted in a consistent improvement of 2.6% (±13.5). Pressure within the main nasal cavity was consistently lower following butterfly graft placement versus a spreader graft or BNI. Butterfly and spreader graft placement also resulted in modest improvements in airflow allocation, whereas BNI demonstrated more variation (-1% to 12%). Heat flux was not significantly different; however, a small improvement in total heat flux was seen with all three interventions.

CONCLUSIONS

The results of this study demonstrate reduction in nasal airway resistance in all three surgical interventions, with the butterfly graft demonstrating superiority to the other two techniques. However, these data only reflect a static environment and not dynamic changes in airflow seen during respiration.

LEVEL OF EVIDENCE

NA Laryngoscope, 130:E817-E823, 2020.

Functional Outcomes, Quantitative Morphometry, and Aesthetic Analysis of Articulated Alar Rim Grafts in Septorhinoplasty

Importance

The design, use, and indications for the articulated alar rim graft (AARG) and the functional and aesthetic improvements that can be achieved have not been fully characterized.

Objective

To analyze the functional and aesthetic outcomes of AARG placement on nasal airway function, nasal base shape change, and appearance.

Design, Setting, and Participants

A case series study of patients who underwent septorhinoplasty with placement of AARG at University of California, Irvine Medical Center, from 2015 to 2018 was carried out. Surgical data recorded included stage of rhinoplasty (primary vs revision), use of spreader grafts, rim grafts (and dimensions), caudal septal extension graft (CSEG), lateral crural tensioning (LCT), and turbinate reductions.

Main Outcomes and Measures

Preoperative and postoperative Nasal Obstruction Symptom Evaluation Survey (NOSE) surveys were analyzed and correlated with AARG geometry, use of CSEG, and the LCT maneuver. Preoperative and postoperative alar base views were evaluated by fitting base shape to a parametric numerical model to categorize each to 1 of 6 shape categories. Blinded reviewers rated alar furrow severity and the alar ridge presence using a Likert scale for both preoperative and postoperative images to subjectively gauge aesthetic outcomes.

Results

Overall, 90 patients with both preoperative and postoperative NOSE scores who underwent septorhinoplasty and placement of an AARG were included. Of the 90 patients, 60 were women (mean age, 38.2 years). Patient NOSE scores (70.4 preoperatively to 25.1 postoperatively) significantly improved from preoperation to postoperation (P < .001), regardless of AARG size, CSEG, or LCT. Alar base shape parametric analysis showed preoperative to postoperative improvements were significant for anterior-to-posterior ratio mass distribution (95% CI, -0.16 to 0.02; P = .05) and vertical projection-to-horizontal base width ratio (95% CI, 0.01-0.32; P = .02) in flat noses and cloverleafing for narrow noses (95% CI, -0.05 to -0.01; P = .001); enhancement approached significance for reduction in lateral scalloping in cloverleaf noses (P = .06). Aesthetic analysis showed that there was a statistically significant improvement for the alar furrow (95% CI, -0.68 to -0.29 for rater 1; -0.54 to -0.27 for rater 2; and -0.59 to -0.27 for rater 3; P < .001) for all raters and for the alar ridge (95% CI, 0.16-0.48; P < .001) for 1 rater.

Conclusions and Relevance

To our knowledge, this is the first study to demonstrate that AARG use is associated with statistically significant improvement in NOSE scores. Placement of AARGs may improve posterior mass ratios in flat noses and lateral cloverleafing in narrow noses as suggested by quantitative shape change parameter analysis. The placement of AARGs was associated with aesthetic and functional enhancement in the cloverleaf deformity, which is associated with a prominent alar furrow, and often external nasal valve collapse. Patient selection is key when placing AARGs.

Level of Evidence

NA.

Impact of endoscopic craniofacial resection on simulated nasal airflow and heat transport

BACKGROUND

Endoscopic craniofacial resections (CFR) are performed for extensive anterior skull base lesions. This surgery involves removal of multiple intranasal structures, potentially leading to empty nose syndrome (ENS). However, many patients remain asymptomatic postoperatively. Our objective was to analyze the impact of CFR on nasal physiology and airflow using computational fluid dynamics (CFD). This is the first CFD analysis of post-CFR patients.

METHODS

Three-dimensional sinonasal models were constructed from 3 postoperative images using Mimics^TM . Hybrid computational meshes were created. Steady inspiratory airflow and heat transport were simulated at patient-specific flow rates using shear stress transport k-omega turbulent flow modeling in Fluent^TM . Simulated average heat flux (HF) and surface area where HF exceeded 50 W/m² (SAHF50) were compared with laminar simulations in 9 radiographically normal adults.

RESULTS

Three adults underwent CFR without developing ENS. Average HF (W/m² ) were 132.70, 134.84, and 142.60 in the CFR group, ranging from 156.24 to 234.95 in the nonoperative cohort. SAHF50 (m² ) values were 0.0087, 0.0120, and 0.0110 in the CFR group, ranging from 0.0082 to 0.0114 in the radiographically normal cohort. SAHF50 was distributed throughout the CFR cavities, with increased HF at the roof and walls compared with the nonoperative cohort.

CONCLUSION

Average HF was low in the CFR group compared with the nonoperative group. However, absence of ENS in most CFR patients may be due to large stimulated mucosal surface area, commensurate with the nonoperative cohort. Diffuse distribution of stimulated area may result from turbulent mixing after CFR. To better understand heat transport post-CFR, a larger cohort is necessary.

Comparative study of simulated nebulized and spray particle deposition in chronic rhinosinusitis patients

BACKGROUND

Topical intranasal drugs are widely prescribed for chronic rhinosinusitis (CRS), although delivery can vary with device type and droplet size. The study objective was to compare nebulized and sprayed droplet deposition in the paranasal sinuses and ostiomeatal complex (OMC) across multiple droplet sizes in CRS patients using computational fluid dynamics (CFD).

METHODS

Three-dimensional models of sinonasal cavities were constructed from computed tomography (CT) scans of 3 subjects with CRS refractory to medical therapy using imaging software. Assuming steady-state inspiratory airflow at resting rate, CFD was used to simulate 1-µm to 120-µm sprayed droplet deposition in the left and right sinuses and OMC with spray nozzle positioning as in current nasal spray use instructions. Zero-velocity nebulization simulations were performed for 1-µm to 30-µm droplet sizes, maximal sinus and OMC deposition fractions (MSDF) were obtained, and sizes that achieved at least 50% of MSDF were identified. Nebulized MSDF was compared to sprayed droplet deposition. We also validated CFD framework through in vitro experiments.

RESULTS

Among nebulized droplet sizes, 11-µm to 14-µm droplets achieved at least 50% of MSDF in all 6 sinonasal cavities. Four of 6 sinonasal cavities had greater sinus and OMC deposition with nebulized droplets than with sprayed droplets at optimal sizes.

CONCLUSION

Nebulized droplets may target the sinuses and OMC more effectively than sprayed particles at sizes achieving best deposition. Further studies are needed to confirm our preliminary findings. Several commercial nasal nebulizers have average particle sizes outside the optimal nebulized droplet size range found here, suggesting potential for product enhancement.

Effect of Nasal Valve Shape on Downstream Volume, Airflow, and Pressure Drop: Importance of the Nasal Valve Revisited

OBJECTIVES

The relative importance of the nasal valve relative to the remainder of the nasal airway remains unknown. The goal of this article was to objectively measure the shape of the nasal inlet and its effect on downstream airflow and nasal cavity volume using a physical model and a physiologic flow model.

METHODS

A patient who had isolated nasal valve surgery and had pre- and postoperative computed tomography scans available for analysis was studied. Nasal inlet shape measurements, computational fluid dynamics, and nasal volume analysis were performed using the computed tomography data. In addition, a physical model was used to determine the effect of nasal obstruction on downstream soft tissue.

RESULTS

The postoperative shape of the nasal inlet was improved in terms of length and degree of tortuosity. Whereas the operated-on region at the nasal inlet showed an only 25% increase in cross-sectional area postoperatively, downstream nonoperated sites in the nasal cavity revealed increases in area ranging from 33% to 51%. Computational fluid dynamics analysis showed that airway resistance decreased by 42%, and pressure drop was reduced by 43%. Intraluminal mucosal expansion was found with nasal obstruction in the physical model.

CONCLUSION

By decreasing the degree of bending and length at the nasal valve, inspiratory downstream nonoperated sites of the nasal cavity showed improvement in volume and airflow, suggesting that the nasal valve could play an oversized role in modulating the aerodynamics of the airway. This was confirmed with the physical model of nasal obstruction on downstream mucosa.