Modeling nasal physiology changes due to septal perforations

Computational analysis of nasal airflow and its alteration by a nasal dilator

Nasal airflow obstruction correlates with several ailments, such as higher patency, increased friction at the mucosal wall or the so-called Little's area, improper air conditioning, and snoring. Nasal dilators are frequently employed, mainly due to their ease of access and use, combined with their non-permanent and non-surgical nature. Their overall efficacy, however, has not been clearly demonstrated so far, with some studies reporting conflicting outcomes, mainly because being based on subjective evaluations. This study employs Computational Fluid Dynamics simulations to analyze the flow inside a real nose, performs an objective assessment of a nasal dilator's effect in terms of airflow and air conditioning, reporting flow paths, friction levels, heat and water fluxes and detailed temperature and humidity distributions. Coincidentally, the studied nose presents a septal deviation, with one nostril being wider than the other. The tubes of the dilator used in both nostrils are identical, as with any standard commercial dilator. Consequently, the dilator widens one nostril, as intended, but results in an obstruction in the other. This allows simultaneously addressing two situations, the nominal function of the dilator, as well as an off-design case. Results indicate a 24 % increase in nasal patency in the design situation. The effect, however, is limited, as quantified by appropriate measures, such as the flow-generated friction at the nose surfaces and the temperature fluxes. Hence, the effect of such a dilator in nominal conditions is perhaps not as large as might be hoped. In the off-design situation, nasal resistance increases by 62 %, an undesirable effect, illustrating the consequences of using an inappropriate dilator.

Nasal Septal Perforation Dimensional Analysis

OBJECTIVE

To describe and illustrate septal perforation shape through the documentation and analysis of length and height measurements. A secondary objective is to correlate perforation size to surgical and nonsurgical etiologies.

STUY DESIGN

Retrospective case series.

SETTING

Tertiary academic medical center.

METHODS

Length and height of consecutively treated perforations over a 3-year period were measured directly or through computed tomography. Mean differences in length and height measurements were compared and regression analysis used to determine perforation shape and the effect of etiology on perforation size. Perforations were classified by length into small (1-5 mm), medium (6-15 mm), and large (>15 mm) and correlated to shape and etiology.

RESULTS

One hundred twenty-four patients (mean age 50.4 years, 60.5% female) met study inclusion criteria. Height was less than length in 93% of perforations 5 mm or greater in length. Mean perforation height was significantly less than length for medium and large perforations (P < .001). Mean length and height measurements of nonsurgical perforations were greater than those for surgical perforations (P < .001).

CONCLUSION

Height is less than length in over 90% of septal perforations. Most perforations assume an elliptical shape as they enlarge. Accurate measurement and presentation of length and height is relevant information to perforation management decisions and for the evaluation of treatment outcomes.

Computational Fluid Dynamics and Its Potential Applications for the ENT Clinician

This article is an examination of computational fluid dynamics in the field of otolaryngology, specifically rhinology. The historical development and subsequent application of computational fluid dynamics continues to enhance our understanding of various sinonasal conditions and surgical planning in the field today. This article aims to provide a description of computational fluid dynamics, the methods for its application, and the clinical relevance of its results. Consideration of recent research and data in computational fluid dynamics demonstrates its use in nonhistological disease pathology exploration, accompanied by a large potential for surgical guidance applications. Additionally, this article defines in lay terms the variables analyzed in the computational fluid dynamic process, including velocity, wall shear stress, area, resistance, and heat flux.

Cadaveric and Computed Tomography Analysis of the Anterior Ethmoidal Artery Flap

BACKGROUND

The anterior ethmoidal artery (AEA) flap has been successful in repairing anterior nasal septal perforations and has been presumed to be axially based on AEA branches coursing through or around the cribriform plate (CP). However, limited evidence supports the flap's axial supply. The purposes of this cadaveric and computed tomography (CT) study were to assess the arterial anatomy from the CP to the septum, and to determine AEA flap length to predict ideal flap base width.

METHODS

Ten fresh latex-injected cadavers were utilized for endoscopic dissection to identify arteries traversing the CPs on each side. First, arterial trajectories along the dorsal septum were recorded. Measurements were then made bilaterally along the septum from the middle turbinate (MT) axilla to the nasal branch of the AEA (NBAEA) traversing the CP. Additionally, 100 sinus CTs were reviewed to measure AEA flap lengths bilaterally.

RESULTS

From 10 cadavers, 20 sides were utilized for measurements. In all cadavers, the AEA septal branches coursed diagonally or horizontally along the dorsal septum, and never directly vertically. The mean distance from the MT axilla to the NBAEA was 1.24 ± 1.93 cm (range = 1-1.5 cm). Based on CTs, the mean AEA flap length was 6.40 ± 0.60 cm.

CONCLUSIONS

Based on the non-vertical courses of AEA septal branches, the AEA flap is more likely a random transposition flap than an axial flap. Average AEA flap length ranged from 6.0 to 7.0 cm. Assuming 3:1 length:width ratios, AEA flap base widths should be about 2.0-2.3 cm.

LEVEL OF EVIDENCE

NA Laryngoscope, 134:2100-2104, 2024.

On the comparison between pre- and post-surgery nasal anatomies via computational fluid dynamics

Nasal breathing difficulties (NBD) are widespread and difficult to diagnose; the failure rate of their surgical corrections is high. Computational fluid dynamics (CFD) enables diagnosis of NBD and surgery planning, by comparing a pre-operative (pre-op) situation with the outcome of virtual surgery (post-op). An equivalent comparison is involved when considering distinct anatomies in the search for the functionally normal nose. Currently, this comparison is carried out in more than one way, under the implicit assumption that results are unchanged, which reflects our limited understanding of the driver of the respiratory function. The study describes how to set up a meaningful comparison. A pre-op anatomy, derived via segmentation from a CT scan, is compared with a post-op anatomy obtained via virtual surgery. State-of-the-art numerical simulations for a steady inspiration carry out the comparison under three types of global constraints, derived from the field of turbulent flow control: a constant pressure drop (CPG) between external ambient and throat, a constant flow rate (CFR) through the airways and a constant power input (CPI) from the lungs can be enforced. A significant difference in the quantities of interest is observed depending on the type of comparison. Global quantities (flow rate, pressure drop and nasal resistance) as well as local ones are affected. The type of flow forcing affects the outcome of the comparison between pre-op and post-op anatomies. Among the three available options, we argue that CPG is the least adequate. Arguments favouring either CFR or CPI are presented.

Impact of nasal septal perforation on the airflow and air-conditioning characteristics of the nasal cavity

We investigated (1) how nasal septal perforations (NSPs) modify nasal airflow and air-conditioning characteristics and (2) how the modifications of nasal airflow are influenced by the size and location of the NSP. Computed tomography scans of 14 subjects with NSPs were used to generate nasal cavity models. Virtual repair of NSPs was conducted to examine the sole effect of NSPs on airflow. The computational fluid dynamics technique was used to assess geometric and airflow parameters around the NSPs and in the nasopharynx. The net crossover airflow rate, the increased wall shear stress (WSS) and the surface water-vapor flux on the posterior surface of the NSPs were not correlated with the size of the perforation. After the virtual closure of the NSPs, the levels in relative humidity (RH), air temperature (AT) and nasal resistance did not improve significantly both in the choanae and nasopharynx. A geometric parameter associated with turbinate volume, the surface area-to-volume ratio (SAVR), was shown to be an important factor in the determination of the RH and AT, even in the presence of NSPs. The levels of RH and AT in the choanae and nasopharynx were more influenced by SAVR than the size and location of the NSPs.

Human nasal cartilage: Functional properties and structure-function relationships for the development of tissue engineering design criteria

Nose reconstruction often requires scarce cartilage grafts. Nasal cartilage properties must be determined to serve as design criteria for engineering grafts. Thus, mechanical and biochemical properties were obtained in multiple locations of human nasal septum, upper lateral cartilage (ULC), and lower lateral cartilage (LLC). Within each region, no statistical differences among locations were detected, but anisotropy at some septum locations was noted. In the LLC, the tensile modulus and ultimate tensile strength (UTS) in the inferior-superior direction were statistically greater than in the anterior-posterior direction. Cartilage from all regions exhibited hyperelasticity in tension, but regions varied in degree of hyalinicity (i.e., Col II:Col I ratio). The septum contained the most collagen II and least collagen I and III, making it more hyaline than the ULC and LLC. The septum had a greater aggregate modulus, UTS, and lower total collagen/wet weight (Col/WW) than the ULC and LLC. The ULC had greater tensile modulus, DNA/WW, and lower glycosaminoglycan/WW than the septum and LLC. The ULC had a greater pyridinoline/Col than the septum. Histological staining suggested the presence of chondrons in all regions. In the ULC and LLC, tensile modulus correlated with total collagen content, while aggregate modulus correlated with pyridinoline content and weakly with pentosidine content. However, future studies should be performed to validate these proposed structure-function relationships. This study of human nasal cartilage provides 1) crucial design criteria for nasal cartilage tissue engineering efforts, 2) quantification of major and minor collagen subtypes and crosslinks, and 3) structure-function relationships. Surprisingly, the large mechanical properties found, particularly in the septum, suggests that nasal cartilage may experience higher-than-expected mechanical loads. STATEMENT OF SIGNIFICANCE: While tissue engineering holds promise to generate much-needed cartilage grafts for nasal reconstruction, little is known about nasal cartilage from an engineering perspective. In this study, the mechanical and biochemical properties of the septum, upper lateral cartilage (ULC), and lower lateral cartilage (LLC) were evaluated using cartilage-specific methods. For the first time in this tissue, all major and minor collagens and collagen crosslinks were measured, demonstrating that the septum was more hyaline than the ULC and LLC. Additionally, new structure-function relationships in the ULC and LLC were identified. This study greatly expands upon the quantitative understanding of human nasal cartilage and provides crucial engineering design criteria for much-needed nasal cartilage tissue engineering efforts.

Nasal Swell Body Characteristics in Patients With Septal Perforation

Objective

To determine whether septal perforations have an effect on nasal swell body (NSB) size.

Study Design

Retrospective cohort study.

Setting

Two tertiary academic medical centers.

Methods

Computed tomography maxillofacial scans of 126 patients with septal perforation and 140 control patients from November 2010 to December 2020 were evaluated. Perforation etiology was determined. Measurements included perforation length and height and swell body width, height, and length. Swell body volume was calculated.

Results

The width and volume of the NSB are significantly smaller in perforation patients when compared to controls. The swell body is significantly smaller and thinner in perforations exceeding 14 mm in height compared to small perforations. Perforation etiology groupings into prior septal surgery, septal trauma, septal inflammatory, and mucosal vasoconstriction categories all demonstrated decreased swell body volume and width compared to controls. Inflammatory etiology had the greatest decrease in swell body size. The hemi-swell body on the contralateral side of a septal deviation is significantly thicker than the ipsilateral side.

Conclusion

The NSB is smaller in patients with septal perforation regardless of perforation size or etiology.

Presenting Symptomatology for Patients With Nasal Septal Perforation: Application of the NOSE‐Perf Scale

OBJECTIVE

To objectively identify and quantitate presenting nasal symptoms in patients with a septal perforation using the validated NOSE-Perf scale.

STUDY DESIGN

Case series retrospective review.

METHODS

The medical records from August 2018 through January 2022 of patients at a tertiary care academic center with a septal perforation, and who completed the NOSE-Perf questionnaire, were reviewed. Perforation symptoms were identified and quantified using the 12-item NOSE-Perf scale (score range 0-48). NOSE-Perf findings were correlated to patient demographics, perforation etiology, and perforation length. NOSE-Perf scores of patients who pursued treatment were compared with those who did not.

RESULTS

NOSE-Perf data were collected from 202 patients. Nasal crusting was noted in 94.1% of patients and was the most severe symptom reported (mean 2.9 of 4.0). Nasal congestion, difficulty breathing, and nasal obstruction followed in prevalence and severity. The mean total NOSE-Perf score was 23.7. Linear regression analysis demonstrated a weakly negative association of NOSE-Perf score with patient age and weakly positive association with increasing perforation length. NOSE-Perf scores were significantly higher in women and in patients pursuing treatment.

CONCLUSION

This is the first study to use the validated NOSE-Perf scale to objectively characterize and establish baseline septal perforation symptomatology. The NOSE-Perf scale can play a role in the standardization of perforation evaluation and treatment outcomes assessment. Laryngoscope, 133:1315-1320, 2023.

The Impact on Nasal Septal Anatomy and Physiology Following Le Fort I Osteotomy for Orthognathic Surgery

ABSTRACT

Orthognathic surgery utilizing a Le Fort I osteotomy is performed by oral and maxillofacial surgeons to correct midface and dental occlusal abnormalities. However, the potential sequelae on sinonasal function have had minimal discussion in the literature. The objective of this study was to assess the impact on nasal septum anatomy and physiology following Le Fort I osteotomy for maxillary repositioning surgery. Thirty patients who previously underwent elective orthognathic surgery with Le Fort I osteotomy were enrolled retrospectively to assess the change in their nasal septal anatomy and nasal breathing. Pre- and postoperative computed tomography (CT) scans were used to determine axial displacement of the septum, in both degrees and millimeters, at 4 different standardized anatomic sites following the surgery. These objective anatomic measurements were then compared to the patient's perception of nasal congestion and difficulty breathing via the validated Chronic Sinusitis Survey-Duration Based (CSS-D). Comparison of the CTs before and after surgery demonstrated a new deviation of the nasal septum in all 30 patients, with maximal axial displacements up to 7.22 mm and a mean of 2.64 mm. Postoperative angular displacement changes ranged from minimal to 24°. The CTs showed persistence of a new septal perforation in 20% (6 of 30 patients) following surgery. The CSS-D results demonstrated a mean worsening of nasal breathing and congestion scores from 1.4 before surgery to 3.0 at least 8 weeks after surgery (P < 0.001). Orthognathic surgery utilizing Le Fort I osteotomy may result in persistent nasal septal perforations, new displacement of the nasal septum, and increased perception of nasal dyspnea not previously reported. Further understanding of anatomic changes and nasal airway obstruction that may be caused following such operations warrants further study in order to improve surgical technique and postoperative outcomes.

Analysis of nasal air conditioning in subjects with unilateral cleft lip nasal deformity

This study evaluated the impact of unilateral cleft lip nasal deformity (uCLND) on the ability of the nasal passages to warm and humidify inspired environmental air using computational fluid dynamics (CFD) modeling. Nasal air conditioning was simulated at resting inspiration in ten individuals with uCLND and seven individuals with normal anatomy. The overall heat and water transfer through nasal mucosa was significantly greater (p = 0.02 for both heat and moisture fluxes) on the non-cleft side than on the cleft side. Unilateral median and interquartile range (IQR) for heat flux (W/m²) was 190.3 (IQR 59.9) on the non-cleft side, 160.9 (IQR 105.0) on the cleft side, and 170.7 (IQR 87.8) for normal subjects. For moisture flux (mg/(s·m²), they were 357.4 (IQR 112.9), 298.7 (IQR 200.3) and 320.8 (IQR 173.0), respectively. Significant differences of SAHF50 between cleft side of uCLND and normal existed except for anterior region. Nevertheless, air conditioning ability in subjects with uCLND was generally comparable to that of normal subjects.

[Closure of Nasal Septal Perforation]

Symptomatic nasal septal perforations can lead to a substantial restriction in the quality of life of patients and present a distinct surgical challenge for the otolaryngologist/head and neck surgeon. Symptomatic patients complain about nasal crusting, recurrent nosebleeds and nasal obstruction. The so called 4 bridge-flap technique including the interposition of autologous ear cartilage presents an established surgical method for closure of a septal perforation. In the present article, the surgical procedure is described in detail.

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.

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.

Optimizing septal perforation repair techniques

PURPOSE OF REVIEW

Multiple successful techniques and approaches for nasal septal perforation repair have been described, yet consistency in perforation and outcome metrics is required to identify the optimal approach to repair. The present article will review the recent literature.

RECENT FINDINGS

Computational fluid dynamic studies continue to expand our understanding of the airflow dynamics in nasal septal perforation and after repair. Combining rhinoplasty and nasal septal perforation repair in appropriately selected patients can be safely done with excellent results. There has been a rise in utilization of a temporoparietal fascia with polydiaxonone plate construct for septal perforation repair with excellent outcomes.

SUMMARY

The present review provides the reconstructive surgeon with an update on nasal septal perforation repair and describes a recently popularized technique of temporoparietal fascia-polydiaxonone plate for perforation reconstruction.

[CFD simulation study of aerodynamics in nasal cavity in a case of septal perforation]

Perforation of the nasal septum remains an actual problem. The success of surgical closure of perforation of the nasal septum depends not only on the surgeon's skill, but also on the degree of disturbance of the nasal cavity physiology. Traditionally, CFD studies of nasal septal perforations are dedicated to the analysis of changes in speed value of the inhaled air depending on the size and localization of perforation of the nasal septum. But there is a lack of studies about warming and moistening of the inhaled air in a case of nasal septal perforation. These studies are necessary not only for studying the pathophysiology of perforation of the nasal septum, but also for planning surgery.

Correlation of sinonasal symptoms with the size and position of nasal septal perforations

OBJECTIVE

To assess the correlation of sinonasal symptoms and quality of life with size and position of nasal septal perforation (NSP).

METHOD

This is a prospective observational study in a tertiary referral center involving adult patients presented with NSP. The Sino-Nasal Outcome Test-22 (SNOT-22) and its clinico-psychometric domains were analyzed, including additional NSP-specific symptoms (nasal crusting, epistaxis, and whistling noise during nasal breathing). The size of NSP was measured radiologically by calculating the area in cm² and anteroposterior (AP) diameter. Position of perforation was determined clinically by distance from columella to the anterior edge of the perforation.

RESULTS

Forty patients were included in this study (22 males). The most common etiology of NSP was iatrogenic. The mean SNOT-22 score was 50.8 (standard deviation 23.8), and mean NSP size was 3.0 cm² . No statistical correlation was observed between the total SNOT-22 score with either position or size of NSP. As for NSP-specific symptoms, there was a statistically significant negative correlation with the size of perforation (A-P diameter) (r = -0.34, P = 0.03) and position of the perforation (r = -0.49, P = 0.0016), suggesting that these symptoms improved with posterior and larger perforations.

CONCLUSION

Reported SNOT-22 scores were comparable to patients with recalcitrant chronic rhinosinusitis, although the scores did not correlate with size and position of NSP. Sinonasal symptoms typically observed in NSP improved with more posteriorly placed and larger sized perforations. This study provides an insight into the quality-of-life impact of NSP and affirms the clinical observation that anterior NSP are more symptomatic.

LEVEL OF EVIDENCE

4 Laryngoscope, 2019.

Approach to Correction of Septal Perforation

Iatrogenic septal perforation is a complication of nasal surgery. Small or posterior perforations cause few symptoms, and need only conservative treatment. Larger and anterior perforations contribute to nasal airflow disturbances and external nasal deformities. When considering surgical candidacy, one should consider the severity of symptoms, location and size of the perforation, and need for revsional rhinoplasty. We repair perforations using intranasal mucosal advancement flaps augmented by an interposition connective tissue graft. Septal perforation repairs are tedious and technically challenging. We review key points to minimize unintended perforation formation following nasal surgery.

Computational investigation of dust mite allergens in a realistic human nasal cavity

Aim: Inhaled allergens from house dust mite (HDM) are a major source of allergic disease such as allergic rhinitis and asthma. It has been a challenge to properly evaluate health risks caused by HDM related allergens including mite bodies, eggs and fecal pellets. This paper presents a numerical study on particle deposition of dust mite allergens in a human nasal cavity. Materials and methods: A realistic nasal cavity model was reconstructed from CT scans and a Computational Fluid Dynamics analysis of steady airflow was simulated. The discrete phase model was used to trace particle trajectories of three dust mite related particles. Results: The flow and particle model were validated by comparing with nasal resistance measurement and previous literature respectively. Aerodynamic characteristics and deposition of dust mite allergens in the nasal cavity were analyzed under different breathing conditions including rest and exercising conditions. Conclusions: The numerical results revealed the roles of different nasal cavity regions in filtering various types of dust mite allergens with consideration of breathing conditions.

Lin E, Poetker DM, Garcia GJM. Clinical Importance of Nasal Air Conditioning: A Review of the Literature

Background

Nasal air conditioning (ie, heating and humidification of inspired air) is an important function of the nasal cavity. This function may be reduced in cases of aggressive nasal surgery. Future virtual surgery planning tools may be used to design surgical approaches that preserve the nasal air conditioning capacity while decreasing airflow resistance. However, it is unclear whether there is a threshold below which impaired nasal air conditioning is associated with negative health consequences.

Objective

This study aims to review the literature on the clinical impact of reduced nasal air conditioning and its implications for nasal surgery outcomes.

Methods

A literature search was performed on PubMed and Scopus databases for articles that investigated the effect of air temperature and humidity on mucociliary clearance, respiratory epithelial structure, and the prevalence and severity of respiratory diseases.

Results

Inspiration of cold, dry air has direct effects on the respiratory epithelium, such as reduced mucociliary clearance and loss of cilia. Nasal surgeries do inflict some changes to the nasal mucosa and geometry that may result in decreased heating and humidification, but it is unclear how long these effects last. Laryngectomy patients serve as a human model for the absence of nasal air conditioning. The heat and moisture exchangers that many laryngectomy patients wear have been shown to improve lung function and reduce pulmonary symptoms associated with breathing unconditioned air, such as increased coughing and thickened mucus.

Conclusion

Nasal air conditioning is an important mechanism to maintain mucociliary clearance and prevent infection by inhaled pathogens. Preservation of nasal air conditioning capacity should be considered in the implementation of future virtual surgery planning tools. However, a threshold for the onset of negative health consequences due to impaired nasal air conditioning is not yet available.

Asymptomatic vs symptomatic septal perforations: a computational fluid dynamics examination

BACKGROUND

A nasal septal perforation (NSP) can lead to frustrating symptoms for some patients while remaining completely asymptomatic for others, without a clear mechanism differentiating them.

METHODS

We applied individual computed tomography (CT)-based computational fluid dynamics (CFD) to examine the nasal aerodynamics differences between 5 asymptomatic and 15 symptomatic NSP patients. Patients' symptoms were confirmed through interviews, 22-item Sino-Nasal Outcome Test score (asymptomatic, 25 ± 18.8; symptomatic, 53.7 ± 18.2), nasal obstruction symptom evaluation score (asymptomatic, 28.0 ± 32.1; symptomatic, 62.2 ± 32.2), and review of medical history.

RESULTS

No statistical differences were found in perforation location, size (asymptomatic, 1.94 ± 1.88 cm² ; symptomatic, 1.36 ± 1.44 cm² ), nasal resistance (asymptomatic, 0.059 ± 0.012 Pa·s/mL; symptomatic, 0.063 ± 0.022 Pa·s/mL), and computed flow rate shunting across the perforation (asymptomatic, 52.9 ± 30.9 mL/s; symptomatic, 27.4 ± 23.6 mL/s; p > 0.05). However, symptomatic patients had significantly higher wall shear stress (WSS) and heat flux, especially along the posterior perforation margin (WSS, 0.54 ± 0.12 vs 1.15 ± 0.49 Pa, p < 0.001; heat flux, 0.21 ± 0.05 vs 0.37 ± 0.14 W/cm² , p < 0.01). A WSS cutoff at 0.72 Pa can separate asymptomatic vs symptomatic NSP with 87% sensitivity and 100% specificity. Flow visualization showed flow peaks toward the posterior margin that may be responsible for the high WSS and heat flux among symptomatic NSPs.

CONCLUSION

This study is the first CFD examination of asymptomatic and symptomatic NSP with regional aerodynamics and stress abnormalities, beyond size or location, being implicated as the mechanism behind the symptomology of NSP. This finding could serve as an objective basis for future personalized treatment decisions and optimization.

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.

Cancer Risks of Hexavalent Chromium in the Respiratory Tract

Hexavalent chromium (Cr(VI)) compounds are recognized as carcinogens in the respiratory tract, giving rise to cancers of the lung, nose and nasal sinuses, especially in certain occupational environments. Inhalation exposure of Cr(VI)-containing particles, dusts and fumes commonly occurs in chromium-related occupational environments, such as chromium production, plating, welding of chromium-containing metals and alloys, electroplating, chromium-containing pigments and paints. Epidemiological surveys of chromium compounds have shown strong associations between exposure to Cr(VI) and mortality due to lung cancer, as well as positive associations with cancers of the nose and nasal cavity. Nasal symptoms, such as nasal irritation, ulceration and perforation of the nasal septum, nasal turbinate engorgement and hypertrophy, are important signs for the early diagnosis of lung cancer and cancers of the nose and nasal cavity in those with an occupational history of Cr(VI) exposure. Cr(VI) exposure in the workplace remains a serious problem as a cause of lung cancer and cancers of nose and nasal cavity, especially in relatively small enterprises that use chromium compounds. Appropriate protection for workers should be considered in occupations that involve exposure to chromium compounds.

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.

Recapitulation of Unilateral Cleft Lip Nasal Deformity on Normal Nasal Structure: A Finite Element Model Analysis

Cleft lip nasal deformity has been challenging to plastic surgeons. A better understanding of the biomechanical aspect of the cleft nose would contribute to a better correction. In this study, finite element model of a normal nose was constructed and loaded with forces to recapitulate the unilateral cleft lip nasal deformity. Tether at the alar base was simulated by a laterally directed force at the lateral crus, and tether at the columella base by a posteriorly directed force at the medial crus. The equivalent von-Mises stress and the total deformation consequent to different patterns of loading were captured. In accordance with clinical observations, unilaterally loaded forces caused deformation on both sides of the nose. A correlation between the patterns of loading and different cleft lip nasal deformities was documented in detail. When set at the same force magnitude, tether at the columella base led to more extensive changes in the nasal morphology and higher level of stress than at the alar base. Clear identification of major pathological tethers in the nasolabial region might lead to more accurate and stable correction of cleft lip nasal deformities.

A CFD approach to understand nasoseptal perforations

INTRODUCTION

Nasoseptal perforations (NSP) are becoming common in the modern world, and can cause a wide variety of symptoms, including a sensation of nasal obstruction, epistaxis, crusting, dryness, headache, nasal pain and a whistling sound. There is an extensive range of surgical treatment techniques, but reported results were rarely statistically significant. The lack of consistent surgical results may be related to the lack of knowledge about the pathophysiology of NSP and how they affect the nasal flow. Computational fluid dynamics (CFD) has proved to be a very useful tool to study nasal function.

METHODS

We have used CFD software (the program MECOMLAND® and the Digbody® tool for virtual surgery) to investigate the behaviour of the parameters R-[Formula: see text] based on CFD results, when four subjects underwent virtual surgery to induce a septal perforation: two subjects with healthy noses and two patients suffering from nasal airway obstruction. For each case a CFD study was performed, before and after creating an anterior (close to nostrils) or a posterior (close to choanae) NSP.

RESULTS

In all cases analyzed, a posterior septal perforation did not result in a significant volumetric flow rate [Formula: see text] through the perforation between nasal passages. However, for anterior defects only in those nasal cavities considered diseased or unhealthy, high values of [Formula: see text] were found.

CONCLUSION

The induced NSP only rendered significant flow alterations in noses with preexisting nasal airway obstruction alterations, whereas in nasal cavities considered as normal the creation of a NSP did not produce significant differences between both sides. We strongly suggest that this finding can explain the variety of symptoms and the number of asymptomatic patients bearing NSP.

Modeling congenital nasal pyriform aperture stenosis using computational fluid dynamics

OBJECTIVES

Congenital nasal pyriform aperture stenosis (CNPAS) is a rare cause of airway obstruction in the neonate. Computational airway modeling has not been done in neonates and young infants to understand the impact of stenosis on functional nasal airflow. In this study, we 1) applied computational fluid dynamics (CFD) model to the airway of a neonate with CNPAS and 2) compare airflow dynamics of a normal and CNPAS airway.

METHODS

Three-dimensional models of the nasal airway of a normal neonate and a neonate with CNPAS were created using computed tomography scans of the facial bones. Measured anatomic parameters included volume, surface area, and cross-sectional area. CFD simulation was then performed. Simulated flow parameters included pressure, average velocity, and resistance.

RESULTS

The neonate with CNPAS had a lesser volume (2.74 cm³ vs. 4.50 cm³) and surface area (18.8 cm² vs. 45.5 cm²) than the normal airway. The CNPAS airway had a lesser bilateral cross-sectional area and average cross-sectional velocity throughout the length of the model. While there is a large pressure drop in the normal airway immediately after the entry point, the pressure drop in the CNPAS airway occurs more posteriorly. The total nasal resistance was approximately eight-fold greater in the CNPAS airway than the normal.

CONCLUSIONS

CFD analysis can be performed on airways of neonates with nasal obstruction, such as in CNPAS. A CFD model may help characterize severity of airway obstruction as it can predict the three-dimensional pattern of airflow. Determining the role of CFD in clinical management of CNPAS requires further investigation.

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.

Effects of nasal septum perforation repair on nasal airflow: An analysis using computational fluid dynamics on preoperative and postoperative three-dimensional models

OBJECTIVE

The purpose of this research is to examine the changes in nasal airflow dynamics before and after the nasal perforation repair.

METHODS

Three dimensional (3D) models of the nasal cavity before and after septal perforation repair was reconstructed using preoperative and postoperative computed tomography (CT) images of a patient. The numerical simulation was carried out using ANSYS CFX V15.0. Pre- and post-operative models were compared by their velocity, pressure (P), pressure gradient (PG), wall shear (WS), shear strain rate (SSR) and turbulence kinetic energy (TKE) in three plains.

RESULTS

In the post-operative state, the cross flows disappeared. In preoperative state, there were areas showing high PG, WS, SSR at the posterior border of the perforation, which exactly correspond to the area showing erosive mucosa on endoscopic inspection of the patient. In postoperative state, such high PG, WS and SSR areas disappeared. High TKEs also disappeared after surgery.

CONCLUSION

The effects of septal perforation repair on airflow dynamics were evaluated using computer fluid dynamics (CFD). High WS, PG and SSR observed at the edge of the septal perforation may be related to the clinical symptom such as nasal bleeding and pain. TKE was considered to cause nasal symptom.

Numerical simulation of two consecutive nasal respiratory cycles: toward a better understanding of nasal physiology

BACKGROUND

Computational fluid dynamic (CFD) simulations have greatly improved the understanding of nasal physiology. We postulate that simulating the entire and repeated respiratory nasal cycles, within the whole sinonasal cavities, is mandatory to gather more accurate observations and better understand airflow patterns.

METHODS

A 3-dimensional (3D) sinonasal model was constructed from a healthy adult computed tomography (CT) scan which discretized in 6.6 million cells (mean volume, 0.008 mm³ ). CFD simulations were performed with ANSYS©FluentTMv16.0.0 software with transient and turbulent airflow (k-ω model). Two respiratory cycles (8 seconds) were simulated to assess pressure, velocity, wall shear stress, and particle residence time.

RESULTS

The pressure gradients within the sinus cavities varied according to their place of connection to the main passage. Alternations in pressure gradients induced a slight pumping phenomenon close to the ostia but no movement of air was observed within the sinus cavities. Strong movements were observed within the inferior meatus during expiration contrary to the inspiration, as in the olfactory cleft at the same time. Particle residence time was longer during expiration than inspiration due to nasal valve resistance, as if the expiratory phase was preparing the next inspiratory phase. Throughout expiration, some particles remained in contact with the lower turbinates. The posterior part of the olfactory cleft was gradually filled with particles that did not leave the nose at the next respiratory cycle. This pattern increased as the respiratory cycle was repeated.

CONCLUSION

CFD is more efficient and reliable when the entire respiratory cycle is simulated and repeated to avoid losing information.

Computational fluid dynamics evaluation of posterior septectomy as a viable treatment option for large septal perforations

BACKGROUND

Numerous surgical techniques exist to treat nasal septal perforation (NSP). The surgical closure of large NSPs (>2 cm) is still challenging. Posterior septectomy has been reported as a simple alternative to treat large NSP, yet its mechanisms for symptom relief are not clear, and if failed, its consequence cannot be easily reversed.

METHODS

Ten NSP patients were recruited: 5 underwent posterior septectomy and 5 underwent conventional flap or button repair. Computational fluid dynamics (CFD) simulated the nasal aerodynamics based on computed tomography (CT) scans. All patients had preoperative CT; however, only 4 had postoperative CT: 2 underwent posterior septectomy and the other 2 underwent flap repair. We examined surgical outcomes and the nasal airflow features among the 2 treatment options.

RESULTS

Both groups of patients had good outcomes based on chart review. Patients undergoing septectomy had significantly larger perforation size (2.32 ± 0.87 vs 1.21 ± 0.60 cm), higher flow rate across the perforation (47.8 ± 28.6 vs 18.3 ± 12.2 mL/second), and higher wall shear stress (WSS) along the posterior perforation margin (1.39 ± 0.52 vs 1.15 ± 0.58 Pa). The posterior WSS significantly correlated with crossover flow velocity (r = 0.77, p = 0.009) and was reduced by almost 67% postseptectomy, and by 29% postrepair.

CONCLUSION

This is the first CFD analysis on an NSP patient cohort. NSP resulted in flow disturbance and increased WSS that potentially led to symptomatology. The removal of high stress points along the posterior margin may explain why posterior septectomy can be an effective treatment option. Aerodynamic abnormalities, in addition to perforation size and location, could serve as basis for future treatment decisions.

Creation of an idealized nasopharynx geometry for accurate computational fluid dynamics simulations of nasal airflow in patient-specific models lacking the nasopharynx anatomy

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.

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.

Bacterial flora and the epidemiology of staphylococcus aureus in the nose among patients with symptomatic nasal septal perforations

Conclusions Patients with symptomatic perforations of the nasal septum had a high prevalence of S. aureus in the nasal mucosa. Pulsed field gel electrophoresis (PFGE) analysis revealed a high genetic heterogeneity of S. aureus among both patients and controls. This indicates that presence of different strains of S. aureus can maintain a chronic inflammation in symptomatic nasal septal perforations. Objective The purpose of this study was to investigate the microbial flora around nasal septal perforations in patients having severe symptoms regarding bleeding, obstruction, and crustation associated with their perforation. Methods Twenty-five patients with untreated symptomatic nasal septal perforations were included. For culture, swabs around the perforations were collected. Bacteria were identified with standard laboratory techniques including a MALDI-TOF mass spectrometer. Epidemiological analysis was done using PFGE protocols. Bacteriological data were compared with data from a healthy control group. Results Staphylococcus aureus was present in the mucosa surrounding the nasal perforation significantly more often (p < 0.0001) in the patients (88%) compared to a control group (13%). Corynebacterium spp. and Propionibacterium spp. were significantly more frequently identified in the control group. The PFGE analysis of S. aureus strains revealed a high genetic heterogeneity and no specific S. aureus genotypes were associated with septal perforation.

A Finite Element Model to Simulate Formation of the Inverted-V Deformity

IMPORTANCE

Computational modeling can be used to mimic the forces acting on the nasal framework that lead to the inverted-V deformity (IVD) after surgery and potentially determine long-range outcomes.

OBJECTIVE

To demonstrate the use of the finite element method (FEM) to predict the formation of the IVD after separation of the upper lateral cartilages (ULCs) from the nasal septum.

DESIGN, SETTING, AND PARTICIPANTS

A computer model of a nose was derived from human computed tomographic data. The septum and upper and lower lateral cartilages were designed to fit within the soft-tissue envelope using computer-aided design software. Mechanical properties were obtained from the literature. The 3 simulations created included (1) partial fusion of the ULCs to the septum, (2) separation of the ULCs from the septum, and (3) a fully connected model to serve as a control. Forces caused by wound healing were prescribed at the junction of the disarticulated ULCs and septum. Using FEM software, equilibrium stress and strain were calculated. Displacement of the soft tissue along the nasal dorsum was measured and evaluated for evidence of morphologic change consistent with the IVD.

MAIN OUTCOME AND MEASURES

Morphologic changes on the computer models in response to each simulation.

RESULTS

When a posteroinferior force vector was applied along the nasal dorsum, the areas of highest stress were along the medial edge of the ULCs and at the junction of the ULCs and the nasal bones. With full detachment of ULCs and the dorsal septum, the characteristic IVD was observed. Both separation FEMs produced a peak depression of 0.3 mm along the nasal dorsum.

CONCLUSIONS AND RELEVANCE

The FEM can be used to simulate the long-term structural complications of a surgical maneuver in rhinoplasty, such as the IVD. When applied to other rhinoplasty maneuvers, the use of FEMs may be useful to simulate the long-term outcomes, particularly when long-term clinical results are not available. In the future, use of FEMs may simulate rhinoplasty results beyond simply morphing the outer contours of the nose and allow estimation of potentially long-term clinical outcomes that may not be readily apparent.

LEVEL OF EVIDENCE

NA.

Modeling alterations in sinonasal physiology after skull base surgery

BACKGROUND

Endonasal endoscopic skull base surgery (EESBS) often requires significant alterations in intranasal anatomy. For example, posterior septectomy (PS) with middle turbinate resection (MTR) is frequently performed to provide access to large sellar and clival tumors. However, little is known about the alterations that occur in sinonasal physiology. This study was designed to assess changes in sinonasal physiology after virtually performed endoscopic skull base surgery.

METHODS

Three-dimensional models of the sinonasal passage were created from computed tomography scans in three subjects with varying anatomy: no SD (SD), right anterior SD, and left anterior SD, respectively. Four additional surgery types were performed virtually on each model: endoscopic transsphenoidal approach (ETSA) with small (1 cm) PS (smPS), ETSA with complete (2 cm) PS, ETSA with smPS and right MTR, and ETSA with complete PS and right MTR. Computational fluid dynamics (CFD) simulations were performed on the 3 presurgery and 12 virtual surgery models to assess changes from surgery types.

RESULTS

Increased nasal airflow corresponded to amount of tissue removed. Effects of MTR on unilateral airflow allocation were unchanged in subject with no SD, worsened in leftward SD, and reversed in rightward SD. Severity of airflow and mucosal wall interactions trended with amount of tissue removed. MTR hindered flow interactions with the olfactory mucosa in subjects with SD.

CONCLUSION

CFD simulations on virtual surgery models are able to reasonably detect changes in airflow patterns in the computer-generated nasal models. In addition, each patient's unique anatomy influences the magnitude and direction of these changes after virtual EESBS. Once future studies can reliably correlate CFD parameters with patient symptoms, CFD will be a useful clinical tool in surgical planning and maximizing patient outcomes.

Prosthetics for Nasoseptal Perforations

Objective

Prosthetics serve as an option for nasoseptal perforation treatment in patients who have active systemic disease, are poor surgical candidates, or wish to avoid surgery. Through systematic review of the literature on prosthetics for nasoseptal perforation treatment, the objective of the present study is to critically appraise previous studies, evaluate the success rate for nasoseptal prosthetics, provide evidence-based guidelines for nasoseptal prosthetic use, and identify areas for further investigation.

Data Sources

Cochrane Controlled Trials Register, EMBASE, PubMed, and Web of Science.

Review Methods

Data sources were queried for relevant articles published from 1965 to 2013. Articles were selected for inclusion if they presented primary data for human nasoseptal perforation treatment utilizing prosthetic materials. Each included article’s level of evidence and risk of bias were identified and grades of recommendation were assigned. A quantitative meta-analysis was performed on articles with low risk of bias.

Results

The search yielded 4756 abstracts for review, with 23 included case series and 5 case reports; 706 total cases of prosthetic nasoseptal perforation treatment were identified. All articles provided level 4 evidence, with an overall conclusion grade of C for improvement in nasoseptal perforation symptoms, prosthetic in situ rate, and complication rate. Meta-analysis of 6 low-risk-of-bias studies with 297 patients demonstrated an overall success rate of 65%.

Conclusions

The literature provides level 4 evidence for the efficacy and safety of prosthetics for nasoseptal perforation treatment with favorable success rates and few reports of complications—only 1 fungal infection and 9 unspecified infections—in 706 cases.

Effects of nasal septum perforation repair surgery on three-dimensional airflow: an evaluation using computational fluid dynamics

The purpose of this research is to determine the cause of nasal perforation symptoms and to predict post-operative function after nasal perforation repair surgery. A realistic three-dimensional (3D) model of the nose with a septal perforation was reconstructed using a computed tomography (CT) scan from a patient with nasal septal defect. The numerical simulation was carried out using ANSYS CFX V13.0. Pre- and post-operative models were compared by their velocity, pressure gradient (PG), wall shear (WS), shear strain rate (SSR) and turbulence kinetic energy in three plains. In the post-operative state, the crossflows had disappeared, and stream lines bound to the olfactory cleft area had appeared. After surgery, almost all of high-shear stress areas were disappeared comparing pre-operative model. In conclusion, the effects of surgery to correct nasal septal perforation were evaluated using a three-dimensional airflow evaluation. Following the surgery, crossflows disappeared, and WS, PG and SSR rate were decreased. A high WS.PG and SSR were suspected as causes of nasal perforation symptoms.

Simulating the nasal cycle with computational fluid dynamics

OBJECTIVES

(1) To develop a method to account for the confounding effect of the nasal cycle when comparing preoperative and postoperative objective measures of nasal patency. (2) To illustrate this method by reporting objective measures derived from computational fluid dynamics (CFD) models spanning the full range of mucosal engorgement associated with the nasal cycle in 2 subjects.

STUDY DESIGN

Retrospective.

SETTING

Academic tertiary medical center.

SUBJECTS AND METHODS

A cohort of 24 patients with nasal airway obstruction was reviewed to select the 2 patients with the greatest reciprocal change in mucosal engorgement between preoperative and postoperative computed tomography (CT) scans. Three-dimensional anatomic models were created based on the preoperative and postoperative CT scans. Nasal cycling models were also created by gradually changing the thickness of the inferior turbinate, middle turbinate, and septal swell body. Moreover, CFD was used to simulate airflow and to calculate nasal resistance and the average heat flux.

RESULTS

Before accounting for the nasal cycle, patient A appeared to have a paradoxical worsening nasal obstruction in the right cavity postoperatively. After accounting for the nasal cycle, patient A had small improvements in objective measures postoperatively. The magnitude of the surgical effect also differed in patient B after accounting for the nasal cycle.

CONCLUSION

By simulating the nasal cycle and comparing models in similar congestive states, surgical changes in nasal patency can be distinguished from physiological changes associated with the nasal cycle. This ability can lead to more precise comparisons of preoperative and postoperative objective measures and potentially more accurate virtual surgery planning.

Facial structure alterations and abnormalities of the paranasal sinuses on multidetector computed tomography scans of patients with treated mucosal leishmaniasis

BACKGROUND/OBJECTIVES

Mucosal leishmaniasis (ML) is a progressive disease that affects cartilage and bone structures of the nose and other upper respiratory tract structures. Complications associated with ML have been described, but there is a lack of studies that evaluate the structural changes of the nose and paranasal sinuses in ML using radiological methods. In this study, we aimed to assess the opacification of the paranasal sinuses in patients with treated ML and any anatomical changes in the face associated with ML using multidetector computed tomography scans (MDCT) of the sinuses. We compared the findings with a control group.

METHODOLOGY/PRINCIPAL FINDINGS

We evaluated 54 patients with treated ML who underwent CT scans of the sinuses and compared them with a control group of 40 patients who underwent orbital CT scans. The degree of sinus disease was assessed according to the Lund-Mackay criteria. Forty of the 54 patients with a history of ML (74.1%) had a tomographic score compatible with chronic sinusitis (Lund-Mackay ≥4). CT scans in the leishmaniasis and control groups demonstrated significant differences in terms of facial structure alterations. Patients from the ML group showed more severe levels of partial opacification and pansinus mucosal thickening (42.6%) and a greater severity of total opacification. Patients from the ML group with a Lund-Mackay score ≥4 presented longer durations of disease before treatment and more severe presentations of the disease at diagnosis.

CONCLUSION/SIGNIFICANCE

CT scans of the sinuses of patients with ML presented several structural alterations, revealing a prominent destructive feature of the disease. The higher prevalence in this study of chronic rhinosinusitis observed in CT scans of patients with treated ML than in those of the control group suggests that ML can be considered a risk factor for chronic rhinosinusitis in this population (p<0.05).

Perception of better nasal patency correlates with increased mucosal cooling after surgery for nasal obstruction

OBJECTIVES

To (1) quantify mucosal cooling (ie, heat loss) spatially in the nasal passages of nasal airway obstruction (NAO) patients before and after surgery using computational fluid dynamics (CFD) and (2) correlate mucosal cooling with patient-reported symptoms, as measured by the Nasal Obstruction Symptom Evaluation (NOSE) and a visual analog scale (VAS) for sensation of nasal airflow.

STUDY DESIGN

Prospective.

SETTING

Academic tertiary medical center.

SUBJECTS AND METHODS

Computed tomography (CT) scans and NOSE and VAS surveys were obtained from 10 patients before and after surgery to relieve NAO. Three-dimensional models of each patient's nasal anatomy were used to run steady-state CFD simulations of airflow and heat transfer during inspiration. Heat loss across the nasal vestibule and the entire nasal cavity, as well as the surface area of mucosa exposed to heat fluxes >50 W/m(2), were compared pre- and postoperatively.

RESULTS

After surgery, heat loss increased significantly on the preoperative most obstructed side (P < .0002). A larger surface area of nasal mucosa was exposed to heat fluxes >50 W/m(2) after surgery. The best correlation between patient-reported and CFD measures of nasal patency was obtained for NOSE against surface area in which heat fluxes were >50 W/m(2) (Pearson r = -0.76).

CONCLUSION

A significant postoperative increase in mucosal cooling correlates well with patients' perception of better nasal patency after NAO surgery. Computational fluid dynamics-derived heat fluxes may prove to be a valuable predictor of success in NAO surgery.

Quantification of airflow into the maxillary sinuses before and after functional endoscopic sinus surgery

BACKGROUND

The effects of increases in maxillary sinus (MS) airflow following functional endoscopic sinus surgery (FESS) are unknown. The goal of this study was to quantify the effects of FESS on airflow into the MS in a cohort of patients with chronic rhinosinusitis, and compare MS flow rate with patient-reported outcome measures.

METHODS

A pilot study was conducted in which preoperative and postoperative computed tomography scans of 4 patients undergoing bilateral or unilateral FESS were used to create 3-dimensional (3D) reconstructions of the nasal airway and paranasal sinuses using Mimics™ (Materialise, Inc.). The size of the maxillary antrostomies post-FESS ranged from 107 to 160 mm(2). Computational meshes were generated from the 3D reconstructions, and steady-state, laminar, inspiratory airflow was simulated in each mesh using the computational fluid dynamics (CFD) software Fluent™ (ANSYS, Inc.) under physiologic, pressure-driven conditions. Airflow into the MS was estimated from the simulations and was compared preoperatively and postoperatively. In addition, patients completed preoperative and postoperative Rhinosinusitis Outcome Measure-31 (RSOM-31) questionnaires and scores were compared with MS airflow rates.

RESULTS

CFD simulations predicted that average airflow rate into post-FESS MS increased by 18.5 mL/second, and that average flow velocity into the MS more than quadrupled. Simulation results also showed that MS flow rate trended with total RSOM-31 and all domain scores.

CONCLUSION

CFD simulations showed that the healed maxillary antrostomy after FESS can greatly enhance airflow into the MS. Our pilot study suggests that to some extent, increasing airflow into the MS may potentially improve chronic rhinosinusitis patients' quality of life pre-FESS and post-FESS.