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

Modified 'cross-stealing' repair of nasal septal perforation using unilateral inverted mucosal flap

Nasal septal perforations (SP) are common yet challenging conditions encountered in otorhinolaryngology. Endoscopic repair of nasal septal perforations using nasal pedicle mucosal flaps has become an important treatment method. However, there are no established guidelines for selecting the appropriate mucosal flaps for repair, and the choice largely depends on the surgeon's experience. This study outlines the procedure and benefits of utilizing a unilateral inverted mucosal flap from the nasal septum, along with criteria for selecting suitable cases for this surgical approach. The technique is best suited for moderate-sized perforations located in the anterior nasal septum, with a diameter of less than 2cm. The mucosa around the perforation is thicker. It is essential that the nasal mucosa is healthy and that the perforation edges have sufficient bony and cartilaginous support to prevent mucosal adhesion on both sides of the septum, which could hinder the complete separation of the inverted mucosal flap. Our findings suggest that, with careful case selection, the repair technique involving a unilateral inverted mucosal flap combined with stitching methods is a feasible option. This approach not only simplifies the surgical procedure but also significantly reduces its complexity, making it more accessible to those new to the field.

Morphological changes in the inferior nasal passage associated with superior repositioning of the maxilla with/without horseshoe osteotomy or turbinectomy

Superior repositioning of the maxilla during Le Fort I osteotomy (LFI) may narrow the inferior nasal passage. This retrospective study was performed to investigate morphological changes in the inferior nasal passage following LFI with/without additional procedures performed for nasal ventilation (horseshoe osteotomy or inferior turbinate partial resection). Three groups of patients were compared: those undergoing conventional LFI (Conv, 63 patients), LFI with horseshoe osteotomy (Hs, eight patients), and LFI with inferior turbinate partial resection (Turb, 21 patients). Coronal computed tomography images were used to evaluate the degree of stenosis of the inferior nasal passage. The soft tissue and bony tissue volumes in the inferior turbinate were also calculated three-dimensionally. The rate of obstruction of the inferior nasal passage postoperative was 65.9%, 50%, and 11.9% in the Conv, Hs, and Turb groups, respectively (Fisher's exact test, P < 0.001). Patients in the Turb group had significantly less nasal obstruction regardless of the pitch direction of the maxillary movement or volume of the bone in the inferior turbinate (all P < 0.001). In conclusion, for patients with high superior repositioning and well-developed bony tissue in the inferior turbinate, additional procedures are recommended to maintain the ventilation of the nasal passage postoperatively.

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.

Application of Biologic Graft in Nasal Septal Perforation Repair

Objective: To explore the clinical outcome when biomaterials are used to repair nasal septal perforations. Methods: A total of 12 patients were treated. The nasal septum was dissected via endoscopic approach. A 4 cm × 7 cm biologic graft (Biodesign® Tissue Graft) was folded to form a double layer, was placed over the perforation, and was affixed into place using suture. Results: Follow-up ranged from 2 to 8 months after the operation. One patient was not completely healed and presented with a remaining defect of about 2 mm × 8 mm in the upper part of the nasal septum. The remaining 11 patients healed completely. Conclusion: Using a biologic graft to repair nasal septal perforations is an easy operation as it prevents the need to take autologous tissue from the patient, allows for a repair to be performed without creating septal flaps, and has good histocompatibility. It is a safe and effective method that can be used clinically.

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.

Numerical and Experimental Analysis of Drug Inhalation in Realistic Human Upper Airway Model

The demand for a more efficient and targeted method for intranasal drug delivery has led to sophisticated device design, delivery methods, and aerosol properties. Due to the complex nasal geometry and measurement limitations, numerical modeling is an appropriate approach to simulate the airflow, aerosol dispersion, and deposition for the initial assessment of novel methodologies for better drug delivery. In this study, a CT-based, 3D-printed model of a realistic nasal airway was reconstructed, and airflow pressure, velocity, turbulent kinetic energy (TKE), and aerosol deposition patterns were simultaneously investigated. Different inhalation flowrates (5, 10, 15, 30, and 45 L/min) and aerosol sizes (1, 1.5, 2.5, 3, 6, 15, and 30 µm) were simulated using laminar and SST viscous models, with the results compared and verified by experimental data. The results revealed that from the vestibule to the nasopharynx, the pressure drop was negligible for flow rates of 5, 10, and 15 L/min, while for flow rates of 30 and 40 L/min, a considerable pressure drop was observed by approximately 14 and 10%, respectively. However, from the nasopharynx and trachea, this reduction was approximately 70%. The aerosol deposition fraction alongside the nasal cavities and upper airway showed a significant difference in pattern, dependent on particle size. More than 90% of the initiated particles were deposited in the anterior region, while just under 20% of the injected ultrafine particles were deposited in this area. The turbulent and laminar models showed slightly different values for the deposition fraction and efficiency of drug delivery for ultrafine particles (about 5%); however, the deposition pattern for ultrafine particles was very different.

Effects of jaw movement in bimaxillary orthognathic surgery on the upper airway: Computational fluid dynamics analysis

Maxillomandibular repositioning in orthognathic surgeries has both morphologic and functional effects. These surgeries are thought to change the pharyngeal space and cause obstructive sleep apnoea syndrome, however. The primary purpose of this study is to evaluate the effects of jaw movement in bimaxillary orthognathic surgery on airway function and to identify the morphometric factors that can predict postoperative airway function. The subjects were 11 males and 12 females who had undergone orthognathic surgeries of the maxilla and mandible. The results of cephalometric analysis, cross-sectional area of the pharynx (CSA), pharyngeal volume and computational fluid dynamics (CFD) were compared. The CSA of the nasal (CSA1), total volume and total nasal volume decreased after surgery with statistical significance. Velocity at the oropharyngeal space (V2) increased after surgery with statistical significance. V2, CSA of the oropharyngeal space (CSA2) and PV were correlated with the horizontal posterior movement of point B, point Menton and overjet. V2 and CSA2 were correlated with SNB before and after surgery in all 46 analyses. Changes in pharyngeal airflow were more affected by pressure drop in the pharyngeal space (ΔPp) than by pressure drop in the nasal space (ΔPn). The relationship between the actual amount of change in the cephalometric reference point and the airway function is evident. CFD may thus be very useful as morphological analysis in preoperative treatment decision making.

Is nasal airflow disrupted after endoscopic skull base surgery? A short review

Even the most delicate endonasal surgery for skull base lesion causes changes in the nasal cavity, some of them permanent. Morphological changes in the nasal cavity and their consequences (changes in nasal airflow) are often studied by advanced numerical analysis called computational fluid dynamics. This review summarizes current knowledge of endoscopic transsphenoidal skull base surgery effects on nasal airflow. Several studies have shown that endoscopic skull base surgery changes nasal anatomy to the extent that nasal airflow changes significantly postoperatively. Removing any intranasal structure increases the cross-sectional area of the respective nasal meatus, leading to increased nasal airflow in this area while airflow in the narrower periphery decreases. Middle turbinate resection increases airflow in the middle meatus and reduces airflow in the superior and inferior meatus. Small posterior septectomy does not cause a significant change in nasal airflow. Nasal septum deviation is an important factor in airflow changes. Current studies describe nasal changes after rather extensive procedures (e.g., middle turbinectomy, ethmoidectomy) that are unnecessary in routine pituitary adenoma surgery. No studies have compared changes using pre- and postoperative scans of the same patients after actual surgery.

Numerical Analysis of Nasal Flow Characteristics with Microparticles

This study was to investigate the airflow characteristics in nasal cavity under different conditions and analyze the effects of different respiratory intensity, particle diameter, and particle density on the deposition of particles carried by airflow in the nasal cavity, respectively. The three-dimensional geometric model of the nasal cavity was established based on typical medical images. The SST k-ω turbulence model in the computational fluid dynamics (CFD) was used to simulate the airflow in the nasal cavity, and the deposition of particles in the airflow was analyzed with the Lagrange discrete phase model. The results showed that the air in the nasal cavity flows in the left and right nasal passages through the perforation in front of the nasal septum and forms a vortex structure at the perforation site, and the particle deposition efficiencies (DE) under perforation nasal cavity are higher than that under normal nasal cavity. Different parameters had different effects on the particle DE. The results showed that the DE of particles with smaller size (≤2.5 μm) is lower; the higher the respiration intensity, the greater the influence on the DE of the larger particle size; and the larger particle density (>1550 kg·m⁻³) has little effect on the DE of larger particle size (DP = 10 μm). The results agree well with the corresponding research data.

Improving Nasal Airflow with a Novel Nasal Breathing Stent

Nasal obstruction requires close attention, as it is a risk factor for obstructive sleep apnea (OSA). This study evaluated airflow rates of our newly designed nasal breathing stent (NBS) compared with those of existing nasal dilators in 10 adult men. We hypothesized that the NBS would expand the nasal passage more than the other nasal dilators by means of airflow measurements. We compared airflow measurements between the NBS and three existing appliances and no appliance. Velocity measurements were recorded by analyzing 499 videographic images when each appliance was placed next to a steam generator at 0, 5, and 10 mm from the outlet port for airflow visualization. The peak nasal inspiratory flow (PNIF) rate was measured using an inspiratory flow meter. The NBS resulted in significantly higher airflow velocity measurements at all distances from the outlet port and a higher PNIF rate than the other appliances. Thus, the NBS offers a significantly decreased resistance to air movement compared with other appliances. Future in-depth investigations are required to demonstrate the use of NBS as a nasal dilator in conjunction with continuous positive airway pressure/oral appliance treatments in patients with OSA.

In-silico investigation of airflow and micro-particle deposition in human nasal airway pre- and post-virtual transnasal sphenoidotomy surgery

Sphenoid sinus, located posterior to the nasal cavity, is difficult to reach for a surgery. Several operation procedures are available for sphenoidotomy, including endoscopic surgeries. Although the endoscopic sinus surgery is minimally invasive with low post-operative side effects, further optimization is required. Transnasal sphenoidotomy is a low invasive alternative to transethmoidal sphenoidotomy, but it still needs to be studied to understand its effects on the airflow pattern and the particle deposition. In this work, we simulated airflow and the micro-particle deposition in the nasal airway of a middle-aged man to investigate the change in particle deposition in the sphenoid sinus after virtual transnasal sphenoidotomy surgery. The results demonstrated that after transnasal sphenoidotomy, particle deposition in the targeted sphenoid sinus was an order of magnitude lower than that observed after virtual transethmoidal sphenoidotomy surgery. In addition, the diameter of the particles for the peak deposition fraction in the targeted sinus was shifted to smaller diameters after the transnasal sphenoidotomy surgery compared with that in the post-transethmoidal condition. These results suggest that the endoscopic transnasal sphenoidotomy can be a better procedure for sphenoid surgeries as it decreases the chance of bacterial contaminations and consequently lowers the surgical side effects and recovery time.

Nasal airflow of patient with septal deviation and allergy rhinitis

A numerical simulation of a patient’s nasal airflow was developed via computational fluid dynamics. Accordingly, computerized tomography scans of a patient with septal deviation and allergic rhinitis were obtained. The three-dimensional (3D) nasal model was designed using InVesalius 3.0, which was then imported to (computer aided 3D interactive application) CATIA V5 for modification, and finally to analysis system (ANSYS) flow oriented logistics upgrade for enterprise networks (FLUENT) to obtain the numerical solution. The velocity contours of the cross-sectional area were analyzed on four main surfaces: the vestibule, nasal valve, middle turbinate, and nasopharynx. The pressure and velocity characteristics were assessed at both laminar and turbulent mass flow rates for both the standardized and the patient’s model nasal cavity. The developed model of the patient is approximately half the size of the standardized model; hence, its velocity was approximately two times more than that of the standardized model.

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.

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.