Voxel-based simulation of flow and temperature in the human nasal cavity.

The nasal airway is an extremely complex structure, therefore grid generation for numerical prediction of airflow in the nasal cavity is time-consuming. This paper describes the development of a voxel-based model with a Cartesian structured grid, which is characterized by robust and automatic grid generation, and the simulation of the airflow and air-conditioning in an individual human nasal airway. Computed tomography images of a healthy adult nose were used to reconstruct a virtual three-dimensional model of the nasal airway. Simulations of quiet restful inspiratory flow were then performed using a Neumann boundary condition for the energy equation to adequately resolve the flow and heat transfer. General agreements of airflow patterns, which were a high-speed jet posterior to the nasal valve and recirculating flow that occupied the anterior part of the upper cavity, and temperature distributions of the airflow and septum wall were confirmed by comparing in-vivo measurements with numerical simulation results.

Is there a relationship between Eustachian tube dysfunction and nasal septal deviation in a sample of the Lebanese population?

BACKGROUND: The Eustachian tube (ET) is considered an organ by itself due to its specific functions. An ET Dysfunction (ETD) is discussed when this tube is unable to ventilate the middle ear properly. Clinically, the patient reports usually some aural fullness, "popping", "under water" sensation as if the ear is clogged. This condition is common affecting at least 5% of the adult population. It can impair quality of life and become disabling. On the other side, the prevalence of nasal septal deviation (NSD) is believed to be around 22.83% in the adult population. Nasal septal deviation is thought to cause a decline in the middle ear ventilation according to certain authors. The primary outcome is to define the predictive value of the side of Eustachian Tube Dysfunction (ETD) symptoms vis-à-vis the side of nasal septal deviation (NSD) in patients having the two conditions concomitantly. METHODS: A cross-sectional study was conducted between July 2018 and September 2019. Overall, 60 consecutive subjects (total of 120 ears), randomly seen at the Otorhinolaryngology Outpatient Clinics at the Eye and Ear International Hospital, Lebanon, all year-round were enrolled and tested without any geographic preferences. The Eustachian Tube Dysfunction Questionnaire (ETDQ) -7 questionnaire was used to evaluate ETD. RESULTS: A significantly higher ETD score was found in males compared to females, in those with left septal deviation compared to right and in those who have symptoms on the left compared to right side. Frequent exposure to higher changes in altitude (commute from home to workplace) was also significantly associated with higher ETD scores (r = 0.265), whereas higher Left Tympanometric peak pressure (TPP in daPa) on tympanometry was significantly associated with lower ETD score (r = - 0.467). Furthermore, 25 patients who had symptoms on the left side had also a septal deviation to the left side (86.2%), whereas 29 (93.5%) patients who had the symptoms on the right side had septal deviation to the right side (p < 0.001). CONCLUSION: Our data highlighted the importance of altitude and geographic distribution of patients especially in a population exposed to barotrauma on a daily basis like the Lebanese population. Tympanometry, on the other hand, failed to correlate with patient reported symptoms and thus needs further evaluation. The reported ETD symptoms of the patient correlates to the side of NSD.

Electrospun polycaprolactone membranes with Zn-doped bioglass for nasal tissues treatment.

In this work, composite membranes were investigated as future components of a layered implant for the reconstruction of nasal septum. Incorporation of zinc ions into nasal implants could potentially provide antibacterial properties to decrease or eliminate bacterial infections and subsequent surgical complications. Two types of membranes were prepared using an electrospinning method: PCL with bioglass and PCL with bioglass doped with Zn. The aim of this work was to investigate the influence of bioglass addition on the morphology, fiber diameter and composition of the membranes. The apatite-forming ability was examined in Simulated Body Fluid (SBF). The cytotoxicity of the membranes, ALP activity and in vitro mineralization were evaluated in cell culture. The mineralization and ALP activity was higher for polycaprolactone membranes modified with Zn doped bioglass than compared to pure PCL membranes or control material. The results proved that the presence of Zn2+ in the electrospun membranes = influence the osteogenic differentiation of cells.

Fibrin-Genipin Hydrogel for Cartilage Tissue Engineering in Nasal Reconstruction.

OBJECTIVES: Nasal reconstruction is limited by the availability of autologous cartilage. The aim is to investigate an adhesive biomaterial for tissue engineering of nasal cartilage by evaluating mechanical properties of hydrogels made of fibrin crosslinked with genipin as compared to native tissue. METHODS: Hydrogels of fibrin, fibrin-genipin, and fibrin-genipin with extracellular matrix (ECM) particles were created and evaluated with mechanical testing to determine compression, tensile, and shear properties. Rabbit nasal septal cartilage was harvested and tested in these modalities for comparison. Transmission electron microscopy characterized hydrogel structure. RESULTS: Fibrin-genipin gels had higher compressive, tensile, and shear moduli compared to fibrin alone or fibrin-genipin with ECM. However, all hydrogel formulations had lower moduli than the rabbit nasal septal cartilage. Electron microscopy showed genipin crosslinking increased structural density of the hydrogel and that cartilage ECM created larger structural features with lower crosslinking density. CONCLUSION: The addition of genipin significantly improved mechanical properties of fibrin hydrogels by increasing the compressive, tensile, and shear moduli. The addition of cartilage ECM, which can add native structure and composition, resulted in decreased moduli values. Fibrin-genipin is a bioactive and biomechanically stable hydrogel that may offer promise as a scaffold for cartilage tissue engineering in nasal reconstruction, yet further augmentation is required to match material properties of native nasal cartilage.

Techniques in Septoplasty: Traditional Versus Endoscopic Approaches.

This article provides a review of modern techniques in the surgical management of the deviated septum with emphasis on the comparison of traditional versus endoscopic septoplasty approaches. Relevant anatomy and physiology of the nasal septum are discussed. A brief history of the evolution of the surgical approaches for the correction of a deviated septum is provided. Traditional and endoscopic septoplasty techniques are reviewed; the indications, advantages, and limitations of each approach are highlighted. Potential complications of septoplasty, with a focus on prevention and management, are also discussed.

The Caucasian Nasal Septum: An In Vivo Computed Tomography Study.

BACKGROUND: The nasal septum is composed of cartilaginous and bony components and an understanding of each component volume is essential in both functional and cosmetic surgery. OBJECTIVES: We sought to radiographically measure septal dimensions on cross sectional computer tomography (CT) images, establishing average parameters for normal anatomy among a single, Caucasian population group. METHODS: One hundred and fifty consecutive sinus CT scan images were examined and 100 cases with appropriate sagittal views were included in the study. On each septum, the sagittal CT images were assessed and 14 points were identified and 23 lengths measured and tabulated. Trigonometric formulae were used to accurately calculate surface areas of 11 resulting triangles which constituted the components of the nasal septum. RESULTS: Measurements from 100 patients were included, with a mean age of 50.2 years, constituting 47 males and 53 females. Our surface area mapping established the following areas for both males and females respectively (mm2): quadrangular cartilage 1148 and 981; vomer 894 and 741; perpendicular plate of ethmoid bone 1244 and 1006; and total surface area 3287 and 2728. Our only statistically significant comparison in the series was found in the female series when age and reducing quadrilateral cartilage size were compared, highlighting reducing size with age (P = 0.04). CONCLUSIONS: The study presents the largest published data series representing nasal septal measurements on CT images in a living Caucasian population. Our data demonstrates that septal size remains constant after adolescence, throughout our age-varied series (18-79 years), except in the female population where the quadrilateral cartilage reduces in size with age.

Structure and function of the septum nasi and the underlying tension chord in crocodylians.

A long rostrum has distinct advantages for prey capture in an aquatic or semi-aquatic environment but at the same time poses severe problems concerning stability during biting. We here investigate the role of the septum nasi of brevirostrine crocodilians for load-absorption during mastication. Histologically, both the septum nasi and the septum interorbitale consist of hyaline cartilage and therefore mainly resist compression. However, we identified a strand of tissue extending longitudinally below the septum nasi that is characterized by a high content of collagenous and elastic fibers and could therefore resist tensile stresses. This strand of tissue is connected with the m. pterygoideus anterior. Two-dimensional finite element modeling shows that minimization of bending in the crocodilian skull can only be achieved if tensile stresses are counteracted by a strand of tissue. We propose that the newly identified strand of tissue acts as an active tension chord necessary for stabilizing the long rostrum of crocodilians during biting by transforming the high bending stress of the rostrum into moderate compressive stress.

Quantifying Changes in Nasal Tip Support.

IMPORTANCE: Imparting surgical change to the nasal tip remains one of the most challenging aspects of rhinoplasty. The surgeon must assess the tip preoperatively and execute the necessary maneuvers to impart the desired change. OBJECTIVE: To assess nasal tip resistance to compression in a cadaveric model before and after specific rhinoplasty maneuvers using a novel method. DESIGN, SETTING, AND MATERIALS: Open rhinoplasty maneuvers were performed at an academic tertiary care center on 6 fresh-thawed cadaver heads. Assessment of tip support was performed with a motorized, computer-controlled test stand equipped with a digital load cell. Tip support was assessed by compression to a depth of 2.5 mm from contact both preoperatively and after each surgical maneuver. All force data were recorded in pound-force and converted to newtons (N) following analysis. MAIN OUTCOMES AND MEASURES: Nasal tip support, measured as resistance to compression, before and after various rhinoplasty maneuvers. RESULTS: Following the elevation of the skin-soft-tissue envelope with septoplasty, resistance to compression (1.82 N) was not significantly different from the preoperative assessment (1.60 N for all specimens). Tip support following placement of a caudal extension graft was significantly different from all other conditions (3.16 N; P < .01), showing support increased by more than 66% from preoperative assessment. Placement of columellar strut (1.28 N) did not show significant increase in tip support. Tip support was decreased slightly after placement of intradomal sutures, which was significant (1.22 N; P < .01). CONCLUSIONS AND RELEVANCE: This study demonstrates the use of materials testing equipment to assess and quantify change in tip support after several rhinoplasty maneuvers. Minor supporting maneuvers that rely on healing and scar do not significantly alter tip support in a cadaveric model. Caudal extension graft is an important maneuver imparting significant effect on nasal tip support. LEVEL OF EVIDENCE: NA.

Cranial Morphology of the Brachystelechid 'Microsaur' Quasicaecilia texana Carroll Provides New Insights into the Diversity and Evolution of Braincase Morphology in Recumbirostran 'Microsaurs'.

Recumbirostran 'microsaurs,' a group of early tetrapods from the Late Carboniferous and Early Permian, are the earliest known example of adaptation to head-first burrowing in the tetrapod fossil record. However, understanding of the diversity of fossorial adaptation within the Recumbirostra has been hindered by poor anatomical knowledge of the more divergent forms within the group. Here we report the results of µCT study of Quasicaecilia texana, a poorly-known recumbirostran with a unique, broad, shovel-like snout. The organization of the skull roof and braincase of Quasicaecilia is found to be more in line with that of other recumbirostrans than previously described, despite differences in overall shape. The braincase is found to be broadly comparable to Carrolla craddocki, with a large presphenoid that encompasses much of the interorbital septum and the columella ethmoidalis, and a single compound ossification encompassing the sphenoid, otic, and occipital regions. The recumbirostran braincase conserves general structure and topology of braincase regions and cranial nerve foramina, but it is highly variable in the number of ossifications and their extent, likely associated with the reliance on braincase ossifications to resist compression during sediment compaction and mechanical manipulation by epaxial and hypaxial musculature. Expansion of the deep ventral neck musculature in Quasicaecilia, autapomorphic among recumbirostrans, may reflect unique biomechanical function, and underscores the importance of future attention to the role of the cervical musculature in contextualizing the origin and evolution of fossoriality in recumbirostrans.

[The influence of the nasal septum tubercle on certain aerodynamic characteristics].

The objective of the present work was to investigate the influence of the tubercle of the nasal septum thickening on the localization of the regions of precipitation of aerosol particles in the nasal cavity under the experimental conditions. The experiment was conducted using the newly developed 3D stereolithographic model of the nasal cavity. The study has demonstrated that the tubercle of the nasal septum thickening is an aerodynamically-conditioned normal anatomical structure, and its absence deteriorates the aerodynamic characteristics of the airflow through the nasal cavity.

What are some tips and pearls for preserving and improving nasal function when performing a cosmetic rhinoplasty?

PURPOSE OF REVIEW: Understanding nasal form and function is critical in performing successful cosmetic rhinoplasty. Careful evaluation of the patient's nasal airway with identification of areas of existing or potential obstruction is important in avoiding potential pitfalls that may compromise nasal function following rhinoplasty. This article will review surgical techniques that can be utilized to preserve and improve nasal function during cosmetic rhinoplasty. RECENT FINDINGS: Recent literature on nasal functionality focuses on the management of the internal and external nasal valve as well as the nasal septum during rhinoplasty. SUMMARY: Successful cosmetic rhinoplasty requires a thorough preoperative analysis of both aesthetic and functional characteristics of the nose. Close attention should be paid to the internal and external nasal valves and nasal septum before and during surgery to preserve and improve nasal function following cosmetic rhinoplasty.

Compressive and tensile mechanical properties of the porcine nasal septum.

The expanding nasal septal cartilage is believed to create a force that powers midfacial growth. In addition, the nasal septum is postulated to act as a mechanical strut that prevents the structural collapse of the face under masticatory loads. Both roles imply that the septum is subject to complex biomechanical loads during growth and mastication. The purpose of this study was to measure the mechanical properties of the nasal septum to determine (1) whether the cartilage is mechanically capable of playing an active role in midfacial growth and in maintaining facial structural integrity and (2) if regional variation in mechanical properties is present that could support any of the postulated loading regimens. Porcine septal samples were loaded along the horizontal or vertical axes in compression and tension, using different loading rates that approximate the in vivo situation. Samples were loaded in random order to predefined strain points (2-10%) and strain was held for 30 or 120 seconds while relaxation stress was measured. Subsequently, samples were loaded until failure. Stiffness, relaxation stress and ultimate stress and strain were recorded. Results showed that the septum was stiffer, stronger and displayed a greater drop in relaxation stress in compression compared to tension. Under compression, the septum displayed non-linear behavior with greater stiffness and stress relaxation under faster loading rates and higher strain levels. Under tension, stiffness was not affected by strain level. Although regional variation was present, it did not strongly support any of the suggested loading patterns. Overall, results suggest that the septum might be mechanically capable of playing an active role in midfacial growth as evidenced by increased compressive residual stress with decreased loading rates. However, the low stiffness of the septum compared to surrounding bone does not support a strut role. The relatively low stiffness combined with high stress relaxation under fast loading rates suggests that the nasal septum is a stress dampener, helping to absorb and dissipate loads generated during mastication.

Impact of airflow communication between nasal cavities on nasal ventilation.

OBJECTIVE: To investigate the impact of airflow communication between bilateral nostril sides on nasal ventilation. In addition, we try to validate the efficacy of the Draf III procedure from the aerodynamics perspective. METHODS: One health model and two disease models were constructed. These included 2 patients with nasal septum perforation and 1 patient who received the Draf III procedure. With the computational fluid dynamics method, indices such as airflow velocity and wall shear stress in the nasal cavity were detected and compared among the 3 subjects. RESULTS: The main pathway for airflow in the nasal cavity is the common meatus. Little airflow exchange occurred in the patient who underwent the Draf III procedure, and the wall shear stress around the communication site was as low as in the adjacent areas. However, when airflow communication occurred in the lower part of the nasal cavity, the airflow velocity and wall shear stress were obviously altered, and the ventilation function of the nasal cavity was impaired. CONCLUSION: Airflow communication in the upper part of the nasal cavity has little impact on nasal ventilation. Nonetheless, airflow communication occurring in the lower part of the nasal cavity disturbs the overall airflow distribution and a repair procedure is necessary.

Shape fidelity of native and engineered human nasal septal cartilage.

OBJECTIVE: To test engineered and native septal cartilage for resistance to deformation and remodeling under sustained bending loads and to determine the effect of bending loads on the biochemical properties of constructs. STUDY DESIGN: Prospective, basic science. SETTING: Laboratory. SUBJECTS AND METHODS: Human septal chondrocytes from 6 donors were used to create 12-mm constructs. These were cultured for 10 weeks and subjected to bending for 6 days. Free-swelling controls and native tissue from 6 donors were used for comparison. Shape retention, photo documentation, live-dead staining, and biochemical properties were measured. RESULTS: Live-dead staining showed no difference in cell survival between loaded constructs and free-swelling controls. The immediate shape retention of the constructs was 39.0% versus 24.4% for native tissue (P = .13). After 2 and 24 hours of relaxation, the constructs possessed similar shape retention to native tissue (26.9% and 16.4%; P = .126; 21.7% and 14.4%; P = .153). There was no significant change in construct shape retention from immediately after release to 2 hours of relaxation (39.0% and 26.9%, respectively; P = .238). In addition, the retention did not change significantly between 2 and 24 hours of relaxation (26.9% and 21.7%; P = .48). There was no significant difference in biochemical properties between loaded constructs and controls. CONCLUSION: The shape retention properties of human septal neocartilage constructs are comparable to human native septal cartilage. In addition, mechanical loading of neocartilage constructs does not adversely affect cell viability or biochemical properties. This study demonstrates that neocartilage constructs possess adequate shape fidelity for use as septal cartilage graft material.

A prospective, randomized, single-blinded controlled trial on biodegradable synthetic polyurethane foam as a packing material after septoplasty.

BACKGROUND: We evaluated synthetic polyurethane foam (SPF; Polyganics BV, Groningen, The Netherlands) as a packing material used after septoplasty compared with Merocel (Medtronic Xomed Surgical Products, Jacksonville, FL) in the aspects of clinical efficacy and the subjective severity of symptoms. METHODS: A prospective, randomized, single-blinded controlled study was performed in 64 patients who had undergone septoplasty. The patients were randomized to receive Merocel or SPF after septoplasty. Assessments of clinical efficacy on bleeding and pain were done and subjective symptoms related to packing materials were evaluated using questionnaires quantified by the visual analog scale. RESULTS: There was no difference in repacking or additional packing due to postoperative bleeding, bleeding and/or septal hematoma on the removal of packing, and the mucosal condition after packing removal during postoperative period between the Merocel and SPF groups. Bleeding and pain during packing removal was significantly lower in patients with SPF packing. Also, in the SPF group, patient's general satisfaction and willingness to reuse the material were higher compared with the Merocel group. CONCLUSION: SPF is as suitable as Merocel to be used after septoplasty with beneficial effects on bleeding and pain at packing removal.

Needle electrode-based electromechanical reshaping of rabbit septal cartilage: a systematic evaluation.

Electromechanical reshaping (EMR) provides a means of producing shape change in cartilage by initiating oxidation-reduction reactions in mechanically deformed specimens. This study evaluates the effect of voltage and application time on specimen shape change using needle electrodes. Rabbit septal cartilage specimens (20 x 8 x 1 mm, n = 200) were bent 90 degrees in a precision-machined plastic jig. Optimal electrode placement and the range of applied voltages were estimated using numerical modeling of the initial electric field within the cartilage sample. A geometric configuration of three platinum needle electrodes 2 mm apart from each other and inserted 6 mm from the bend axis on opposite ends was selected. One row of electrodes served as the anode and the other as the cathode. Constant voltage was applied at 1, 2, 4, 6, and 8 V for 1, 2, and 4 minutes, followed by rehydration in phosphate buffered saline. Samples were then removed from the jig and bend angle was measured. In accordance with previous studies, bend angle increased with increasing voltage and application time. Below a voltage threshold of 4 V, 4 minutes, no clinically significant reshaping was observed. The maximum bend angle obtained was 35.7 ± 1.7 º at 8 V, 4 minutes.

Physiologic and pathologic septal deviations: subjective and objective functional rhinologic findings.

OBJECTIVE: A high incidence of septal deviation with significant inter-rater variability has been reported. An explanation could be the presence of physiological septal deviation besides pathological ones. We differentiated an unselected cohort by their nasal resistance into groups with physiological normal and pathologically increased resistance to detect differences and analogies in comparison to healthy subjects and a pathological cohort. STUDY DESIGN: Prospective cohort study. SETTING: A total of 356 patients were assessed using rhinoresistometry, acoustic rhinometry, endoscopy and visual analogue scales. After definition of a benchmark between physiological and pathological nasal resistance, group differences were calculated and correlations analysed. RESULTS: The normal one-sided inspiratory nasal resistance was defined as less or equal to 0.35 sPa/cm^3 at a flow-velocity of 250 cm^3/s (R250). Using this benchmark, the unselected group of non-rhinological patients was differentiated into 114 subjects with physiological nasal resistance and 44 with pathological septal deviation. Nasal resistance after decongestion was significantly lower for normal or patients with a physiological septal deviation in comparison to the rhinological one on both nasal sides. Healthy subjects and patients with physiological septal deviation showed similarities in objective rhinological parameters as well as rhinological patients and patients with pathological septal deviation derived from the unselected group of non-rhinological patients. Furthermore, this benchmark of nasal resistance shows significant correlations with subjective assessment of nasal breathing. CONCLUSION: Inspiratory nasal resistance obtained at a flow-velocity of 250 cm^3/s using rhinoresistometry may be useful to distinguish patients with physiological and pathological septal deviation. Correlation with subjective assessment and endoscopic findings is improved.

Anatomy and physiology of the upper airway.

The nose is the major portal of air exchange between the internal and external environment. The nose participates in the vital functions of conditioning inspired air toward a temperature of 37°C and 100% relative humidity, providing local defense and filtering inhaled particulate matter and gases. It also functions in olfaction, which provides both a defense and pleasure for the individual. Understanding normal physiology provides the basis for recognizing abnormalities.