Structure-function relationships in the nasal cavity of Arctic and subtropical seals.

The heating and moistening of inhaled air, and the cooling and moisture removal from exhaled air, are crucial for the survival of animals under severe environmental conditions. Arctic mammals have evolved specific adaptive mechanisms to retain warmth and water and restrict heat loss during breathing. Here, the role of the porous turbinates of the nasal cavities of Arctic and subtropical seals is studied with this in mind. Mass and energy balance equations are used to compute the time-dependent temperature and water vapor profiles along the nasal passage. A quasi-1D model based on computed tomography images of seal nasal cavities is used in numerical simulations. Measured cross-sectional areas of the air channel and the perimeters of the computed tomography slices along the nasal cavities of the two seal species are used. The model includes coupled heat and vapor transfer at the air-mucus interface and heat transfer at the interfaces between the tissues and blood vessels. The model, which assumes constant blood flow to the nose, can be used to predict the temperature of the exhaled air as a function of ambient temperature. The energy dissipation (entropy production) in the nasal passages was used to measure the relative importance of structural parameters for heat and water recovery. We found that an increase in perimeter led to significant decreases in the total energy dissipation. This is explained by improved conditions for heat and water transfer with a larger complexity of turbinates. Owing to differences in their nasal cavity morphology, the Arctic seal is expected to be advantaged in these respects relative to the subtropical seal.

Nasal air conditioning following total inferior turbinectomy compared to inferior turbinoplasty - A computational fluid dynamics study.

BACKGROUND: The aim of this study was to use computational fluid dynamics (CFD) to investigate the effects on nasal heat exchange and humidification of two different surgical techniques for reducing the inferior turbinate under different environmental conditions. METHODS: Virtual surgery using two techniques of turbinate reduction was performed in eight nasal airway obstruction patients. Bilateral nasal airway models for each patient were compared: 1) Pre-operative 2) Post inferior turbinoplasty 3) Post total inferior turbinate resection (ITR). Two representative healthy models were included. Three different environmental conditions were investigated 1) ambient air 2) cold, dry air 3) hot, humid air. CFD modelling of airflow and conditioning was performed under steady-state, laminar, inspiratory conditions. FINDINGS: Nasal conditioning is significantly altered following inferior turbinate reduction surgery, particularly with ITR under cold, dry inspired air (CDA). The degree of impairment is minor under the simulated range of environmental conditions (temperature = 12-40 °C; relative humidity = 13-80%). Streams of significantly colder air are found in the nasopharynx and more prevalent under CDA in ITR. These are related to high velocity flow streams, which remain cool in their centre throughout the widened inferior nasal cavity. INTERPRETATION: Reduced air-mucosal heat exchange and moisture carrying capacity occurs under cooler temperatures in patients following inferior turbinate surgery. The clinical impact in extremely cold and dry conditions in groups with poor baseline respiratory function, respiratory illness, or endurance athletes is of special interest.

Convergent evolution of olfactory and thermoregulatory capacities in small amphibious mammals.

Olfaction and thermoregulation are key functions for mammals. The former is critical to feeding, mating, and predator avoidance behaviors, while the latter is essential for homeothermy. Aquatic and amphibious mammals face olfactory and thermoregulatory challenges not generally encountered by terrestrial species. In mammals, the nasal cavity houses a bony system supporting soft tissues and sensory organs implicated in either olfactory or thermoregulatory functions. It is hypothesized that to cope with aquatic environments, amphibious mammals have expanded their thermoregulatory capacity at the expense of their olfactory system. We investigated the evolutionary history of this potential trade-off using a comparative dataset of three-dimensional (3D) CT scans of 189 skulls, capturing 17 independent transitions from a strictly terrestrial to an amphibious lifestyle across small mammals (Afrosoricida, Eulipotyphla, and Rodentia). We identified rapid and repeated loss of olfactory capacities synchronously associated with gains in thermoregulatory capacity in amphibious taxa sampled from across mammalian phylogenetic diversity. Evolutionary models further reveal that these convergences result from faster rates of turbinal bone evolution and release of selective constraints on the thermoregulatory-olfaction trade-off in amphibious species. Lastly, we demonstrated that traits related to vital functions evolved faster to the optimum compared to traits that are not related to vital functions.

Safety and efficacy of superior turbinate biopsies as a source of olfactory epithelium appropriate for morphological analysis.

PURPOSE: There is no standardized approach for preserving olfactory function in the side of the nose where biopsy of the olfactory epithelium (OE) is performed. Moreover, a gold standard technique for obtaining human OE in vivo is still lacking. We determined the efficacy of obtaining good-quality OE specimens suitable for pathological analysis from the lower half of the superior turbinate and verified the safety of this procedure in maintaining bilateral and unilateral olfactory function. METHODS: In 21 individuals without olfactory complaints and who had undergone septoplasty and inferior turbinectomy OE biopsy was made during septoplasty. Olfactory function, both unilateral and bilateral, was assessed using the University of Pennsylvania Smell Identification Test (UPSIT) before and 1 month after the procedure. Specimens were marked with the olfactory marker protein for confirmation of OE presence. RESULTS: Ninety percent of the samples contained OE, although clear histological characterization was possible from only 62%. There was no deterioration of UPSIT scores either bilaterally or unilaterally on the side of the biopsy. Patients also maintained the ability to identify individual odorants. CONCLUSION: Biopsies of the lower half of the superior turbinate do not affect olfactory function and show strong efficacy in yielding OE tissue and moderate efficacy for yielding tissue appropriate for morphological analysis. Future studies are needed to assess the safety of this procedure in other OE regions.

The complexities of nasal airflow: theory and practice.

The objective of this study was to investigate the effects of nasal valve area, valve stiffness, and turbinate region cross-sectional area on airflow rate, nasal resistance, flow limitation, and inspiratory "hysteresis" by the use of a mathematical model of nasal airflow. The model of O'Neill and Tolley (Clin Otolaryngol Allied Sci 13: 273-277, 1988) describing the effects of valve area and stiffness on the nasal pressure-flow relationship was improved by the incorporation of additional terms involving 1) airflow through the turbinate region, 2) the dependence of the flow coefficients for the valve and turbinate region on the Reynolds number, and 3) effects of unsteady flow. The model was found to provide a good fit for normal values for nasal resistance and for pressure-flow curves reported in the literature for both congested and decongested states. Also, by showing the relative contribution of the nasal valve and turbinate region to nasal resistance, the model sheds light in explaining the generally poor correlation between nasal resistance measurements and the results from acoustic rhinometry. Furthermore, by proposing different flow conditions for the acceleration and deceleration phases of inspiration, the model produces an inspiratory loop (commonly referred to as hysteresis) consistent with those reported in the literature. With simulation of nasal flaring, the magnitude of the loop, the nasal resistance, and flow limitation all show change similar to that observed in the experimental results.NEW & NOTEWORTHY The present model provides considerable insight into some difficult conundrums in both clinical and technical aspects of nasal airflow. Also, the description of nasal airflow mechanics based on the Hagen-Poiseuille equation and Reynolds laminar-turbulent transition in long straight tubes, which has figured prominently in medical textbooks and journal articles for many years, is shown to be seriously in error at a fundamental level.

Efficacy and Safety of Transnasal CoolStat Cooling Device to Induce and Maintain Hypothermia.

Targeted temperature management (TTM) is recommended as a standard of care for postcardiac arrest patients. Current TTM methods have significant limitations to be used in an ambulatory setting. We investigated the efficacy and safety of a novel noninvasive transnasal evaporative cooling device (CoolStat™). Eleven Yorkshire pigs underwent hypothermia therapy using the CoolStat device. CoolStat induces evaporative cooling by blowing dehumidified ambient air over the nasal turbinates in a unidirectional fashion. CoolStat's efficacy and safety were assessed by applying different cooling strategies (groups A, B and C). In group A (efficacy study; n = 5, TTM for 8 hours), time to achieve brain target temperature (2°C reduction from baseline), and the percentage of time in which the temperature ranged within ±0.5°C after reaching the target temperature were investigated. In the safety assessment (groups B and C), two worst-case therapy situations were reproduced: in group B (n = 3), continuous maximum air flow (65 L/min) was applied without temperature control and, in group C (n = 3), subjects underwent 24-hour TTM (prolonged therapy). Hemodynamic and respiratory parameters, nasal mucosa integrity (endoscopic assessment), and other therapy-related adverse effects were evaluated. Efficacy study: CoolStat cooling therapy successfully induced and sustained managed hypothermia in all subjects. Brain target temperature was achieved in 0.5 ± 0.6 hours and kept within a ±0.5°C range for the therapy duration (99.9% ± 0.1%). All animals completed the safety studies. Maximum air flow (group B) and 24-hour (group C) therapies were well tolerated and no significant damage was observed on nasal mucosa for neither of the groups. CoolStat was able to efficiently induce and maintain hypothermia using unidirectional high flow of dry air into the nostrils of porcine models. CoolStat therapy was well tolerated and no damage to nasal mucosa was observed under either maximum air flow or prolonged therapy.

The inferior turbinate: An autonomic organ.

The inferior turbinate has well-recognized respiratory and immune functions to provide the airway with appropriate warmth, humidification, and filtration of the inspired air while sampling the environment for pathogens. Normal functioning of the inferior turbinate relies on an intact autonomic system to maintain homeostasis within the nasal cavity. The autonomic nervous system innervates the submucosal glands and the vasculature within the inferior turbinate, resulting in control of major turbinate functions: nasal secretions, nasal patency, warmth, and humidification. This review will summarize the autonomic innervations of the turbinates, both the normal and abnormal autonomic processes that contribute to the turbinate functions, and the clinical considerations regarding optimal functioning of the turbinate autonomic system.

DNA Methylation of Proximal PLAT Promoter in Chronic Rhinosinusitis With Nasal Polyps.

Background Nasal polyps (NP) are characterized by pseudocysts derived from stromal tissue edema and cause persistent infections in patients with chronic rhinosinusitis (CRS). A low level of tissue-type plasminogen activator (gene name PLAT) is considered a cause of stromal tissue edema because of insufficient plasmin activation in NP; however, the mechanism regulating PLAT gene expression levels is still unclear. The epigenetic mechanism regulating the PLAT gene expression has been studied in other tissues. Objective We aimed to investigate the methylation levels in the proximal PLAT promoter and their effects on gene expression in NP tissue. Methods We investigated the methylation levels at 3 CpG sites in the proximal PLAT promoter regions (-618, -121, and -105 with respect to the transcription initiation site) by bisulfite pyrosequencing and their effects on the gene expression by quantitative real-time polymerase chain reaction (qPCR) in 20 paired samples of NP and inferior turbinate tissue (IT) from patients with CRS. Results The DNA methylation levels at all CpG sites were higher ( P < .01), and the PLAT expression was lower ( P < .001) in NP compared with IT. The methylation changes at the -618 site showed a negative correlation with the gene expression changes between NP and IT ( r = -.65, P < .01). Conclusions Hypermethylation of PLAT promoter may downregulate the gene expression in NP, leading to excessive fibrin deposition by aberrant coagulation cascade. DNA methylation of proximal PLAT promoter may contribute to NP growth and have a potential as a new therapeutic target.

Flow and air conditioning simulations of computer turbinectomized nose models.

Air conditioning for the human respiratory system is the most important function of the nose. When obstruction occurs in the nasal airway, turbinectomy is used to correct such pathology. However, mucosal atrophy may occur sometime after this surgery when it is overdone. There is not enough information about long-term recovery of nasal air conditioning performance after partial or total surgery. The purpose of this research was to assess if, based on the flow and temperature/humidity characteristics of the air intake to the choana, partial resection of turbinates is better than total resection. A normal nasal cavity geometry was digitized from tomographic scans and a model was printed in 3D. Dynamic (sinusoidal) laboratory tests and computer simulations of airflow were conducted with full agreement between numerical and experimental results. Computational adaptations were subsequently performed to represent six turbinectomy variations and a swollen nasal cavity case. Streamlines along the nasal cavity and temperature and humidity distributions at the choana indicated that the middle turbinate partial resection is the best alternative. These findings may facilitate the diagnosis of nasal obstruction and can be useful both to plan a turbinectomy and to reduce postoperative discomfort. Graphical Abstract ᅟ.

The Inferior Turbinate in Rhinoplasty.

There is controversy regarding optimum treatment of the hypertrophied inferior turbinate. Patients undergoing rhinoplasty will likely need treatment of bony hypertrophy as well as possibly soft tissue hypertrophy. Although inferior turbinate hypertrophy is a heterogeneous entity, future studies should standardize outcome measures and compare treatment methods with rigorous clinical trials.

Functional Rhinoplasty.

Understanding nasal anatomy and physiology are the most important points for successful functional rhinoplasty. Anatomic structures playing major roles in nasal breathing functions include the septum, and internal and external nasal valves, so physical examination of these regions is essential. Planning for functional rhinoplasty involves the identification of the sites of nasal airway obstruction or old trauma, and addressing those regions during the operation with a number of different techniques that have been described.

Nasal conchae function as aerodynamic baffles: Experimental computational fluid dynamic analysis in a turkey nose (Aves: Galliformes).

We tested the aerodynamic function of nasal conchae in birds using CT data from an adult male wild turkey (Meleagris gallopavo) to construct 3D models of its nasal passage. A series of digital "turbinectomies" were performed on these models and computational fluid dynamic analyses were performed to simulate resting inspiration. Models with turbinates removed were compared to the original, unmodified control airway. Results revealed that the four conchae found in turkeys, along with the crista nasalis, alter the flow of inspired air in ways that can be considered baffle-like. However, these baffle-like functions were remarkably limited in their areal extent, indicating that avian conchae are more functionally independent than originally hypothesized. Our analysis revealed that the conchae of birds are efficient baffles that-along with potential heat and moisture transfer-serve to efficiently move air to specific regions of the nasal passage. This alternate function of conchae has implications for their evolution in birds and other amniotes.

Model demonstrates functional purpose of the nasal cycle.

BACKGROUND: Despite the occurrence of the nasal cycle being well documented, the functional purpose of this phenomenon is not well understood. This investigation seeks to better understand the physiological objective of the nasal cycle in terms of airway health through the use of a computational nasal air-conditioning model. METHOD: A new state-variable heat and water mass transfer model is developed to predict airway surface liquid (ASL) hydration status within each nasal airway. Nasal geometry, based on in-vivo magnetic resonance imaging (MRI) data is used to apportion inter-nasal air flow. RESULTS: The results demonstrate that the airway conducting the majority of the airflow also experiences a degree of ASL dehydration, as a consequence of undertaking the bulk of the heat and water mass transfer duties. In contrast, the reduced air conditioning demand within the other airway allows its ASL layer to remain sufficiently hydrated so as to support continuous mucociliary clearance. CONCLUSIONS: It is quantitatively demonstrated in this work how the nasal cycle enables the upper airway to accommodate the contrasting roles of air conditioning and the removal of entrapped contaminants through fluctuation in airflow partitioning between each airway.

Nasal air-conditioning after partial turbinectomy: myths versus facts.

BACKGROUND: Turbinectomy, although a common procedure, is often accused of having a negative impact in all nasal functions. This study is the first in vivo study that evaluates objectively the effect of partial turbinectomy on nasal air-conditioning capacity. METHODS: In total, 57 patients with prior partial inferior turbinectomy and 28 healthy controls were examined. Intranasal temperature and humidity values were measured at the level of the head of inferior and middle turbinate. Nasal patency was evaluated by means of acoustic rhinometry. The clinical assessment was completed with nasal endoscopy and the Nasal Obstruction Symptom Evaluation questionnaire for subjective evaluation of nasal patency. RESULTS: Significant changes of temperature were found in both detection sites with 13% reduced heating capacity of the air at the level of the inferior and 19% at the level of the middle turbinate, respectively. No similar results were found for humidity measurements. No correlations were found between air-conditioning values and acoustic rhinometry results for both study groups. Nasal endoscopy revealed normal healing in all patients. No major complications were reported by the patients. Their subjective ratings of nasal obstruction were similar to healthy controls. CONCLUSION: Partial turbinectomy seems to have a negative impact on intranasal air heating but not to humidification. This effect has no impact on clinical condition and subjective perception of surgical outcome.

Endoscopic modified medial maxillectomy for odontogenic cysts and tumours.

BACKGROUND: Odontogenic maxillary cysts and tumours originate from the tooth root and have traditionally been treated through an intraoral approach. Here, we report the efficacy and utility of endoscopic modified medial maxillectomy (EMMM) for the treatment of odontogenic maxillary cysts and a tumour. METHODOLOGY: We undertook EMMM under general anaesthesia in six patients: four had radicular cysts, one had a dentigerous cyst, and one had a keratocystic odontogenic tumour. RESULTS: The cysts and tumours were completely excised and the inferior turbinate and nasolacrimal duct were preserved in all patients. There were no peri- or postoperative complications, and no incidences of recurrence. CONCLUSION: Endoscopic modified medial maxillectomy appears to be an effective and safe technique for treating odontogenic cysts and tumours.

[Sneezing as a mechanical defence - a numerical simulation and analysis of the nasal flow]. / Niesen als mechanische Abwehr - Numerische Simulation mit Analyse der durchströmten Nasenbereiche.

INTRODUCTION: The nose is responsible for humidification, heating and cleaning of the inhaled air. The sneeze reflex leads to a shock-like cleaning of the nose in strong particle exposure. The aim of this study was the simulation of intranasal air flow of sneezing in a realistic computer model. MATERIALS AND METHODS: Based on the CT scan of a 40 year old man a three-dimensional computer model of the nasal cavity and the ethmoid sinuses was created. Flow simulations were performed for different inspiratory and expiratory velocities (± 2 m/s to ± 45 m/s) in order to simulate sneezing. RESULTS were visualized and analyzed by video simulation. RESULTS: During inspiration the main airflow takes place along the middle turbinate. During expiration, the flow is located more cranially. This effect is caused by the shape of the nasopharynx and the posterior portions of the nasal turbinates. During very high speeds (sneezing) also adjacent ethmoid sinuses and the olfactory region are covered by the shock-like expiratory flow. A large vortex formation in the nasopharynx is responsible for a uniform distribution of the airflow also on lower nasal areas. CONCLUSION: Sneezing is a protective reflex that provides for cleaning of the nose. From a flow rate of 10 m/s, the cranial nasal areas as well as adjacent ethmoid sinuses are covered by the -airflow. Compared to the inspiratory airflow the exhalation is not just vice versa. Particles that deposed in the cranial nasal areas during quiet breathing are removed.

Surgery for allergic rhinitis.

BACKGROUND: Allergic rhinitis (AR) is a highly prevalent disorder that significantly impacts quality of life and affects millions of people annually. The most bothersome complaint is nasal obstruction, which is most commonly due to inferior turbinate hypertrophy. METHODS: This work presents a review of the literature and an overview of operative techniques. RESULTS: A variety of methods are available for addressing inferior turbinate hypertrophy in patients afflicted with AR. Although no single modality has been defined as the gold standard for treatment, the otolaryngologist should be familiar with an armamentarium of surgical techniques. CONCLUSION: The inferior turbinate is the initial deposit point for allergens and undergoes dynamic changes through the allergic cascade, which results in nasal obstruction. Targeting the inferior turbinate to augment the nasal airway is the mainstay of surgical treatment in AR. Judicious technique and a mucosal sparing philosophy are necessary to maximize outcomes and improve quality of life.

[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.