Reliability of parental reporting of child snoring in children referred for obstructive sleep apnea.

Despite the high number of studies based on subjective reports of snoring, self-reported snoring has hardly been validated at all. As there is no "gold-standard" for objective snoring measurements, studies must evaluate whether the presence of snoring based on parental judgement is linked to objective measurements of nasal and/or pharyngeal obstruction in children referred for obstructive sleep apnea. A total of 146 children (median age 11 years) underwent polysomnography (with snoring recording using nasal cannula signal), acoustic rhinometry and pharyngometry, while their parents filled out the Spruyt-Gozal questionnaire assessing both frequency and loudness of subjective snoring. Three categories were further differentiated (null, low and high) for both frequency and loudness. The apnea-hypopnea index was significantly different in the three groups for both frequency (p = 0.04) and loudness (p = 0.01) of subjective snoring. Children in the low or high groups (frequency or loudness), compared with those in the null group, experienced a decline in both pharyngeal (sitting and supine positions) and nasopharyngeal (supine position) volumes (frequency, pharynx sitting: p = 0.03; supine: 0.005 and nasopharynx: p = 0.002; loudness, p = 0.03; p = 0.007 and p = 0.03; three group comparisons). Objective snoring frequency during the night obtained with cannula was weakly related to loudness of subjective snoring but not to subjective snoring frequency during the week, and was biased by nasal obstruction. In conclusion, our study showed that parental assessment of snoring is related to a reduction in both pharyngeal and nasopharyngeal volumes in snorers, arguing for the adequacy of their evaluation of both snoring frequency and loudness.

Influence of postural changes on nasal resistance in patients with obstructive sleep apnea.

OBJECTIVE: Increased nasal resistance (NR) can augment upper airway collapse in patients with obstructive sleep apnea (OSA). Posture change can lead to altered nasal resistance. Our study aimed to investigate the influence of posture changes on NR in patients with OSA. METHODS: Healthy controls without subjective nasal obstruction (apnea-hypopnea index (AHI) < 5 events/h), patients with OSA and subjective nasal obstruction, and patients with OSA and no subjective nasal obstruction were recruited. NR was measured by active anterior rhinomanometry in sitting, supine, left-lateral, and right-lateral postural positions. Total NR and postural change-related NR increments were calculated and compared among groups. RESULTS: In total, 26 healthy controls and 72 patients with OSA (mean AHI 39.7 ± 24.8 events/h) were recruited. Of patients with OSA, 38/72 (53%) had subjective nasal obstruction. Compared with controls, patients with OSA and no subjective nasal obstruction had lower total NR (inspiration, p = 0.037; expiration, p = 0.020) in the supine postural position. There was no difference in sitting, left-lateral, and right-lateral total NR among groups. Total NR was higher in lateral compared to sitting posture in both patients with OSA and in controls. The NR increment for sitting to supine postural change was significantly lower in patients with OSA (inspiration, p = 0.003; expiration, p = 0.005) compared with controls. The change in NR showed no statistically significant difference among groups in supine-left or supine-right postural change. CONCLUSION: Patients with OSA had lower supine total NR and lower total NR increment in the sitting to supine postural change, which may be related to a different posture-related NR regulatory mechanism. This study provides a new exploratory direction for the compensatory mechanism of the upper airway to collapse during sleep.

Nasal patency and mandibular movement: clinical application in prosthodontics.

This case report describes a patient with a primary concern of persistent mandibular deviation during speech who experienced clinically significant improvement (mandibular movement without deviation) after improvements to nasal resistance. At the initial consultation, temporary placement of a nasal valve dilator immediately eliminated the patient's mandibular deviation during speech, indicating the need for referral to an otolaryngologist. The patient was also provided with a dental appliance to address secondary concerns of temporomandibular joint noises and cervicofacial pain. Although the dental treatment provided some relief, resolution of the patient's mandibular deviation during speech did not occur until after nasal surgery was completed. This case illustrates the importance and effects of nasal resistance and nasal patency to obtaining a reproducible mandibular position.

Understanding potential associations between anatomic and other factors in OSA severity.

PURPOSE: The aim of this prospective study was to investigate associations between nasal/oropharyngeal structures and a range of factors including age, gender, daytime sleepiness, and body mass index (BMI). METHODS: Patients with OSA were prospectively selected as research participants in rhinomanometric analysis as well as for otolaryngological evaluation. Participants were grouped as follows according to their apnea/hypopnea index (AHI) scores: no OSA (AHI < 5), mild OSA (5 ≤ AHI ≤ 15), moderate OSA (15 ≤ AHI < 30), and severe OSA (AHI ≥ 30). One-way analysis of variance (ANOVA), Kruskal-Wallis H, and Mann-Whitney U tests were performed to assess OSA severity in terms of the relationships between nasal resistance (NR) and anthropometric indices (body mass index (BMI), Friedman tongue position (FTP)), age, and gender. RESULTS: The study cohort of 177 men and 81 women ranged in age between 21 and 76 years, with BMI ranging from 23 to 45. In total, 37 patients were simple snorers (AHI < 5), and 221 patients were diagnosed with OSA. There was no significant difference among the AHI groups in terms of nasal volume (Vol05) (p = 0.952), mean flow (p = 0.778), and mean NR total (p = 0.723). A statistically significant difference was found between the AHI groups in terms of mean BMI and median FTP scores (p < 0.001). CONCLUSION: This study provides evidence that that the oropharyngeal region (oropharynx, tongue, and vallecula) is a more important determinant of OSA severity than the nasal region.

Nasal dilator and physiological parameters associated to running performance: A systematic review and meta-analysis.

Nasal dilators were created to expand the nasal valve area. The aim of this systematic review was to verify physiological parameters associated to running performance with the use of nasal dilators. This study was registered in PROSPERO (CRD42021225795). According to the PICOS framework studies were included: Population: healthy subjects; Intervention: nasal dilators; Comparison: control group, placebo, minimal intervention, health education or other intervention; Outcomes: cardiorespiratory parameters and subjective perceptions; Study: randomized controlled trials, repeated measures or within-subjects design. The databases searched were MEDLINE, EMBASE, CENTRAL The Cochrane Library, CINAHL, SPORTDiscus, Web of Science, PEDro and Scopus. The descriptors "Running", "Nasal Dilator", "Randomized Controlled Trial", and synonyms were used. The risk of bias was assessed using the PEDro scale. Random effects Der Simonian and Laird model were used. The assessment of the certainty of the evidence was carried out using the GRADE approach. Eleven articles were included. There was a difference in favour of the nasal dilator when compared to placebo for maximal oxygen uptake and rating of perceived exertion. The certainty of the evidence was very low. Future studies will probably have an impact on estimation of the effect.

Short report: nasal obstruction recovery after septoplasty in patients with nasal septal deviation affected by anxiety and depression.

This research was aimed to explore whether the recovery of subjective symptoms and objective examination in nasal septum deviation (NSD) patients after septoplasty were related to the degree of preoperative anxiety or depression, in the hope of providing new ideas for clinical treatment. A total of 150 NSD patients were included in this prospective research. Visual analogue scale (VAS) scores, Nasal Obstruction Symptom Evaluation (NOSE) scores, self-rating anxiety scale (SAS) scores, self-rating depression scale (SDS) scores, total inspiratory and expiratory nasal resistance were recorded before and 6 months after operation. The results showed preoperative anxiety or depression was not statistically different between groups in terms of age, gender and course, but positively correlated with nasal obstruction (VAS and NOSE). The recovery of nasal obstruction in patients with anxiety or depression was worse than that in normal NSD patients 6 months after surgery, and was decreased with the increase of anxiety or depression degree. And no significant difference showed in the reduction of total inspiratory and expiratory nasal resistance between groups. In conclusion, anxiety and depression affected the improvement of nasal obstruction feeling in NSD patients after septoplasty, and the improvement was negatively correlated with the degree of anxiety and depression. It is necessary to evaluate the anxiety and depression of NSD patients before septoplasty.

Three-dimensional modeling and automatic analysis of the human nasal cavity and paranasal sinuses using the computational fluid dynamics method.

PURPOSE: The goal of this study was to develop a complete workflow allowing for conducting computational fluid dynamics (CFD) simulation of airflow through the upper airways based on computed tomography (CT) and cone-beam computed tomography (CBCT) studies of individual adult patients. METHODS: This study is based on CT images of 16 patients. Image processing and model generation of the human nasal cavity and paranasal sinuses were performed using open-source and freeware software. 3-D Slicer was used primarily for segmentation and new surface model generation. Further processing was done using Autodesk® Meshmixer TM. The governing equations are discretized by means of the finite volume method. Subsequently, the corresponding algebraic equation systems were solved by OpenFOAM software. RESULTS: We described the protocol for the preparation of a 3-D model of the nasal cavity and paranasal sinuses and highlighted several problems that the future researcher may encounter. The CFD results were presented based on examples of 3-D models of the patient 1 (norm) and patient 2 (pathological changes). CONCLUSION: The short training time for new user without a prior experience in image segmentation and 3-D mesh editing is an important advantage of this type of research. Both CBCT and CT are useful for model building. However, CBCT may have limitations. The Q criterion in CFD illustrates the considerable complication of the nasal flow and allows for direct evaluation and quantitative comparison of various flows and can be used for the assessment of nasal airflow.

Does the external nasal dilator strip help in sports activity? A systematic review and meta-analysis.

BACKGROUND: Numerous studies have shown that the external nasal dilator (END) increases the cross sectional area of the nasal valve, thereby reducing nasal resistance, transnasal inspiratory pressure, stabilizing the lateral nasal vestibule, and preventing its collapse during final inhalation. OBJECTIVES: Our objective was to carry out a systematic review of the literature and meta-analysis on the effects of the END during physical exercise. METHODS: After selecting articles in the PubMed, Cochrane Library and EMBASE databases, 624 studies were identified. However, after applying the inclusion and exclusion criteria, 19 articles were considered eligible for review. RESULTS: Those studies included in the meta-analysis, the maximal oxygen uptake (VO2max.) outcome was assessed in 168 participants in which no statistically significant difference was found, MD (95% CI) = 0.86 [- 0.43, 2.15], p = 0.19, and I2 = 0%. The heart rate (HR) outcome was assessed in 138 participants in which no statistically significant difference was found, MD (95% CI) = 0.02 [- 3.19, 3.22], p = 0.99, and I2 = 0%. The rating of perceived exertion (RPE) outcome was assessed in 92 participants in which no statistically significant difference was found, MD (95% CI) = - 0.12 [- 0.52, 0.28], p = 0.56, and I2 = 27%. CONCLUSIONS: The external nasal dilator strip showed no improvement in VO2max., HR and RPE outcomes in healthy individuals during exercise.

Role of rhinomanometry in the prediction of therapeutic positive airway pressure for obstructive sleep apnea.

BACKGROUND: This study was conducted to evaluate the relationship between nasal resistance in different posture and optimal positive airway pressure (PAP) level. Other potential factors were also assessed for possible influence on PAP pressure. METHODS: Forty- three patients diagnosed with obstructive sleep apnea (OSA) were prospectively recruited in this study. Nasal resistance was assessed by active anterior rhinomanometry in a seated position and then in a supine position at pressures of 75, 150, and 300 pascal. The factors correlating with PAP pressure were analyzed, including nasal resistance and patients' clinical data. RESULTS: Univariate analysis revealed that PAP pressure was correlated to nasal resistance in the supine position at 75 and 150 pascal (SupineNR75 and SupineNR150) (P = 0.019 and P = 0.004 in Spearman's correlation coefficient analysis), but not correlated to nasal resistance in the seated position at different pressures or in the supine position at 300 pascal. The multiple linear regression analysis revealed that both SupineNR150 and body mass index (BMI) significantly predicted PAP pressure (ß = 0.308, p = 0.044; ß = 0.727, p = 0.006). The final PAP pressure predictive model was: PAP pressure = 0.29 BMI + 2.65 SupineNR150 + 2.11. CONCLUSIONS: Nasal resistance in the supine position measured at 150 pascal may provide valuable information regarding optimal PAP pressure. Rhinomanometry should be included in the treatment algorithm of OSA patients when PAP therapy is considered.

Side asymmetry in nasal resistance correlate with nasal obstruction severity in patients with septal deformities: Computational fluid dynamics study.

OBJECTIVES: The objective of this study was to investigate the relationship between side asymmetry in nasal resistance (NR) and severity of the nasal airway obstruction (NAO) in patients with different types of nasal septal deformity (NSD). DESIGN: Computational fluid dynamics (CFD) study. SETTING: The study was conducted in a tertiary medical centre. PARTICIPANTS: The study included 232 patients, who were referred to the CT examination of the paranasal sinuses. Exclusion criteria were sinonasal and respiratory diseases that may interfere with the nasal obstruction. The presence and the type of NSD were recorded according to the Mladina's classification. MAIN OUTCOME MEASURES: The presence and severity of NAO in each patient were assessed by NOSE questionnaire. Eight computational models of the nasal cavity were created from CT scans. Models represented seven Mladina's NSD types and a straight septum of a symptomless patient. CFD calculated airflow partitioning and NR for each nasal passage. Side differences in NR were calculated by the equation ∆NR = NRleft  - NRright . The relationship between NOSE scores, airflow partitioning and side differences in NR was explored using Spearman's correlation analysis. RESULTS: Mladina's types of NSD showed differences in airflow partitioning and the degree of side asymmetry in NR. A significant positive correlation was detected between side differences in NR and NOSE scores (R = .762, P = .028). A significant negative correlation was found between the per cent of unilateral airflow and NR (R = -.524, P = .037). CONCLUSIONS: Our results demonstrated that side asymmetry in NR could explain differences in NAO severity related to the NSD type.

[Numerical flow simulation : A new method for assessing nasal breathing]. / Numerische Strömungssimulation : Eine neue Methode zur Beurteilung der Nasenatmung.

The current options for objective assessment of nasal breathing are limited. The maximum they can determine is the total nasal resistance. Possibilities to analyze the endonasal airstream are lacking. In contrast, numerical flow simulation is able to provide detailed information of the flow field within the nasal cavity. Thus, it has the potential to analyze the nasal airstream of an individual patient in a comprehensive manner and only a computed tomography (CT) scan of the paranasal sinuses is required. The clinical application is still limited due to the necessary technical and personnel resources. In particular, a statistically based referential characterization of normal nasal breathing does not yet exist in order to be able to compare and classify the simulation results.

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.

Nasal airway resistance in patients with different degrees of operated unilateral cleft lip: Evaluation of ventilation in 112 patients.

OBJECTIVE: The aim of this study was to compare the nasal airway resistance between the cleft and non-cleft sides in operated unilateral cleft lip (UCL) patients with varying severities at birth, as well as to assess the differences in nasal airway resistance between UCL patients and healthy individuals. METHODS: This retrospective study was conducted on 112 UCL patients who have undergone primary lip reconstructions but not advanced surgeries as the study group and 20 healthy participants as the control group between February 2023 to March 2024. The study group patients were grouped based on the severity of their cleft lip at birth, divided into occult cleft lip group, incomplete cleft lip group, and complete cleft lip group. The anterior rhinomanometry was used to evaluate nasal resistance, including unilateral effective resistances during inspiration (Reffin), expiration (Reffex), and the entire breath (ReffT), as well as unilateral vertex resistance during inspiration (VRin) and expiration (VRex). The Kolmogorov-Smirnov test was used to assess normality. Paired t-tests were utilized to analyze the differences in nasal resistance between the healthy and affected sides within the same group of patients. Student's t-test was used to analyze the differences in nasal resistance among patients with different degrees of cleft lip. A p-value of <0.05 was considered statistically significant. RESULTS: The nasal resistances of the occult cleft and incomplete cleft lip groups showed no significant differences between the cleft and non-cleft sides, and were similar to the control group. However, in the complete cleft lip group, the cleft side nasal resistance was significantly higher than the non-cleft side and control group. Among the groups, the complete cleft lip group had significantly higher nasal resistances on the cleft side for Reffin, VRin, and ReffT compared to the occult cleft group. CONCLUSION: Understanding the nasal resistance of different degrees of operated UCL patients can benefit clinical diagnosis and treatment. Patients with complete cleft lip have more severe nasal obstruction on the cleft side, with greater impact on inhalation than exhalation. For these patients, treatment by an otolaryngologist is recommended to improve nasal airflow.

Nasal resistance and inflammation: mechanisms for obstructive sleep apnea from chronic rhinosinusitis.

STUDY OBJECTIVES: We have previously estimated that the prevalence of obstructive sleep apnea (OSA) among World Trade Center rescue and recovery workers is 75% and identified that having symptoms of chronic rhinosinusitis (CRS) is an independent risk factor for OSA in this population. Nasal inflammation and/or elevated awake nasal resistance that carried over into sleep could explain this association. To understand the mechanism(s) for the elevated risk of OSA observed in World Trade Center responders with CRS symptoms we examined if elevated awake supine nasal resistance was associated with OSA, CRS and/or nasal inflammatory biomarkers. METHODS: A total of 601 individuals (83% male, average age 53 years, body mass index = 29.9 ± 5.5 kg/m2) enrolled in the World Trade Center Health Program and without significant snoring prior to September 11, 2001 underwent 2 nights of home sleep apnea testing, measurements of anterior rhinomanometry in the supine position, and nasal lavage. RESULTS: Awake supine nasal resistance was not associated with OSA; 74.8% and 74.4% of the participants with low and high nasal resistance respectively, had OSA. Patients with CRS had elevated nasal inflammatory markers (interleukin 6, interleukin 8, eosinophilic cationic protein, and neutrophil) but did not have high nasal resistance. Nasal inflammatory markers were not correlated with nasal resistance. CONCLUSIONS: As awake nasal resistance did not explain the relationship of CRS to OSA in this large and well characterized dataset, our findings suggest that either "sleep" nasal resistance or other factors such as increased supraglottic inflammation, perhaps through impairing upper airway reflex mechanisms, or systemic inflammation are involved in the pathophysiology of OSA in the World Trade Center population. CITATION: Ayappa I, Laumbach R, Black K, et al. Nasal resistance and inflammation: mechanisms for obstructive sleep apnea from chronic rhinosinusitis. J Clin Sleep Med. 2024;20(10):1627-1636.

Rhinomanometry: A Comprehensive Review of Its Applications and Advancements in Rhinology Practice.

Rhinomanometry is a pivotal diagnostic technique in rhinology, providing a quantitative assessment of nasal airflow and resistance. This review comprehensively examines the historical development, principles and clinical applications of rhinomanometry, emphasising its role in diagnosing nasal obstructions, preoperative evaluations and monitoring therapeutic outcomes. Recent advancements, including the integration with imaging technologies and the application of artificial intelligence (AI), have significantly enhanced the accuracy and utility of rhinomanometry. Despite facing challenges such as technical limitations and the need for standardisation, rhinomanometry remains an invaluable tool in both clinical and research settings. The review also explores future directions, highlighting the potential for device miniaturisation, telemedicine integration, personalised protocols and collaborative research efforts. These advancements will likely expand the accessibility, accuracy and clinical relevance of rhinomanometry, solidifying its importance in the ongoing evolution of rhinology practice.

Nasal Patency Across Seated, Supine, and Recumbent Postures in Individuals With and Without Allergic Rhinitis.

Objectives: This study aimed to investigate the effects of seated, supine, and recumbent postures on nasal resistance in individuals with allergic rhinitis (AR) and healthy controls, which has not been investigated in the past. Methods: A visual analog scale (VAS) assessed subjective nasal obstruction, while acoustic rhinometry and video endoscopy provided objective measures. Sixty participants, comprising 30 AR patients and 30 healthy controls, were evaluated across 4 postures without decongestion: seated, supine, left recumbent, and right recumbent. Results: In patients with AR, we noted no significant changes in subjective nasal blockage under various postures (all P > .18). However, significant reductions of minimal cross-sectional area (mCSA) were found (seated vs supine, P = .014; seated vs left recumbent, P = .001; seated vs right recumbent, P < .001) and significant increases in the inferior turbinate hypertrophy were observed on the dependent side of the nose when in recumbent posture (right nose: seated vs right recumbent, P = .013; left nose: seated vs left recumbent, P = .003). On the contrary, healthy controls experienced increased subjective nasal obstruction (VAS scores: seated vs supine, P < .001; seated vs left recumbent, P = .003; seated vs right recumbent, P < .001), reductions in mCSA (seated vs supine, P = .002; seated vs right or left recumbent, both P = .001), and increased inferior turbinate hypertrophy on the dependent side of the nose (right nose: seated vs right recumbent, P = .003; left nose: seated vs left recumbent, P = .006). Conclusions: Healthy controls reported better nasal patency when shifting from supine or recumbent to more upright or less gravity-dependent seated postures, which was further supported by objective examinations. On the contrary, despite patients with AR not subjectively perceiving increased nasal patency while adopting more upright postures, objective evaluations demonstrated an improvement in their nasal airflow in these less gravity-dependent postures.Level of Evidence: 4.

Computational Rhinology: Unraveling Discrepancies between In Silico and In Vivo Nasal Airflow Assessments for Enhanced Clinical Decision Support.

Computational rhinology is a specialized branch of biomechanics leveraging engineering techniques for mathematical modelling and simulation to complement the medical field of rhinology. Computational rhinology has already contributed significantly to advancing our understanding of the nasal function, including airflow patterns, mucosal cooling, particle deposition, and drug delivery, and is foreseen as a crucial element in, e.g., the development of virtual surgery as a clinical, patient-specific decision support tool. The current paper delves into the field of computational rhinology from a nasal airflow perspective, highlighting the use of computational fluid dynamics to enhance diagnostics and treatment of breathing disorders. This paper consists of three distinct parts-an introduction to and review of the field of computational rhinology, a review of the published literature on in vitro and in silico studies of nasal airflow, and the presentation and analysis of previously unpublished high-fidelity CFD simulation data of in silico rhinomanometry. While the two first parts of this paper summarize the current status and challenges in the application of computational tools in rhinology, the last part addresses the gross disagreement commonly observed when comparing in silico and in vivo rhinomanometry results. It is concluded that this discrepancy cannot readily be explained by CFD model deficiencies caused by poor choice of turbulence model, insufficient spatial or temporal resolution, or neglecting transient effects. Hence, alternative explanations such as nasal cavity compliance or drag effects due to nasal hair should be investigated.

Numerical simulation of the influence of nasal cycle on nasal airflow.

To study the characteristics of nasal airflow in the presence of nasal cycle by computational fluid dynamics. CT scan data of a healthy Chinese individual was used to construct a three-dimensional model of the nasal cavity to be used as simulation domain. A sinusoidal airflow velocity is set at the nasal cavity entrance to reproduce the breathing pattern of a healthy human. There was a significant difference in the cross-sectional area between the two sides of the nasal cavity. Particularly, the decongested side is characterized by a larger cross-section area, and consequently, by a larger volume with respect to the congested side. The airflow velocity, pressure, and nasal resistance were higher on the congested narrow side. The temperature regulation ability on the congested narrow side was stronger than that on the decongested wider side. During the nasal cycle, there are differences in the nasal cavity function between the congested and decongested sides. Therefore, when evaluating the impact of various factors on nasal cavity function, the nasal cycle should be considered.

Effects of Mucosal Decongestion on Nasal Aerodynamics: A Pilot Study.

OBJECTIVE: Mucosal decongestion with nasal sprays is a common treatment for nasal airway obstruction. However, the impact of mucosal decongestion on nasal aerodynamics and the physiological mechanism of nasal airflow sensation are incompletely understood. The objective of this study is to compare nasal airflow patterns in nasal airway obstruction (NAO) patients with and without mucosal decongestion and nondecongested healthy subjects. STUDY DESIGN: Cross-sectional study of a convenience sample. SETTING: Academic tertiary medical center. METHODS: Forty-five subjects were studied (15 nondecongested healthy subjects, 15 nondecongested NAO patients, and 15 decongested NAO patients). Three-dimensional models of the nasal anatomy were created from computed tomography scans. Steady-state simulations of airflow and heat transfer were conducted at 15 L/min inhalation rate using computational fluid dynamics. RESULTS: In the narrow side of the nose, unilateral nasal resistance was similar in decongested NAO patients and nondecongested healthy subjects, but substantially higher in nondecongested NAO patients. The vertical airflow distribution within the nasal cavity (inferior vs middle vs superior) was also similar in decongested NAO patients and nondecongested healthy subjects, but nondecongested NAO patients had substantially less middle airflow. Mucosal cooling, quantified by the surface area where heat flux exceeds 50 W/m2, was significantly higher in decongested NAO patients than in nondecongested NAO patients. CONCLUSION: This pilot study suggests that mucosal decongestion improves objective measures of nasal airflow, which is consistent with improved subjective sensation of nasal patency after decongestion.

Assessing nasal airway resistance and symmetry: An approach to global perspective through computational fluid dynamics.

This study aimed to explore the variability in nasal airflow patterns among different sexes and populations using computational fluid dynamics (CFD). We focused on evaluating the universality and applicability of dimensionless parameters R (bilateral nasal resistance) and ϕ (nasal flow asymmetry), initially established in a Caucasian Spanish cohort, across a broader spectrum of human populations to assess normal breathing function in healthy airways. In this retrospective study, CT scans from Cambodia (20 males, 20 females), Russia (20 males, 18 females), and Spain (19 males, 19 females) were analyzed. A standardized CFD workflow was implemented to calculate R-ϕ parameters from these scans. Statistical analyses were conducted to assess and compare these parameters across different sexes and populations, emphasizing their distribution and variances. Our results indicated no significant sex-based differences in the R parameter across the populations. However, moderate sexual dimorphism in the ϕ parameter was observed in the Cambodian group. Notably, no geographical differences were found in either R or ϕ parameters, suggesting consistent nasal airflow characteristics across the diverse human groups studied. The study also emphasized the importance of using dimensionless variables to effectively analyze the relationships between form and function in nasal airflow. The observed consistency of R-ϕ parameters across various populations highlights their potential as reliable indicators in both medical practice and further CFD research, particularly in diverse human populations. Our findings suggest the potential applicability of dimensionless CFD parameters in analyzing nasal airflow, highlighting their utility across diverse demographic and geographic contexts. This research advances our understanding of nasal airflow dynamics and underscores the need for additional studies to validate these parameters in broader population cohorts. The approach of employing dimensionless parameters paves the way for future research that eliminates confounding size effects, enabling more accurate comparisons across different populations and sexes. The implications of this study are significant for the advancement of personalized medicine and the development of diagnostic tools that accommodate individual variations in nasal airflow.