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Correlation between Subjective Nasal Patency and Intranasal Airflow Distribution.

ABSTRACT: Objectives (1) Analyze the relationship between intranasal airflow distribution and subjective nasal patency in healthy and nasal airway obstruction (NAO) cohorts using computational fluid dynamics (CFD). (2) Determine whether intranasal airflow distribution is an important objective measure of airflow sensation that should be considered in future NAO virtual surgery planning. Study Design Cross-sectional. Setting Academic tertiary medical center and academic dental clinic. Subjects and Methods Three-dimensional models of nasal anatomy were created based on computed tomography scans of 15 patients with NAO and 15 healthy subjects and used to run CFD simulations of nasal airflow and mucosal cooling. Subjective nasal patency was quantified with a visual analog scale (VAS) and the Nasal Obstruction Symptom Evaluation (NOSE). Regional distribution of nasal airflow (inferior, middle, and superior) was quantified in coronal cross sections in the narrowest nasal cavity. The Pearson correlation coefficient was used to quantify the correlation between subjective scores and regional airflows. Results Healthy subjects had significantly higher middle airflow than patients with NAO. Subjective nasal patency had no correlation with inferior and superior airflows but a high correlation with middle airflow (| r| = 0.64 and | r| = 0.76 for VAS and NOSE, respectively). Anterior septal deviations tended to shift airflow inferiorly, reducing middle airflow and reducing mucosal cooling in some patients with NAO. Conclusion Reduced middle airflow correlates with the sensation of nasal obstruction, possibly due to a reduction in mucosal cooling in this region. Further research is needed to elucidate the role of intranasal airflow distribution in the sensation of nasal airflow.

SUBMITTER: Casey KP

PROVIDER: S-EPMC6062004 | biostudies-literature | 2017 Apr

REPOSITORIES: biostudies-literature

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Correlation between Subjective Nasal Patency and Intranasal Airflow Distribution.

Casey Kevin P KP Borojeni Azadeh A T AA Koenig Lisa J LJ Rhee John S JS Garcia Guilherme J M GJ

Otolaryngology--head and neck surgery : official journal of American Academy of Otolaryngology-Head and Neck Surgery 20170131 4

Objectives (1) Analyze the relationship between intranasal airflow distribution and subjective nasal patency in healthy and nasal airway obstruction (NAO) cohorts using computational fluid dynamics (CFD). (2) Determine whether intranasal airflow distribution is an important objective measure of airflow sensation that should be considered in future NAO virtual surgery planning. Study Design Cross-sectional. Setting Academic tertiary medical center and academic dental clinic. Subjects and Methods ...[more]

PMID: 28139171

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Project description:PurposeVirtual surgery planning based on computational fluid dynamics (CFD) simulations of nasal airflow has the potential to improve surgical outcomes for patients with nasal airway obstruction (NAO). Virtual surgery planning requires normative ranges of airflow variables, but few studies to date have quantified inter-individual variability of nasal airflow among healthy subjects. This study reports CFD simulations of nasal airflow in 47 healthy adults.MethodsAnatomically accurate three-dimensional nasal models were reconstructed from cone beam computed tomography scans and used for steady-state inspiratory airflow simulations with a bilateral flowrate of 250 ml/s. Normal subjective sensation of nasal patency was confirmed using the nasal obstruction symptom evaluation and visual analog scale. Healthy ranges for several CFD variables known to correlate with subjective nasal patency were computed, including unilateral airflow, nasal resistance, airspace minimal cross-sectional area (mCSA), heat flux (HF), and surface area stimulated by mucosal cooling (defined as the area where HF > 50 W/m2). The normative ranges were targeted to contain 95% of the healthy population and computed using a nonparametric method based on order statistics.ResultsA wide range of inter-individual variability in nasal airflow was observed among healthy subjects. Unilateral airflow varied from 60 to 191 ml/s, airflow partitioning ranged from 23.8 to 76.2%, and unilateral mCSA varied from 0.24 to 1.21 cm2. These ranges are in good agreement with rhinomanometry and acoustic rhinometry data from the literature. A key innovation of this study are the normative ranges of flow variables associated with mucosal cooling, which recent research suggests is the primary physiological mechanism of nasal airflow sensation. Unilateral HF ranged from 94 to 281 W/m2, while the surface area stimulated by cooling ranged from 27.4 to 64.3 cm2.ConclusionsThese normative ranges may serve as targets in future virtual surgery planning for patients with NAO.

Project description:Background:External nasal dilator strips are used as nonpharmacological therapy to reduce snoring and daytime sleepiness. In a product improvement initiative, a marketed strip (BRNS) and 2 prototype nasal strips were evaluated. Objective:To compare the nasal patency and multiple-use dermal tolerability of the BRNS and prototype nasal strips using both objective and subject-reported outcome measures. Methods:Two studies were conducted separately in healthy volunteers ?18 years of age. A single-day nasal patency randomized crossover study assessed minimal cross-sectional area (MCA; second restriction) and nasal volume (using acoustic rhinometry); nasal inspiratory flow and resistance (using posterior rhinomanometry); and subject-reported evaluations of the BRNS compared with the butterfly strip and teardrop strip prototypes. A single-center, randomized, controlled, parallel-group, evaluator-blinded study assessed dermal tolerability of the BRNS and the butterfly strip over 7 consecutive nights of use, using the Dermal Response Scale (DRS) and subject-reported comfort and ease of removal. Results:In the Patency study (N?=?50), all 3 strips demonstrated significant improvement from baseline in MCA, nasal volume, and nasal flow parameters (resistance and peak flow). The prototype strips demonstrated significantly more improvement in nasal volume than the BRNS, and the butterfly strip showed significantly more improvement in MCA than the BRNS; all strips were similar with respect to nasal flow and subject-reported nasal breathing outcomes. In the Dermal Tolerability study (N?=?82), all subjects scored 0 (no evidence of irritation) on the DRS at all 7 morning assessments; the BRNS was numerically, but not significantly, superior to the butterfly strip on subject-reported outcomes. Conclusion:The Patency study demonstrated significant improvement from baseline in nasal dimensions and flow for all 3 evaluated strips; between-strip differences were confined to nasal dimensions. Both the BRNS and butterfly strip were generally well tolerated, with no evidence of dermal response over 7 consecutive nights of use.ClinicalTrials.gov identifiers: NCT01105949 and NCT01495494.

Project description:Monitoring of nasal airflow and conductance provides crucial insights into the variable nature of the nasal resistance, nasal cycle, and ventilation. We have previously shown that tracking of pressure swings at the entrance of each nasal passage by a dedicated catheter system allows bilateral monitoring of nasal airflow over several hours but requires complex linearization and calibration procedures. Side-selective nasal conductance is derived from linearized and calibrated bilateral nasal pressure swings and corresponding driving pressure, i.e., the transnasal pressure difference derived from an epipharyngeal catheter. Manual analysis of such recordings and computation of instantaneous conductance as the ratio of flow to driving pressure over several hours is extremely tedious, time consuming, and therefore not suitable for routine practice. To address this point, we developed and validated a software for automatic processing of nasal and epipharyngeal pressure recordings as a convenient tool for studying the nasal ventilation. The software applies an eight-parameter logistic model to transform nasal pressure swings into side-selective estimates of airflow that are calibrated and further processed along with epipharyngeal pressure to compute bilateral nasal conductance over consecutive, user-selectable time-segments. Essential processing steps include (1) offset correction, (2) low-pass filtering, (3) cross-correlation, (4) cutting of signals into individual breaths, (5) normalization, (6) ensemble averaging to obtain a mean pressure signal for each nasal side, (7) derivation of airflow, conductance, and further variables. Among four evaluated algorithms for calculation of nasal conductance, the derivative of the airflow-pressure curve according to the mean value theorem agreed closest with the gold standard, i.e., the conductance derived from airflow measured by a pneumotachograph attached to an oral-nasal mask and transnasal pressure. In combination with the nasal catheter system, our novel software represents a valuable tool for use in clinical practice and research to conveniently investigate nasal ventilation and its changes occurring spontaneously or in response to various exposures and therapeutic interventions.

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Correlation between Subjective Nasal Patency and Intranasal Airflow Distribution.

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Correlation between Subjective Nasal Patency and Intranasal Airflow Distribution.

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