Septal deviation and nasal resistance: an investigation using virtual surgery and computational fluid dynamics

BACKGROUND

Septal deviation is an extremely common anatomic variation in healthy adults. However, there are no standard criteria to determine when a deviated septum is clinically relevant. Presently, selection of patients for septoplasty is based on mostly clinical examination, which is prone to observer bias and may lead to unsuccessful treatment. The objective of this article is twofold. First, we investigate whether the location of a septal deviation within the nasal passages affects nasal resistance. Second, we test whether computer simulations are consistent with rhinomanometry studies in predicting that anterior septal deviations increase nasal resistance more than posterior deviations.

METHODS

A three-dimensional computational model of a healthy nose was created from computed tomography scans. Geometry-deforming software was used to produce models with septal deviations. Computational fluid dynamics techniques were used to simulate nasal airflow and compute nasal resistance.

RESULTS

Our results revealed that the posterior nasal cavity can accommodate significant septal deviations without a substantial increase in airway resistance. In contrast, a deviation in the nasal valve region more than doubled nasal resistance. These findings are in good agreement with the rhinomanometry literature and with the observation that patients with anterior septal deviations benefit the most from septoplasty.

CONCLUSION

In the model, anterior septal deviations increased nasal resistance more than posterior deviations. This suggests, in agreement with the literature, that other causes of nasal obstruction (dysfunction of the nasal valve, allergy, etc.) should be carefully considered in patients with posterior septal deviations because such deviations may not affect nasal resistance. This study illustrates how computational modeling and virtual manipulation of the nasal geometry are useful to investigate nasal physiology.

Acoustic rhinometric assessment of nasal obstruction after treatment with fluticasone propionate in patients with perennial rhinitis

OBJECTIVE

To investigate the effect of fluticasone propionate (FP) on the symptom of nasal obstruction and to assess the correlation between the subjective visual analogue score (VAS) and the objective acoustic rhinometry (AR) measurements.

METHODS

A prospective study of 45 consecutive patients, 30 males and 15 females with a mean age of 27 years (range: 16-59 years), with moderate/severe symptoms of perennial rhinitis who were treated by FP nasal spray for 4 weeks. AR and VAS were used to evaluate, compare and correlate the efficacy of FP nasal sprays.

RESULTS

There was a significant improvement in the VAS post-treatment (3.9) compared with pre-treatment (6.3). There was also a significant increase in the nasal volume (V) and minimum cross-sectional area (MCA) after intranasal FP. Good correlation between the total MCA and total V was noted. Subjective improvements in symptoms did not correlate well with objective measurements as the correlation between VAS and AR was poor.

CONCLUSION

Our study provides subjective and objective evidence on the efficacy of intranasal FP in improving nasal obstruction in perennial rhinitis. AR also proved to be a useful instrument in monitoring the effectiveness of medical therapy for perennial rhinitis.

Junior JF, Mion O, Voegels RL. Avaliação da cavidade nasal e nasofaringe através da rinometria acústica antes e após adenoidectomia

INTRODUÇÃO: A hipertrofia adenoideana é vista com freqüência na prática otorrinolaringológica e é importante avaliar a patência nasal antes do início do tratamento. Neste trabalho, os autores buscam avaliar as mudanças na geometria nasal e nasofaringe antes e após adenoidectomia através de um método objetivo de mensuração da patência nasal, a rinometria acústica. FORMA DE ESTUDO: Clínico prospectivo. OBJETIVO: Os autores avaliam a área de secção transversal mínima (ASTM) e o volume das cavidades nasais e nasofaringe através da rinometria acústica (RA) antes e após a cirurgia de adenoidectomia. MATERIAL E MÉTODO: Vinte e três crianças que tinham indicação cirúrgica para adenoidectomia com ou sem tonsilectomia foram submetidas ao exame de RA antes e 15 dias após a cirurgia. RESULTADOS: A ASTM das fossas nasais variou, antes do uso de vasoconstritor (VC), de 0,73 cm² antes da cirurgia para 0,79 cm² após a cirurgia; após o uso de VC variou de 0,87 cm² para 0,93 cm². O volume das fossas nasais variou, antes do uso de VC, de 6,18 cm³ antes da cirurgia para 6,47 cm³ após a cirurgia; após o uso de VC variou de 8,31 cm³ para 8,65 cm³. Na nasofaringe a ASTM variou, antes do uso de VC, de 2,43 cm² antes da cirurgia para 2,69 cm² após a cirurgia; após o uso de VC variou de 2,76 cm² para 3,79 cm². Na nasofaringe o volume variou, antes do uso de VC, de 5,57 cm³ antes da cirurgia para 6,14 cm³ após a cirurgia; após o uso de VC variou de 6,51 cm³ para 8,78 cm³. CCINCLUSÃO: O aumento de ASTM e volume da nasofaringe, indicando melhora da permeabilidade nasal, concorda com a melhora dos sintomas obstrutivos referidos pelo paciente e familiares após a cirurgia de adenoidectomia.

Assessment of antihistamine efficacy and potency

H1 antihistamines are widely used in the treatment of conditions such as seasonal and perennial allergic rhinitis, urticaria and angioedema, as well as being an adjunct therapy for anaphylaxis. The development of new compounds within this class of pharmacological agents is based on preclinical and clinical assessments prior to registration. Preclinical assessment of novel compounds has been advanced both by the definition of the molecular structure of the H1 receptor and by high throughput screening, which allows the definition of potent and selective candidate compounds. The elimination, in subsequent evaluations, of those compounds with potential for central nervous system and cardiotoxic effects and those with inappropriate pharmacokinetics restricts the subsequent toxicological and clinical evaluation of novel H1 antihistamines. Clinical evaluation is based initially on human volunteer studies to define pharmacodynamic, pharmacokinetic and safety parameters. Local challenge models such as in the skin or nose for oral therapy or nose and conjunctiva for topical drug development allow definition of potential dose for administration, speed of onset of activity and duration of effect, both in comparison to placebo and to reference compounds. While a range of laboratory allergen challenge models, pollen chamber challenge studies and acute 'day in the park' study designs have been used in the early clinical evaluation of H1 antihistaminic activity, ultimately it is the efficacy of novel compounds in naturally occurring disease that is of importance. The assessment of the magnitude and profile of clinical disease improvement in specific disease areas is thus the crucial evaluation. The appropriate selection and characterization of patients, the optimization of the trial design, dependent upon the nature of the disease, and the appropriate selection of endpoints for analysis are thus critical considerations, as well as evaluation of appropriate safety criteria.

Acoustic rhinometric assessment of the nasal valve

The aims of this study are to assess nasal valve cross-sectional areas in healthy noses and in patients with nasal obstruction after rhinoplasty and to evaluate the effect of an external nasal dilator on both healthy and obstructive nasal valves. Subjects consisted of (i) volunteers with no nasal symptoms, nasal cavities unremarkable to rhinoscopy and normal nasal resistance and (ii) patients referred to our clinic complaining of postrhinoplasty nasal obstruction. All subjects were tested before and after topical decongestion of the nasal mucosa and with an external nasal dilator. In 79 untreated healthy nasal cavities the nasal valve area showed two constrictions: the proximal constriction averaged 0.78 cm2 cross-section and was situated 1.18 cm from the nostril, the distal constriction averaged 0.70 cm2 cross-section at 2.86 cm from the nostril. Mucosal decongestion increased cross-sectional area of the distal constriction significantly (p < 0.0001) but not the proximal. External dilation increased cross-sectional area of both constrictions significantly (p < 0.0001). In 26 post-rhinoplasty obstructed nasal cavities, only a single constriction was detected, averaging 0.34 cm2 cross-section at 2.55 cm from the nostril and 0.4 cm2 at 2.46 cm from the nostril, before and after mucosal decongestion respectively. External dilation increased the minimum cross-sectional area to 0.64 cm2 in these nasal cavities (p < 0.0001). We conclude that the nasal valve area in patients with postrhinoplasty nasal obstruction is significantly smaller than in healthy nasal cavities as shown by acoustic rhinometry. Acoustic rhinometry objectively determines the structural and mucovascular components of the nasal valve area and external dilation is an effective therapeutical approach in the management of nasal valve obstruction.