The hitch-hikers guide to nasal airway patency

Normal nasal patency: problems in obtaining standard reference values for the surgeon

This review examines why there is no normal range of nasal patency available to the surgeon when assessing nasal obstruction, and discusses the factors that influence nasal patency. Current normal ranges are examined and criticised because of the variability of normal values and the poor sampling methods used. Instability of physiological nasal patency is related to factors such as the nasal cycle and the nose's direct exposure to the external environment. Decongestion of the nose is proposed as a way of stabilising anatomical nasal patency, and measurements of patency in this state may be more useful to the surgeon. Population studies are needed to establish a normal range, but these studies must control for factors such as age, height, sex, and nasal shape and size related to climatic adaptation. Rather than classify populations according to unscientific categories such as race, anthropometric measures such as the nasal index are proposed.

Diagnosis and management of rhinitis: complete guidelines of the Joint Task Force on Practice Parameters in Allergy, Asthma and Immunology. American Academy of Allergy, Asthma, and Immunology

This document contains complete guidelines for diagnosis and management of rhinitis developed by the Joint Task Force on Practice Parameters in Allergy, Asthma and Immunology, representing the American Academy of Allergy, Asthma and Immunology, the American College of Allergy, Asthma and Immunology and the Joint Council on Allergy, Asthma and Immunology. The guidelines are comprehensive and begin with statements on clinical characteristics and diagnosis of different forms of rhinitis (allergic, non-allergic, occupational rhinitis, hormonal rhinitis [pregnancy and hypothyroidism], drug-induced rhinitis, rhinitis from food ingestion), and other conditions that may be confused with rhinitis. Recommendations on patient evaluation discuss appropriate use of history, physical examination, and diagnostic testing, as well as unproven or inappropriate techniques that should not be used. Parameters on management include use of environmental control measures, pharmacologic therapy including recently introduced therapies and allergen immunotherapy. Because of the risks to patients and society from sedation and performance impairment caused by first generation antihistamines, second generation antihistamines that reduce or eliminate these side effects should usually be considered before first generation antihistamines for the treatment of allergic rhinitis. The document emphasizes the importance of rhinitis management for comorbid conditions (asthma, sinusitis, otitis media). Guidelines are also presented on special considerations in patients subsets (children, the elderly, pregnancy, athletes and patients with rhinitis medicamentosa); and when consultation with an allergist-immunologist should be considered.

Evaluation of nasal patency: comparison of patient and clinician assessments with rhinomanometry

The correlation between the objective measurement of nasal resistance and nasal airflow sensation is usually regarded as poor. The aim of the study was to assess the relation between objective indices of nasal patency, as assessed by the occlusion method (RN) and the Youlten peak nasal inspiratory flow meter (PNIF), with subjective sensations of nasal blockade by either the patient or the clinician in groups of patients with rhinitis, asthma, rhinitis and asthma, nasal septal deformity and ill normal controls. We studied nasal airway patency in 254 subjects (37 women, 217 men), mean age 21 years (range 14-78) by RN and PNIF. Nasal resistance was also measured by the application of Ohm's law for parallel resistors (NRO) by estimating the unilateral resistance separately. Subjective sensation of nasal blockade was assessed either by the patient on a 10-point Borg scale (SUB), or the clinician (CLN) on a 6-point scale (3 for each side of the nose). The latter was done in a controlled fashion with the aid of reference sensations. Adjusting for age, height, smoking status and airway calibre, we found good correlation between RN and CLN (r=0.57, p=10(-4)), whereas the association between RN and SUB was moderate and of borderline significance (r=0.42. p=0.05). By logistic regression analysis, we found that the only independent predictors of abnormal nasal resistance at a cut-off value of 0.30 kPa/l/s were the nasal scores as assessed by the clinician (r-=0.26, odds=2.45). We conclude that PNIF measurement and SUB scores are of limited use as indices of nasal patency, although the latter showed an improved association in comparison to older studies. As there is a necessity for some sort of objective measurement to assess nasal patency, the described clinician evaluation may be clinically useful in place of PNIF, but due to its somewhat subjective nature and its inability to detect milder levels of nasal obstruction it cannot be recommended as an alternative to rhinomanometry.

Acoustic rhinometry in the study of the acute nasal allergic response

Acoustic rhinometry is a recently developed method for the objective assessment of nasal patency. In this study, acoustic rhinometry was used to measure changes in nasal cavity dimensions in the immediate response to nasal allergen challenge in eight pollen-sensitive subjects. Acoustic rhinometric changes were compared with subjective symptoms, as well as histamine in nasal secretions, cytology of nasal mucosal scrapings, and changes in olfactory function. A significantly greater decrease in nasal airway caliber occurred following allergen challenge as compared to buffer diluent challenge in the same individuals (70% +/- 7% versus 22% +/- 5%). During an allergic response, a strong correlation was found between the minimum cross-sectional area and the volume of the nasal cavity measured by acoustic rhinometry (r = .9). However, no correlation was observed between nasal airway caliber and concomitant subjective congestion reported by the subjects. A modest decrease in olfactory function was seen following allergen challenge (3.1 +/- 1.4 fewer odors identified correctly out of 20; p = .08). However, the alterations of olfactory function did not correlate with changes in nasal patency. The results presented in this study demonstrate that acoustic rhinometry has great potential as a reproducible method for the objective assessment of nasal obstruction occurring in nasal allergen challenge studies.

Sources of variability in posterior rhinomanometry

Sources of variability in nasal airway resistance measured by posterior rhinomanometry were studied in 5 subjects tested on 5 different days and 56 subjects tested on 2 different days. On each day, a questionnaire on upper airway health and nasal symptoms was completed. The mean individual difference in nasal airway resistance between the 2 test days in the group of 56 subjects was 5.3% (SD 52.7%). Between-subject variability accounted for 74.9% and 72.5% of the total variability in the group of 5 and the group of 56 subjects, respectively. For the 5 subjects, by accounting for a change in upper airway symptoms or upper respiratory tract infection that occurred over the 5 test days, there was a significant decrease in the between-subject variability. The difference in sources of variation due to a change in upper airway symptoms was not seen in the group of 56 subjects. We conclude that the largest source of variability in nasal airway resistance is due to between-subject differences.