Key words: students, random sample, health survey, nasal patency, rhinomanometry, upper airway functional status.
Rhinomanometry is a method for measuring the air flow through the nasal cavity. It was invented by Kayser in 1895 . Thanks to technological progress, from 1958 rhinomanometry could be used in clinical research . Initially, only monitoring of the treatment was possible through comparing subsequent measurements. Intepretation of a single measurement was not possible as differences in equipment and procedures made it impossible to create norms . In the 1970's efforts were undertaken aimed at standardization of the method, which finally resulted in the publication of technical requirements and recommendations for the execution of rhinomanometric measurements . Comparisons of results from different centres, as well as elaboration of population norms were at last possible . The final version of the recommendations was approved in 1983 by the Normalisation Committee of the European Rhinology Society (ERS) .
The aim of the present study was to measure nasal airflow in random students of the Silesian Medical Academy, and to compare the results with the norms published by the ERS.
16 students (8 females and 8 males, aged 24 - 30 years) participated in the study. None of them complained of any symptoms from the upper airways. All were residents of Upper Silesia, having spent in this heavily industrialised province of Poland at least 9 months/year for at least 5 preceding years. The measurements were done in seating position, after 30-min adaptation to the laboratory's microclimate (temp. 24°C), on 2 consecutive days of May 1992 between 13.00 and 15.00 hrs. Anterior active rhinomanometry was carried out using rhinomanometer Rhinotest MP 500 (EVG Electronic, Germany) . According to the ERS recommendations, nasal airflow was measured at differential pressure between anterior and posterior nares of 150 Pa. The measurements were interpreted according to the ERS norms (Table I) . The following parameters were analysed: total nasal flow, flow ratio and flow increase.
|Total nasal flow at 150 Pa||flow sum.||> 870||cm3 s-1|
|Flow increase from 75 to 150 Pa||flow inc.||> 35||%|
|Flow ratio||flow ratio||1.00 - 1.50||-|
Only in 2 students the total nasal flow was within normal range. In 5 students the values were between 500 and 870 cm3/s, suggesting a medium degree of nasal obstruction (Table II). In 9 students, the measured values were below 500 cm3/s, indicating high degree of nasal obstruction. Flow increase values were below the norm in 3 students - in 2 unilaterally, and in 1 bilaterally. The flow increase below 35% is an indication of aerodynamic turbulence of the air stream passing through the nose. Typically, this is due to anatomical abnormalities. Flow ratio exceeded recommended normal values (1.00 - 1.50) in 10 students, which suggests a relevant asymmetry between both nasal canals (possibly septal deviation).
|Student||Flow sum.||Flow inc. R||Flow inc. L||Flow ratio|
|SJ f s||870||40||40||1.15|
|RM f n||295 *||32 *||40||2.18 *|
|LA f n||468 *||29 *||28 *||14.53 *|
|KA f s||822 *||48||41||1.04|
|WK f s||743 *||43||47||1.29|
|CJ f n||888||40||38||1.60 *|
|MA f n||471 *||40||59||2.32 *|
|KJ f s||409 *||42||43||1.11|
|ZJ m s||234 *||54||233||4.85 *|
|KN m s||604 *||50||46||1.62 *|
|SA m n||466 *||84||38||2.32 *|
|KR m s||536 *||44||40||3.85 *|
|WL m s||754 *||38||34 *||1.76 *|
|BW m n||447 *||43||49||1.20|
|KM m s||380 *||82||43||3.72 *|
|BG m n||395 *||52||49||1.18|
|Legend: f - female, m - male, n - non-smoker, s - smoker, asterisk (*) denotes pathological values.|
Nasal patency is determined by the shape of bone and cartilage scaffolding of the nose, and the functional status of nasal mucosa [3, 8]. Thickness changes of the nasal mucosa have a relevant influence on the inner lumen of the nasal cavity, thus on the aerodynamic resistance to the passing air . Rhythmical changes of the nasal mucosa's thickness are referred to as the "nasal cycle" . Nasal patency is controlled by a wide range of factors: neurovegetative  and endocrine  stimuli, physical activity , O2 and CO2 pressure in the blood , air temperature and humidity .
Low nasal patency of the examined students may be due to anatomical differences between Polish and Western-European populations (the norms were worked out for the latter). Another possible explanation could be differences in internal or external factors that influence the functional status of the nasal mucosa. The feature common to all study participants was the long-lasting residence in the polluted area of Upper Silesia. Previous observations suggest that industrial pollution of this region causes adverse effects on the respiratory system [12-14]. Other causes are, however, also possible. Identification of these causes requires further, more extensive research that should include also anatomical, histological and environmental aspects. The need for a broader work-up of this problem is also supported by a previous study of students from the same medical school that showed relevant disturbances of the hearing apparatus among them .
From a group of 16 random "healthy" students of the Silesian Medical Academy, in 15 students nasal patency was out of the normal range recommended by the European Rhinology Society.
© Radoslaw Spiewak
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