The results of the present study demonstrate that the values of otherwise healthy population for TNR in a large sample of 20 to 80-year-old Koreans were 0.19±0.08 Pa/cm3/second (0.19±0.08 Pa/cm3/second in women and 0.18±0.08 Pa/cm3/second in men) at 100 Pa and 0.22±0.09 Pa/cm3/second (0.22±0.09 Pa/cm3/second in women and 0.21±0.09 Pa/cm3/second in men) at 150 Pa; women had higher TNR values than men. Additionally, our results confirm that increasing age was associated with decreasing TNR in both genders. To our knowledge, this is the first large sampled community-based study to determine the values of otherwise healthy population for nasal resistance in East Asians.
There have been several studies reporting the values of otherwise healthy population for nasal resistance. Jones et al. (13
) suggested that the normal range of TNR was 0.20 to 0.55 Pa/cm3
/second at a transnasal pressure of 150 Pa from a study of 59 healthy individuals. Cole (14
) reported that the normal range of TNR was 0.20±0.05 Pa/cm3
/second at 100 Pa, and that it was approximately 25% greater at 150 Pa. The mean TNR of normal noses has also been reported as 0.31 Pa/cm3
/second (range, 0.13 to 0.84 Pa/cm3
), 0.24±0.07 Pa/cm3
), and 0.23±0.006 Pa/cm3
/second (range 0.15 to 0.39 Pa/cm3
) at 150 Pa. However, most previous studies reporting normal TNR values have been performed in small populations of European descent. Since facial anatomy exhibits significant geographic variation across human populations, assessments of the values of otherwise healthy population for nasal resistance may also differ across populations. Ohki et al. (1
) investigated dimensions of the external nose, nostrils, and nasal airflow resistances in healthy young adult subjects of European, East Asian, and African descent. The average nasal width and difference between dorsi-ventral and transverse nostril diameters are significantly different between these populations. The noses of European subjects were leptorrhine, African subjects were platyrrhine, and East Asian subjects were of intermediate dimension. Mean nasal resistances were lowest in subjects of African descent, highest in European descent, and intermediate in Asian descent. The present study demonstrated that average TNRs were 0.19±0.08 Pa/cm3
/second at 100 Pa and 0.22±0.09 Pa/cm3
/second at 150 Pa, relatively lower than reported in previous European studies (14
). However, it is similar to Southeast Asian study (16
) after consideration of age. This difference can be explained by the facts that the current study sample consisted of East Asians and was older than in previous studies, as increasing age is correlated with decreasing TNRs (18
Nasal resistance is highest in infants at approximately 1.2 Pa/cm3
/second and decreases to adult values at approximately 16 to 18 years of age, thereafter demonstrating a slow decline with increasing age (19
). In healthy subjects, it has also been reported that nasal resistance declines with increasing age from 0.60 Pa/cm3
/second (age, 5 to 12 years) to 0.29 Pa/cm3
/second (age, 13 to 19 years), followed by 0.22 Pa/cm3
/second (age >20 years) in male subjects (18
). In this study, the TNR also decreased with increasing age in both genders. These results can be interpreted as a consequence of the lower temperature and humidity, enlarged nasal cavity, and atrophic mucosal change that are characteristic of increasing age (20
). Additionally, weak inspiratory forces in elderly subjects may also contribute to decreasing TNR as age increases.
In regards to the relationship between TNR and gender, previous studies have reported contradictory results. One study found that men had higher TNRs than women (18
). However, other studies have reported that the average TNR of women was higher than that of men at 150 Pa (3
). The current study also demonstrated that women have a higher TNR value than men. This may be related to the differences in anatomical, physiological, and hormonal factors between women and men.
The present study demonstrated that increased TNR values were associated with smoking status (current smoker>ex-smoker>never smoker) and low height at 150 pa in men, and low body weight in women, after adjusting for confounding factors; these findings are in agreement with prior studies (3
). In women, a lower body weight was associated with increased TNR values, but smoking status was not. This may be due to errors related to the small number of smoking women in the current study sample. In men, a low body weight was not associated with TNR, but smoking status and low height at 150 pa were independently related to increased TNR. Suzina et al. (16
) reported that height was significantly related to TNR, but the present study showed this relationship only in men at 150 Pa. These discrepancies in weight and height according to gender are unclear. However, it has been reported that nasal subcutaneous fat is important for the nasal structure (21
). Since women have almost twice as much subcutaneous fat as men (22
), women might response more sensitive to the change of weight but not to the height. Further study is needed to confirm the effects of height and weight according to gender on TNR.
One of the strengths of this study is that the study sample was large and included participants enrolled from a community-based, healthy general population. However, this study has limitations. The distribution of study subjects was relatively small in the 20 to 39-year-old range, as compared with the overall Korean population structure. As the KoGES focuses on disease in middle-aged adults, the composition of the study sample was likewise biased. Additionally, the mechanisms underlying various parameters' effects, according to gender, on TNR could not be elucidated.
In conclusion, the present study demonstrated the values of otherwise healthy population for TNR and parameters associated with increasing TNR in a large, community-based, East Asian sample. These results may contribute to the understanding of nasal patency and resistance and can assist the clinicians to diagnose, treat and follow-up the clinical course of nasal disease.