Assessment of the impact of altitude on nasal airflow via expiratory nasal sound spectral analysis

The aim of the study was to evaluate the effects of high altitude (HA) on the expiratory nasal sound spectra. The design consisted of a prospective analysis. The study group consisted of 24 otorhinolaryngologists and a student (2 females, 23 males) climber of the mountain of Kackar in Rize, a city located in northeastern Turkey. The elevation of the highest peak of the Kackar Mountain is 3,937 m (12,920 ft) and that of mountain plateaus at about 3,000 m (9,800 ft). Nasal sound spectral analysis was performed on 25 subjects at 700 and 3,937 m, respectively. We found that sound intensity (dB) at high frequency (Hf) was below 18.6 dB in the subjects at low altitude, while the results were found to be above 25.1 dB in the subjects at HA during expiration. A correlation was observed between the degree of HA and 'Odiosoft-rhino' findings at Hf intervals of the subjects. At the top of the mountain, the sound intensities at low and medium frequency were observed to be significantly lower than at low altitude (p < 0.05). We concluded that Hf values of HA were significantly higher than at low altitude because of nasal congestion and also narrowing of the cross-sectional area of the nasal airway. Nasal conchal and mucosal congestion affects airflow through the nasal cavity at HA, transforming it from a laminar pattern to turbulent flow. We found significant increases in the sound intensity level at Hf in the sound spectra at HA. Awareness of the impact of HA in nasal airflow is important in the diagnosis and treatment of nasal obstruction symptoms.