NASAL FUNCTION CHANGES AT HIGH ALTITUDE

Background: An ever-increasing number of people are involved in sport activities at high altitude. Objective: This study aimed to evaluate the pulmonary and nasal functions, including nasal cytology, in healthy volunteers moving for 1 week from an altitude of 2000 m to another of 3400 m. Methods: Peak nasal inspiratory flow (PNIF), pulmonary function, including peak expiratory flow (PEF), mucociliary transport time (MCTt), nasal cytology, and oxygen saturation (O2 sat) were studied in 5 different occasions—T1: at base camp (2000 m); T2: at the mountain refuge (3400 m); T3: after 7 days at 3400 m; T4: after the return at the base camp (2000 m); and T5: at the base camp (2000 m) after 15 days. Results: With respect to T1, PEF values decreased at T2 (P =.004), T3 (P =.004), T4 (P =.000), and T5 (P =.001). Forced expiratory volume in the first second and forced vital capacity did not differ among the 5 different times of measurements. In regard to T1, PNIF values increased at T2 (P =.003) and T3 (P =.001). MCTt and O2 sat showed similar but opposite changes with MCTt increased at T2 and T3 in respect to T1 (P =.000 for both), while O2 sat decreased at T2 and T3 in respect to T1 (P =.000 for both). At nasal cytology, the number of neutrophils increased at T2 in respect to T1 (P =.008). At multivariate analysis, PNIF changed with altitude from T1 to T4 even accounting for the effect of all the other variables (T1 vs T2 PNIF, P =.009; T1 vs T3 PNIF, P =.007; T1 vs T4 PNIF, P =.021). Conclusions: Although the study has some limitations, being conducted on a small cohort and at no controlled environmental conditions, data seem to support the utility of MCTt for studying nasal mucosa damage induced by high altitude. Nasal cytology seems to be able to identify the inflammation of the nasal mucosa exposed to hypoxia. Further investigations on larger series and possibly conducted in hypobaric chamber at controlled standardized conditions are necessary in order to confirm these results and, most importantly, the improvement of PNIF at high altitude.