Effects of nasal prongs on nasal airflow resistance

Study objectives: The aim of this study was to investigate whether nasal pr ongs, which have been proposed to assess nasal flow during sleep, affect na sal airflow resistance (NR). Design: NR was estimated by posterior rhinomanometry at a 0.5 L/s flow, und er eight conditions: in the basal state, and with seven different nasal pro ngs. Participants: The study was performed in 17 healthy supine subjects, 8 of w hom had basal NR values within the normal range (less than or equal to 2 cm H2O . L-1. s, group 1), and 9 had increased basal NR values (> 2.5 cm H2O . L-1. s, group 2), because of nare narrowness and/or deviated nasal septum . Measurements and results: NR increased significantly while breathing with n asal prongs (p < 0.0001 in both groups). The changes in NR (Delta NR) induc ed by the different nasal prongs were characterized by large intersubject a nd intrasubject variability, with a maximum Delta NR of 24.2 cm H2O . L-1. s. Significant differences were found between the Delta NR induced by the d ifferent nasal prongs (p < 0.001 in group 1, and p < 0.0003 in group 2), an d for six of them, Delta NR was significantly higher in group 1 than in gro up 2 (p < 0.02), Conclusions: This study demonstrates that nasal prongs can markedly increas e NR in subjects presenting with nare narrowness and/or deviated nasal sept um. Further investigations that would include nocturnal polysomnography are still required to evaluate the possible influence of nasal prongs on the d iagnosis of obstructive sleep apnea syndrome and its severity.