Combined effects of a nasal dilator and nasal prongs on nasal airflow resistance

STUDY OBJECTIVES: Nasal prongs (NPs), when used to assess nasal flow, can result in dramatic increases in nasal airflow resistance (NR). The aim of this study was to investigate whether the NP-induced increases in NR could be corrected by the simultaneous use of an internal nasal dilator (ND). DESIGN: NR was estimated by posterior rhinomanometry, in the basal state (NRb), and while breathing with NP (NRp), with ND (NRd), and with both ND and NP (NRd + p). PARTICIPANTS: The study was performed in 15 healthy subjects. Measurements and results: NR (mean NRb [+/- SEM], 2.5 +/- 0.4 cm H(2)O/L/s) significantly decreased with ND (NRd = 1.4 +/- 0.2 cm H(2)O/L/s; p < 0.001) and significantly increased with NP (NRp = 3.8 +/- 0.8 cm H(2)O/L/s; p < 0.001). A significant logarithmic relationship was found between NRd and NRb (r(2) = 0.95; p < 0.0001), and a significant exponential relationship was found between NRp and NRb (r(2) = 0.99; p < 0.0001). While breathing with both ND and NP, NRd + p was significantly lower than NRb (1.9 +/- 1.4 cm H(2)O/L/s; p < 0.02). CONCLUSIONS: Our results demonstrate that the ND tends to slightly overcorrect the NP-induced increase in NR and suggest that, in view of the possible effects of NPs on upper airway resistance, the combination of both devices might be used for nasal airflow monitoring during nocturnal polysomnography in patients presenting with highly resistive nares.