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 H2O/L/s)
significantly decreased with ND (NRd = 1.4 ± 0.2 cm
H2O/L/s; p < 0.001) and significantly increased with NP
(NRp = 3.8 ± 0.8 cm H2O/L/s; p < 0.001). A
significant logarithmic relationship was found between NRd and NRb
(r2 = 0.95; p < 0.0001), and a
significant exponential relationship was found between NRp and NRb
(r2 = 0.99; p < 0.0001). While
breathing with both ND and NP, NRd + p was significantly lower than
NRb (1.9 ± 1.4 cm H2O/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