(Chest. 1999;115:1514-1518.)
© 1999
American College of Chest Physicians
Combined Effects of a Mechanical Nasal Dilator and a Topical Decongestant on Nasal Airflow Resistance*
Anne-Marie Lorino , PhD;
Frédéric Lofaso , MD;
Estelle Dahan;
André Coste , MD;
Alain Harf , MD and
Hubert Lorino , PhD
*
From INSERM U 492 et Service de Physiologie-Explorations Fonctionnelles,
Hôpital Henri Mondor, AP-HP, Créteil, France.
 |
Abstract
|
|---|
The goal of this study was to compare the isolated and combined
effects of two treatments being used to reduce nasal airflow resistance
(NR): an internal nasal mechanical dilator (Nozovent; Prevancure;
Sté Pouret, Paris, France) and a topical decongestant,
fenoxazoline hydrochloride (Aturgyl; Synthelabo; Le
Plessis-Robinson, France). The study was performed in 17 healthy
subjects. NR was estimated by active posterior rhinometry at a 0.5 L/s
flow under four conditions: in the basal state, with the internal nasal
mechanical dilator, after treatment with fenoxazoline
hydrochloride, and with both fenoxazoline hydrochloride
and the mechanical dilator. The mean NR (± SD) decreased from
1.65 ± 0.54 cm H2O/L/s in the basal state to
1.02 ± 0.27 cm H2O/L/s with the mechanical dilator
(p < 0.001), 1.03 ± 0.47 cm H2O/L/s with fenoxazoline
hydrochloride (p < 0.001), and 0.48 ± 0.15 cm H2O/L/s
with both the mechanical dilator and fenoxazoline hydrochloride
(p < 0.001). The decreases in NR observed after using either the
mechanical dilator (
NRN) or fenoxazoline hydrochloride
(NRA) were not significantly different. The decrease in
NR observed with both (NRN + A) was not
significantly different from the sum
NRN + NRA: 1.16 ± 0.53 cm
H2O/L/s vs 1.25 ± 0.63 cm H2O/L/s,
respectively (p > 0.05). NRN + A
strongly correlated with NRN + NRA:
NRN + A = 0.80
(NRN + NRA) + 0.15 (r = 0.96;
p < 0.0001). However, the slope of the regression line of
NRN + A vs
NRN + NRA was significantly lower than
unity (p < 0.003). These results demonstrate that, although not
totally additive, the effects of using the mechanical dilator and
fenoxazoline hydrochloride are cumulative. Further studies that include
patients with nasal obstruction would allow us to better evaluate
the benefit of a therapy combining both
treatments.
Key Words: active posterior rhinometry • nasal airflow resistance • nasal mechanical dilator device • topical decongestant
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Introduction
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The
main sites of nasal airflow resistance (NR) are the nasal valves and
the turbinates. Ordinarily, NR accounts for approximately one half of
the total flow resistance of the respiratory system1
2
and
is responsible for the same ratio of the total work of
breathing.3
However, anatomic and physiologic
factors may induce nasal obstruction and dramatically increase NR.
Besides surgical therapies, two types of treatments used to reduce NR
and, therefore, to improve breathing are presently available:
vasoconstrictors and nasal dilators. Chemical treatments, such as
vasoconstrictors, act by decreasing the nasal mucosal swelling and
reducing the turbinate section, and their effectiveness in lessening NR
has been widely reported.4
5
6
7
Mechanical treatments, such
as nasal dilators, act by expanding ala nasi and increasing the nasal
valve area, and objective decreases in NR have been reported with
different internal mechanical nasal devices.6
7
8
9
10
As the
nasal valves and turbinates are anatomically associated in series, one
may ask whether the effects of a vasoconstrictor and a nasal dilator
should be cumulative, especially because a previous study showed no
significant correlation between the decreases in NR induced by either
treatment.7
The goal of this study, therefore, was to evaluate the isolated and
combined effects of an internal nasal dilator (Nozovent; Prevancure;
Sté Pouret; Paris, France) and a topical decongestant (Aturgyl;
Synthelabo; Le Plessis-Robinson, France) on NR assessed by active
posterior rhinometry at the 0.5 L/s flow level.
|
Materials and Methods
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Subjects
The study was performed in a group of 17 asymptomatic healthy
subjects (9 were male and 8 were female), aged 20 to 24 years, with no
upper or lower respiratory complaints. Each subject gave informed
consent to participate in the study. All subjects tolerated the nasal
dilator well.
NR Measurement
NR was measured by active posterior rhinometry. The subjects
breathed quietly through a rigid nasal mask with the mouth occluded by
a closed mouthpiece in which a catheter with an inside diameter
of 3 mm was inserted to measure pharyngeal pressure. Transnasal
pressure (PTN) was measured by a differential pressure
transducer (model SCX 01D; Sensym; Sunnyvale, CA) with one port
connected to the nasal mask and the other to the catheter. Nasal flow
(
) was measured by a screen pneumotachograph (Jaeger Lilly;
Würzburg, Germany) connected to a similar pressure transducer.
Pressure and flow signals were low-pass filtered and sampled at 128 Hz
for 16 s by an analog to digital converter. To determine
the nonlinear NR, PTN and data were analyzed by
linear regression analysis of PTN over
||||, according to the following equation:
 | (1) |
where Po is a constant, and K is a
constant that accounts for the nonlinear flow dependence of
PTN.
NR was then calculated for a flow of 0.5 L/s, as NR = 0.5 K. Three to
four consecutive measurements were performed, and NR was taken as the
average of the NR estimates corresponding to an
r2 value > 99%.
Experimental Protocol
In each subject, NR was measured under four conditions: (1) in
the basal state; (2) while breathing with the nasal mechanical dilator,
which consists of a plastic bar with each extremity ending in a tab to
be placed inside each nostril; (3) after inhalation of two puffs of an
-adrenergic agonist consisting of a 0.1% solution of fenoxazoline
hydrochloride; and (4) after pretreatment with a topical decongestant
while breathing with the internal nasal dilator.
For each treatment, a 10-min stabilization period was observed before
NR measurements were taken. The order of the treatments was the same
for all the subjects. In five subjects, NR was measured again 20 min
after treatment with both the internal nasal dilator and the topical
decongestant. The efficacy of each treatment was assessed by the
corresponding decreases in NR when using the nasal dilator
(NRN), after using fenoxazolide hydrochloride
(NRA), and when using both
(NRN + A).
Data Analysis
NRs were compared by one-factor analysis of variance for
repeated measures, completed as necessary by modified paired
t tests and by linear regression analysis. A p value
< 0.05 was considered to be statistically significant. Values are
given as mean ± SD, except when otherwise indicated.
|
Results
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Typical PTN- curves obtained in a
representative subject at the basal state and with the different
treatments are shown in Figure 1
.
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Figure 1. Typical PTN- curves obtained in
a representative subject in the basal state, with the internal nasal
dilator, after treatment with the topical vasoconstrictor, and with the
association of the two.
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|
In the basal state, NR was 1.65 ± 0.54 cm
H2O/L/s. When breathing with the nasal dilator,
NR was 65 ± 16% of its basal value (p < 0.001) with a mean
NRN of 0.63 ± 0.46 cm H2O/L/s
(Figs 2
and 3
). After treatment with the topical decongestant, NR was 63 ± 18% of
its basal value (p < 0.0001) with a mean NRA of
0.62 ± 0.36 cm H2O/L/s (Figs 2
and 3)
. No
significant difference was found between NRN and
NRA (Fig 3)
; however, no significant correlation was
observed between these latter decreases. When breathing with the nasal
dilator after treatment with the topical decongestant, NR was
31 ± 10% of its basal value (p < 0.001) with a mean
NRN + A of 1.17 ± 0.51 cm
H2O/L/s (Figs 2
and 3)
.
NRN + A was significantly higher than
NRN and NRA (p < 0.0001).
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Figure 2. Mean values (n = 17) in NR observed in the basal
state (base) with the internal nasal dilator (No) after treatment with
the topical vasoconstrictor (At), and with the
association of both (No + At). Bars indicate SE.
** = significantly lower than basal NR values
(p < 0.001); •• = significantly lower than NR with
the nasal dilator and NR with the topical decongestant
(p < 0.001).
|
|
No significant difference was found between
NRN + A and the sum
NRN + NRA. As shown in
Figure 4
, NRN + A strongly correlated with the sum
NRN + NRA
(NRN + A = 0.80 [NRN +
NRA] + 0.15; r = 0.96; p < 0.0001), but the
slope of the regression line of NRN + A vs
NRN + NRA was significantly lower than
unity (p < 0.003).
In the five subjects in whom additional NR measurements were performed,
the NR values measured 20 min after the treatment with both the nasal
dilator and the topical decongestant were not significantly different
from those measured 10 min after inhalation of the topical
decongestant.
|
Discussion
|
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The efficacy of topical decongestants in reducing NR has been
widely reported, and vasoconstrictors actually remain the reference
pharmacologic treatment for nasal obstruction. By contrast, the
objective efficacy of the mechanical treatments recently designed to
open the nasal passages remains less well documented.6
7
8
9
10
A recent study has demonstrated that an internal nasal dilator was as
effective as treatment with a topical decongestant in improving nasal
breathing but that most subjects responded differently to each of these
two treatments.7
The most plausible explanation is that
the two treatments act at different anatomic levels, and anatomy is
likely to vary from one subject to another, which suggests that the
effects of the two treatments might be cumulative. The present study
was therefore initiated to compare the isolated and combined effects of
an internal nasal dilator and of a topical decongestant on NR.
Active posterior rhinometry, which allows direct NR measurement during
normal tidal breathing, is now used to evaluate NR. As NR is flow
dependent, a choice has to be made regarding the flow or pressure level
at which it is calculated. In this study, NR was calculated at the 0.5
L/s flow level, because previously it has been demonstrated a higher
sensitivity of NR when calculated at a fixed flow than when calculated
at a fixed PTN for assessing the effects of decongestants
or nasal mechanical dilators.7
The high r2 values (> 99%) prove that an
equation as simple as equation 1
is sufficient to accurately describe
the PTN-flow relationship, at least in normal subjects.
Furthermore, as demonstrated in the Appendix, equation 1
provides NR
values similar to those calculated at the same flow level as the Rohrer
equation, whether at the basal state or under mechanical and
decongestant treatments.
To avoid the possible influence of diurnal variation on total
NR,11
all our subjects were studied at the same time of
day. The order of the conditions was the same for all subjects, namely,
base, nasal dilator, topical decongestant, and topical decongestant
plus nasal dilator, because the decongestant effects of an
-adrenergic agonist persist for variable periods of time after its
administration.4
The duration of the stabilization period
observed for each treatment was chosen on the basis of the study by
Hamilton,4
who observed that NR was always significantly
decreased and relatively stable within the 10- to 20-min period
following topical decongestant administration.
Our basal values of NR were in the range of those calculated in normal
subjects at the same or a similar reference flow.1
7
12
13
The NRN was similar to those previously reported in
patients with respiratory sleep disorders8
10
and in
normal subjects,7
and the percentage of NRA
was in the range of those previously reported in normal
subjects7
and in patients with nasal congestion after
inhalation of topical decongestants.4
As previously
observed in healthy subjects without upper airway complaints, the nasal
dilator and a topical vasoconstrictor resulted in comparable, but not
significantly correlated, mean decreases in NR.7
As illustrated by Figures 2
and 3
, the combination of the nasal dilator
and the topical decongestant decreased NR significantly more than
either one alone. This result could be expected because the two
treatments increase the nasal cross-sectional area at different
anatomic levels. Indeed, the nasal dilator acts by expanding nasal
valves, whereas the topical decongestant acts by reducing the turbinate
section via local decongestion of the nasal mucosa. Similar results
relating to an internal spring nasal dilator and a nasal decongestant
were obtained previously in patients with anterior nasal
obstruction6
by using an anterior rhinomanometric
technique and by calculating resistances for each nostril separately at
a 1.5 cm H2O PTN.
The fact that no significant difference was found between
NRN + A and the sum
NRN + NRA does not
allow the conclusion that the effects on NR of the nasal dilator and
the topical decongestant are additive. Indeed, the flow dependence of
the resistance of the nasal valves and turbinates makes it impossible
to resolve total NR into the resistive components of the different nare
segments. Besides, the fact that the slope of the regression line of
NRN + A vs
(NRN +
NRA) is significantly lower than unity
suggests that, in subjects without complaint of nasal congestion or
obstruction, the effects of the nasal dilator and topical decongestant
are not totally additive. This might be explained by a slight expanding
effect of the nasal dilator on the turbinates and/or a slight
decongestant effect of the topical decongestant in the valve region. By
contrast, a time decrease of the topical decongestant effect is highly
improbable because in the five subjects in whom an additional NR
measurement was performed, the NR values obtained 20 min after the
treatment with both the nasal dilator and the topical decongestant were
similar to those previously measured 10 min after inhalation of the
topical decongestant.
In conclusion, our results demonstrate the synergetic effects of a
nasal dilator and a topical decongestant. Further studies that include
patients with a deviated nasal septum and/or nasal congestion would
allow us to better evaluate the benefit of such therapy and to
correlate its effectiveness with the nasal obstruction etiology.
|
Appendix 1
|
|---|
Let us consider the two following equations that describe the
nonlinear PTN- relationship:
 | (2) |
 | (3) |
where K1 is a constant that accounts for
the linear flow dependence of PTN and
K2 is a constant that accounts for its nonlinear
flow dependence. Because NR is calculated at the 0.5 L/s flow, NR
derived from equation 1
is given by
 | (4) |
and NR derived from equation 2
is given by
 | (5) |
In our previous study,7
we showed that the relative
contributions of the K1 and
K2 terms to NR2 were
identical, either at the basal state or under mechanical and
decongestant treatments, ie, that the
K1/K2 ratio in each
condition was about 1:2. Consequently, equation 4
reduces to
 | (6) |
Comparison of equation 5
with equation 3
shows that
NR2 and NR1 are similar NR
estimates, with K = 2K2. This explains why
comparable NR values and NR responses to mechanical or decongestant
treatments are found whether NR is calculated from equation 1
or
equation 2
.
|
Acknowledgements
|
|---|
We gratefully acknowledge Juliette Delavennat,
Cécile Durand, Marieke Geminel, and Audrey Gourdin for their
valuable assistance.
|
Footnotes
|
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Correspondence to: Anne-Marie Lorino, PhD, Service de
Physiologie-Explorations Fonctionnelles, Hôpital Henri Mondor,
94010 Créteil, France; e-mail:
anne-marie.lorino@hmn.ap-hop-paris.fr
Abbreviations: NR = nasal airflow resistance; NRA = decrease in
nasal airflow resistance observed after using fenoxazoline
hydrochloride; NRN = decrease in nasal airflow
resistance observed when using the mechanical dilator;
NRN + A = decrease in nasal airflow
resistance observed when using both the mechanical dilator and
fenoxazoline hydrochloride; PTN = transnasal pressure;
= nasal flow
Received for publication July 28, 1998.
Accepted for publication January 6, 1999.
|
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TOP
Abstract
Introduction
