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E. Hizal and O. Cakmak
as a treatment for chronic nasal obstruction: a systematic review. Clin Otolaryngol. 2011;36(2):106–13.
51. Andre RF, Vuyk HD, Ahmed A, Graamans K, Nolst
Trenite GJ. Correlation between subjective and
objective evaluation of the nasal airway. A systematic review of the highest level of evidence. Clin
Otolaryngol. 2009;34(6):518–25.
52. Batra PS, Seiden AM, Smith TL. Surgical management of adult inferior turbinate hypertrophy: a
systematic review of the evidence. Laryngoscope.
2009;119(9):1819–27.
53. Straszek SP, Taagehoj F, Graff S, Pedersen
OF. Acoustic rhinometry in dog and cat compared
with a uid-displacement method and magnetic resonance imaging. J Appl Physiol. 2003;95(2):635–42.
54. Straszek SP, Pedersen OF.Nasal cavity dimensions
in guinea pig and rat measured by acoustic rhinometry and uid-displacement method. J Appl Physiol.
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55. Kaise T, Ukai K, Pedersen OF, Sakakura Y.Accuracy
of measurement of acoustic rhinometry applied
to small experimental animals. Am J Rhinol.
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56. Mostafa BE. Detection of adenoidal hypertrophy using acoustic rhinomanometry. Eur Arch
Otorhinolaryngol. 1997;254(Suppl 1):S27–9.
57. Riechelmann H, O'Connell JM, Rheinheimer MC,
Wolfensberger M, Mann WJ.The role of acoustic rhinometry in the diagnosis of adenoidal hypertrophy in
pre-school children. Eur J Pediatr. 1999;158(1):38–41.
58. Riechelmann H, Rheinheimer MC, Wolfensberger
M.Acoustic rhinometry in pre-school children. Clin
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59. Isaac A, Major M, Witmans M, Alrajhi Y, FloresMir C, Major P, etal. Correlations between acoustic
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60. Buenting JE, Dalston RM, Drake AF.Nasal cavity
area in term infants determined by acoustic rhinometry. Laryngoscope. 1994;104(12):1439–45.
61. Buenting JE, Dalston RM, Smith TL, Drake
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New Measurement Methods
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intheDiagnostic ofNasal
Obstruction
GunterH.Mlynski, GiorgiGogniashvili,
andAchimG.Beule
27
Core Messages
• Accurate preoperative analysis of extent and
causes of nasal breathing complaints in combination with a stronger physiological perspective in surgical therapy is needed if we
want to make progress beyond unsatisfactory
long-term outcomes with inadequate improvement in nasal airway obstruction and frequent
postoperative sicca symptoms.
• New measurement methods need to be used to
objectify nasal obstruction, since rhinomanometry is only capable of adequately differentiating the degree of obstruction, but not
all its causes.
• Rhinoresistometry, a renement of rhinomanometry, makes it possible to objectively
determine not only the degree of obstruction
G. H. Mlynski
Stolpe auf Usedom, Germany
e-mail: stolpe@mlynski.com
G. Gogniashvili
Khujadze-Gogniashvili ENT Clinic, Tbilisi, Georgia
A. G. Beule (*)
Department of Otorhinolaryngology, University
Hospital Münster, Münster, Germany
Department of Otolaryngology, Head and Neck
Surgery, University Medicine Greifswald,
Greifswald, Germany
e-mail: achimgeorg.beule@ukmuenster.de
but also to differentiate between swelling,
skeletal stenosis, inspiratory collapse of the
nasal valves and pathological turbulence as
possible uid dynamics causes of nasal
obstruction.
• By combining rhinoresistometry with acoustic
rhinometry, it is possible to accurately localize
skeletal stenosis and determine the causes of
pathological turbulence.
• Rhinoresistometry and acoustic rhinometry
only enable the objective measurement of
conditions in the nose at the time of measurement. Long-term rhinometry has been developed to overcome this limitation.
• Long-term rhinometry yields information
about the nasal cycle in specic conditions
and provides an objective measurement of
reactive congestion over a 24-h period under
the usual conditions of the patient’s everyday
livings conditions.
• New techniques for the diagnostic evaluation
of nasal obstruction make it possible to set
better surgical indications prior of functional
nasal surgical interventions and to better plan
the surgery.
• Rhinoresistometry, acoustic rhinometry and
long-term rhinometry now offer the practitioner tools that allow essential postoperative
quality control in functional rhinosurgery.
© The Author(s), under exclusive license to Springer Nature Switzerland AG 2023
Ö. Ö. Celebi, T. M. Önerci (eds.), Nasal Physiology and Pathophysiology of Nasal Disorders,
https://doi.org/10.1007/978-3-031-12386-3_27
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27.1 Preliminary Remarks
Despite several signicant advances in the area of
procedures for the diagnostic evaluation of nasal
obstruction, there has been a striking failure until
now to implement routine objective preoperative
diagnostic testing prior to functional and aesthetic
rhinosurgery, and for postoperative quality
control.
To objectify nasal obstruction currently rhinomanometry (RMM) is being used worldwide [1].
This method measures nasal airow provided
pressure and thereby enables the physician to
estimate the extent of nasal obstruction. Also, differentiation between a constriction caused by
congestion or skeletal stenosis is possible. A critical functional analysis of the important nasal
valve area is not possible even though a pathological internal nasal valve is a frequent cause for
an obstructed nasal breathing. Moreover, the
important endonasal airow pattern regarding the
transition of laminar to turbulent ow is not sufciently objectied. This is one reason for the
fact that pathological turbulence is being seldom
analysed as possible pathophysiological factor in
the pathophysiology of nasal obstruction and
thereby the underlying causes overlooked, resulting in unsatisfactory surgical results.
However, evaluation of nasal airway patency
is not sufcient by itself and in some cases may
even be misleading. Thus, nasal airway resistance can be decreased by resecting the nasal turbinates, thereby improving airow. The results of
RMM testing might simulate functional improvement [2], even though, in fact, nasal respiratory
function has been largely destroyed after resection of the nasal turbinates [3–13].
RMM only provides an evaluation of nasal
airow at one ow velocity. However, nasal resistance varies depending on the ow velocity due
to constantly changing endonasal generation of
turbulence and also often varies dynamically
because of the collapse of the nasal valve from
negative pressure as a result of the Bernoulli
effect (see Sect. 20.2.2).
For these reasons, we must consider RMM as
being of limited value for the diagnostic evaluation of nasal obstruction [2]. Until now, this has
the effect of leaving many surgeons sceptical
about the overall value of functional testing in the
eld of functional rhinosurgery. Consequently,
RMM has been further rened to rhinoresistometry (RRM) [2, 14–17].
In recent years, acoustic rhinometry (ARM)
has been established as an additional analysis
tool for rhinologic diagnostic testing (see Chap.
26). It enables measurement of the cross- sectional
areas of the nasal ow channel in relation to the
distance from the external nasal ostium [1, 18].
Because airway resistance does not solely depend
on the magnitude of the cross-sectional area of a
ow channel but also on its shape, ARM cannot
be used to estimate the magnitude of nasal
obstruction. However, ARM permits conclusions
about the location of narrowings and possible
causes and locations of pathological turbulence
in the nose (see Sects. 27.2.1.1 and 27.2.3).
RMM, RRM and ARM only permit an assessment of nasal obstruction at the time of measurement. To gain insight into the rhinologic function
of the nose during patient’s normal physical
activity, long-term rhinometry (LRM) was developed [19, 20]. LRM technique permits sidespecic measurement of the nasal cycle over a
24-h period. It yields information on the functionality and adaptive capacity of the nose during
periods of increased oxygen demand resulting
from physical activity under the typical conditions of a patient’s everyday life.
This book devotes a separate Chapter to RMM
and to ARM.In this chapter, RRM and LRM will
be described in Sects. 27.2.1 and 27.2.2. In addition, we will show how ARM can be used to
make deductions about the causes of pathological
nasal valve collapse and of pathological nasal
turbulences (see Sect. 27.2.1.1). Moreover, we
will demonstrate how the combination of RRM
an ARM (and in specic cases LRM) makes it
possible not only to objectify the extent of nasal
obstruction but also to differentiate among its
possible causes. This diagnostic algorithm will
be illustrated by means of clinical examples.
The subjective sensation of nasal obstruction
depends not solely on airway resistance but also
on several additional factors, and therefore, it
cannot be completely measured even with the
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337
most rened methods [21]. Especially because of
the known discrepancy between objective measurements of functional impairment and subjective sensations [22–26], the objectication of the
different aetiologies of functional impairment is
important for effective planning of the appropriate treatment.
A precise preoperative analysis of the extent
and the cause of breathing difculties in the nose
in combination with a greater consideration of
physiological aspects in surgical therapy is necessary if we want to make progress in long-term
results [3–5, 7–9, 13, 27–32]. The latency
between surgery and the emerging of sicca symptoms, which often takes several years, reects the
compensatory capacity of the healthy mucosa
[33]. This makes it more difcult to recognize the
causal relationship with previous surgery, something that will only be possible in the context of
prospective cohort studies that look at long-term
outcomes [34, 35].
27.2 New Techniques
fortheDiagnostic Evaluation
ofNasal Obstruction
In the following sections, we will describe new
techniques for objectifying nasal obstruction and
its causes.
27.2.1 Rhinoresistometry (RRM)
Motivated by the inadequacy of information
obtained through rhinomanometric testing and
the capabilities of modern computer technology,
RMM was further rened into RRM [2, 14–17].
Based upon the laws of uid dynamics, this
method uses values measured by rhinomanometry of the pressure difference between the external nasal orice and the choanal area
simultaneously with the airow velocity to compute diagnostically relevant parameters. The
equipment and the measurement procedure used
in RRM completely correspond to this used in
active anterior RMM. However, for the RRM
equipment, the guidelines established by the
“International Committee on Objective
Assessment of the Upper Airways” [1] need to be
followed. In addition, to determine not only the
extent of nasal obstruction, RRM permits the differentiation between the possible causes of a
nasal obstruction: narrowing caused by swelling,
and/or by skeletal stenosis, and/or by inspiratory
collapse of the nasal valves, and/or pathologically turbulence behaviour.
The results of RRM are presented by means of
graphs and numerical values. The graphs allow
the reader to make a “diagnostic at a glance”, and
the numerical values are used for precise analysis
and pre- and post-therapeutic comparisons.
27.2.1.1 Graphical Presentation
Figure 27.1 shows the graphic illustrations used
in rhinoresistometry. The ndings are presented
in red for the right side of the nose and blue for
the left side. Measurements taken before mucosal
decongestion are shown in a light colour.
Measurements taken after decongestion are
shown in a dark colour.
Flow-dependent increase in resistance is presented in the upper graph (Fig.27.1). It is apparent that in both inspiration and expiration, nasal
airway resistance rises with increasing ow
velocity.
We know from physiology that during moderate physical activity, maximal breathing ow
(both sides of the nose combined) of approx.,
500mL/s is required to maintain adequate oxygen supply. During heavy physical activity, the
oxygen requirement is met through supplemental
bypass breathing through the mouth. As a result,
ow velocities rarely exceed 500 mL/s in the
nose. For this reason, we describe the range
between 0 and 500mL/s as “physiologic breathing range” (see Sect. 20.1). Experience tells us
that during the rhinometric test situations,
patients breathe more deeply than necessary. The
patient achieves ow velocities of up 800mL/s.
This is reason why we observe very long inspiratory and expiratory curves in rhinomanometric
testing. Therefore, in RRM, the inspiratory and
expiratory portions of the curves are marked with
points to indicate where the ow through the
right and left side of the nose together contributes
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R[sPa/ml] R[sPa/ml]
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3.0
2.5
2.0
1.5
1.0
0.5
Inspiration InspirationExpiration
0.0
-750 -500 -250
turb. turb.
Inspiration Expiration Inspiration Expiration
lam.
750‒500‒250
Fig. 27.1 Graphic representation of the ndings from
RRM.Right side of the nose, red; left, blue. Light-colored
curves: before decongestion of the mucosa. Dark-colored
curves: after decongestion of the mucosa. Upper graph:
nasal airway resistance. Lower graph: turbulence ow
Flow[ml/s]
Flow[ml/s] 250 500 750
250 500
750
3.0
2.5
2.0
1.5
1.0
0.5
0.0
-750 -500 -250
lam.
750‒500‒250
behavior of the nasal airstream. x-axis: left of the midline:
inspiratory ow in mL/s. right of the midline: expiratory
ow in mL/s. y-axis: upper graph: resistance in sPa/mL.
lower graph: turbulent ow behavior: lam. laminar, turb.
turbulent
Flow[ml/s]
Flow[ml/s] 250 500 750
Expiration
250 500 750
up to 500mL/s. This makes it possible to see at a
glance how much each side of the nose is contributing to total ow if moderate physical activity is
performed and what levels of nasal ow resistance are acting on each side of the nose during
“physiologically required airow”.
The graph enables us to evaluate nasal airway
resistance for each side of the nose “at a glance”:
the higher the course of the curve, the more pronounced is the nasal obstruction. In Fig.27.1 the
right side of the nose is moderately obstructed
before decongestion. After decongestion the
resistance has normalized. On the left side, the
resistance is physiological before and after
decongestion.
As in RMM, by examining the distance
between the curves before and after decongestion, we can differentiate between the portions of
nasal airway resistance due to congestion and due
to skeletal narrowing. Figure27.2 shows rhinoresistometric resistance curves of a nose with
mucosal swelling on both sides. After decongestion, on the left side the resistance drops to very
small values but on the right side an increased
resistance remains, indicating an additional skeletal narrowing.
In addition to identifying swelling and skeletal
stenosis at a glance, the graph can also be used to
identify whether or not there is signicant inspiratory nasal valve collapse (NVC). For this purpose, a calculated curve for inspiration is shown
as a dotted line, which shows the ow-dependent
increase in airway resistance with a stable vestibular sidewall without collapse. The measured
and calculated curves are congruent if the nasal
valves are not sucked in Fig.27.2. Deviations of
the measured (solid) line from the dotted line
indicate abnormalities in the width of the ow
channel, such as those caused by NVC (Fig.27.3).
The greater the extent of NVC, the more pronounced the measured curve will deviate from
the calculated curve [36]. A slight deviation at
1.5
1.0
R[sPa/ml] R[sPa/ml]
Flow[ml/s]
Flow[ml/s]
Flow[ml/s]
Flow[ml/s]
750
R[sPa/m] R[sPa/m]
before decong. after decong. before decong. after decong.
ab
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3.0
2.5
2.0
0.5
Inspiration InspirationExpiration Expiration
0.0
-750 -500 -250
Fig. 27.2 Rhinoresistometry resistance curves of a nose obstructed by mucosal congestion on both sides and additional
skeletal constriction on the right
3.0
2.5
2.0
250 500 750 -750 -500 -250
3.0
2.5
2.0
1.5
1.0
0.5
0.0
250 500 750
3.0
2.5
2.0
1.5
1.0
0.5
Inspiration
0.0
-750 -500 -250
Fig. 27.3 Resistance curves measured by rhinoresistometry (continuous lines) and resistance curves calculated
with a stable lateral vestibular wall (dotted lines on the
inspiratory side of the curve). (a) Before decongestion: no
NVC. (a) After decongestion and left before deconges-
high ow velocities (> 500 mL/s) indicates a
physiological collapse of the nasal valve
(Fig.27.3a). One can identify pathological collapse of the nasal valve based on a signicant
250 500 750
deviation of the measured from the calculated
curves (Fig.27.3b).
In the RRM, the lower graph (Figs.27.1 and
27.5) displays the turbulence behaviour of nasal
airow in relation to airow velocity. The level
on the X-axis corresponds to pure laminar ow,
1.5
1.0
0.5
InspirationExspiration Exspiration
0.0
-750 -500 -250
tion: physiological NVC.Left after decongestion: pathological NVC rhinoresistometric resistance curves of a
nose with nasal valve collapse (a) physiologic nasal valve
collapse; (b) pathological nasal valve collapse
250 500
and the upper blue-grey striped bars correspond
to complete turbulence.
At very low ow velocities, the ow is completely laminar in any ow channel and thus in
the nose as well [37]. As the velocity of ow
increases, both in inspiration and expiration
laminar ow portions transition more and more
into turbulent ow portions (see 20.4). This
“transition range” is important for the respiratory function of the nose. It creates the optimal
340
turb
Flow[ml/s]
Flow[ml/s]
0750
before decong. after decong.
before decong. after decong.
Right
Left
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G. H. Mlynski et al.
situation for conditioning the air. It provides
adequate mucosal contact by the streaming air
without leading to dryness or pathological cooling of the mucosa (see Sect. 20.4). At very high
ow velocities, nasal airow becomes completely turbulent [37–42]. Complete turbulence
hardly ever occurs in a normal nose. When high
airow velocities are required to provide adequate oxygen supplies during heavy physical
stress, mouth-bypass breathing is unconsciously
employed so that the nasal airstream decreases
(see Sect. 20.1).
Nasal airow should become more turbulent
when the mucosa is in a decongested state (corresponding to the working phase of the nasal
cycle; see Sect. 20.4) as a condition for sufcient
mucosal contact than in the congested state (corresponding to a resting phase in the nasal cycle).
In the resting phase (decongested mucosa), the
ow character should not become purely turbulent up to an airow velocity of 200 mL/s
(Fig.27.1 bilaterally; Fig.27.4 right side of the
nose; see Sect. 20.4), and thus reduces turbulence
in the nose.
At pathological turbulence, there is a rapid
transition so that pure turbulence will already
develop in the nose at ow velocities <200mL/s
(Fig.27.4. left side of the nose).
Complete turbulence in the nose can generate elevated airway resistance, and besides it
also causes sicca symptoms with a sense of
obstruction.
27.2.1.2 Numerical Evaluation
Besides using the graphical representation to get
a “diagnosis at a glance” numerical values are
calculated for a more precise assessment of
extent and causes of obstruction (Fig.27.5).
Differences between individuals with the
same degree of nasal obstruction may have quite
varied levels of symptoms depending on age,
gender, body mass index, level of the physical tness and additional medical conditions.
Therefore, the reference values presented here
.
Inspiration
lam.
-750 -500 -250
250
Exspiration
500 750
turb.
Inspiration Exspiration
lam.
-750 -500 -250
Fig. 27.4 Turbulence curves of rhinoresistometric measurements
before after
Decongestant
Resistance [sPa/ml]
inspr. at Flow 250 ml/s
4,67 1,51
Hydraulic Diameter [mm]
3,5 4,4
Resistance Increase [%]
due to nasal valve
-- >100
Begin of nasal valve
collapse
-- 159
Full turbulence
inspr. at flow [ml/s]
42 68
= extrapolated
before decong. after decong. before decong. after decong.
R[sPa/ml]
3.0
2.5
2.0
1.5
1.0
0.5
Inspiration Expiration
0.0
-750 -500 -250 250 500 750
turb.
Inspiration Expiration
lam.
-750 -500 -250 250 500 750Flow[ml/s]
Flow[ml/s]
R[sPa/ml]
3.0
2.5
2.0
1.5
1.0
0.5
Inspiration Expiration
0.0
-750 -500 -250 250 500 750
turb.
Inspiration
lam.
-750 -500 -250 250 500 750Flow[ml/s]
Flow[ml/s]
Expiration
Fig. 27.5 Rhinoresistometric resistance curves and turbulence curves with corresponding numerical values
250 50
before after
Decongestant
Resistance [sPa/ml]
inspr. at Flow 250 ml/s
0,16 0,04
Hydraulic Diameter [mm]
5,1 7,8
Resistance Increase [%]
due to nasal valve
-- --
Begin of nasal valve
collapse
-- --
Full turbulence
inspr. at flow [ml/s]
337 201
R
Max. inspir. flow
NVC
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341
should not be applied too rigidly. They are simple
benchmarks for the purpose of orientation. The
values were determined through studies on both
rhinologically healthy patients and patients with
nasal obstruction [21, 43–45].
Nasal resistance (R) is numerically represented at a ow velocity of 250mL/s before and
after decongestion. As reported in Sect. 20.6, an
airow of approx. 500 mL/s is required in the
physiological breathing range. If both nasal sides
make an equal contribution to this requirement,
250 mL/s would ow per second through each
nasal side.
Thus, for the practical evaluation of nasal
obstruction, the resistance measured at 250mL/s is
an appropriate value ([42, 46]; see also Sect. 20.1).
The extent of nasal obstruction can be estimated
according to the reference values in Table27.1.
The hydraulic diameter (dh) is a measure for
the width of the nasal cavum. The nasal cavity is
a space with irregular cross sections. Therefore,
its width cannot be dened simply by its diameter
as it is common with a perfectly round tube. In
technological science, the usual practice when
dealing with an irregular cross section of a channel is to use the “hydraulic diameter”. This is the
diameter of a tube of the same length with a
round cross section for a channel that has the
same resistance to airow as the irregularly
shaped ow channel. The gures shown in
Table 27.2 can be used as reference values for
estimating the width of the interior of the nose.
The hydraulic diameter of both sides of the
nose is calculated before and after the decongestion. Using these values, one can identify a mucosal swelling and a skeletal narrowing as causes
for nasal obstruction. The increase in magnitude
Table 27.1 Reference values of nasal obstruction via
resistance
Extent of obstruction
Resistance at
250mL/s
<0.17sPa/mL No obstruction Physiological
0.17–
0.35sPa/mL
0.36–
0.70sPa/mL
>0.70sPa/mL Severe obstruction
on one side of the
nose Interpretation
Slight obstruction
Moderate
obstruction
resistance
Pathological
resistance
Table 27.2 Reference values for the interior of the nose
based on the hydraulic diameter
Hydraulic diameter Width of the nose
<5.0mm Too narrow
5.0–6.5mm Normal width
>6.5mm Too wide
∆R
R
Inspir. flow 500ml/s F
Fig. 27.6 Calculation of numerical value (∆R) for the
increase of nasal resistance by the nasal valve collapse
of the hydraulic diameter by decongestion is an
index of the extent of mucosal swelling. If the
hydraulic diameter remains low after decongestion, this is evidence of skeletal stenosis. A very
large hydraulic diameter indicates a nose that is
pathologically too wide.
Numerical values for the NVC are calculated
before and after decongestion. Therefore, the calculated course of the ow-dependent increase of
resistance without nasal valve collapse (see Sect.
27.2.1.2) is used. The numerical value for the
increase of nasal resistance caused by the valve
collapse (∆R) is calculated at a ow of 500mL/s
(Fig. 27.6). Using this parameter, physiological
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G. H. Mlynski et al.
and pathological nasal valve collapse can be differentiated. The reference values are indicated in
Table 27.3. In addition, the minimal ow at the
starting point of the inspiratory nasal valve collapse (F
) is indicated as value. This parameter
NVC
indicated the ow, at which the calculated curve of
nasal resistance starts to differ from the measured
one. Physiologically, the nasal valve should not
show an inspiratory nasal valve collapse up to
500mL/s.
The numerical value for the increase in resistance from NVC (∆R) allows us to estimate the
magnitude of the suction phenomena as well as to
differentiate between physiological and pathological NVC in accordance with Table27.3. In
addition, the nasal airow velocity at which collapse begins (F
) is quantied (Table 27.4).
NVC
The nasal valves should not be signicantly collapsed in (∆R>25%) at airow velocities up to
the maximum physiologically required nasal airow of 500mL/s.
The transition to turbulence in endonasal airow is numerical classied according to the ow
velocity, at which ow is completely turbulent.
For the respiratory function of the nose airow
within the physiologic breathing range (see Sect.
20.1) in the transition from laminar to turbulent
ow allows a physiological amount of contact to
the endonasal mucosa (see Sect. 20.4). In a
decongested state, like a working phase of the
nasal cycle (see Sect. 20.5), complete turbulence
Table 27.3 Differentiation between physiologic and
pathologic nasal valve collapse (NVC)
ΔR NVC
≤25%
>25% Pathological
Table 27.4 Classication of turbulence based on the
commencement of full turbulent ow at an inspiratory
ow
Full turbulence at inspiratory ow
(mL/s)
≥200mL/s
<200mL/s Pathological
NVC nasal valve collapse, ΔR refers to the difference
between measured and calculated resistance at 500 m/s
endonasal ow
Physiological
Turbulence
behaviour
Physiological
should be achieved at a ow velocity of
<200mL/s. This ow value is indicated as “Full
turbulence inspiratory at ow (mL/s)” and corresponds in the graph to a dotted (red or blue) line
in the inspiratory section (Figs.27.4 and 27.5).
27.2.1.3 Objectication ofNasal
Obstruction withRRM
The diagnostic possibilities of RRM are illustrated in the following part using a rhinoresistometric result of the patient (cf. Fig.27.5).
At one glance, the graph of the right nasal side
allows detection of a severe obstruction due to the
steep course of nasal resistance curve. As aetiology,
a skeletal stenosis can be detected because resistance after decongestion persists in an increased
matter despite some effect of decongestion.
Besides, on this nasal side a pathological NVC
(with the steeper course of the measured, continuously illustrated resistance line than the calculated,
dotted resistance line) and a pathological behaviour
of turbulence generation (fast transition to full turbulence at an inspiratory ow of <200mL/s) attribute to the increase of nasal resistance.
The corresponding numerical values after
decongestion conrm these pathologies. On the
right nasal side after decongestion, the ow resistance is pathologically increased with 1.51sPa/
mL, and the nose remains too narrow after decongestion (hydraulic diameter: 4.4 mm). Besides,
the contribution of inspiratory nasal valve collapse to nasal resistance at 250 mL/s is larger
than 100% and nasal airow is already completely turbulent at 68mL/s.
The curve of nasal resistance on the left nasal
side is very shallow. With 0.04 sPa/mL, nasal resistance after decongestion is pathologically
decreased. This nasal side is pathologically wide
(hydraulic diameter: 7.8 mm). Also, after decongestion the behaviour of turbulence is marginal
(complete turbulence already at a ow of 201mL/s).
27.2.2 Acoustic Rhinometry (ARM)
Acoustic rhinometry has been extensively presented in Chap. 26 with its possibilities and
limitations.
10.0
11.0
12.0
[cm2]
https://t.me/medicina_free
27 New Measurement Methods intheDiagnostic ofNasal Obstruction
ARM is an appropriate method to objectify
stenosis due to congestion and skeletal deformities [1, 2, 15–17]. It is not suitable to assess the
extent of nasal obstruction, because nasal resistance depends not only on the magnitude of the
cross-sectional area but also on their conguration. In case of similar cross- sectional areas, the
channel with a slit-like conguration has a higher
resistance than the more circular one, because the
wall area and thereby the friction are larger
within the slit-like channel (see Sect. 20.2.1).
ARM should therefore only be used in connection with a dynamic measurement method for
assessment of resistance, like rhinomanometry or
rhinoresistometry. Apart from this limitation,
9.0
8.0
7.0
6.0
5.0
4.0
3.0
2.0
1.0
0.0
-1.0
-5.0
-4.0 -3.0 -2.0 -1.0 0.01.0 2.03.0 4.05.0
ARM nevertheless accomplishs a valuable contribution to the diagnostic of nasal obstruction. It
allows a sufciently exact assessment of the
Fig. 27.7 Calculation of the opening angle of the diffuser
φ using acoustic rhinometry
geometry within the nasal vestibule and the anterior cavum. Shape changes in this for the nasal
airow important inow area of the nose are
Table 27.5 Impact of diffuser opening angle φ on endo-
nasal turbulence
common causes for symptoms of the patient (see
Sect. 20.3.1).
27.2.2.1 New Parameter inARM
Using the previously in Sect. 27.2.1 described
RRM, an objectication of the effect of a skeletal
Turbulence in the nose
Slight turbulence formation <7°
Moderate turbulence
formation
Severe turbulence formation >9°
stenosis or nasal valve collapse on nasal resistance becomes possible. However, information is
missing regarding localization of the stenosis or
shape changes causing air pathological valve
function or pathological turbulence in the nose.
However, for effective correction of these shape
changes by functional rhinologic surgery all this
information is valuable.
To improve the detection of pathological
shape changes in the inow area, the previously
calculated parameter was supplemented by two
newly introduced ones [2, 15–17]; Fig.27.8.
• Opening angle of the diffuser φ: From the
enlargement of the cross-sectional area inside
the anterior cavum, an opening angle of the
nasal diffuser can be calculated from the areas
measured by ARM (Fig.27.7, Table27.5). This
parameter makes it possible to distinguish two
aetiologies of increased pathological turbulence of the nose:
– A narrow diffuser entrance area (small
MCA1).
– A large increase in the cross-sectional area
within the diffuser (see Sect. 20.4).
• MCA0 for the external ostium (external nasal
valve): This inow opening for the inspiratory
27.2.2.2 Objectication ofCauses
air ow is the rst physiological constriction,
which often causes an increase in the nasal
resistance due to an additional permanent pathological constriction. Dynamic stenosis during
inspiration (collapse of the outer nasal valve)
can also lead to pathological resistance.
The extent of an obstruction cannot be assessed
with the ARM (see above). However, the method
is suitable to localize pathological constrictions
and to objectify the ow dynamic causes of pathological turbulence.
343
MCA1
Diffuser opening angle
φ
7°–9°
forNasal Obstruction
withARM
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