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231
Fig. 20.7 Course of inspiratory ow in nasal models
with various positions of the vestibulum to the cavum. (a)
Normal vestibulum position: air is distributed over the
entire region of turbinates. (b) Vestibulum rotated downwards (like at a drooping nose) with pathologically dimin-
In cases presenting with an abnormal nasolabial angle, the rhinosurgical challenge is to
reconstruct a normal position of the alar cartilages. This means that the cephalic portion of the
alar cartilage must be positioned on the caudal
edge of the lateral cartilage. Excessive elevations
of the tip of the nose for aesthetic considerations
should be avoided from a functional point of
view.
Since the external ostium is larger than the
internal valve area, the vestibulum has also a
nozzle effect in inspiratory direction. In a nozzle, progressive restriction of the cross-sectional
area causes reduction in turbulent ow. This
guarantees that laminar ow can pass through
the following narrowest part of the nose, the
internal nasal valve (Fig.20.6). This is of importance, since turbulent ow behaviour in this narrowing would result in a high level of resistance
to ow.
The nozzle effect of the vestibulum must be
preserved during rhinosurgical procedures. That
means that one must not enlarge the internal
valve in an effort to reduce resistance too much.
The internal ostium must remain proportionately
smaller than the external ostium. Excessive
enlargement leads to a ballooning phenomenon
that creates highly turbulent ow in the cavum as
a result of eliminating the nozzle effect in the
vestibulum.
The function of the vestibulum as a nozzle
results also in an acceleration of local ow veloc-
ishes nasolabial angle: airow runs only through the upper
part of the nasal cavum. (c) Vestibulum rotated upwards
with pathologically enlarged nasolabial angle: airow
runs only through the lower part of the nasal cavum
ity, which causes a negative pressure on the
mobile lateral vestibular wall. Because of this
Bernoulli phenomenon the nasal wing collapses
and increases abrupt the resistance. The “nasal
valve collapse” is physiologically, if it acts at
high breathing ow velocities (>500mL/s). If a
resistance increase caused by valve collapse
occurs only in ow velocities above 500 mL/s,
the effect is known as “physiological nasal valve
collapse”. It is an upstream resistor to protect the
mucosa in the deeper airways against excessive
airow. By contrast, “pathological nasal valve
collapse” arises already within the “Physiological
Breathing Range”.
Most cases of nasal valve collapse result from
constrictions of the vestibulum, particularly
within the internal ostium. The negative pressure
on the wall of a ow channel depends on the local
ow velocity, which is inuenced by the width of
the channel: the narrower the channel, the higher
the local ow velocity, and the higher the negative pressure. The rhinosurgical concept in these
cases is the enlargement of the narrowing to a
normal width.
20.3.1.2 Internal Nasal Ostium
The inner nasal ostium is the narrowest region
along the nasal ow channel and is therefore also
known as the “Isthmus nasi”. Due to the high
friction within the constriction (see Sect. 20.2.1),
it has the largest share in the formation of ow
resistance in the nose [10, 11, 25, 26].
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Fig. 20.8 Fluid dynamic experimental representation of
the inspiratory airow in a nose model without a vestibulum. The concavely curved shape of the inner ostium
causes a divergence of the ow paths in the cavum
In inspiratory ow direction, the inner
ostium serves as an opening for the air owing
from the vestibulum to the cavum. With its
concave curvature, it inuences the direction
of airow. It has the same inuence on the distribution of the airow as a concave lens does
on light rays: it creates a divergence of the subsequent ow and thus contributes to the distribution of the ow over the entire surface in the
area of the turbinates (Figs.20.7 and 20.8) [20,
21, 26].
Given the relationship between form and
function, resections of the caudal edge of the lateral cartilage should be performed in such a way
that the concave shape of the inner ostium is
preserved.
20.3.1.3 Anterior Nasal Cavum
Due to its cross-sectional increase in the direction of the inspiratory ow, the anterior cavum
has the uid dynamic effect of a diffuser.
Turbulence is generated and regulated here (see
Sect. 20.4).
From a functional point of view, another positive effect of the expansion of the cross-sectional
area in the anterior cavum is a decrease in the
ow velocity. The lower ow velocity in the area
of the turbinates leads to an increase in the contact time for air with the mucous membrane,
which is advantageous for the conditioning and
cleaning of the inhaled air.
A. G. Beule et al.
20.3.2 Functional Area
The functional area in the nose is the area of the
turbinates. The turbinates not only enlarge the
surface of the respiratory mucosa but also narrow
the nasal cavum into a slit-shaped space. As a
result, the nasal cavum is actually not a cavity at
all, but a slit-shaped space [26]. This slit-shaped
space is an important prerequisite for the breathing function of the nose (see Sect. 20.1). Analysis
of CT images through the middle of the nasal
cavum (Fig.20.9 shows some examples) shows
that the width of the slit remains fairly constant
over the entire cross section of the cavum even
with strong septal deviations (Fig.20.9). The lateral walls of the cavum are always asymmetrical.
The septum divides the nasal cavum into two
unequally wide and differently structured cavities. The shape and size of the turbinates adapt to
the available space between the lateral walls of
the cavum and the septum, thus creating a continuous, uniform slit-shaped space. With its shape
and variable thickness, the septum also helps create a slit.
At the end of the nineteenth century,
Zuckerkandl (1882; [27]) discovered from his
large collection of human skulls that the septum
in the always asymmetrical skulls is normally not
straight, but deviated. He introduced the term
“physiological septal deviation”. The joint observation of almost all ENT specialists that not every
deviation of the septum leads to an obstructed
nose conrms the validity of the concept of a
physiological deviation [28, 29]. In the literature,
an incidence of septal anomalies in the normal
population of up to 90% is indicated [30–34]. It
can be assumed that some of them are physiological deviations, since experience shows that the
incidence of nasal obstruction is considerably
lower.
We dene “physiological septum deviation”
as a curved septum without signicant narrowing
of the slit-shaped space and therefore without
pathological airway resistance.
Due to the uniform width of the slit, the airow can be distributed over the entire crosssectional area (Fig. 20.10a). Since the airow
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b
233
Fig. 20.9 Coronal CT images through the functional area
of different noses. The turbinates adapt to the space provided by the lateral wall of the nasal cavum and the sep-
Fig. 20.10 Flow experimental representations of the
inspiratory airow in nose models (a) before an (b) after
signicant reduction in the size of the middle turbinate.
Flow is distributed in (a) across the entire turbinate region,
follows the paths of least resistance, local
enlargement, as seen after extensive surgical
reduction of the size of the turbinates, results in a
signicant disruption of the nasal airow. In
these cases, the air ows almost exclusively
tum (a) with slight asymmetry of the two sides of the nose
and slight septal deviations and (b) even with strong
cavum asymmetry and severe deviations
but in (b) it is limited almost exclusively to the wide space
in the centre of the nasal cavity. As a result, the inferior
and superior turbinates are unable to contribute to respiratory function
through the enlarged space (Fig.20.10b), so that
large areas of the mucous membrane of the middle and superior turbinate cannot contribute to
the respiratory function, as the air no longer ows
in these areas [20].
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These results have two important implications
for rhinosurgery [26]:
• It is necessary to keep the slit-shaped space as
even as possible or, if necessary, to reconstruct
the slit-shaped space (e.g. in cases of atrophic
rhinitis or empty nose syndrome).
• In the case of a compensatory enlargement of
the turbinate in connection with a septal deviation, the surgical intervention on the turbinate should be very gentle and, if possible, not
include a resection. This is especially true for
post-pubertal septal deviations, since the
enlargement of the turbinates in these cases is
almost always caused by compensatory swelling rather than compensatory hyperplasia.
After the septum correction, the turbinates
often adapt to the new space between the septum and the lateral cavum wall with the extent
of their swelling [8, 35]. Especially in pre-
pubertal septal deviations, in particular, the
lower turbinates grow far into the concavity of
the deviation. In these cases, lateral positioning of the inferior turbinate is often an appropriate treatment.
• Physiological septal abnormalities need to be
identied as such and should not be surgically
corrected. Figure20.11 demonstrates that inadequate surgery in these cases can lead to non-physiological, excessively wide nasal spaces.
Unsatisfactory long-term results after septoplasty
can be attributed to septoplasties in patients with
physiological septal deviations [36–38].
• Pathological septal deviations should not be
fully straightened. The mobilized septum
should be positioned midway between the turbinates on both lateral sides of the nose. This
converts the pathological deviation into a less
extensive physiological deviation. As a consequence, an excessive reduction of the turbi-
Fig. 20.11 (a) Coronal CT scan through the middle of
the nose of a patient with a pre-pubertal septal deviation.
Since there is no constriction in the slit-shaped space, it is
a physiological septal deviation. (b) Imitated complete
straightening of the septum with resection of the lateral
wall of the concha bullosa and reduction in size of the
inferior turbinate on the opposite (concave) side of the
septal deviation
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Fig. 20.12 (a) Coronal CT scan through the middle of
the nose of a patient with a pre-pubertal septal deviation.
Because there are narrowings in the slit-shaped space
(right side between the inferior turbinate and septum, left
side within the middle nasal passage due to a spur), it is a
pathological septum deviation (pathologically increased
resistance, objectied by objective rhinologic diagnostics,
see Chap. 27). (b) Imitated complete straightening of the
septum with size reduction of the middle and inferior tur-
nate is not necessary. In some cases, lateral
positioning of the lower turbinate is efcient
to create a symmetrical slit space (Fig.20.12).
The goal of surgical interventions to relieve
nasal congestion caused by septal deviations
must not be a completely straight septum and
small turbinates to create a wide ow channel in
the nose. The frequent occurrence of sicca symptoms after functional rhinosurgery [26, 34, 39–
47] should provide the impetus for a more precise
consideration of physiological aspects in functional rhinosurgery. Instead, the aim should be
the maintenance or reconstruction of the slitshaped space for optimal respiratory function.
20.3.3 Outow Area
The outow area of the nose congures the inspiratory airow so that it is adapted for passage
into the lower airways:
binates on the opposite (concave) side of the septal deviation. As a result, a very large space is created, which leads
to a disturbance of the ow distribution, as shown in
Fig. 20.11b. (c) Imitated conversion of the pathological
into a physiological deviation, with only removal of the
spur, a slight shift of the lower septum to the left and a
slight lateral positioning of the right inferior turbinate. A
physiological slit-shaped space is created
20.3.3.1 Nasopharyngeal Meatus
In the nasopharyngeal meatus, the cross-sectional areas become smaller in the inspiratory
direction. From a uid dynamic point of view,
this structure has the effect of a nozzle that
reduces the turbulent sections within the airow. In the subsequent deeper airways, the
resistance must be low, and therefore, the ow
should be laminar.
20.3.3.2 Choana
In the direction of inspiration, the choana is a
convex opening between the cavum and the nasopharynx. This leads to convergence of endonasally distributed airow paths (see Table 20.1).
The airow becomes narrower and adapts to the
dimensions of the lower airways.
20.3.3.3 Nasopharynx
Because it is formed like a bend, the nasopharynx
redirects the owing air towards the lower
airways.
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20.4 Generation andRegulation
ofTurbulence intheNose
With laminar ow, all air particles move forward
parallel to the wall of the nasal ow channel, so
that only particles owing along the wall come
into contact with the mucous membrane and can
thus be warmed up, moistened, and cleaned.
Centrally owing particles are not conditioned.
For a sufcient contact between air and mucous
membrane in the nose, both forward and lateral
movements of air particles due to turbulent airow portions are important prerequisites.
In the nose, turbulent airow sections are created in the anterior nasal cavum. In this area the
cross-sectional area between the inner nasal
ostium and the centre of the nasal cavity increases.
A channel with an increasing cross-sectional area
is called a diffuser (see Sect. 20.3.1.3). In a diffuser, the extent of creation of turbulence depends
on the extent of the increase in cross-sectional
area. This parameter and thus the degree of turbulence are characterized by the opening angle of
the diffuser ф. A large diffuser opening angle
leads to strong turbulence. Conversely, a smaller
diffuser opening angle leads to less turbulence
(Fig.20.13).
By congestion and decongestion during the
nasal cycle, not only the long-term regulation of
endonasal ow resistance is achieved (see Sect.
20.2.3) but also the regulation of turbulence dur-
ing the nasal cycle. Fig.20.14b shows that on the
right side the nasal cavum at the end of the diffuser is wide due to a decongestion of both, the
septal erectile tissue and the head of the inferior
turbinate. As a result, the increase in cross section
in the nasal diffuser (diffuser opening angle ф)
becomes large and the formation of turbulence is
pronounced. This corresponds to a working phase
in the nasal cycle, in which sufcient air–mucosal
contact is required. On the left side of the nose,
the “erectile tissue” is congested, the diffuser
opening angle ф is small. This means that the airow within the left side of the nose is largely
more laminar. This is important in the resting
phase. Less air–mucous membrane contact
favours the storage of heat energy and moisture.
aa
b
Fig. 20.13 Creation of turbulence in diffusers with different opening angles ф. With laminar ow, the coloured
ow paths are clearly bordered due to the exclusively parallel, forward-owing particles. A diffuse colouring as a
result of sideways motions indicates turbulent ow.
Within a diffuser with a small opening angle (a), turbulence only occurs at the end of the diffuser, while with a
large opening angle (b), turbulent ow portions are
already formed at the beginning of the diffuser
The regulation of the turbulence behaviour in
the nasal diffuser during the change of nasal
swelling in the nasal cycle is shown in Fig.20.15
by ow experiments.
Inside a pipe, the transition from laminar to
turbulent airow occurs abruptly. In the nose,
due to its specic aerodynamic channel structure, the increase in turbulence occurs continuously with increasing nasal airow. In this
large “transition area” (Fig. 20.16) the nasal
airow is not completely laminar and also not
completely turbulent. This is an important prerequisite for the respiratory function of the
nose: with purely turbulent ow, the heat and
uid supply of the mucous membrane would
quickly be exhausted, while with purely laminar the owing air would not be adequately
conditioned (see above). In the nose, we can
register a reasonable ratio of laminar and turbulent ow portions. Figure20.16 shows that
the ow is completely turbulent only with a
very small volume of owing air. With increasing ow, turbulent ow portions increase continuously. The more the air volume ows, the
more efciently the air–mucous membrane
contact becomes possible by sideways move-
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Fig. 20.14 Regulation of the turbulence in the nasal diffuser by congestion and decongestion of the lower turbinates ( ) and the septal erectile tissue ( ). (a) Model of
an anterior cavity with its structures for regulating turbulence: the head of the lower turbinate and the septal erec-
tile tissue. (b) CT scan of the end of the nasal diffuser.
Changes in the cross-sectional area of the nasal airways
and thus the degree of turbulence due to decongestion
(right side) and obstruction (left side) within the nasal
cycle
Fig. 20.15 As a consequence of turbulence regulation in
the anterior cavum, the inspiratory airstream in the functional area of the nose is predominantly laminar during
ments. Only at maximum airow it is completely turbulent. The gure also shows that
the ow is less turbulent before decongestion
(resting phase) than after decongestion (working phase).
the resting phase (a) and predominantly turbulent during
the working phase (b)
A steep transition from laminar to complete
turbulent airow, like to see in Fig. 20.17, is
assessed as pathological.
Patients with complaints due to endonasal dry
mucosal surfaces and incriminating creation of
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turb
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laminar
A. G. Beule et al.
ulent
Inspiration Exspiration
-750 -500 -250 250 500 750Flow(ml/s)
Stress
breathing
range
Fig. 20.16 Physiological turbulence behaviour with
transition from laminar to turbulent ow behaviour in a
nasal cavum in relation to ow. Light red line: before,
dark red line: after decongestion. In the physiological
breathing area, the ow behaviour is predominantly in the
ulent
Inspiration Exspiration
laminar
nspiration
–750 –500 –250 250 500 750Flow(ml/s)
Stress
breathing
range
Physiological
breathing
range
transition range to completely turbulent airow. Green
area: completely laminar ow, yellow area: “transition
range” from laminar to turbulent ow, red area: completely turbulent ow
Physiological
breathing
range
Stress
breathing
range
xspiratio
Stress
breathing
range
Fig. 20.17 Pathological transition from laminar to turbulent airow in a nasal side. Within the physiological
breathing range predominantly complete turbulent airow
endonasal crusts become more and more frequent.
Turbulence as cause of these complaints have up
to now been only considered in cases with excessive dry mucosa, like atrophic rhinitis and Empty
Nose Syndrome. Because the extent of turbulent
airow portions could not be objectively diagnosed, these pathophysiological factors have been
sections can be observed. Green area: completely laminar
ow, yellow area: transition from laminar to turbulent
ow, red area: completely turbulent ow
neglected in the diagnostic of nasal functional disturbances. Using rhinoresistometry the increase
of turbulent streaming portions can be objectied
and graphically depicted during inspiration and
expiration (see Chap. 27).
Pathological turbulence in the nose has two
negative consequences: dryness of the endonasal
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239
mucosa and an increase in nasal resistance.
Dryness with crusts in the nose are of greater
clinical importance due to their negative impact
on quality of life. Endonasal dryness and atrophic
rhinitis with their sicca syndrome lead more and
more frequently to consultations of the affected
patients with the rhinologist.
The inuence of pathologically increased
turbulence on the increase in nasal resistance is
much smaller than the effects of local constrictions, since the width of the airow channel is
indirectly proportional to the resistance in the
fourth to fth power. In addition, a nose with a
high degree of turbulence is often characterized
by a very large width, which is associated with a
rather small nasal resistance. The aetiology of
the subjectively complained nasal obstruction in
these patients is endonasal dryness with crust
formation as a result of the pathological
turbulence.
20.5 The Nasal Cycle
lation, the storing capacity is limited for a steady
respiratory function during a long time period.
The necessary uninterrupted air conditioning
function of the nose is possible due to the nasal
cycle and the division of the nose into two sides
by the septum. The reciprocal congestion and
decongestion of the erectile tissue on both sides
of the nose, controlled by the central nervous system, ensures that sufcient air can ow during
the working phases according to the oxygen
requirement and sufciently warmed up und
humidied. During the resting phase, the mucous
membrane has sufcient time to regenerate heat,
energy, and moisture.
Changes in mucosal swelling not only enable
the alternation of working and resting phases but
also modify the entire nasal airow according to
the physical activity by changing the ow resistance and thus the breathing ow corresponding
to the required oxygen demand (see Sect. 20.1).
In Fig.20.18 the adaption to oxygen supply
during various stages of physical activity is
illustrated:
The nasal cycle as a cyclical change in endonasal
resistance due to congestion and decongestion of
the nasal erectile tissue was rst described by
Kayser [48]. It is a basic requirement for the
respiratory function of the nose [1, 26, 49–53].
A large amount of energy is required to warm
up and humidify the inhaled air. Although energy
and moisture are partially recovered during exha-
Flow
Max.
800
inspir.
600
nasal
flow
400
200
0
00 0:00 2:00 10 : 30 12 : 30 14 : 30 16 : 00 18 : 00 20 : 00 0 : 00 12 : 00 14 : 00
Time
Physical
activity
Adaptation of
nasal cycle on
-demand
O
2
Nomenclature
No
Classic type with
complete resting
phases
Resting breathing 1th compensation level 2nd compensation level 3rd compensation level Decompensation
Fig. 20.18 Representation of the temporal change of
maximal inspiratory ow on the right (red) and left (blue)
nasal side in relation to the extent of physical activity.
4:
Classic type with
incomplete resting
Slight Moderate Heavy
incomplete resting phases
phases
and increasing flow
• During physical inactivity a classical type
with periodic reciprocal changes of working
and resting phases exists. The left nasal side
starts in the working phase, thus the right in
the complete resting phase with only minimal
ow being registered. After about three hours
the right nasal side changes into the working
phase and the left nasal side converts into a
0 : 30 2 : 30 4 : 30
Very heavy
Classic type with
on both nasal sides
Adaptation of maximal inspiratory ow by the nasal cycle
as necessary for a sufcient oxygen supply during different physical activities and their nomenclature
In-Concert-Type
with transition to
mouth-bypass-breathing or complete mouth-breathing
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A. G. Beule et al.
complete resting phase. This is an example of
a classical type of the nasal cycle.
• Also during slight physical activity the classical
type persists, but resting phases become incomplete. The nasal side in its resting phase contributes with a relatively small airow to the oxygen
supply. This classical type with incomplete resting phases is called “1. stage of compensation”
according to increasing oxygen requirement.
• During moderate physical activity the classical type persists with incomplete resting
phases, but with increasing nasal airow on
both nasal sides (“2. stage of compensation”
according to increased oxygen requirement).
• During heavy physical activity, the nasal cycle
converts into an “in-concert-type”. Both nasal
sides become synchronously decongested for
working phases to achieve a transnasal airow
as high as possible. This is the third stage of
compensation according to highly increased
oxygen demand.
• Flow resistance increases exponentially with
increasing airow (see Sect. 20.2.1). If the
resistance is sufciently high, nasal airow is
limited. Therefore, with extreme physical
activity, mouth-bypass breathing occurs
increasingly (see Sect. 20.1). Since the nose is
then partially bypassed, it can only perform its
respiratory function insufciently. With total
mouth breathing, the respiratory function of
the nose is completely eliminated. This is
called decompensation of nasal breathing during maximally increased oxygen demand.
• Which level of physical activity leads to which
level of compensation varies enormously
between individuals. This depends on both
endonasal and extranasal factors, including
age, gender, body mass index, physical constitution, and extranasal diseases, particularly of
the cardiopulmonary system.
Figure 20.19 illustrates in an example of a
healthy subjects with non-obstructed nasal
breathing how this compensation mechanism of
the nasal cycle reacts to the oxygen demand during different physical activities. Illustrated are
transnasal airow of both nasal sides in the upper
graph and synchronous measurements for:
• Heart rate as indicator of physical activity.
• Nasal respiratory minute volume as parameter
for total transnasal airow.
• Breathing frequency.
In the lower graph, these continuously mea-
sured data are related to the physical activity
based on a study protocol.
Figure 20.19a shows the adaptation of the
nasal cycle during 24h with breathing at rest up
to heavy physical stress. The curves for heart
rate (measure of physical stress) and nasal minute volume run synchronously: with increasing
physical activity nasal ow increases. The
curves in Fig. 20.19b were recorded with the
same subject on the following day for about 6h
with very heavy physical stress. As a result of
extreme physical stress (recognized by the very
high heart rate), complete mouth breathing can
be recognized by the drop in the nasal minute
volume to zero. Because nasal breathing is
bypassed completely, no breathing rate can be
registered.
The division of the nose by the septum into
two parts becomes understandable taken the
nasal cycle into account. For a steady, sufcient
supply of oxygen with simultaneous conditioning of the breathing air, it is necessary for the
nose to continuously exercise its respiratory
function. Due to the division into two parts, one
side of the nose can always condition air, while
the other side stores heat, energy, and
moisture.
The bisection of the nose and the nasal cycle
are important prerequisites for the respiratory
function of the nose. However, these conditions
only make sense if both sides of the nose
• are sufciently wide so that they can take over
a working phase in the nasal cycle with a
physiologically low breathing resistance and
• are only so wide that they can physiologically
increase the resistance by swelling the nasal
side for a resting phase. Too wide nasal sides,
which can no longer be adequately closed for
a resting phase due to swelling, are forced to
work continuously, and thus, exhaustion (sicca
symptoms) is inevitable.
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