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Файл:Ординатура / Хирургия / Библиотека им академика М.И. Перельмана / Книга_4450_Библиотеки_им_академика_М_И_Перельмана
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Fig. 2.152Acoustic rhinogram. The normal curve shows the cross-sectional area of the
internal nose in relation to the distance from the sound source. MCA 1 was formerly
considered to represent a part of the nasal valve. Nowadays it is assumed to be an
artifact due to the nose piece. MCA 2 corresponds to the head of the inferior turbinate is
now called MCA (ISCOANA).
Fig. 2.153Position of MCA in a nondecongested and a decongested nose. MCA moves
forward after decongestion because it induces a shortening of the acoustic wave
(arrows).
The last part of the curve is ascending, and shows the
squared diameter of the nasal cavity versus distance. The
method actually reduces the real cross-sectional area of the
nose, which is slitlike and very irregular, to a circular crosssection with the area πr2 in which r is the hydraulic radius.
To distinguish between a mucosal and a septal narrowing,
acoustic rhinometry is carried out before and after mucosal
decongestion (▶ Fig. 2.154 and ▶ Fig. 2.155).
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Fig. 2.154Acoustic rhinogram before (b) and after (a) decongestion on the right side in
a patient with hyperplasia of the head of the inferior turbinate. After decongestion the
distance to MCA is reduced.
Fig. 2.155Acoustic rhinogram in a patient with a septal deviation on the right before
(b) and after (a) decongestion. The first part of the right nasal cavity is almost
completely blocked. After decongestion, the stenosis has decreased, but there is still a
considerable difference between the right and left side, indicating an anatomical
deformity.
The great advantage of acoustic rhinometry is its simplicity.
It is fast and noninvasive, and can therefore also be used in
young children ([58]). A short tube and a special nozzle is
then required.
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Diagnostic Value of Acoustic Rhinometry
Rhinomanometry and acoustic rhinometry are
complementary tools. The first is a dynamic method that
records nasal pressure in relation to inspiratory and
expiratory flow; the second is a static method that
measures the cross-sectional area and volume of the nasal
cavity. Acoustic rhinometry has the following limitations:
It cannot be used when the nasal cavity is blocked.
Only obstructions at the level of the valve area and in
the anterior part of the nasal cavity can be measured
reliably.
The method loses its sensitivity with distance:
pathology beyond 4 cm cannot be determined.
Pathology posterior to an obstruction cannot be
measured because the acoustic energy of the clicks is
not high enough to measure reliably behind a stenosis.
It cannot record alar and valvular collapse, as these are
dynamic phenomena that occur on inspiration when the
negative pressure in the vestibule or valve area,
respectively, exceed a certain limit.
It cannot be applied in patients with a septal
perforation.
Measuring Nasal Inspiratory Peak Flow
An inspiratory flow meter is used to measure nasal
inspiratory peak flow (NIPF). A disadvantage of this
method is that the mucosa may be sucked inward on forced
inspiration. Nonetheless, several authors have claimed a
good correlation with the outcome of rhinomanometry.
Although the latter is to be preferred, peak flow
measurements might be used to measure the effect of
surgery or long-term medication. An advantage of
measuring NIPF is that the apparatus is rather inexpensive
and easy to handle. The patient can take it home and
document his or her own breathing obstruction.
2.4.2Olfactometry
Unlike audiometry in otology, olfactometry has not (yet)
become a routine examination in rhinological patients. In
some clinics, every patient’s smell is tested prior to
rhinoplastic surgery. One reason for this is to avoid a
medicolegal conflict if a patient claims a decreased sense of
smell postoperatively. In patients with polyposis, hyposmia
or anosmia is usually a major complaint. Olfaction tests
may then be useful to show the effects of surgery. At
present, the UPSIT test (University of Pennsylvania Smell
Identification Test) and the “Sniffin’ Sticks” test are the
best tests available.
Screening Tests
Screening tests are helpful to distinguish between normal
and impaired olfactory function. The most commonly used
method is the “Sniffin’ Sticks” test. It is available as a short
test with 3 or 5 odor probes, or a more elaborate test with
12 odors ([180], [146], [217]). The odor is presented by
removing the cap of a pen containing an odorant, which is
held under both nostrils for about 3 seconds. The patient
has to identify the odor from four choices.
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Threshold and Identification Tests
Threshold and identification tests are used to assess
olfactory functions in more detail.
The threshold test is carried out by a forced choice
procedure with the patient blindfolded. Usually, a dilution
series of 16 steps is used. At each step, three sticks are
offered, one of them bearing the odorant (usually n-butanol
or phenylethyl alcohol, which have negligible effects on
trigeminal nerve endings) and the other two bearing only
solvent. The concentration of the odorant is increased in a
stepwise manner until it is correctly identified twice in a
row. The concentration is then lowered until the test person
is unable to correctly identify the offered odorant. In this
way, the olfactory threshold is determined.
The discrimination test is performed in a similar way. The
test person is offered three sticks, two of which release the
same odor whereas the third has a different odor.
2.4.3Measuring Air-Conditioning Capacity
Humidifying Capacity
The humidifying capacity of the nose can be determined by
measuring the relative humidity of the inspired and expired
air. This may be done at different levels of ambient
humidity. At present, humidity measurements have not
been introduced in clinical practice as the implications of
such measurements are not clear.
Warming-Up Capacity
The same applies to measuring the warming-up capacity of
the nose. Tests to determine the humidifying and the
warming-up capacity of the nose will be introduced in the
future.
2.4.4Measuring Nasal Defense
Since the nose is the main defense organ of the respiratory
tract, we need tests to study its protective functions. The
tests should measure the following known aspects of nasal
defense:
Ciliary beat frequency (CBF) and ciliary ultrastructure
Mucus composition and rheologic properties
Mucociliary transport (MCT)
Cellular defense
Humoral defense
Cilia and Ciliary Activity
Ciliary function may be examined directly by measuring
CBF, and studying ciliary structure by transmission
electron microscopy (TEM). Indirectly, it may be tested by
measuring MCT.
Ciliary Beat Observation and Measurement of Ciliary
Beat Frequency
Ciliary function can be examined by phase-contrast
microscopy or by studying ciliary beat using a photoelectric
method. This is always done when primary (or secondary)
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ciliary dyskinesia is suspected. A brush or a small biopsy is
taken from the medial surface of the inferior turbinate
without the use of any local anesthetic or decongestants, as
these drugs are known to affect ciliary activity. The brush
or biopsy is best stored and examined in Locke-Ringer
solution (sodium chloride, potassium chloride, calcium
chloride, magnesium chloride, sodium bicarbonate, and
dextrose in water), not in isotonic (0.9%) saline (Boek et al
1999). If no ciliary movement is seen, the cilia are studied
morphologically by means of TEM.
Transmission Electron Microscopy
A more precise diagnosis of primary ciliary dyskinesia
(PCD) can be made by TEM of the cilia. When structural
anomalies like missing dynein arms are observed, the
diagnosis of ciliary akinesia is very likely. The ultimate
diagnosis of PCD is established by ciliogenesis in vitro, a
technique that is only available in a limited number of
institutions worldwide. Nasal nitric oxide (NO)
measurement may, however, represent a good alternative
and an elegant screening test for PCD. Low levels of nasal
NO make a diagnosis of PCD very likely.
Mucociliary Transport Testing
Nasal clearance is tested by measuring MCT time. A small
amount of an inert compound is deposited just posterior to
the head of the inferior turbinate (or on the septum at the
level of the valve area). The time that elapses until the test
substance arrives in the nasopharynx is measured. In a
normally functioning nose, MCT time varies from 8 to 12
minutes. This large variation diminishes the value of the
test.
The substances most commonly used to measure MCT are
dyes (such as charcoal, methylene blue, or edicol orange), a
sweet-tasting substance like saccharine, or radioactive
technetium. The test substance must not interact with
mucus or the mucosal membrane, and it must be easily
detectable in the nasopharynx. The arrival of a dye in the
nasopharynx is established by posterior rhinoscopy using a
rigid endoscope. When saccharine is used, the test subject
is asked to inform the examiner as soon as he or she
notices a sweet taste. The transport of technetium is
determined by measuring radioactivity with a gamma
camera. The combination of charcoal and saccharine is
most commonly used in a clinical setting. Radioactive
technetium is advocated for research purposes, as it is the
most sensitive method.
Charcoal–Saccharine Test
A small amount of charcoal and saccharine is deposited just
posterior to the head of the inferior turbinate. The method
records the time elapsing until the charcoal becomes
visible in the choana (as observed by posterior rhinoscopy
with a rigid 70° endoscope) and/or until the saccharine is
tasted. The method is simple but not very precise.
Technetium Test
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