Stridor

Scott brown learning 2020
Volume : 2 "Paediatrics
The ear skull base"
Chapter : 28. Stridor ( p.no: 311 to 324)

PAEDIATRIC
STRIDOR
Presentor :Dr. Vinoth .S , PG in ENT ,

Introduction
• A child presented with stridor may have significant underlying
pathology. Stridor is a symptom and not a diagnosis.
• History and general examination alone are insufficient to confirm the
diagnosis.
• Deciding which patients to investigate is sometimes difficult.
• With non-invasive investigations such as imaging differential
diagnoses can be given.
• Awake flexible endoscopy confirm the diagnosis upto the level of
glottis.

• The definitive diagnostic technique of laryngotracheobronchoscopy
(LTB) requires an experienced team of surgeon, anaesthetist and
nursing staff. Both the equipment and expertise are not available in
all institutions.
• Transfer of the child with stridor may be necessary and should be
carefully managed.
• A child with stridor should give the first priority because the child can
detoriate very rapidly in the acute situation
• In a specialized we can manage with experienced anaesthetists to
intubate and surgeons to perform the rare emergency tracheostomy.

Why it is severe ???
• But in a paediatric ward, emergency room or non-hospital setting,
rapid deterioration can prove a real challenge.
• Neonates and young children develop upper airway obstruction and
respiratory failure more readily than older children and adults.
• this increased risk is due to the structure of the airway in the younger
child.
• Mucosal swelling is more likely to result in a comparatively greater
degree of obstruction of the smaller upper airway.

Poiseuille’s law
• (the Hagen–Poiseuille equation) may be applied to the airway and
dictates that the airway resistance is inversely proportional to the
fourth power of its radius
• a 50% reduction in the radius of the airway therefore results in a 16-
fold increase in resistance to airflow.
• One millimetre of narrowing in a 4 mm diameter infantile airway thus
results in a 75% change in airflow

Bernoulli principle
• Cross sectional area decreases, airflow velocity increases. The smaller
the airway, the greater the impact of airway oedema.
• The Bernoulli principle is also related to the paediatric airway.
Increased airflow velocity results in negative pressure on the walls of
the airway leading to inward collapse.
• Previously smooth or ‘laminar’ airflow
then becomes more turbulent.

‘Reynolds number’
• defines the point at which the transition between laminar and
turbulent flow occurs.
• depends on density, viscosity and velocity of the ‘fluid’, and the
diameter of the trachea.
• Increased turbulence , increasing the airway resistance. Increased
airway collapse occurs with vibration of closely apposed tissues and
the resultant noise of stridor.

Stridor / stertor :
• Noise originating in the larynx or trachea is typically high-pitched and
termed ‘stridor’. It may have a musical quality.
• In contrast, the low-pitched snoring type of noise made by naso- and
oropharyngeal obstruction (and rarely by the supraglottic larynx) has
a rougher quality and is best described as ‘stertor’.
• Obstruction of the small intrathoracic airways, such as in asthma, is
termed ‘wheezing’.

Causes :
• Typically, inspiratory stridor is due to an extrathoracic obstruction
from the larynx or high trachea.
• Bronchial or low tracheal obstruction produces an expiratory stridor.
• Biphasic stridor can occur with obstruction anywhere in the
tracheobronchial tree.
• Even if expiratory stridor is absent, a prolonged expiratory phase may
be present, indicating an intrathoracic obstruction

Increasing collapse on inspiration
with extrathoracic obstruction.
Increasing collapse on expiration
with intrathoracicobstruction.

EVALUATION OF THE CHILD WITH STRIDOR
• The aim of the history, examination and special investigations is to
determine not only the site and cause of the obstruction (the
diagnosis) but also its effect on the airway (the severity).
• It is important to consider the effect of airway obstruction on
feeding, sleep, exercise and growth

History - PERINATAL HISTORY
• The obstetric and perinatal history is important to rule out prematurity and NICU
admissions regarding ventilation
• A history of a difficult delivery is also linked to vocal cord palsy. Stridor that is
present at birth, i.e. with the child’s first breath, is unusual. This generally
denotes a significant fixed congenital narrowing such as a laryngeal web,
subglottic or tracheal stenosis or bilateral vocal cord palsy.
• Other dynamic conditions such as laryngomalacia typically become evident in
the first few weeks of life.
• A gradual increase in severity of airway compromise implies progression of an
obstruction which may be intrinsic (luminal), as in the case of a subglottic
haemangioma, or extrinsic, as with a mediastinal mass.

PATTERN OF STRIDOR
• Stridor is seldom constant. Any variation can help pinpoint the cause,
though asking parents about the timing of stridor in the respiratory
cycle is seldom profitable.
• Typically, laryngomalacia – as with other laryngotracheal causes of
stridor – is better when the child is at rest or asleep but made worse
by crying, feeding and excitement.
• Upper airway obstruction at the level of the pharynx is in contrast
worse when the child is asleep and is associated with stertor.

• Airway obstruction greatest in a supine position can occur with a
pedunculated laryngeal mass , supralaryngeal obstruction such as
micrognathia and resultant tongue base occlusion.
• Improvement in the airway with crying occurs in significant nasal
obstruction such as bilateral choanal atresia

ASSOCIATED FEATURES
• apnoeas, cyanosis, ‘dying spells’, cough and hoarseness
• increased work of breathing (dyspnoea, tachypnoea, recession, nasal
flaring, head bobbing).
• Apnoeic episodes associated with cyanosis are typical of severe
tracheobronchomalacia and referred as ‘dying spells’ and also known
as apparent life-threatening events (ALTEs) , brief resolved
unexplained event (BRUE)

• Parents will usually attempt resuscitation if these episodes are severe.
It is often unclear how many of these attacks are otherwise self-
limiting.
• Tachypnoea and dyspnoea are not limited to upper airway
obstruction but a clear description of exertional dyspnoea in an older
child provides a useful functional assessment of severity
• Cough is typical of tracheo-oesophageal fistula (TOF) and
tracheomalacia and is rarely due to ‘infantile asthma’.
• Hoarseness suggests a laryngeal lesion such as papillomatosis and
also occurs in vocal cord palsy.

FEEDING HISTORY
• Feeding is one of the most strenuous activities for a neonate and is
closely connected with breathing. It is therefore vulnerable to
compromise in upper airway pathology.
• A change in feeding or inability to feed is a key indicator of upper
airway status.
• An accurate picture of the feeding pattern must be obtained.
Breastfed babies with airway obstruction will characteristically ‘come
up for air’; bottle-fed babies may require thickened feeds or a ‘slow
teat’ (i.e. one with small holes).

• Regurgitation (‘posseting’) is common in neonates and by itself may
not represent significant gastro-oesophageal reflux.
• there may be failure to thrive with demonstrably poor weight gain.
• Formal mapping of weight gain in a growth chart is useful in both the
assessment of severity and planning of appropriate management.
• Aspiration suggests vocal cord palsy, tracheoesophageal fistula,
neuromuscular pathology or rarely a laryngeal cleft.
• Significant repeated aspiration may be associated with recurrent
chest infections.

Causes of stridor – laryngeal cause

Causes of stridor – tracheal cause

GENERAL MEDICAL CONDITIONS
• Enquiry into the general past medical history may explain a vocal cord
palsy occurring as a result of neurological disease or cardiothoracic
surgery.
• Iook for vascular compression which is associated with congenital
cardiac disease.
• The presence of any skin lesions is important;
a cutaneous haemangioma may be associated
with a subglottic haemangioma.

ACUTE OBSTRUCTION
• In acute airway obstruction the history is taken in parallel with the
examination and resuscitation.
• Look for any possibility of foreign body aspiration
• Rapid progression of airway obstruction typically occurs in acute
infection and in foreign body inhalation.

Examination-OBSERVATION
• Observing the child at rest to look for the degree
of respiratory distress and the characteristics of
any stridor and also gives time to gain the child’s confidence.
• The characteristics of the stridor need to be observed as well as the effects
of airway obstruction such as recession.
• An abnormal voice, wheeze or cough is a useful localizing sign.
• The site of the abnormal vibration can rarely be pinpointed with the aid of
a stethoscope due to the variable transmission of sound through the
thorax.

• Auscultation is useful to detect abnormal heart sounds and wheeze.
• With rapidly advancing technology, carers can record the sounds in
mobile devices with audiovisual recording capabilities.
• Useful information can sometimes be obtained from reviewing a
parental recording of a symptomatic episode.
• The pre-endoscopy assessment helps to identify the type and degree
of pathology discovered at endoscopy.
• The combination of a thorough history, examination and limited
investigation can be useful

• in a suspected mild laryngomalacia these combined approach will provide
sufficient diagnostic probability to conclude and avoid progression to immediate
endoscopy unneccesarily.
• The type of stridor may be characteristic of a particular pathology but is never
diagnostic.
• A second pathology alongside laryngomalacia may be present in up to 20% of
cases though few will require treatment.
• The diagnosis can only be confirmed by endoscopic evaluation.
• This does not mean that every child with stridor requires
laryngotracheobronchoscopy. In most children seen in a secondary or tertiary
referral centre, endoscopy will be required and in most conditions is the gold
standard.

ASSOCIATED FEATURES
• Subcostal, intercostal and suprasternal recession may occur and also be
associated with ‘see-saw’ respiration.
• The severity of recession is a better indicator of the severity of airway
compromise than the degree of stridor.
• Accessory muscles of respiration are not usually employed by the younger
child, who depends predominantly on diaphragmatic movement. Nasal
flaring and head bobbing are important
• abnormal posturing; the child may adopt a position of
neck extension and head rotation with airway obstruction
• The volume of stridor can paradoxically reduce as the
obstruction increases due to the diminishing airflow.

• No comfort should be taken from the fact that a child still looks pink.
Cyanosis is a very late event and suggests obstruction has been severe or
prolonged.
• If a supralaryngeal component is suspected, nasal patency should be
assessed with a metal instrument or mirror, a wisp of cotton wool or using
the bell end of a stethoscope.
• Examine the ears, nose, throat and lastly neck with the usual caution that
you must not use any instrumentation to examine the throat of child in
whom pathology such as epiglottitis is suspected. Observing the child
while attempting feeding is essential if there is a feeding or aspiration
concern.

IMAGING
• Plain anteroposterior (AP) and lateral views of the neck, digitally
enhanced to demonstrate the subglottis, oropharynx and
nasopharynx, are rapid, inexpensive tests that do not require sedation
or anaesthesia.
• The term ‘Cincinatti view’ describes a high kilovolt filter AP film
designed to highlight the soft tissues of the neck
• Xray neck shows the ‘steeple sign’ in croup ,
subglottic cysts, papillomata.

• A plain chest radiograph may show the ground-glass appearance of
bronchopulmonary dysplasia or mediastinal shift resulting from a foreign
body.
• If a foreign body is suspected in young children, diaphragmatic screening
with videofluoroscopy is a more sensitive technique.
• In older children, inspiratory and expiratory films may demonstrate
diaphragmatic immobility on the side of the obstruction.
• It doesnot detect the foreign bodies that do not cause complete lower
airway obstruction, and the radiolucent objects

• Airway fluoroscopy has been found to be highly specific in the
diagnosis of both laryngotracheomalacia and fixed airway lesions, but
its sensitivity is poor
• Airway fluoroscopy can be combined with a contrast swallow looking
for vascular compression and aspiration but limited diagnostic value
• Endoscopy preceeds the contrast swallow
when cases of a vascular ring or
tracheooesophageal fistula is suspected.

• Bronchography may be performed using
non-ionic contrast media.
• Risk in infants and those prone to apnoea.
• useful for the lower airway, demonstrating tracheobronchial stenosis
and malacia.
• Opening pressures of the collapsed bronchi and lower trachea can be
measured and used to determine the level of airway support needed.

• Echocardiography can be used in cases of suspected vascular
compression, coincidental or symptomatic congenital heart disease.
• With experience, ultrasound of the vocal cords can be used to
demonstrate vocal cord palsy with reasonable accuracy.
• Laryngeal ultrasound may also demonstrate structural lesions such as
cysts, polyps and papillomata; but it is non-diagnostic.

CT / MRI :
• Both CT and MRI can be useful in cases of
extrinsic tracheal compression.
• CT and MRI may also aid in the evaluation of airway
lesions but not sensitive to fully characterize a lesion
or stenotic segment.
• Helical or multidetector CT with multiplanar and 3D reconstruction offers
increasingly better definition of fixed tracheal lesions, which are effectively
‘virtual bronchoscopy’.

• Dynamic changes – primary and secondary tracheobronchomalacia –
are not well evaluated by cross-sectional imaging. The degree,
maturity and mucosal quality of a stenosis can be more accurately
assessed at endoscopy.
• Imaging may not be appropriate in situations of acute and severe
upper airway obstruction.
• imaging should be performed with close medical supervision to
monitor the airway and intervene in case of emergency

RESPIRATORY FUNCTION TESTS
• Lung function tests such as flow-volume-loops provide a graphical
representation of inspiratory and expiratory flow. This can help to localize
the site of obstruction; it may differentiate between intra- and
extrathoracic obstruction and between fixed and variable pathologies.
• Other lung function tests such as peak flow testing may be done and
reviewed with the advice of a pulmonologist.
• These tests require a degree of patient cooperation and are non-diagnostic.
They may, however, assist in the assessment of severity, decision-making
regarding management and monitoring of clinical progress.

• Polysomnography or ‘sleep studies’ are also not often used in the
assessment of the stridulous child
• Airway obstruction that worsens during sleep is usually a feature of
pharyngeal obstruction such as adenotonsillar obstruction or a
craniofacial anomaly.
• Laryngomalacia and most laryngotracheal pathologies are rarely
worse during sleep.

ASSESSMENT OF REFLUX
• It is difficult to gauge whether reflux is secondary to airway obstruction
with negative intrathoracic pressure drawing gastric contents into the
oesophagus or if the reflux is a separate entity.
• Occasionally, reflux may be a primary causative factor with secondary
reflux laryngitis
• Gastro-oesophageal reflux can be assessed with a radiopaque contrast
study, milk scan (nuclear medicine), pH study or endoscopy.
• Contrast studies have low specificity and sensitivity and are dependent on
positioning and radiological interpretation.

• The other investigations are more sensitive but are usually interpreted by
gastroenterologists looking for reflux into the lower oesophagus.
• The laryngologist is interested in the pH in the upper oesophagus and
pharynx, which can be measured using a second probe in the upper
oesophagus.
• Episodes of reflux occur without an associated pH change. These events
may be detected by impedance testing (multiple intraluminal impedance);
this newer technique is, however, more expensive and less widely available

Endoscopy
• The two principal concerns in paediatric upper airway endoscopy are
safety and diagnostic accuracy.
• To achieve these objectives requires not only a full range of
specialized paediatric endoscopy equipment but, most significantly, a
high level of experience in the endoscopist, anaesthetist and nursing
staff.
• A systematic approach will provide a diagnosis in most cases.

AWAKE FLEXIBLE ENDOSCOPY IN THE OFFICE/WARD
• The introduction of ultra-thin endoscopes with good optics and a diameter
of less than 2 mm has allowed even neonates to be evaluated without the
need for a general anaesthetic.
• Peroral passage of an endoscope may be performed in the edentulous
neonate using a finger between the gums to
protect the instrument.
• This alternative approach is preferred by
many to transnasal introduction in the
young infant.

• Flexible laryngoscopy may be considered a diagnostic screening procedure.
• Awake flexible endoscopy is particularly useful to assess dynamic abnormalities
such as vocal cord palsy.
• Flexible endoscopy under sedation in an endoscopy is an adjunct to rigid
endoscopy
• Awake flexible endoscopy is most feasible in the infant who may be swaddled
(under 9–12 months) and in the older, cooperative child.
• Office-based flexible endoscopy of the lower airway to the level of the carina has
also been described as feasible and safe in a paediatric population although this
practice is not widespread

LARYNGOTRACHEOBRONCHOSCOPY
• Gold standard in the assessment of the stridulous child.
• a highly technical procedure.
• The whole team (surgeon, anaesthetist and nursing assistant) need to work
closely together to perform the examination safely, and to optimize the
assessment.
• The advent of video and high-quality image reproduction on a viewing monitor
has been invaluable in training and teamworking.
• The anaesthetist and theatre team may also view the live image and may be able
to anticipate interventions required.

ANAESTHESIA FOR UPPER AIRWAY ENDOSCOPY
• Major units around the world use a variety of techniques;
• it is probably more important that a theatre team work together effectively
than that one particular technique is followed.
• High levels of cooperation and skill are required.
• Practice varies between centres as to whether intubation is used at the
start of the procedure, however most units would now use spontaneous
respiration rather than paralysis.
• Spontaneous respiration has much to recommend it as a technique: it
maintains muscle tone, promotes gas exchange and is essential to detect
dynamic conditions.

• Some units will use a premedication such as atropine or glycopyrrhonium bromide to
facilitate a dry surgical field and improve the efficacy of topical anaesthesia.
• Pre- operative steroids are a good safeguard if significant stenosis or likelihood of
increased inflammation is suspected.
• Intravenous induction is preferable for older children;gas induction is best in infants,
younger children, those with poor venous access and those with a precarious airway.
• Topical local anaesthetic spray (typically lignocaine) should be applied to the vocal cords
when the anaesthetic level is sufficiently deep for this to be tolerated.
• This amount needs to be carefully measured as the preparations used in adults can easily
result in overdosage

Maintenance of anaesthesia
• Two principal anaesthetic techniques are used for general anaesthesia with
spontaneous respiration: maintenance with a volatile agent (e.g.
sevofluorane) and total intravenous anaesthesia (TIVA) with an infusion
such as propofol and remifentanil.
• A volatile agent and oxygen mix can maintain a level of anaesthesia that
allows a thorough examination in a child who is breathing spontaneously.
• Sevoflurane is non-irritant to the airway and has the
advantages of rapid onset and no pungency, allowing
immediate delivery of high concentrations.

• This advantage of rapid induction may be offset by rapid termination
of effect during periods of relative hypoventilation or airway
obstruction.
• Now superseded by sevofluorane, halothane gas was also useful for
this purpose.
• The anaesthetist needs to be able to control anaesthesia in response
to surgical conditions and for this a video monitor visible to the
anaesthetist is invaluable.

Airway tube technique
• An endotracheal tube may be used as a nasopharyngeal airway or ‘prong’ to
provide oxygen and volatile anaesthetic agent, if used.
• if transnasal passage not be possible, an oropharyngeal tube may be used,
placed at the angle of the mouth.
• A significant advantage of a nonintubation technique is that the endoscopist has
a view of an airway that has not been altered by the passage of an endotracheal
tube.
• Confusion relating to lesions caused by intubation for the procedure cannot
occur and at any time airway control can be regained with intubation or the use
of a bronchoscope

• An alternative technique is to intubate the child prior to withdrawal
of the tube for endoscopy.
• Intubation does facilitate rapid progress to the required level of
anaesthesia.
• Nasotracheal intubation allows the endotracheal tube to be
withdrawn into the nasopharynx once the child is breathing
spontaneously.
• Careful positioning of the tube over the glottis by the endoscopist
can also achieve good oxygen and volatile agent provision, when
required.

Jet ventilation
• This technique allows the child to be paralysed, preventing coughing and
gagging.
• Gas exchange is maintained by short pulses of oxygen and anaesthetic gas.
• Subglottic jet ventilation may be provided in adults using a transglottic
cannula but this is not only impractical but also risks barotrauma
(pneumothorax and air trapping) in children.
• Dynamic conditions such as malacia and
cord palsy cannot be well identified.

Laryngeal mask airway
• A laryngeal mask airway (LMA) is useful for fibre-optic
tracheobronchoscopy, particularly if the patient is difficult to intubate
because of mandibular hypoplasia

LARYNGOTRACHEOSCOPY TECHNIQUE
• The following description assumes that the patient may have been intubated,
suspension laryngoscopy is employed and that the larynx and/or trachea is to be
examined with rigid telescope or microscope.
• A small sandbag or pad is usually required under the shoulders with sandbags
laterally to support the head if required. A Mayo table supports the laryngostat
(laryngeal support) clear of the chest.
• It is important to prepare and check all equipment prior to the endoscopy so that
the endoscopist is fully prepared for all eventualities.
• The range of Hopkins rod rigid endoscopes should include all lengths and
diameters that could be needed.
• A 30° telescope may be able to better assess the supraglottic larynx without
splinting.

• A microscope should be available, though is often not used unless
surgical intervention is required when two hands are needed for
manipulation.
• If a microscope is used, a 400 mm lens allows the use of standard
laryngeal instruments but a 350 mm lens brings the patient closer,
allowing easier laryngeal manipulation, which is particularly
important in small neonates.
• For routine examination, the Hopkins rod and camera can be held in
the left hand with a probe used in the right

• The image quality available using a rigid endoscope is far superior to
that of the microscope.
• Every unit should have a chart listing the appropriate sizes of
bronchoscope for different ages.
• The age-appropriate bronchoscope should be checked and one at
least a size smaller instantly available as well
• Laryngeal examination is usually begun by gently inserting the
lubricated suspension laryngoscope, taking care to protect the teeth
and lips and to keep the tongue central to provide a well-centred
view.

Handheld laryngoscope and
Hopkins rod technique
Supension laryngoscopy and
microscope technique.

• As in adults, it is important to check the overall appearance of the
pharynx and supraglottis during introduction of the laryngoscope.
• The endotracheal tube, if present, is followed to the tip of the
epiglottis.
• The epiglottis should be gently lifted forward making certain that it
does not curl up in front of the laryngoscope preventing a complete
view of the anterior commissure.
• An overall assessment of the larynx can be made with a tube in situ,
providing a degree of stability that is particularly welcome in the child
with a compromised airway.

• Laryngeal examination with the endotracheal tube removed provides
a superior view and, by using a probe to move the arytenoids
independently, the mobility of the cricoarytenoid joints can be
assessed.
• If an interarytenoid scar is present, the arytenoids will not move
independently.
• A posterior laryngeal cleft is excluded by passing the probe between
the arytenoids, comparing the lower limit of the interarytenoid
groove with that of the posterior commissure.
• Finally, great care should be taken to pass through the vocal cords if a
rigid endoscope is used to inspect the subglottis.

• The time available for the examination will depend on the airway and
respiratory reserve.
• In a child breathing spontaneously with a normal airway and normal
lung function, anaesthesia can be maintained solely by the use of
inhalational or intravenous agents and a nasopharyngeal airway.
• In some cases the time may be very limited and it is essential to be
prepared to move ahead with bronchoscopy at any stage.
• If there is significant subglottic stenosis, an ultra-fine telescope
passed through the laryngoscope will cause less trauma than a
bronchoscope

BRONCHOSCOPY TECHNIQUE
• Traditionally, a ventilating bronchoscope has been used which
provides a means of actively ventilating the patient if required.
• With spontaneous ventilation, a smaller diameter rigid Hopkins rod
telescope can be used with less trauma and reduced splinting of the
airway.

• An anaesthetic laryngoscope can be used in the vallecula to lift the
larynx forward while passing either the tip of the Hopkins rod or the
bevel of the bronchoscope through the vocal cords.
• If a bronchoscope is used, this can be performed under video control
with a Hopkins rod coupled into the bronchoscope.
• Tracheomalacia should be observed with a small bronchoscope
withdrawn from the area in question and without positive airways
pressure to avoid splinting

• The subglottis, trachea, the carina and main bronchi are all
systematically examined and videographs or digital images recorded.
• Photodocumentation of the endoscopic findings and printing of a
compilation of images not only benefits the patient record but also is
a useful visual tool for explaining findings to the family.
• A minimum of a ‘four-shot view’ of the supraglottis, glottis, subglottis
and trachea, and lastly of the carina and main bronchi is suggested.
• Video recording of dynamic pathologies such as abnormal vocal cord
movement, laryngomalacia and tracheobronchomalacia is also
recommended

• It is vital that accurate records are kept. Use of a standardized data
capture form facilitates this.
• This provides an invaluable source of information for sequential
clinical comparisons, medicolegal purposes and teaching.
• Use of a recognized staging system is important for research
purposes, collaboration and publication of results

Ventilating bronchoscope and Hopkins rod.

DYNAMIC ASSESSMENT OF THE LARYNX ON
RECOVERY FROM ANAESTHESIA
• Typically, this can be achieved by withdrawal of the bronchoscope to
just posterior to the tip of the epiglottis. This gives a good view of the
vocal cords to exclude a cord palsy and of the arytenoids to exclude
the common posterior form of laryngomalacia, though anterior
collapse of the epiglottis may be masked.
• In this case, a 30° telescope can be used. The anaesthetist should
describe the phase of respiration to enable the endoscopist to check
for paradoxical vocal cord movements.

• Techniques for dynamic assessment of the vocal cord movement are
to insert a laryngeal mask with a fibreoptic bronchoscope passed
through this to just above the laryngeal inlet or passage of the scope
through a specially adapted face mask.
• If a bilateral vocal cord palsy is suspected and structural
abnormalities have been excluded with a full microlaryngoscopy and
rigid bronchoscopy, it is sometimes necessary to reschedule the
patient for a further examination in which a laryngeal mask and
fibreoptic scope are used from the outset, reducing the influence of
prolonged anaesthesia on the cord function.

MANAGEMENT OF ACUTE AIRWAY OBSTRUCTION
• In the acute situation, assessment, history taking and resuscitation will
often proceed in parallel.
• In the example of a child arriving in the emergency room with suspected
croup, the physician will be assessing the child for the degree of airway
obstruction by gauging the recession and dyspnoea at the same time as
asking the parent/carer for the length of history and whether there is any
possibility of foreign body inhalation
• A nurse may be checking the oxygen saturation and setting up humidified
oxygen

• Another member of the team may have to call and alert the operating
room that the child may need intubation as well as calling the
anaesthetist and otolaryngologist.
• This situation clearly benefits from careful planning, with most units
having a protocol for how to deal with the stridulous and airway-
compromised child.
• The protocols vary considerably, with some units insisting on the
presence of an otolaryngologist at intubation in case a tracheostomy
is needed while others have managed for many years without.

• In a child with a compromised but functional airway it is crucial that
upsetting the child does not cause deterioration.
• Coughing, crying and distress may result and change obstruction from
partial to complete.
• Significant consideration and skill are required in the management of such
a patient.
• The child should be kept in a position of comfort with its carers in a calm
environment and the applications of adjuncts such as pulse oximetry,
oxygen and nebulized adrenaline carefully tailored.
• Interventions such as venepuncture, taking of radiographs and flexible
nasendoscopy may jeopardize the critical airway.

Suggested minimum equipment standard for
paediatric airway endoscopy
• Adjustable laryngeal suspension system
• Operating microscope with 400f lens
• Selection of age-appropriate paediatric laryngoscopes of varying size and with a variety of viewing
angles
• Dedicated laryngeal microsurgical instruments, e.g. microscissors, probes, cupped and straight
forceps
• Selection of age-appropriate ventilating bronchoscopes with Hopkins rod telescopes to fit
• Suitable light source with fibre-optic cable
• Camera and monitor with image-capture facilities – video and still
• Colour printer
• Selection of forceps for the removal of foreign bodies
• Optical forceps with rigid telescope(s) of corresponding length
• Selection of fibre-optic bronchoscopes and a nasopharyngoscope
• Full range of paediatric tracheostomy tubes

Medical management - OXYGEN THERAPY
• With an obstruction to airflow and normal alveolar function, raising the
concentration of inspired oxygen will reduce the ventilatory requirement to
maintain adequate oxygen saturation levels but will not aid carbon dioxide
clearance.
• So long as the possibility of hypercarbia is appreciated, oxygen is a useful drug in
the treatment of airway obstruction.
• As previously emphasized, a face mask applied to the conscious child is likely to
be upsetting and should be avoided.
• Use of nasal cannulae, wafting or ‘head box’ oxygen
• Persistent hypoxia and cyanosis are very late signs in
a child and are likely to precede rapid respiratory collapse

HUMIDIFICATION
• There is no objective evidence that
raising the humidity of the inspired
air is beneficial in upper airway
obstruction and in croup.
• Humidification has however been
used for decades but few units still
use humidity tents or ‘croupettes’
as these have the disadvantage of
decreased visibility and may also
frighten the child.

HELIUM-OXYGEN MIXTURES (HELIOX®)
• Addition of helium to inspired gases is associated with a reduction in the
turbulence of flow.
• Helium–oxygen mixtures are thus recognized to decrease airway resistance
and have been used for several decades in the management of patients
with upper airway obstruction.
• Use of 70% helium/30% oxygen inhalation has been
systematically reviewed for use in treatmentof croup in children;
• there is some evidence to suggest a short-term
benefit in moderate to severe croup

PHARMACOTHERAPY – steroids :
• Intravenous and oral steroids such as dexamethasone have been shown to be beneficial
in croup, with inhaled steroids having a similar effect.
• Klassen summarizes: ‘All children with croup symptoms who demonstrate increased
work of breathing in the clinics or emergency departments should be treated with
glucocorticoids.’
• This treatment may be with nebulized budesonide (2 mg) or oral or intramuscular
dexamethasone (the optimal dose needs to be defined; 0.15–0.6 mg/kg has been
described).
• Oral glucocorticoids such as dexamethasone and prednisolone may be the best options
due to ease of administration, widespread availability, and lower cost.
• Inhaled or nebulized budesonide can be used at home for children with recurrent croup.

Nebulized adrenaline
• (400 μg/kg or 0.4 mL/kg of 1 : 1000 to a maximum of 5 mL) may
result in a transient improvement within 10-30 minutes, lasting up to
2 hours.
• This should be considered in pathologies that have an inflammatory
component, such as croup, with moderate or severe distress.
• Again, a nebulizer should be applied only
if it does not increase the distress
of the patient

Transfer of the child with stridor
• Transfer of a seriously ill child with stridor
to a centre of anaesthetic and surgical
expertise may be necessary.
• The Advanced Paediatric Life Support
(APLS) framework teaches that the right
child should be taken at the right time, by
the right people, to the right place, by the
right form of transport, and receive the
right care throughout.
• This is often best achieved by a
specialized children’s retrieval team with
advanced life-support capabilities.

• It may be necessary and appropriate for the airway to be secured by
intubation prior to transfer.
• Short-term placement of an LMA may be an alternative in cases
where intubation is not possible.
• The systematic approach requires preparation and planning for
transfer.
• Frequent reassessment of the child by appropriately skilled staff is
vital.
• Continuous monitoring should also be used where possible: oxygen
saturations, pulse, arterial pH and gases, temperature, blood
pressure, carbon dioxide monitoring (if intubated).

Surgical management
• The increasing use of intubation as an alternative
to tracheostomy in acute airway obstruction has been
brought about by advances in anaesthesia and
paediatric intensive management
• paediatric tracheostomy can be associated with significant morbidity and
potential mortality.
• Intubation may not be possible in all cases, despite anaesthetic skill, careful
planning and monitoring.
• Severe subglottic stenosis, impacted foreign bodies and advanced
epiglottitis are key examples

• laryngeal atresia with ventilation being achieved via a tracheo-
oesophageal fistula also necessitate a tracheostomy.
• It is this uncertainty combined with the precipitate nature of
paediatric airway obstruction that makes it mandatory in most
hospitals for an ENT surgeon to be informed if a child with airway
obstruction of unknown aetiology is to be intubated.
• Depending on the circumstances, it may be necessary to have an
emergency tracheostomy set open with a tube of the correct size
already selected

• Once the child has been slowly induced with a volatile anaesthetic
agent it is possible to inspect the larynx and exclude epiglottitis.
• This may be all that is required; it may be possible to manage the
child using a nasopharyngeal airway (prong) and/or continuous
positive airway pressure (CPAP).
• If intubation is required, it is important to minimize any damage to
mucosa that may already be inflamed;
• Very gentle intubation with a small tube
just large enough for adequate ventilation
and suction of secretions is recommended.

• Even if an initial intubation is oral, which tends to be easier, the tube
should be replaced with a nasal tube; this may be more secure and
better tolerated.
• The sizing of the tube can be assessed by checking for a leak and the
tracheobronchial secretions suctioned.
• If the secretions are very tenacious or there is still an element of
airway obstruction, a ventilating bronchoscope should be passed to
exclude bacterial tracheitis or a foreign body.
• Significant tracheobronchomalacia is another reason for continuing
airway difficulty after intubation and this will usually respond to CPAP.

EMERGENCY TRACHEOSTOMY
• With experienced paediatric anaesthetists,
this is now very unusual.
• Otolaryngologists are often asked to attend a potentially difficult
intubation, but are rarely needed.
• A ventilating bronchoscope may be easier to pass than an endotracheal
tube.
• An endotracheal tube mounted on a Hopkins rod telescope may also be
particularly useful in a difficult intubation

• If there is any potential for an emergency tracheostomy, the surgical
set and appropriate tube need to be instantly available.
• It is important to stay strictly in the midline so the child needs to be
carefully positioned without neck or head deviation.
• A finger either side of the larynx is helpful with a vertical incision
through the skin and down to the trachea.
• If a paediatric tracheostomy tube is not available, a paediatric
endotracheal tube can be used, ensuring it remains above the carina

‘CHAOS’ AND ‘EXIT’
• Advances in the availability and quality of antenatal imaging has led
to significant advances in the recognition and treatment planning of
children with congenital high airway obstruction syndrome (CHAOS).
• A significant risk of airway compromise at the time of delivery with
associated morbidity and mortality at birth may be avoided by anex
utero intrapartum treatment (EXIT).
• This highly specialized technique requires expert multidisciplinary
input and is a broad topic with links and overlap with foetal surgery

• In brief, the underlying principle of the technique is to ‘operate on placental
support’; materno-placental and placento-foetal blood and gas exchange are
maintained while the neonate’s airway is secured.
• This is achieved by delivery of the foetal head and upper torso through a
hysterotomy incision.
• Intubation, bronchoscopy, tracheostomy and excision of the obstructing lesion
may be performed as permitted and indicated.
• Naturally, the EXIT technique requires an antenatal diagnosis of the pathology
causing CHAOS and multidisciplinary care at a centre of expertise to coordinate
this elective surgery.
• Parental counselling and consideration of ethical aspects, particularly in the
foetus with multiple congenital abnormalities, are of fundamental importance.

BEST CLINICAL PRACTICE
• In the acute situation, assessment, history taking and active
resuscitation may proceed simultaneously.
• In suspected epiglottitis, instrumentation of the oral cavity and
pharynx for clinical examination must be avoided.
• All children with croup who demonstrate increased work of breathing
should be treated with glucocorticoids. Nebulized adrenaline may
also be given.
• Wherever possible, endotracheal intubation is preferable to
emergency tracheostomy.

• If a child with airway obstruction of unknown aetiology is to be
intubated, an ENT surgeon should be informed. It may be necessary
to have an emergency tracheostomy set open with a tube of the
correct size already selected although this is very rarely needed.
• A difficult endotracheal intubation may be facilitated by the use of a
small ventilating bronchoscope or by passing a Hopkins rod telescope
on which a endotracheal tube has been mounted.

FUTURE RESEARCH
➤➤ The optimal glucocorticoid dose and agent for use in
inflammatory upper airway obstruction conditions such as croup is yet
to be determined.
➤➤ A growing trend towards specialization within otolaryngology will
ensure that airway endoscopy in children is increasingly the remit of
otolaryngologists with a special interest and training in this work.

To conclude :
• Stridor is the noise from a narrowed airway and is a symptom, not a
diagnosis.
• The aim of the history, examination and special investigations is to
determine not only the site and cause of the obstruction (the
diagnosis) but also its effect on the airway (the severity).
• Hypoxaemia is a late feature of airway obstruction, particularly in
children treated with oxygen.
• Improvement in stridor may paradoxically be due to worsening
obstruction.

• Laryngomalacia is common but it is important not to assign failure to
thrive to this without first having considered and excluded other
causes.
• Rapid progression of airway obstruction typically occurs in acute
infection and in foreign body inhalation.
• Laryngotracheobronchoscopy is the gold standard in the assessment
of the stridulous child and is a highly skilled procedure involving a
team approach between anaesthetist, endoscopist and operating
room personnel. Adequate facilities are not available in all institutions

Stridor

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