a)  List the possible causes of stridor at rest in a previously well 3 year old child

b)  What features elicited on history, examination and imaging would help in refining the diagnosis

c) What are the indications for intubation in this situation?

d)  List the key management issues in securing the airway

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College Answer

a)  List the possible causes of stridor at rest in a previously well 3 year old child

•    viral croup
•     epiglottitis
•    inhaled foreign body
•    severe bilateral tonsillitis, meeting in the midline (eg: infectious mononucleosis)
•    tonsillar abscess
•    retropharyngeal infection/abscess
•    spasmodic (recurrent allergic) croup
•    allergic reaction/angio-oedema
•    bacterial tracheitis
•    intra-thoracic  obstruction  vascular  rings  (less  likely  in  prev.  well),  peri-tracheal tumours
•    diphtheria
•    other   congenital   causes   (laryngomalacia,   tracheomalacia,   tracheal   webs   etc)
unlikely in this setting, no marks for these responses

b)  What features elicited on history, examination and imaging would help in refining the diagnosis

1.   History:
•    past history including neonatal problems, previous intubation
•    vaccination especially HiB
•    prodrome, URTI symptoms
•    choking episodes (FB)
•    febrile symptoms
•    cough (implies epiglottitis unlikely)

2.   Examination
•    (minimise disturbance to child, examine in parent’s lap)
•    toxicity & fever
•    swallowing / drooling
•    petechial rash in HiB sepsis
•    inspect the throat (without instrumentation  and if child cooperative),  looking for tonsillar hyperplasia, uvula swelling, FB

3.   Radiology:
•    very limited utility, may be unsafe to transfer
•    possibly if radio-opaque FB suspected
•    lateral soft tissue neck of no/little value

c) What are the indications for intubation in this situation?

•    Complete or imminent airway obstruction
•    Worsening airway obstruction despite appropriate therapy (eg steroids + nebulised adrenaline in croup)
•    Dangerous reduction in conscious state
•    Uncorrectable hypoxaemia

d)  List the key management issues in securing the airway

•    Call for help
•    Choice of anaesthetic technique  - inhalational versus intravenous
•    Failed intubation drill

Discussion

a)  List the possible causes of stridor at rest in a previously well 3 year old child

Causes of stridor in children, according to timing of onset
Acute Subacute Chronic
  • Foreign body
  • Airway burns
  • Thermal epiglottitis
  • Caustic burns (ingestion)
  • Anaphylaxis
  • Epiglottitis
  • Laryngotracheitis (croup)
  • Retropharyngeal abscess
  • Peritonsillar abscess
  • Laryngomalacia
  • Tracheomalacia
  • Subglottic stenosis
  • Vocal cord dysfunction, Paradoxical vocal cord motion
  • Vocal cord paralysis
  • Vascular ring
  • Bronchogenic cyst
  • Laryngeal malformation
  • Infantile haemangioma
  • Tumour
  • Hypocalcemic laryngeal spasm
  • Recurrent respiratory papillomatosis
Causes of stridor according to anatomy of obstruction
Anatomical region Causes
Nose, pharynx
  • Choanal atresia
  • Choanal stenosis
  • Pierre Robin sequence
  • Craniofacial anomalies
  • Lingual thyroid and thyroglossal duct cyst
  • Hypertrophy of adenoids and/or tonsils
  • Retropharyngeal or peritonsillar abscess
  • Epiglottitis
  • Caustic or thermal airway burns
  • Tumour
Larynx
  • Laryngomalacia
  • Vocal cord paralysis
  • Subglottic stenosis (due to infection or trauma)
  • Laryngeal cyst
  • Laryngeal (laryngo-tracheo-oesophageal) cleft
  • Laryngeal web
  • Subglottic haemangioma
  • Lymphangioma
  • Laryngotracheitis (croup)
  • Supraglottitis
  • Respiratory papillomatosis
  • Hypocalcemic laryngeal spasm
  • Anaphylaxis
  • Hereditary angioedema
  • Inducible laryngeal obstruction
  • Foreign body aspiration
  • Vascular ring
  • Tumour
Trachea
  • Tracheomalacia
  • Bacterial tracheitis
  • Tumour
Causes of stridor arrayed by aetiology
Domain Causes
Vascular
  • Vascular ring
  • Haemangioma
Infectious
  • Epiglottitis
  • Laryngotracheitis (croup)
  • Retropharyngeal abscess
  • Peritonsillar abscess
  • Tracheitis
  • Recurrent respiratory papillomatosis (RRP)
  • Diphtheria
Neoplastic
  • Tumours at any level
  • Lymphadenopathy
Drug-induced
  • Anaphylaxis
  • Caustic ingestion
Idiopathic
  • Laryngomalacia
  • Tracheomalacia
  • Inducible laryngeal obstruction
  • Laryngeal cyst
  • Laryngeal web
  • Vocal cord paralysis
Congenital
  • Laryngeal (laryngo-tracheo-oesophageal) cleft
  • Craniofacial anomalies
  • Choanal atresia
  • Choanal stenosis
  • Pierre Robin sequence
Autoimmune
  • Hereditary angioedema
  • Anaphylaxis
Traumatic
  • Thermal burns
  • Post-traumatic subglottic stenosis
  • Foreign body
Endocrine
  • Hypocalcemic laryngeal spasm

b)  What features elicited on history, examination and imaging would help in refining the diagnosis

Assessment of stridor: history, examination, labs and imaging
HISTORY
Age
  • Neonates and young infants: congential problems
  • Infants and toddlers: croup and foreign body
  • School-aged: abscesses and vocal cord dysfunction
  • All ages: anaphylaxis and tracheitis
Acuity
  • Hyperacute: anaphylaxis, angioedema
  • Acute: bacterial tracheitis or epiglottitis
  • Subacute: laryngotracheitis
  • Chronic: anatomical problem, eg. stenosis or neoplasm
Associated symptoms
  • Fever (infectious causes)
  • Drooling (supraglottic obstruction)
  • Muffled voice (supraglottic obstruction)
  • Cough (barking = croup)
  • Voice quality (vocal cord lesion)
  • Stridor during feeding (tracheo-oesophageal fistula)
  • Onset during activity (vocal cord dysfunction)
  • Urticaria (anaphylaxis)
  • Onset during sleep (spasmodic croup, tonsillar enlagement)
  • Altered mental state (cause of stridor, or consequence of hypoxia)
EXAMINATION  
General inspection
  • Failure to thrive (poor feeding, weight loss)
  • Congential abnormalities
  • "Funnel Chest" - pectus excavatum suggestive of chronic airway obstruction
Skin
  • Urticaria (anaphylaxis)
  • Haemangiomas (one may be in the airway
  • Cafe au lait spots (neurofibromatosis of the airway)
Posture
  • "tripid position" of epiglottitis
  • Cyanosis, hypoxia
Timing of stridor
  • Inspiratory: supraglottic onstruction
  • Expiratory: intrathoracic obstruction
  • Biphasic: fixed obstruction, or something in the glottis itself
  • "Stertor" - low pitched snoring sound, coming from an obstruction in the nasopharynx or oropharynx
LABORATORY TESTS
Infectious testing
  • FBC for WCC
  • Cultures
  • Nasal swabs for viral PCR (especially for parainfluenza types 1, 2, and 3)
Autoimmune
  • FBC for eosinophil count
  • Mast cell tryptase for anaphyalxis
  • Allergen testing
Endocrine
  • CMP: for calcium level
  • Vitamin D for rickets
IMAGING
Plain radiographs of the airway
  • Foreign body
CT of the neck and chest
  • Abscesses
  • Tumours
  • Fistulae
Video-nasendoscopy
  • Vocal cord dysfunction
  • Laryngomalacia
  • Foreign body retrieval

c) What are the indications for intubation in this situation?

...little can be added to the college answer...

d)  List the key management issues in securing the airway

In brief:

  • Call for senior anaesthetic help. The person with the best paediatric airway management expertise should intubate the child.
  • Explore alternatives to intubation. In the case of the child with an airway obstruction or stridor, this may consist of  the following options:
    • Heliox 
    • Adrenaline nebs
    • Steroids (if the aetiology calls for it)
  • Optimise pre-intubation management: This consists of adequate pre-oxygenation. It may be necessary for the child to be pre-oxygenated in the parents' lap
    • Sit up 90°
    • CPAP may help by reducing the dynamic component of stridor 
    • Atropine can be given (20 µg/kg) to dry secretions
  • Explore airway control options: 
    • Inhalational induction is usually Plan A. The whole point is to maintain spontaneous respiration throughout the process, using gas to attain a level of anaesthesia which permits intubation. Best to induce them in a sitting position. Be prepared to wait- gas induction is slow in airway obstruction. When the patient is ready, they are rapidly made supine and intubated by laryngoscopy.
    • IV induction with paralysis is usually Plan B.
    • If unable to intubate, proceed to LMA. If LMA ventilation is sucessful, one can prepare for a repeat attempt at intubation, with a variety of difficult intubation equipment avalable, senior staff on standby, and with manoeuvres to improve visibility (eg. improved head position, BURP, videolaryngoscopy)
    • If unable to ventilate with LMA, proceed to needle cricothyroidotomy. This is difficult in children. Skileld proceduralists only seem to have a 60% success rate, and puncture the posterior wall of the trachea about 47% of the time.
    • If jet oxygenation can be accomplished, one has some time to set up for a Seldinger dilation and insertion of a pediatric ETT, or for a retrgrade intubation.
    • If jet ventilation cannot be accomplished, one must assess the difficulty of anterior neck anatomy.
      • if the anatomy is easy, one can proceed to a scalpel-bougie tecnique (where one makes an incision in the cricothyroid membrane and railroads the tube in over a hollow jet ventilation bougie)
      • if the anatomy is difficult, one must perform a scalpel-needle cricothyroidotomy (where the cricothyroid membrane is identified by palpation through an incision, so that the jet cannula can be inserted)
  • Optimise team communication: Ensure all team personnel are aware of the algorithm and understand the steps.
  • Optimise first attempt:
    • Videolaryngoscopy
    • Skilled staff present and briefed about Plan A and Plan B
  • Optimise subsequent attempts:
    • Checked equipment with backup models
    • Senior anaesthetist and ENT surgeon available
    • Ensure availability of ultra-fine (~ 2mm) intubating bronchoscope for paediatric work

References

Cavanagh, Florence. "Stridor in children." Proceedings of the Royal Society of Medicine 58.4 (1965): 272.

Pfleger, Andreas, and Ernst Eber. "Assessment and causes of stridor." Paediatric respiratory reviews 18 (2016): 64-72.