Question 8

1. 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 (e.g.: 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

2. 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

3. What are the indications for intubation in this situation?

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

Discussion

Causes of stridor are potentially numerous:

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

So, given that this is a "previously well 3-year-old child",  one can probably forget about all the chronic causes. Thus:

• Foreign body
• Airway burns
• Thermal epiglottitis
• Caustic burns (ingestion)
• Anaphylaxis
• Epiglottitis
• Laryngotracheitis (croup)
• Retropharyngeal abscess
• Peritonsillar abscess

For 40% of the marks, one would not be expected to reproduce the table offered below, but occasionally the author feels the need to list every possible permutation of answer content:

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

Indications for intubation: one might benefit from bringing up the Croup Score at this stage:

Score	0	1	2
Breath sounds	Normal	Harsh, wheeze	Delayed
Stridor	None	Inspiratory	Inspiratory and expiratory
Cough	None	Hoarse cry	Bark
Recession/flaring	None	Flaring, suprasternal recession	Flaring, suprasternal and intercostal recession
Cyanosis	None	In air	In oxygen 40%

By this scoring system, intubation should be considered in anybody who scores 7-10. Though this is a directive which comes from a truly ancient manuscript (Downes et al, 1975), it still gets quoted in modern literature. Also, this might not be croup. 

Alternatively, one might turn to more modern non-croup related literature, such as an authoritative article by Gray et al (2017). It appears to have been written by an anaesthetic registrar for the purpose of increasing the CME point score of his co-authors. However unglamorous, it contains an excellent list of very sensible indications for intubation, which is plagiarised here:

Situations where immediate intubation should be considered include:

• Suspected epiglottitis
• Inhalational injury
• Falling conscious level
• Increasing respiratory failure, indicated by:
  • Rising PaCO₂
  • Exhaustion
  • Hypoxia (SpO2 <9₂% despite high flow oxygen administered via mask)