1. Stridor In Infants
SAI YAN AU

2. Stridor
Harsh, high pitched, musical sound produced by turbulent airflow through a partially obstructed airway.
A sign
May be inspiratory, expiratory or biphasic
Inspiratory stridor – extrathoracic lesion (laryngeal, nasal, pharyngeal)
Expiratory stridor – intrathoracic lesion (tracheal or bronchial)
Biphasic stridor - subglottic or glottic anomaly

3. Stridor: Mechanism Venturi principle
Gases produce equal pressure in all direction
When gas move in a linear direction, it produces pressure in the forward vector and decreases the lateral pressure
When air passes through a narrowed flexible airway in child, the lateral pressure that holds the airway can drop and causes airway to close – airflow obstruction – stridor

4. Stridor In Infants: Causes
Laryngomalacia (congenital laryngeal stridor)
Subglottic stenosis
Laryngeal webs

5. Laryngomalacia (congenital laryngeal stridor)
Most common cause of persistent stridor in infants (first 6 weeks of life)
Congenital abnormality of the laryngeal cartilage
Delay in maturation of cartilaginous support for the supraglottic structures
No known sex and race predilection exists
Causes – congenital

6. Laryngomalacia: pathophysiology
May affect the epiglottis, arytenoid cartilages or both
Epiglottis – elongated and the walls fold in on themselves ( OMEGA, Ω shaped)
Arythenoid cartilage – enlarged
Either cases, cartilage is floppy; prolapsed over the larynx during inspiration
Increase risk of GOER
Reflux laryngitis

7. Laryngomalacia History:-
Hx of inspiratory noises; may sound like nasal congestion
Stridor worse in the supine position, increased activity, URTI and during feeding but improved in the prone position with the head up
Assoc. with pectus excavatum
On Examination:-
mild tachypnoea
Normal or slight drop in O2 saturation
Nasal airflow increase in supine position
Noise is purely inspiratory

8. Laryngomalacia Investigations:- O2 saturation Fluoroscopy
Laryngoscopy and bronchoscopy
Treatment:-
> 99%, no Rx is needed
Simple tracheotomy or laryngoplasty

9. Subglottic Stenosis
Narrowing of the subglottic which is housed in the cricoid cartilage
no racial predilection exists
equal sex distributions
Causes: -
congenital (in utero malformation of the cricoid cartilage)
Acquired ( infections e.g. TB, diphtheria, typhoid and syphilis, mechanical trauma due to endotracheal intubation and GOER)

10. Subglottic Stenosis: Pathophysiology
Congenital – incomplete canalization of the subglottis and cricoid rings, assoc. with trisomy 21
Acquired: -
Trauma causes mucosal oedema and hyperemia; leads to pressure necrosis
GOER – subglottis bathed in acid, irritates and inflames the area and prevent from healing

11. Subglottic Stenosis History: -
Presence of biphasic and obstructive breathing
Hoarseness or vocal weakness
Clinical examination:-
Complete head and neck examination
Evaluate the child’s appearance, voice and neurological status
Auscultate lung and neck
Identify any associated features

12. Subglottic stenosis Investigations:-
Direct laryngoscopy and bronchoscopy
AP and lateral neck x ray
Fluoroscopy
Dual channel pH probe testing
MRI and CT Scan
Treatment:-
Medical (steroids)
Surgical (tracheostomy, cricoid split and laryngoplasty)

13. Laryngeal Web Uncommon (5% of congenital laryngeal abnormalities)
Incomplete canalization of the larynx
Sporadic and equal sex distribution
Causes – congenital
4 types – based on the degree of occlusion
Type I, II, III, IV

14. Laryngeal Web Pathophysiology: -
Type I – 35% covering the anterior glottis
Type II – 35 to 50% occlusion of the lumen with vocal cord visible
Type III – 50 to 70% occlusion of the lumen with the vocal cord possibly visualized; most common
Type IV – 75 to 90% occlusion with vocal cords not visualized
Pathophysiology: -
Developmental abnormality occurring between the 4th to 10th weeks of gestation
Epithelial fusion between 2 sides of larynx fails to dissolve resulting in incomplete recanalization of the primitive larynx.

15. Laryngeal webs: Clinical Features
Inspiratory and expiratory stridor +/- upper airway obstruction with respiratory distress
Paroxysmal dyspnoea +/- cyanosis
Aphonia, weak cry
Poor feeding
Assoc with respiratory and CVS problems (10% - 15%)

16. Laryngeal Webs Investigations:- Direct laryngoscopy or bronchoscopy
Treatment:-
Supportive (emergency)
Surgery (thinner, thicker webs)

17. SUMMARY
Laryngomalacia – delay in maturation of the cartilaginous support of supraglottic structures
Subglottic stenosis – incomplete canalization of subglottis and cricoid cartilage
Laryngeal web – fusion of the anterior portion of true vocal cords