SAI YAN AU

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Stridor In Infants

• SAI YAN AU

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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

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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

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Stridor In Infants Causes

• Laryngomalacia (congenital laryngeal stridor)
• Subglottic stenosis
• Laryngeal webs

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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

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Laryngomalacia pathophysiology

• May affect the epiglottis, arytenoid cartilages
  or both
• Epiglottis elongated and the walls fold in on
  themselves ( OMEGA, O shaped)
• Arythenoid cartilage enlarged
• Either cases, cartilage is floppy prolapsed over
  the larynx during inspiration
• Increase risk of GOER
• Reflux laryngitis

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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

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Laryngomalacia

• Investigations-
• O2 saturation
• Fluoroscopy
• Laryngoscopy and bronchoscopy
• Treatment-
• gt 99, no Rx is needed
• Simple tracheotomy or laryngoplasty

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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)

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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

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Subglottic Stenosis

• History -
• Presence of biphasic and obstructive breathing
• Hoarseness or vocal weakness
• Clinical examination-
• Complete head and neck examination
• Evaluate the childs appearance, voice and
  neurological status
• Auscultate lung and neck
• Identify any associated features

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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)

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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

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Laryngeal Web

• 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.

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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)

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Laryngeal Webs

• Investigations-
• Direct laryngoscopy or bronchoscopy
• Treatment-
• Supportive (emergency)
• Surgery (thinner, thicker webs)

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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