Acute upper airway obstruction in children: Imaging essentials

Carlos J. Sivit MD Rainbow Babies and Children’s Hospital Case Western Reserve School of Medicine

►Clinical perspective ►Infections ►Foreign body ►Masses

1 Clinical

Clinical

► Common cause of in children ► Potentially life-threatening in younger children because of smaller airway diameter ► Narrowing of upper airway has exponential effect on airflow

2 Clinical

► Majority of children are otherwise healthy ► Appropriate management results in good outcomes ► Improper management has dire consequences ► Imaging plays critical role in diagnosis

Clinical

► § Respiratory distress § Dysphagia § Odynophagia § Stridor § Absence of air entry § Tachycardia

3 Stridor

► Harsh respiratory noise caused by turbulent air flow through narrowed airway ► Specific for severe upper airway obstruction ► Intensifies in inspiration ► Does not help specify nature or location

Infections

4 Infections

► Acute laryngotracheobronchitis ► Acute ► Acute bacterial ► ► Infectious mononucleosis

Croup

► Heterogenous group of acute infections characterized by brassy “croupy” cough ► May or may not be accompanied by stridor, hoarseness and respiratory distress ► Typically seen in younger children § 6 months – 5 years

5

► Parainfluenza viruses account for 75% ► Adenoviruses, RSV, and measles cause most remaining cases ► Secondary bacterial infection is rare

Imaging

►Imaging § Performed to exclude other conditions particularly foreign body or epiglottitis ►Findings § Subglottic tracheal narrowing 5–10 mm below “steeple sign” § Overdistension of hypopharynx

6 NORMAL CROUP

7 “Steeple sign” - Ddx

► Croup ► Bacterial tracheitis ► Epiglottitis ► Vocal cord paralysis ► Laryngeal web ► Congenital subglottic stenosis

8 Epiglottitis

► Lifethreatening condition ► Typically younger children (2-7 years) ► Exclusively Hemophilus influenza prior to vaccine availability ► Incidence has decreased dramatically

Epiglottitis

► Preceding fever and sore throat ► Rapidly progressive drooling, stridor and respiratory distress ► May progress to complete airway obstruction within hours ► Diagnosis made by visualization of edematous

9 Epiglottitis

►Imaging § Lateral radiograph obtained upright § May aggravate clinically if lie down ►Findings § Thickened epiglottis § Thickened aryepiglottic folds § Subglottic narrowing (non-specific)

10 Acute bacterial tracheitis

► Acute bacterial infection of upper airway ► Capable of causing life-threatening airway obstruction ► S aureus most common pathogen ► Moraxilla catarrhalis and H influenza other pathogens

11 Acute bacterial tracheitis

► Typically begins with viral URI symptoms ► Gradually worsening inspiratory stridor ► Rapid development of high fever, cough, stridor & copious secretions ► May develop acute tracheal obstruction ► Major pathology is mucosal swelling at level of cricoid cartilage

Acute bacterial tracheitis

► Diagnosis based on evidence of acute bacterial upper airway disease and absence of epiglottitis ► Imaging not central to diagnosis § Subglottic narrowing (low specificity) § Irregular tracheal contour (low sensitivity)

12 13 Retropharyngeal abscess

► Retropharyngeal space bound by visceral fascia anteriorly and prevertebral fascia posteriorly ► Contains lymph nodes & lymphatic channels that drain nasopharynx ► Rupture of suppurative nodes result in cellulitis and abscess formation

Retropharyngeal abscess

► Alar fascia divides space into true retropharyngeal space and danger space ► Danger space extends to ► Allows for spread of infection

14 Retropharyngeal abscess

► Clinical presentation § Younger children; typically < 4 years § Prior URI § Fever, neck pain, drooling ► Etiology § Suppurative lymphadenitis associated with tonsilitis & sinoasal & dental infections § Staphylococcus or Streptococcus

Imaging

► § Increased retropharyngeal soft tissues § Mass effect on posterior pharyngeal wall § Unable to differentiate cellulitis from abscess § Lacks sensitivity or specificity

15 Pitfall

► Pseudothickening of soft tissues (retropharyngeal pseudomass) § Airway not fully distended § Spine not fully extended ► True soft tissue swelling results in anterior airway displacement

16 Initial exam Repeat exam

17 Imaging

►CT § Focal low-attenuation collections § Oval or rounded configuration § Fills space from side to side § Thick enhancing wall § Mass effect with anterior displacement of

18 19 20 Infectious mononucleosis

► Caused by Epstein Barr virus ► Transmission by exchange of saliva ► Long incubation (30-50 days) ► Moderate to severe with marked tonsillar enlargement

Imaging

► Not central to diagnosis ► Occasionally performed if concern for airway obstruction ► Massive enlargement of tonsils and adenoids ► May see prevertebral soft tissue swelling due to associated cellulitis

21 22 Airway foreign body

23 Airway foreign body

► Common cause of respiratory distress in young children (6 months – 3 years) ► Symptoms include stridor, wheezing, cough, hemoptysis and

Airway foreign body

► Symptoms depend on location & size § Endobronchial > Laryngotracheal § Complete vs partial obstruction ► Nonopaque > Opaque ► Greater morbidity with laryngotracheal

24 Imaging

Findings ► Filling defect in airway ► Unilateral hyperinflation ►

Airway foreign body

► Always obtain expiratory view § Film at normal inspiration often normal ► Lateral decubitus views in younger children who can not follow instructions

25 Expiration

Inspiration

Inspiration

Expiration

26 2/24/06 2/25/06

3/3/06

Lateral decubitus views

Left side down Right side down

27 28 Unilateral hyperlucent lung

§ § CLO § Bronchial atresia § Extrinsic bronchial obstruction § Intrinsic bronchial obstruction § Pulmonary hypoplasia

29 Reactive airway disease

3/10/08

3/16/08

Foregut cyst

30 Masses

Masses

►Hemangioma ►Papilloma ►Granuloma

31 Subglottic hemangioma

► Clinical presentation § Neonatal period § Inspiratory stridor § Dyspnea § Cutaneous hemangiomas in 1/2

Imaging

► Radiography § Eccentric subglottic narrowing ► CT & MR § Well circumscribed intraluminal mass § Useful for preoperative planning with large masses

32 Subglottic hemangioma

33 Papilloma

► Laryngeal or tracheal- bronchial ► Caused by human papilloma virus ► Multiple lesions in 80% ► Recurrence common § Recurrent respiratory papillomatosis

34 Granuloma

► Most occur post intubation or tracheostomy ► May also occur secondary to infection

Acute upper airway obstruction in children: Imaging essentials

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