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 respiratory failure 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 ► Signs and symptoms § 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 epiglottitis ► Acute bacterial tracheitis ► Retropharyngeal abscess ► 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 Croup ► Parainfluenza viruses account for 75% ► Adenoviruses, RSV, influenza 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 vocal cords “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 epiglottis 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 mediastinum ► 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 ►Radiography § 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 pharynx 18 19 20 Infectious mononucleosis ► Caused by Epstein Barr virus ► Transmission by exchange of saliva ► Long incubation (30-50 days) ► Moderate to severe pharyngitis 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 pneumonia 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 ► Atelectasis 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 § Pneumothorax § 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 35 .