Pediatric Stridor

Author Credentials 

Shelby C. Leuin, MD
Associate Professor of Pediatrics and Surgery
University of California, San Diego School of Medicine
Children’s Hospital and Health Center of San Diego
3020 Children’s Way, MC 5024, San Diego, CA 92123
email: sleuin@rchsd.org

Module Summary

Stridor is the result of disturbed or turbulent airflow in the airway. A rapid and thorough approach to determining the cause of stridor is critical to patient management. The initial objective of managing a patient with stridor is to assess the degree of respiratory distress and establish a secure airway if necessary. Once the etiology of the stridor is made, appropriate management requires an understanding of the natural history of the abnormality and implementation of appropriate treatment.

Module Learning Objectives 
  1. Explain the physiology of stridor and how structural and functional problems interact to cause stridor.
  2. Review the most common airway abnormalities associated with stridor in pediatric patients.
  3. Recognize the signs and symptoms of airway obstruction and effectively determine the urgency for intervention.
  4. Implement appropriate diagnostic studies and clinical examinations to evaluate stridor.
  5. Review the treatment options for managing the most common causes of pediatric stridor.

Embryology

Learning Objectives 
  1. Understand the fetal development of the larynx and trachea:
    1. Fetal stage associated with laryngeal structures
    2. Failures of development: 
      1. Laryngeal atresia
      2. Laryngotracheo-esophageal clefts (Types 1,2 3 and 4)
      3. Congenital subglottic stenosis
      4. Laryngeal webs
      5. Tracheal stenosis
      6. Complete tracheal rings
  2. Understand postnatal development of the larynx
  3. Understand the changes in the airway after birth:
  4. Changes in the position of the larynx
  5. Changes in the configuration and size of the larynx
  6. Ossification of the larynx
References 
  1. Benjamin B, Inglis A. Minor congenital laryngeal clefts: diagnosis and classification. Ann Otol Rhinol Laryngol. 1989;98:417-20.
  2. Isaacson, G. In: Bluestone C, Stool S, Alper C, Arjmand E, Casselbrant M, Dohar J, Yellon R, editors. Pediatric otolaryngology. 4th ed. Philadelphia: Saunders; 2003:1361-70.
  3. Lim TA, Spanier SS, Kohut RI. Laryngeal clefts: a histopathologic study and review. Ann Otol Rhinol Laryngol. 1979;88:837-45.

Anatomy

Learning Objectives 
  1. Know the anatomy of the supraglottic structures:
    1. Epiglottis, aryepiglottic folds, arytenoids
    2. Corniculate and cuneiform cartilages
  2. Know the anatomy of the glottic structures:
    1. Vocal folds
  3. Know the anatomy of the subglottis:
    1. Cricoid ring - the only complete cartilaginous ring of the trachea
References 
  1. Bosma, JF. Anatomy of the infant head. Baltimore: Johns Hopkins University Press; 1986:366-7.

Pathogenesis

Learning Objectives 
  1. Describe Bernoulli’s principle of airflow and pressure:
    1. Increased airflow results in decreased pressure within lumen and collapse of structure.
  2. Know the characteristics of functionally obstructive airway lesions:
    1. Increased airflow results in collapse of airway.
  3. Know about fixed obstructive lesions:
    1. Cross-sectional area of airway is not dependent upon airflow.
    2. Understand relationship between reduction in diameter of airway and decreased size of airway.
  4. Know the difference between inspiratory and expiratory stridor
    1. Inspiratory typically is extrathoracic and above the vocal folds
    2. Expiratory typically is intrathoracic and below the vocal folds
    3. Biphasic stridor can occur at the glottis or immediate subglottis
References 
  1. Hartnick CJ, Cotton RT. In: Bluestone C, Stool S, Alper C, Arjmand E, Casselbrant M, Dohar J, Yellon R, editors. Pediatric otolaryngology. 4th ed. Philadelphia: Saunders; 2003:1437-8.

Incidence

Learning Objectives 
  1. Understand the most common etiologies of stridor for ages of children
    1. Neonates/infants usually have congenital stridor: vocal cord paralysis, subglottic stenosis (congenital and acquired), laryngomalacia, tracheomalacia, laryngeal web
    2. Preschool: viral croup, foreign body, respiratory papillomatosis
  2. Incidence of airway abnormalities in patients with cutaneous hemangiomas
     
References 
  1. Masters IB, Chang AB, Patterson L, Wainwright C, Buntain H, Dean BW, et al. Series of laryngomalacia, tracheomalacia, and bronchomalacia disorders and their associations with other conditions in children. Pediatr Pulmonol. 2002;34:189-95.

Genetics

Learning Objectives 
  1. Understand presence of airway abnormalities in patients with craniofacial syndromes:
    1. Laryngeal webs
    2. Velocardiofacial syndrome
    3. Down syndrome
References 
  1. Jacobs IN, Gray RF, Todd NW. Upper airway obstruction in children with Down syndrome. Arch Otolaryngol Head Neck Surg. 1996;122:945-50.
  2. Shprintzen RJ. Velo-cardio-facial syndrome: 30 Years of Study. Dev Disabil Res Rev. 2008;14(1):3-10.

Patient Evaluation

Learning Objectives 
  1. Know the important aspects of the patient’s history:
    1. Onset of stridor: neonatal period, pre-school age, school age
    2. History of airway instrumentation: neonatal intensive care unit, intubation for meconium aspiration, intubation for surgical procedure
    3. Associated signs and symptoms of infection
    4. Acute onset in unsupervised setting - consider foreign body aspiration
    5. Progression of symptoms
  2. Know the pertinent aspects of the physical examination:
    1. Assess urgency for intervention as initial focus of physical examination.
    2. Evaluate for signs of respiratory distress: nasal flaring, retractions, cyanosis
    3. Physical examination should initially focus on determining the area of the airway involved.
    4. Phase of respiration associated with stridor: inspiratory, expiratory, biphasic
    5. Principles of locating airway obstruction: inspiratory (supraglottic), expiratory (trachea and distal airway), biphasic (fixed lesion, glottic and subglottic)
    6. Change in position affecting stridor: supine, prone, side
    7. Auscultation of airway
    8. Airway endoscopy: office flexible endoscopy - can be difficult to accurately assess vocal cord movement in neonates
    9. Topical anesthesia should be used sparingly in neonates and neurologically impaired children
    10. Operative laryngoscopy and bronchoscopy with anesthesia: spontaneous respiration, secure environment

Measurement of Functional Status

Learning Objectives 
  1. Know that functional status related to stridor is usually related to signs of respiratory distress such as nasal flaring, suprasternal retractions, abdominal breathing.
  2. Understand that pulmonary function tests are rarely employed to measure degree of airway obstruction.
  3. Understand possible role for electromyography for vocal cord paralysis.
  4. Understand grading systems for subglottic stenosis: Cotton Meyer grade I-IV.
References 
  1. Gartlan MG, Peterson KL, Luschei ES, Hoffman HT, Smith RJ. Bipolar hooked-wire electromyographic technique in the evaluation of pediatric vocal cord paralysis. Ann Otol Rhinol Laryngol. 1993;102:695-700.
  2. Myer CM 3rd, O'Connor DM, Cotton RT. Proposed grading system for subglottic stenosis based on endotracheal tube sizes. Ann Otol Rhinol Laryngol. 1994;103:319-23.
  3. Mancuso, RF. Stridor in neonates. Pediatr Clin North Am. 1996;43:1339-56.

Imaging

Learning Objectives 
  1. Know the best types of radiographic evaluation, such as:
    1. High KV film of airway for subglottic abnormality
    2. Chest x-ray: tracheal narrowing, suspected foreign body (mediastinal shift, hyperinflation)
    3. Esophagram for suspected vascular ring
    4. Magnetic Resonance Imaging/Magnetic Resonance Angiography (MRI/MRA) for pulsatile tracheal compression
  2. Understand the limitations of radiographic studies to assess degree of obstruction
  3. Know the best imaging for tracheomalacia
    1. Consider the need to assess for vascular compression
    2. MRI, MRA, esophagram, fluoroscopy, virtual endoscopy
  4. Know the imaging for croup-steeple sign on A-P neck x-ray
  5. Understand the imaging for tracheal stenosis
References 
  1. Casselbrant M, Alper C. In: Bluestone C, Stool S, Alper C, Arjmand E, Casselbrant M, Dohar J, Yellon R, editors. Pediatric Otolaryngology. 4th ed. Philadelphia: Saunders; 2003:1379-93.
  2. Walner DL, Ouanounou S, Donnelly LF, Cotton RT. Utility of radiographs in the evaluation of pediatric upper airway obstruction. Ann Otol Rhinol Laryngol. 1999;108;378-83.
  3. Burke AJ, Vining DJ, McGuirt WF Jr, Postma G, Browne JD. Evaluation of airway obstruction using virtual endoscopy. Laryngoscope. 2000;110:23-29.
  4. Kaditis AG, Wald ER. Viral croup: current diagnosis and treatment. Pediatr Infect Dis J. 1998;17:827-34.
     

Medical Therapies

Learning Objectives 
  1. Know that stridor is a symptom of airway obstruction.
  2. Know that medical therapy must be directed at the etiology of stridor.
  3. Understand the medical therapy for subglottic hemangiomas:
    1. Propranolol
  4. Know that medical therapies may be targeted at managing factors contributing to stridor such as:
    1. Gastroesophageal reflux
      1. Changing foods and feeding schedule
      2. H2 blockers, proton pump inhibitors
    2. Allergies
    3. Infectious agents
      1. Parainfluenzae related croup
        1. Topical and systemic steroids
        2. Nebulized epinephrine
          • Awareness for rebound edema            
          • Appropriate monitoring of airway
      2. Papillomatosis
      3. Bacterial tracheobronchitis
References 
  1. Brown JC. The management of croup. Br Med Bull. 2002;61:189-202.
  2. Derkay CS. Recurrent respiratory papillomatosis. Laryngoscope. 2001;111:57-69.
  3. Hughes CA, Rezaee A, Ludemann JP, Holinger LD. Management of congenital subglottic hemangioma. J Otolaryngol. 1999;28:223-8.
  4. Strople J, Kaul A. Pediatric gastroesophageal reflux disease--current perspectives. Curr Opin Otolaryngol Head Neck Surg. 2003;11:447-51.
  5. Yellon RF, Goldberg H. Update on gastroesophageal reflux disease in pediatric airway disorders. Am J Med. 2001;111 Suppl 8A:78S-84S.
  6. Weber JE, Chudnofsky CR, Younger JG, Larkin GL, Boczar M, Wilkerson MD, et al. A randomized comparison of helium-oxygen mixture (Heliox) and racemic epinephrine for the treatment of moderate to severe croup. Pediatrics. 2001;107:E96.
  7. Leaute-Labreze, Dumas de la Roque E, Hubiche T, Boralevi F, Thambo JB, Taieb A. Propranolol for severe hemangiomas of infancy. New Engl J Med. 2008 Jun 12;358(24):2649-51.

Surgical Therapies

Learning Objectives 
  1. Understand that the first principle of intervention is to establish a safe airway.
    1. Urgent management of stridor with compromised airway:
      1. Mask assisted positive pressure ventilation with oral airway or laryngeal mask
      2. Intubation with availability of endoscopy
      3. Surgical airway if intubation not possible
  2. Understand the indications and types of procedures for airway abnormalities associated with stridor.
    1. Laryngomalacia
      1. Supraglottoplasty with aryepiglottic fold division, possible removal of arytenoid mucosa and/or cartilage
      2. Surgical management of gastroesophageal reflux
    2. Unilateral and bilateral vocal fold paralysis
      1. Tracheostomy
      2. Cordotomy
      3. Arytenoidectomy
      4. Glottic expansion surgery
      5. Non-destructive laryngeal surgery
    3. Subglottic stenosis
      1. Tracheostomy
      2. Dilation
      3. Laser
      4. Cricoid split
      5. Laryngotracheal reconstruction with graft
      6. Cricotracheal resection and reconstruction
    4. Subglottic hemangioma
      1. Tracheotomy
      2. Laser
      3. Intralesional steroids
      4. Open resection
      5. Debrider
    5. Recurrent respiratory papillomatosis
      1. Debulking with forceps
      2. Laser removal
      3. Debrider
      4. Avoid anterior commissure to prevent formation of laryngeal web
    6. Airway foreign bodies
      1. Microlaryngoscopy and Bronchoscopy with removal with optical forceps
References 
  1. Derkay CS. Recurrent respiratory papillomatosis. Laryngoscope. 2001;111:57-69.
  2. Hartnick CJ, Brigger MT, Willging JP, Cotton RT, Myer CM 3rd. Surgery for pediatric vocal cord paralysis: a retrospective review. Ann Otol Rhinol Laryngol. 2003;112:1-6.
  3. Inglis AF Jr, Perkins JA, Manning SC, Mouzakes J. Endoscopic posterior cricoid split and rib grafting in 10 children. Laryngoscope. 2003;113:2004-9.
  4. Olney DR, Greinwald JH Jr, Smith RJ, Bauman NM. Laryngomalacia and its treatment. Laryngoscope. 1999;109:1770-5.
  5. Patel N, Rowe M, Tunkel D. Treatment of recurrent respiratory papillomatosis in children with the microdebrider. Ann Otol Rhinol Laryngol. 2003;112:7-10.
  6. Rimell FL, Stool SE. Diagnosis and management of pediatric tracheal stenosis. Otolaryngol Clin North Am. 1995;28:809-27.
  7. Tan HK, Brown K, McGill T, Kenna MA, Lund DP, Healy GB. Airway foreign bodies (FB): a 10-year review. Int J Pediatr Otorhinolaryngol. 2000;56:91-9.
  8. Toynton SC, Saunders MW, Bailey CM. Aryepiglottoplasty for laryngomalacia: 100 consecutive cases. J Laryngol Otol. 2001;115:35-8.
  9. Van Den Abbeele T, Triglia JM, Lescanne E, Roger G, Nicollas R, Ployet MJ, et al. Surgical removal of subglottic hemangiomas in children. Laryngoscope. 1999;109:1281-6.

Staging

Learning Objectives 
  1. Understand that stridor is characterized by severity of respiratory distress and phase of respiration in which stridor is present:
    1. Inspiratory
    2. Expiratory
    3. Biphasic
  2. Be aware that some abnormalities resulting in stridor can be graded or staged:
    1. Laryngomalacia-mild, moderate, severe
      1. mild: inspiratory stridor with no other symptoms
      2. moderate: cough, choking, regurgitation, feeding difficulty
      3. severe: apnea, cyanosis, failure to thrive, pectus, pulmonary hypertension, cor pulmonale
    2. Subglottic stenosis
      1. Size of endotracheal tube permitted by stenosis
      2. Percentage of normal airway present
    3. Recurrent respiratory papillomatosis
      1. Anatomic regions of airway involved
      2. Degree of anatomic region involved with papilloma
References 
  1. Richter GT, Thompson DM. The surgical management of laryngomalacia. Otolaryngol Clin North Am. 2008;41(5):837-864.

Case Studies

  1. Subglottic hemangioma: A two-month old child presents with biphasic stridor that had been treated twice with systemic steroids for the diagnosis of croup with transient improvement of the stridor. The child has no history of intubation, prematurity or evidence of an active respiratory infection when diagnosed with croup.
    1. Subglottic hemangiomas usually present after 2 months of age as the hemangioma enters the proliferative phase.
    2. The natural history of subglottic hemangiomas is eventual involution; however, medical or surgical intervention is necessary because of  the development of airway obstruction.
  2. Airway foreign body: A three year old male has acute onset of stridor after having been left unattended for ten minutes while playing. Auscultation of the lung fields reveals decreased right-sided breath sounds and a chest radiograph is normal.
    1. The history of acute onset of stridor in a child who was unattended raises the possibility of a foreign body aspiration.
    2. A chest radiograph may show hyperinflation of the lung distal to a foreign body because of air trapping and a ball-valve effect allowing air to pass the foreign body towards the distal lung on inspiration without permitting air movement out of the lung on expiration.

Complications

Learning Objectives 
  1. Know that stridor is a sign of disturbed airflow and therefore indicates partial obstruction of the airway.
  2. Understand that stridor may precede complete airway obstruction and, if not managed properly, may lead to respiratory arrest.

Review

Review Questions 
  1. What are the 3 most common airway abnormalities causing stridor in a child within the first month of life?
  2. What is the natural history of subglottic hemangiomas?
  3. Discuss the development of the larynx with regard to its position relative to the oral cavity.
  4. Discuss the relationship between the location of the airway abnormality and the characteristics of the related stridor.