Supraglottic obstruction is a medical or surgical emergency. It can result in increased work of breathing and respiratory distress and can progress to fatal cardiopulmonary arrest. Prompt correction of the causative factor can relieve obstruction and lead to improvement of the respiratory and cardiac status as well as the mental status of the patient. 

The pediatric airway is at increased risk for fatal outcomes from obstruction owing to narrow calibers, the position of the larynx, a large tongue, and the poor tone of the pediatric patient. Deterioration from a patent airway to a partial obstruction and progression to a complete obstruction can occur rapidly. Immediate recognition, prompt correction, and intervention to relieve airway obstruction can be life-saving.

Supraglottic obstruction can be acute or chronic and can present as a partial obstruction or complete obstruction. Careful assessment of the airway is important, keeping in mind, not to agitate or aggravate the patient, which can lead to worsened respiratory distress.[1][2][3]

Airway obstructions can be acute or chronic. Acute causes of supraglottic obstruction include laryngotracheobronchitis, croup, foreign body aspiration, epiglottitis, angioedema, acute bacterial tracheitis, facial or oral cavity burns, retropharyngeal abscess, and peritonsillar abscess. Chronic causes of supraglottic airway obstruction include laryngomalacia, tracheomalacia, laryngeal cysts, hemangiomas, obstructive sleep apnea, and progressive compression from masses. The obstruction presents as stridor, a harsh vibrating sound heard best during inspiration. The level of obstruction directly corresponds to the intensity of the stridor. Etiology may not be clear on initial presentation, and key factors in history and examination have to be taken into account.[4][5][6]

In obtunded patients, the tongue is the most common cause of upper airway obstruction.[7] Airway obstruction may be classified into either infectious, inflammatory or neoplastic[8]

Inspiratory stridor represents supraglottic obstruction while expiratory stridor originates at or below the glottis level. [9] Transient swelling of the lips, tongue, pharynx and larynx may be caused by angioedema. The swelling may occur rapidly and may emergently obstruct the airway.[10]

In neonates there are several congenital craniofacial anomalies that are associated with airway obstruction. These include craniofacial clefts, Pierre Robin sequence, midface hypoplasia, achondroplasia and Down syndrome may have micrognathia, obstructive sleep apnea or tongue-based airway obstruction.[11]

Viral agents most often cause upper airway obstruction in the pediatric age group. Bacterial causes like diphtheria, bacterial tracheitis, and epiglottitis are fairly uncommon especially since the introduction of vaccination with Haemophilus influenzae type b Haemophilus influenzae type b (Hib) and Pneumococcal vaccines. Males are commonly more affected by croup. Viruses like parainfluenza and influenza are the most common viral etiological agents.

Foreign body aspirations are common in young children between 2 to 5 years of age. Laryngomalacia is a  chronic cause of upper  airway obstruction and is the most common laryngeal anomaly in the infant age group.[12]

Odynophagia may be indicative of peritonsillar (quinsy) lingual or retropharyngeal abscess formation.[13][14][15][16]

Supraglottic obstruction in pediatric patients is more common in children than in adults with a similar illness, and this is due to factors that make the pediatric airway more susceptible to airway obstruction and distress. The pediatric airway is narrower and more prone to obstruction. The relatively high larynx, larger head, large tongue, poor tone, increased compliance which predisposes to kinking, and the narrowest diameter at the cricoid make the pediatric airway increasingly challenging. Air flowing in and out of a more limited airway flows under greater resistance. This results in stridor for upper airway obstruction and wheezing for lower airway obstruction. The presence of stridor indicates the loss of 50% of the airway diameter. [17] Airway inflammation and infections accelerate the edema around the airway. This worsens obstruction and respiratory distress. Most common findings associated are stridor/ noisy breathing, respiratory distress, and tachypnea with improper aeration of the lower airways. Increasing rates of immunizations with Hib and Streptococcal vaccines have resulted in a dramatic decrease in upper airway infections and inflammation. This has led to a dramatic decrease in rates of intubation or invasive interventions to relieve airway obstruction.

Angioedema has multiple mechanisms, but a common presentation.  Histamine-mediated  angioedema results in mast cell degranulation.  Bradykinin-mediated angioedema results from an overproduction of bradykinin due to  either an acquired or inherited C-1 deficiency. [10]Angioedema may also be caused by certain drugs such as angiotensin-converting enzyme inhibitors.[18]

Oversedation during procedures may contribute to airway obstruction and adverse events. In closed-claims analysis, 24% of liability claims during sedation were related to respiratory events.[19]

Neck hematomas may obstruct the upper airway by external compression of the trachea. These may occur post-surgery or due to trauma (blunt and penetrating)

or post-extubation.