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 child. 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 progress to a complete obstruction can take place rapidly. Rapid recognition, prompt correction, and intervention to relieve airway obstruction can be life-saving. Supraglottic obstruction can be acute or chronic and can present as partial obstruction or complete obstruction. Careful assessment of the airway is important, keeping in mind, not to agitate or aggravate the child's distress and anxiety, which can, in turn, worsen respiratory distress.
Etiology can be acute or chronic. Acute causes of supraglottic obstruction include laryngotracheobronchitis, or croup, foreign body aspiration, epiglottitis, allergic reaction or anaphylaxis, acute bacterial tracheitis, burns to the face or oral cavity, retropharyngeal abscess, peritonsillar abscess and causes of upper airway edema or swelling. Chronic causes of supraglottic obstruction include laryngomalacia, tracheomalacia, laryngeal cysts or hemangiomas, obstructive sleep apnea or chronic compression from malignancies or lymphomas. 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.
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. Chronic causes like laryngomalacia or tracheomalacia are common in the infant age group.
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. 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.
History depends on the age of presentation of the patient. The younger the patient, the more severe the manifestations of the obstruction. Differences in the presentation also depend on whether the process is acute, subacute, or chronic. The common clinical complaints include a cough, stridor or noisy breathing, difficulty breathing, and respiratory distress. The severity of the respiratory distress can range from mild to moderate or severe. Head bobbing, altered mental status, lethargy, coma, and loss of consciousness are present when the obstruction is severe and impedes breathing. This results in severe hypoxemia or hypocarbia. Initial exam findings include respiratory distress, increased work of breathing, anxiety and chest retractions. Audible stridor is usually appreciated, which worsens with agitation or crying. Wheezing is an uncommon finding with upper airway obstruction and often demonstrates lower airway or chest pathology.
Evaluation should include a complete assessment of the child including the respiratory distress. Work of breathing can be assessed under different categories in categorizing pediatric respiratory distress. This should include the mental status of the child, work of breathing, the use of accessory muscles, respiratory rate, pulse oximetry or end-tidal carbon dioxide monitoring, and auscultation of breath sounds. All parameters should be used in conjunction to evaluate the level of respiratory compromise in a child. Altered mental status and lethargy or fatigue without increased work of breathing or tachypnea should raise concerns for impending respiratory or cardiovascular failure.
The next step in the evaluation of the respiratory status is the assessment of the airway. Various scoring systems are available for evaluation of the airway. Commonly used systems are the Mallampatti scoring system and the ASA (American Society of Anesthesiologists). Assessment of the airway should include management interventions and correction in a step-wise management.
Management of upper airway obstruction depends on the etiology. Primary management should focus on keeping the patient calm, reducing anxiety, and getting the patient in a position of comfort. Airway, breathing, and circulation should be assessed in the primary survey. Any causes of obstruction should be relieved immediately. A foreign body in the oral cavity or upper pharynx can be removed with forceps after direct visualization. Care should be taken to avoid any interventions that may make the child anxious or irritate the child. Avoid intravenous access, painful procedures in patients with acute epiglottitis or tracheitis, to minimize respiratory distress and impending respiratory failure.
Corticosteroids have proven to be a benefit for causes related to edema and inflammation of the upper airway in conditions like croup. Mechanism of action includes anti-inflammatory and reduction of edema. Racemic epinephrine via nebulized route has both alpha and beta action and causes upper and lower airway lumen dilation, which improves air entry and results in a more laminar airflow.
Invasive airway adjunct like oropharyngeal and nasopharyngeal airway help in relieving airway obstruction and can be used in cases of tongue edema or inflammation. Positive pressure ventilation is used for relief via bag and mask ventilation if the patient is in severe distress, has increased work of breathing and in patients en route to intubation. Endotracheal obstruction can be used if all other methods of relief are unsuccessful and the patient has an impending respiratory failure, is comatose, altered mental status, or has worsening respiratory distress.
Surgical airway with tracheostomy or cricothyroidotomy is used in rare instances when attempts to relieve upper airway obstruction fail. There are instances of facial burns or facial trauma where obtaining an upper airway adjunct or endotracheal intubation are unsuccessful. The surgical airway should be initiated by an experienced health care provider with adequate training. Best outcomes are achieved when it is initiated promptly with experienced and skilled personnel.