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  Respiratory disorders are potentially life-threatening and must be identified and treated rapidly.

  
  
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  Certain physiologic differences make pediatric patients more at risk of respiratory failure than adults.

  
  
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  Conduct patient assessment in a calm, efficient manner, attempting to localize the underlying source of distress.

  
  
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  Initial treatment may be required for stabilization before a complete history and physical examination can be performed.

  
  
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  Patient appearance and clinical status always supersede lab values and imaging.

Respiratory distress is a very common presentation in the emergency department (ED). It accounts for 10% of pediatric visits to the ED, 20% of pediatric admissions, and 20% of deaths in infants. Respiratory distress can potentially lead to respiratory failure (the inability of oxygenation and ventilation to meet metabolic demands) and should be recognized and treated promptly.

Several anatomic and physiologic characteristics put pediatric patients at higher risk for respiratory compromise. Infants <4 months of age are obligate nose breathers. Nasopharyngeal obstruction significantly increases the work of breathing. The location of the narrowest part of the airway, where a foreign body is likely to lodge, differs in adults (vocal cords) and children (cricoid cartilage). The diameter of the pediatric airway is a third that of adults. Narrowing of the airway leads to a greater relative increase in resistance to airflow (1-mm occlusion decreases cross-sectional diameter by 20% in adults vs. 75% in children). Abdominal musculature is a primary contributor to respiratory effort in children. Abdominal distension and muscle fatigue can negatively impact ventilation. Pediatric lungs have a lower functional residual capacity (FRC) with less reserve potential. PaO₂ decreases more rapidly when ventilation is interrupted.

Respiratory distress may result from either upper airway obstruction, lower airway disorders, or other organ dysfunction compromising the respiratory system. Upper airway obstruction is the leading cause of life-threatening acute respiratory distress. Upper airway obstruction is defined as blockage of airflow in the larynx or trachea. It is characterized by stridor, an inspiratory sound caused by air flow through a partially obstructed upper airway. The age of the patient can aid in diagnosis.

Common causes of upper airway obstruction in children <6 months include laryngotracheomalacia (chronic, usually resolves by age 2) and vocal cord paresis or paralysis. Laryngomalacia and tracheomalacia are congenital conditions that affect the structural integrity of supporting structures in the upper airway. This leads to collapse of the affected tissues into the airway during respiration.

In children >6 months, important causes of upper airway obstruction include viral croup, foreign body aspiration, epiglottitis, bacterial tracheitis, retropharyngeal abscess, peritonsillar abscess, airway edema from trauma, thermal or chemical burn, or allergic reaction. Croup (laryngotracheobronchitis) is the most common cause of upper airway obstruction and stridor in children aged 3 months to 3 years. It occurs in 5% of children during their second year of life and is caused by a viral infection affecting the subglottic region. The patient presents with a barking cough, inspiratory stridor, and fever.

Upper airway obstruction from foreign body aspiration is most common in children aged 1 to 4 years. About 3,000 patients die each year from asphyxia related to foreign body aspiration.

Bacterial infections in the upper airway include epiglottitis and tracheitis. Epiglottitis is less common now since routine immunization against Haemophilus influenzae type B. Currently, tracheitis is more likely to be the cause of acute respiratory failure from airway obstruction than epiglottitis.

Lower airway obstruction has several causes, including asthma, bronchiolitis, pneumonia, allergic reaction, respiratory distress syndrome, aspiration, and environmental or traumatic insults. Asthma is the most common chronic disease in children, affecting 5–10% of the population. Bronchiolitis is most famously caused by respiratory syncytial virus (RSV), although other pathogens include parainfluenza, influenza, and adenovirus. It is a respiratory infection that causes inflammation of the bronchioles. Edema and mucous production lead to obstruction of the airways with V/Q mismatch and hypoxia. It is most common in infants 2 to 6 months and is associated with increased likelihood of asthma developing in the future. Pneumonia incidence varies inversely with age, whereas the etiology changes based on the season and age of the patient.

Important secondary causes of respiratory distress include congenital heart disease, cardiac tamponade, myocarditis/pericarditis, tension pneumothorax, central nervous system infection, toxic ingestion, peripheral nervous system disease (eg, Guillain-Barré syndrome, myasthenia gravis, botulism), metabolic disorders (eg, diabetic ketoacidosis), hyperammonemia, and anemia.

History

Initial treatment may be required for stabilization before a complete history and physical examination can be performed.

Ask for a description of respiratory problems, including onset, duration, and progression of symptoms. Keep in mind that respiratory distress can present as difficulty with feedings in infants and decreased activity or feeding in toddlers. Inquire about precipitating or exacerbating factors. Ask if there was any recent history of choking, as this may be the only clue for a foreign body aspiration. Inquire if they have ever had a similar presentation in the past. Review all prior medications (chronic and acute) and note time of administration. For example, how many times albuterol was given per day in the past several days and the last time given before coming to the ED. Ask if immunizations are up to date, as failure to do so could put the child at risk for rare diseases (ie, epiglottitis, pertussis). Review in detail all past medical history. Infants born prematurely may have bronchopulmonary dysplasia (BPD), making reactive airway disease, respiratory infections, hypoxia, and hypercarbia more likely. When treating children with asthma, ask about frequency of exacerbations, if they ever required intubation or positive pressure ventilation, previous admissions (ED, general floor, intensive care unit) and the last time they were on steroids. A history of chronic cough or multiple previous episodes of pneumonias may be suggestive of a congenital condition, undiagnosed reactive airway disease, or foreign body aspiration.

Physical Examination

The assessment should be conducted in a calm, efficient manner, with assistance from parents. Agitating a child can worsen symptoms and even precipitate acute decompensation, especially in suspected upper airway obstruction. Allow the child to assume a position of comfort. Take extra caution if the patient is presenting in the sniffing position (head and chin are positioned slightly forward), as this may indicate severe upper airway obstruction. Likewise, if the patient is presenting in the tripod position (leaning forward and supporting the upper body with their hands), this indicates severe lower airway obstruction, and this position will optimize their accessory muscle use. Respiratory rate varies in relation to age: newborn (30–60); 1–6 months (30–40); 6–12 months (25–30); 1–6 years (20–30); > 6 years (15–20). Heart rate also varies with age: newborn (140–160), 6 months (120–160), 1 year (100–140), 2 years (90–140), 4 years (80–110), 6–14 years (75–100), >14 years (60–90). Keep in mind that tachycardia is typical with albuterol treatment.

Skin exam can show diaphoresis, cyanosis (peripheral or central), rash (eg, hives), bruising, or trauma and can be a clue to the cause of respiratory distress. Make sure to fully unclothe the patient, taking care not to worsen distress.

Stridor indicates upper airway obstruction, and the phase of the respiratory cycle in which it occurs is a clue to the location of obstruction. Inspiratory stridor is seen with subglottic/glottis obstruction above the larynx (eg, epiglottitis). Nasal flaring, dysphonia, and hoarseness also suggest upper airway obstruction. Expiratory stridor is consistent with obstruction below the larynx, in the bronchi or lower trachea. Croup is the most common cause, but also consider foreign body, epiglottitis, anaphylaxis, angioedema, peritonsillar abscess, retropharyngeal abscess, tracheomalacia, laryngomalacia, or obstructing mass.