Wheezing and Asthma in Infants and Young Children

Asthma Attack

3D Model

In general, the likelihood of future asthma development in a child with recurrent wheezing depends on the interplay between genetic (ie, a family history of atopy and/or asthma) and environmental (eg, infections, allergens, pollution) factors (1). In infants and young children, wheezing with viral illnesses, particularly those caused by respiratory syncytial virus and human metapneumovirus, is associated with an increased risk of developing childhood asthma (2, 3). An eventual diagnosis of asthma is more likely in children who have atopic symptoms, more severe wheezing episodes, and a family history of atopy and/or asthma.

Wheezing may be associated with atopic disease (ie, food allergies, allergic rhinitis, atopic dermatitis) in some children. In one study of children with recurrent wheezing, those with atopic disease had a higher individual risk of developing asthma because both conditions are driven by the same T2-high (ie, high CD4+ T-helper 2 cell cytokines) inflammatory pathways; however, nonallergic phenotypes constituted the majority of asthma diagnoses at 5 years of age (4).

In about one-third of young children, recurrent wheezing episodes are the initial manifestations of asthma, and these children will continue to have persistent wheezing later in childhood or adolescence (1). In other children, wheezing episodes, even if recurrent, are transient and stop by age 6 to 10 years; thus, they are not thought to represent a phenotype of asthma.

Wheezing usually results from bronchospasm that may be worsened by inflammation of the small and medium airways that causes edema and further airway narrowing. An acute wheezing episode in infants and young children is usually triggered by respiratory viral infections, but airway inflammation may also be triggered (or worsened) by allergies or inhaled irritants (eg, tobacco smoke).

The cause of recurrent wheezing in young children can often be unclear. Some causes that could be associated with recurrent wheezing include frequent viral respiratory infections, allergies, or asthma. Less common causes of recurrent wheezing include chronic dysphagia that causes recurrent aspiration, gastroesophageal reflux, airway malacia (eg, tracheomalacia), a retained aspirated foreign body, or heart failure.

(See also Pathophysiology of Asthma in adults).

Wheezing is often accompanied by recurrent dry or productive cough. Wheezing without cough is uncommon; however, a subset of children with a true asthma phenotype may have cough in the absence of wheezing (also called cough-variant asthma).

Other symptoms depend on the etiology and may include fever, runny nose (viral infection), and feeding difficulties (eg, due to heart failure or dysphagia). Dyspnea and, in older children, a feeling of chest tightness, may be present. Children with respiratory infection–induced wheezing may have fever.

Children with a history of concomitant atopic disease are more likely to develop wheezing on exertion (eg, exercising, laughing, crying) or in the absence of respiratory infection (1).

On examination, wheezing is appreciable mainly on expiration, unless airway narrowing is severe, in which case wheezing can be heard on inspiration as well. Other findings present with more severe illness may include tachypnea, nasal flaring, intercostal and/or subxiphoid retractions, and cyanosis. In very advanced cases of respiratory distress, wheezing may not be appreciable (also called silent chest), which is an ominous sign requiring immediate management.

• Chest radiograph for severe initial episode and sometimes for atypical or recurrent episodes

• Tests to exclude other causes

For a first episode of severe wheezing, most clinicians perform chest radiography to exclude other causes (eg, detect signs of an aspirated foreign body, pneumonia, or heart failure) and pulse oximetry to assess the need for supplemental oxygen therapy. The presence of generalized hyperinflation on radiographs suggests diffuse air trapping as seen in asthma, whereas localized findings suggest structural abnormalities or foreign body aspiration. The chest radiograph may also indicate the presence of a vascular ring as the cause of wheezing (eg, right aortic arch).

For children with recurrent episodes, exacerbations typically do not require testing unless there are signs of respiratory distress. Spirometry can be done in patients ≥ 6 years of age to assess for airway obstruction and its reversibility with bronchodilators. Tests such as swallowing studies (eg, contrast esophagram), CT, or bronchoscopy (to exclude aspirated foreign bodies, airway malacia, or other abnormalities) (1, 2) may have clinical use in excluding causes other than asthma for the few children with frequent or severe exacerbations or symptoms who do not respond to bronchodilators or other asthma medications.

• For acute wheezing episodes, inhaled bronchodilators and, if warranted, systemic glucocorticoids

• For children with frequent severe wheezing episodes, a trial of maintenance therapy (eg, inhaled corticosteroids [glucocorticoids]) as used for asthma

Infants and young children with acute wheezing are given inhaled bronchodilators (eg, short-acting beta agonists such as albuterol) and, if the wheezing is severe, systemic glucocorticoids (Infants and young children with acute wheezing are given inhaled bronchodilators (eg, short-acting beta agonists such as albuterol) and, if the wheezing is severe, systemic glucocorticoids (1) (see Treatment of acute asthma exacerbation).

Children who are unlikely to develop persistent asthma, such as children who do not have atopy or a family history of atopy or asthma, and whose wheezing episodes are relatively mild and infrequent can usually be managed with only intermittent inhaled bronchodilators used as needed.

Most young children with more frequent and/or severe wheezing episodes benefit from maintenance therapy with bronchodilators as needed and anti-inflammatory medications (eg, inhaled corticosteroids [glucocorticoids]) as used for asthma. The use of a leukotriene modifier (eg, montelukast), after relevant . The use of a leukotriene modifier (eg, montelukast), after relevantboxed label warnings have been appropriately communicated, may also provide relief of symptoms in patients with persistent asthma with concomitant atopic disease (especially allergic rhinitis) (1). However, although chronic use of a leukotriene modifier or low-dose inhaled corticosteroid (glucocorticoid) decreases the severity and frequency of wheezing episodes, it does not alter the natural course of the disorder.

About two-thirds of children with recurrent wheezing in early childhood will not have clinically important wheezing later in life (1). Conversely, of all older children and adults with chronic asthma, a substantial proportion first experienced wheezing in early childhood.