Pediatric Asthma: Diagnosis and Management

Asthma is a chronic inflammatory disease of the lower airways that remains one of the most common reasons for pediatric consultations and hospital admissions. Characterized by bronchial hyperresponsiveness and variable airflow obstruction, it presents clinically through recurrent episodes of wheezing, cough, chest tightness, and dyspnea. While the pathophysiology involves complex interactions between genetic factors and various inflammatory mediators, the clinical approach focuses on achieving long-term control and preventing life-threatening exacerbations.

Clinical Diagnosis and Phenotypes

The diagnosis of asthma begins with a thorough clinical history and physical examination. Clinicians must investigate family history (asthma or atopy), personal history, exposure to tobacco smoke, and environmental factors such as daycare attendance.

In infants and preschool children (under 6 years), the term "asthma" is often replaced by Preschool Recurrent Wheezing due to the difficulty of performing objective lung function tests and the different underlying pathophysiology in this age group. Clinicians often use the Modified Asthma Predictive Index (API) to identify children at high risk of developing atopic asthma. A positive API includes major criteria (parental asthma or physician-diagnosed atopic dermatitis) and minor criteria (allergic rhinitis, egg sensitization, or peripheral eosinophilia $>4\%$).

Identifying Airway Inflammation

Laboratory testing helps identify specific phenotypes to guide treatment:

• Allergic Phenotype: Suggested by elevated total or specific IgE and eosinophilia ($>4\%$).
• Non-Allergic/Other Phenotypes: Neutrophilia may indicate infectious asthma, cystic fibrosis, or primary ciliary dyskinesia.
• FeNO Testing: Fractional exhaled Nitric Oxide (FeNO) is a non-invasive way to assess eosinophilic inflammation. Values $>30\text{--}35\text{ ppb}$ suggest eosinophilic inflammation, often seen in allergic asthma or poorly controlled cases.