From the Guidelines
The most appropriate initial step in diagnosing this 7-year-old girl's condition is spirometry (option E). Spirometry is the first-line diagnostic test for suspected asthma, which this patient likely has based on her presentation of chronic dry cough, nasal congestion, intermittent wheezing for two months, and history of eczema (suggesting atopic tendency) 1. According to the European Respiratory Society clinical practice guidelines for the diagnosis of asthma in children aged 5-16 years, spirometry is recommended as part of the diagnostic work-up of children with suspected asthma (strong recommendation for the intervention, moderate quality of evidence) 1.
The key benefits of spirometry include:
- Objective measurement of airflow limitation and its reversibility with bronchodilators, which are hallmarks of asthma
- Non-invasive and readily available
- Can be performed in children as young as 5-6 years with proper coaching
While other tests, such as methacholine challenge testing, can help diagnose asthma when spirometry is normal, they are not the initial test of choice 1. Chest x-ray might be considered if there's concern for an alternative diagnosis, but isn't needed as the first step. Serum IgE levels may support an allergic component but don't establish the diagnosis, as recommended against by the task force (strong recommendation against the intervention, moderate quality of evidence) 1. Arterial blood gas analysis is unnecessary in a patient with normal oxygen saturation and no respiratory distress.
Spirometry provides the most useful initial objective data to confirm the suspected diagnosis of asthma in this child with classic symptoms and risk factors, and is in line with the diagnostic algorithm proposed by the European Respiratory Society 1.
From the Research
Diagnostic Approach
The patient's symptoms of dry cough, nasal congestion, and intermittent wheezing, along with a history of eczema, suggest a possible diagnosis of asthma. To confirm this diagnosis, the following steps can be considered:
- The patient's history and physical examination are crucial in diagnosing asthma, as diagnostic tests can only increase or decrease the probability of the diagnosis 2.
- Spirometry is an essential clinical measurement for diagnosing and managing respiratory diseases, including asthma 3.
Initial Diagnostic Step
The most appropriate initial step in diagnosing this patient's condition is:
- Spirometry, as it can provide evidence of airway obstruction and a large bronchodilator response, making asthma more likely 2.
- Spirometry can also help rule out other conditions, such as chronic obstructive pulmonary disease (COPD), and is an important tool in assessing lung health 3, 4.
Rationale for Choosing Spirometry
The reasons for choosing spirometry as the initial diagnostic step are:
- Spirometry is a non-invasive and widely available test that can provide valuable information about lung function 3.
- Baseline spirometry parameters, such as forced expiratory flow (FEF50%), can be used as surrogate markers for airway hyperresponsiveness (AHR) in patients with suspected asthma 5.
- Spirometry can help identify patients who may require further testing, such as a methacholine challenge test, to confirm the diagnosis of asthma 6, 5.