A 10-year-old boy has recurrent episodes of wheezing, cough, and chest tightness, particularly at night and after exercise. He is completely asymptomatic between episodes. Physical examination is normal today. Spirometry performed while symptomatic shows an FEV₁ of 68% predicted, FVC of 94% predicted, and FEV₁/FVC below the age-appropriate lower limit of normal. Following administration of an inhaled bronchodilator, his FEV₁ shows a clear improvement consistent with significant bronchodilator responsiveness.
Which of the following spirometric patterns is most consistent with this child’s condition?
A. Reduced FEV₁ and FVC with a preserved FEV₁/FVC ratio and reduced TLC
B. Reduced FEV₁ with relatively preserved FVC, reduced FEV₁/FVC, and significant bronchodilator responsiveness
C. Reduced FVC with a preserved FEV₁/FVC ratio and reduced TLC
D. Reduced FEV₁ and FVC with a reduced FEV₁/FVC ratio and reduced TLC
E. Normal or increased FEV₁ and FVC with a preserved or increased FEV₁/FVC ratio and no bronchodilator responsiveness
Correct Answer Explanation:
Correct Answer
B. Reduced FEV₁, preserved FVC, reduced FEV₁/FVC, with significant bronchodilator reversibility
Explanation: Spirometry Pattern in Asthma
Asthma is characterized by variable respiratory symptoms together with variable expiratory airflow limitation. In a child with typical symptoms such as recurrent wheezing, cough, chest tightness, and exercise- or night-related symptoms, spirometry commonly demonstrates an obstructive ventilatory pattern.
The key finding is a reduced FEV₁/FVC ratio below the age-appropriate lower limit of normal (LLN). FEV₁ may be reduced, while FVC is often preserved because the primary abnormality is increased airway resistance rather than reduced total lung volume.
In this child, the FEV₁ is 68% predicted, the FVC is relatively preserved at 94% predicted, and the FEV₁/FVC ratio is below the LLN. This establishes an obstructive pattern. The substantial improvement in FEV₁ after inhaled bronchodilator provides evidence of variable expiratory airflow limitation, which strongly supports asthma in the appropriate clinical setting.
In children, the FEV₁/FVC ratio should be interpreted using age-appropriate reference equations and the lower limit of normal (LLN), rather than applying the fixed adult cutoff of 0.70. [GINA 2026 Strategy Report]
Why the other options are incorrect
A. Reduced FEV₁, reduced FVC, preserved FEV₁/FVC, and reduced TLC
This pattern suggests a restrictive ventilatory defect rather than typical asthma. Restriction is characterized by a reduced FVC with a preserved or increased FEV₁/FVC ratio, and it is confirmed when TLC is below the LLN. The presence of a low FEV₁/FVC ratio in this child argues against a pure restrictive defect.
C. Preserved FEV₁, reduced FVC, preserved FEV₁/FVC, and reduced TLC
This is also consistent with a restrictive pattern, particularly because TLC is reduced. It does not describe the typical spirometric pattern of asthma, in which airflow obstruction produces a reduced FEV₁/FVC ratio.
D. Reduced FEV₁, reduced FVC, reduced FEV₁/FVC, and reduced TLC
This describes a possible mixed obstructive and restrictive ventilatory defect because both the FEV₁/FVC ratio and TLC are reduced. Although severe asthma can sometimes produce air trapping and a reduced FVC, the usual asthma pattern tested in this question is obstructive airflow limitation with a preserved FVC.
E. Increased FEV₁, increased FVC, and increased FEV₁/FVC with no bronchodilator response
This represents neither the typical obstructive pattern nor the characteristic variability expected in asthma. The child’s reduced FEV₁/FVC and bronchodilator response instead support variable airflow limitation.
Clinical Pearl
Asthma → variable expiratory airflow limitation → FEV₁/FVC ↓ ± FEV₁ ↓ → improvement after bronchodilator.
A normal spirometry result does not exclude asthma because airflow limitation may be intermittent. If spirometry is normal when the child is asymptomatic, repeat testing during symptoms or use another appropriate test for demonstrating variability when clinically indicated. GINA specifically notes that lung function can vary over time and that more than one test may sometimes be required to confirm asthma.
Exam Clue
When a school-aged child has recurrent wheeze + reduced FEV₁/FVC + demonstrable bronchodilator responsiveness, the spirometric pattern is obstructive with variable airflow limitation, making asthma the most likely diagnosis in the appropriate clinical context.
You can also read the detailed topic on Pulmonary Function Tests in Children
References
- Global Initiative for Asthma. Global Strategy for Asthma Management and Prevention: 2026 Update. Fontana, WI: Global Initiative for Asthma; 2026.
- Stanojevic S, Kaminsky DA, Miller MR, Thompson B, Aliverti A, Barjaktarevic I, et al. ERS/ATS technical standard on interpretive strategies for routine lung function tests. Eur Respir J. 2022;60(1):2101499.
- Kliegman RM, St Geme JW, Blum NJ, Shah SS, Tasker RC, Wilson KM, editors. Nelson Textbook of Pediatrics. Elsevier.
