Pulmonary function testing for the diagnosis of asthma in preschool children

Bo Chawes, Varpu Elenius


PURPOSE OF REVIEW: To highlight the recent evidence of the lung function techniques used in preschool children to diagnose asthma.

RECENT FINDINGS: Several techniques are available to measure lung function and airway inflammation in preschool children, including spirometry (from age 5 years), impulse oscillometry (>3 years), whole-body plethysmography (>3 years), fractional exhaled nitric oxide (FeNO) (>5 years), multiple breath washout (>3 years), structured light plethysmography (>1-2 years) and impedance pneumography (>1 years). If applicable, measuring forced expiratory volume in 1 s (FEV1) and FEV1/forced vital capacity (FVC) ratio using spirometry is useful (cut-off < 80% predicted or below lower limit of normal [LLN] defined as z-score < -1.64) for diagnosing preschool asthma. For those unable to perform spirometry, whole-body plethysmography (sRaw > 1.6 kPa/s) and impulse oscillometry (Rrs and Xrs at 5 Hz z-score > 2) may be useful. Adding a bronchodilator reversibility test (FEV1 increase > 12%, sRaw decrease > 25-30%, Rrs at 5 Hz decrease > 40%) or a bronchial challenge test, for example, exercise test (FEV1 decrease > 10%), may improve the sensitivity of these tests. Elevated FeNO (>25-35 ppb) is a promising adjunctive test for diagnosing preschool asthma.

SUMMARY: With trained personnel, lung function testing can be done with high reliability even in children between 2 and 4 years of age. To avoid over and undertreatment of asthma, objective measurement of lung function is clinically important in preschool children.

Original languageEnglish
JournalCurrent Opinion in Allergy and Clinical Immunology
Issue number2
Pages (from-to)101-106
Number of pages6
Publication statusPublished - 1 Apr 2022


  • Asthma/diagnosis
  • Breath Tests
  • Bronchial Provocation Tests/methods
  • Child, Preschool
  • Forced Expiratory Volume
  • Humans
  • Nitric Oxide
  • Reproducibility of Results
  • Spirometry/methods


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