Spirometry in children

Abstract

Respiratory disorders are responsible for considerable morbidity and mortality in children. Spirometry is a useful investigation for diagnosing and monitoring a variety of paediatric respiratory diseases, but it is underused by primary care physicians and paediatricians treating children with respiratory disease. We now have a better understanding of respiratory physiology in children, and newer computerised spirometry equipment is available with updated regional reference values for the paediatric age group. This review evaluates the current literature for indications, test procedures, quality assessment, and interpretation of spirometry results in children. Spirometry may be useful for asthma, cystic fibrosis, congenital or acquired airway malformations and many other respiratory diseases in children. The technique for performing spirometry in children is crucial and is discussed in detail. Most children, including preschool children, can perform acceptable spirometry. Steps for interpreting spirometry results include identification of common errors during the test by applying acceptability and repeatability criteria and then comparing test parameters with reference standards. Spirometry results depict only the pattern of ventilation, which may be normal, obstructive, restrictive, or mixed. The diagnosis should be based on both clinical features and spirometry results. There is a need to encourage primary care physicians and paediatricians treating respiratory diseases in children to use spirometry after adequate training.

Figure 1. Errors in spirometry test identified by flow-volume curves: (A) poor patient effort; (B) cough; (C) premature finish and restart

Figure 2. Sample report of spirometry test produced by MIR Spirolab III. Interpretation of the report is: (1) it is acceptable (no artifact, good start and satisfactory exhalation); (2) there is repeatability (two largest forced vital capacity (FVC) measurements within 150mL (2700–2580=120mL) and two largest forced expiratory volume in one second (FEV₁) measurements within 5% of FVC (1700–1650/2700=1.8%)); (3) obstructive pattern (FEV₁ 91%, FEV₁/FVC 71%, and FEF_25–75 44%); (4) grading of severity mild (FEV₁ 91%); (5) there is significant bronchodilator response (30% change in FEV₁); and (6) diagnosis consistent with asthma.

Figure 3. Identification of ventilation pattern by spirometry curves: (A) normal flow-volume (in middle) and volume-time (at top) curves: grey shaded area is predicted curve and the blue line is actual tracing; (B) flow-volume curve suggestive of mild to moderate airway obstruction with significant bronchodilatation: grey line is predicted curve, blue line is actual tracing, and blue dotted line is post bronchodilatation curve; (C) flow-volume curve suggestive of restrictive pattern: blue dotted line is predicted curve and the grey line is actual tracing; (D) flow-volume curve suggestive of extrathoracic obstruction: blue dotted line is predicted curve and the grey line is actual tracing