Introduction: Spirometry is a widely used pulmonary function test that requires several steps to be performed. In Thailand, there is only limited amount of data on the success rate and associated factors in children.
Objective: To determine the success rate and factors affecting spirometry performance.
Method: This cross-sectional study involved participants aged 5–18 years who underwent spirometry testing at the Naresuan University Hospital between 1 January 2015 and 31 December 2020. The subjects were divided into success and failure groups using the American Thoracic Society and European Respiratory Society 2005 criteria for acceptability and repeatability. The data collected include general characteristics, spirometry techniques and processes to determine the success rate and its associated factors.
Results: A total of 132 subjects underwent spirometry testing, with a success rate of 71.2%. The success group’s mean age, weight and height were significantly greater than the failure group. The most unsuccessful spirometry step in the failure group was a prolonged exhalation. Between the two groups, there was a statistically significant difference in the plateau phase of the volume time curve (85.1% vs. 55.3%, P < 0.001).
Conclusion: Children’s age, weight and height are all considered predictor variables of success. The most frequently step failure in spirometry tests is prolonged exhalation phase. However, the plateau on volume time curves is a critical component of success. To achieve optimal success, encourage children to blow vigorously as long as they can be stable throughout the prolonged exhalation phase and assess their ability to follow instructions.
