Introduction: After the onset of the COVID-19 pandemic, it has been observed that the course is milder in children compared to adults. However respiratory symptoms are frequently observed in long-term. The aim of this study was to investigate pulmonary function tests (PFT) of children with persistent respiratory symptoms.
Methods: We conducted a single center, cross sectional, prospective study of children with respiratory symptoms in long-term after COVID-19 infection. Spirometry, lung volumes, diffusing capacity of lungs for carbon monoxide (DLCO), fractional exhaled nitric oxide (FeNO) and 6-minute-walk test (6MWT) were done for both COVID-19 survivors and healthy controls.
Results: Fifty-five children with persistent respiratory symptoms and 55 healthy controls were enrolled. Weight, height and BMI z-scores were similar in both groups (p=1.000, p=1.000, p=1.000, respectively). In the study group the restrictive pattern was observed significantly higher (p=0.021) and 6 children had low DLCO (16.2%). Percentages of predicted values of spirometry and lung volumes, 6MWT distance and DLCO z-scores were found significantly lower but in normal range in children with long-COVID, while average DLCO, FeNO and 6MWT % predicted values were similar in the two groups.
Conclusion: Persistent respiratory symptoms are a condition that is frequently encountered in the long-term after COVID-19 infection and these children should be evaluated in detail. Restrictive pattern was detected in approximately one third of the children with long-COVID. Children with abnormalities in lung imaging should be followed carefully, especially in terms of spirometry and lung volumes. FeNO measurement was not found to be useful in long-COVID monitoring.