Effect of a microaerosol filter on spirometry in children with cystic fibrosis

Aim: To measure the effect of an in-line microaerosol filter on spirometric values in cystic fibrosis (CF). Methods: Twenty-six subjects with CF undertook a randomized, open, cross-over comparison of spirometry with and without an in-line filter. Results: The filter had no significant effect on spirometric parameters nor was there any order effect. Measurement error was unrelated to the magnitude of the measurement. Conclusion: In-line microaerosol filters do not affect spirometric values or variability in children with CF.