Assessment of expiratory vs inspiratory resistance and reactance using FOT as a measure of air trapping

Abstract

Background: Forced oscillometry technique (FOT) measures resistance, R, and reactance, X in the respiratory system. Resmon Pro, a new FOT technique, provides analysis of inspiratory and expiratory resistance (Rin and Rexp) and reactance (Xin and Xexp) separately. This provides simple assessment of peripheral and central airway resistance and reactance, and adding a measure of air trapping. Aim: To investigate the difference in inspiratory and expiratory resistance and reactance in obstructive diseases as a measure of air trapping. A secondary aim was to investigate airtrapping assessment in comparison to baseline measurements by Resmon Pro and the more established method impulse oscillometry (IOS). Methods: A total of 61 subjects (20 healthy, 9 Rhinitis, 16 asthma, 16 COPD) performed spirometry and measurements with Resmon Pro followed by IOS. Results: The difference in expiratory and inspiratory parameters obtained by Resmon Pro showed that subjects with COPD had more difference (p Conclusion: The increased difference in expiratory versus inspiratory resistance and reactance in subjects with COPD suggest increased dynamic air trapping and loss of elasticity. This air trapping correlated most prominent to parameters measuring peripheral resistance and reactance.