Two-compartment model of gas mixing in patients with asthma and cystic fibrosis

Conclusion Multiple breath inert gas washout (MBW) is a technique for quantifying ventilation heterogeneity (VH), the uneven distribution of ventilation, through analysis of the efficiency and pattern with which an inert tracer gas is washed out of the lungs during tidal breathing. Lung clearance index (LCI) is the most commonly reported MBW parameter, and may be elevated by (i) unequal convective ventilation between large lung units, or (ii) increased respiratory dead space. We aimed to derive novel parameters (LCIvent and LCIds) that would distinguish between these two mechanisms.