Effect of ventilation distribution on aerosol bolus dispersion and recovery

It has been speculated that convective ventilatory inhomogeneities are an i mportant factor influencing aerosol bolus behavior in the compromised lung. Multiple-breath Xe-133 washout (MBWXe) is a commonly accepted test of vent ilation distribution. By comparing aerosol bolus parameters to MBWXe in 9 h ealthy subjects and 14 cystic fibrosis patients with mild-to-moderate airwa y obstruction, we have attempted to discern the effect of altered ventilati on distribution on aerosol bolus dispersion and recovery. Aerosol boluses ( 150-ml width) were delivered to the volumetric penetrations of 250 and 500 mi. Similar tidal volumes (similar to 1.25 liters) and flow rates (0.4 l/s) were used for aerosol bolus and MBWXe maneuvers. Associations between bolu s parameters and ventilation distribution were only observed in the cystic fibrosis patients. We conclude that aerosol bolus dispersion and recovery a re both influenced by convective ventilatory inhomogeneities induced by air way obstruction in these patients.