Optimization of aerosol deposition by pressure support in children with cystic fibrosis - An experimental and clinical study

Nebulized aerosols are commonly used to deliver drugs into the lungs of pat ients with cystic fibrosis (CF). The aim of this study was to assess the ef fectiveness of pressure-support (PS) ventilation in increasing aerosol depo sition within the lungs of children with CF. An in vitro study demonstrated the feasibility of coupling a breath-actuated nebulizer to a PS device. An in vivo study was done with 18 children (ages 6 to 21 yr) with clinically stable CF, each of whom underwent both a standard and a PS-driven ventilati on scan (control session and PS session, respectively). In addition, a perf usion scan was used to determine lung outlines and to construct a geometric model for quantifying aerosol deposition by radioactivity counting in MBq. Homogeneity of nebulization was evaluated from the four first-order moment s of aerosol distribution in the peripheral and central lung regions. The t ime-activity nebulization curve was linear in all patients, with higher slo pes during the PS than during the control session (0.43 +/- 0.07 [mean SDI MBq/min and 0.32 +/- 0.23 MBq/min, respectively; p < 0.018). Quantitatively , aerosol deposition was about 30% greater after the PS session (4.4 +/- 2. 7 MBq) than after the control session (3.4 +/- 2.1 MBq; p < 0.05). Similarl y, deposition efficacy las a percentage of nebulizer output) was significan tly better during the PS session than during the control session (15.3 +/- 8.3% versus 11.5 +/- 5.7%, p < 0.05). No differences in the regional deposi tion pattern or in homogeneity of uptake were observed. In conclusion, our data show that driving the delivery of a nebulized aerosol by noninvasive P S ventilation enhances total lung aerosol deposition without increasing par ticle impaction in the proximal airways.