Aerosol delivery by an ultrasonic nebulizer during different mechanical ventilation settings in a lung model--a pilot...

Aerosol delivery of Iloprost is a promising therapeutic approach. The aim of this study was to determine the output of an ultrasonic nebulizer in different ventilation set-ups at the tip of different endotracheal tubes.

In set-up A, an ultrasonic nebulizer was connected directly to the endotracheal tube. In set-up B, the nebulizer was incorporated into the inspiratory limb of the ventilator circuit; a bypass arrangement allowed to selectively direct the expiratory air discharged from the model lung. The test lungs were ventilated through a standard endotracheal tube (ET) and through a double-lumen tube (DLT). The nebulizer was filled with 5 ml of a Tc-99m 0.9%-NaCl solution. After nebulization, distribution of radioactivity was detected by gamma scintigraphy.

Set-up A, ventilation in volume-controlled mode (VCV) via an ET: Delivered dose (1.61 +/- 0.41 ml), nebulization time 10.13 +/- 1.71 min. Set-up A, pressure-controlled ventilation (PCV), via a DLT: Delivered dose (1.33 +/- 0.88 ml), nebulization time 13.27 +/- 2.58 min. Set-up B, VCV mode via an ET: Delivered dose (1.57 +/- 0.44 ml), nebulization time (25.9 +/- 3.8 min). Set-up B, PCV mode, via a DLT: Delivered dose (1.3 +/- 0.17 ml), nebulization time (25.6 +/- 4.0 min). Set-up B did not yield a significantly higher output (p < 0.05), but the nebulization time was significantly longer (p > 0.05) compared with set-up A.

Set-ups which involve connecting the nebulizer directly to an ET or a DLT exhibit sufficient output of aerosol and short nebulization times.