Introduction

Volume-controlled ventilation has been suggested during nebulization to optimize lung deposition although promoting spontaneous ventilation is targeted for ventilated patient management. Comparing topographic lung aerosol deposition during volume-controlled and spontaneous ventilation in pressure support has never been performed.

Objectives

The aim of this study was to compare lung deposition of a radiolabeled aerosol generated with a vibrating-mesh nebulizer during invasive mechanical ventilation, using two ventilation modes: pressure support ventilation (PS) and volume-controlled ventilation (VC).

Methods

Seventeen postoperative neurosurgical patients without pulmonary disease volunteered to participate in the study and were randomly ventilated in PS (n = 8) or VC (n = 9) with constant inspiratory flow. Diethylenetriaminepentaacetic acid labelled with technetium-99 m (2 mCi/3 mL) was administered using a vibrating-mesh nebulizer (Aerogen Solo®, Aerogen Ltd., Galway, Ireland) connected to the endotracheal tube. Pulmonary and extrapulmonary particles deposition was analyzed by planar scintigraphy.

Results

Mean lung deposition expressed as a percent of nominal dose was 10.5 ± 3.0% and 15.1 ± 5.0% during PS and VC, respectively (p < 0.05). Higher endotracheal tube and tracheal deposition was observed during PS (27.4 ± 6.6% versus 20.7 ± 6.0%, p < 0.05). a similar aerosol penetration from the inner to the outer region of the right lung (p = 0.347) and the left lung (p = 0.239) was observed.

Conclusions

Volume-controlled ventilation improved lung deposition of aerosolized particles as compared to pressure support ventilation. The clinical benefit of this effect warrants further studies.