Nebulization through tracheostomy cannula : from bench to bed

Pitance, Laurent [UCL]

(eng) Drug delivery to the lung has mainly been studied in spontaneously breathing patients and in patients who are mechanically ventilated through endotracheal tubes. Nebulization through tracheostomy in spontaneously breathing tracheostomized patients has been poorly studied. The main aim of this thesis was to increase the knowledge in nebulization through tracheostomy tube. Our first objective was to select the most appropriate configuration of a jet nebulizer to administrate the larger amount or nebulized drug through a tracheostomy cannula. Therefore, in vitro measurements were realized by laser diffraction and residual gravimetric method. Lung deposition was investigated by imagery techniques and pharmacokinetic study. The second objective was to determine the influence of cannula diameter on drug delivery. We also wanted to examine whether the inner cannula should be removed during nebulization in spontaneously breathing patients. The third objective was to compare, in a clinical study, the drug delivered to the lung by a nebulizer through the mouth of through the tracheostomy cannula. Unvented jet nebulizer with a corrugated piece of tubing was delivering a higher amount of drug compared to unvented jet nebulizer alone or open vent jet nebulizer. Those results were observed in spontaneously breathing healthy subjects, in baboons and in vitro measurements through different inner diameter sizes of tracheostomy cannulas. We showed that the inner cannula should be removed before the nebulization in order to increase the amount of drug delivered in patient’s lung. Finally, we showed that drug delivery into the lung is as efficient when delivered through a tracheostomy as when delivered to the normal mouth breathing route. Our work therefore clarifies the influence of various jet nebulizer configurations on the amount of inhaled drug and provides new informations for the treatment of tracheostomized spontaneously breathing patients. Further studies are needed to further improve our understanding of nebulization through tracheostomy tubes.