[Aerosol therapy in spontaneously breathing tracheostomized patients: an in vitro study]

Aerosol therapy is widely used in tracheostomized patients, particularly during prolonged weaning, to improve mucociliary clearance and manage bronchoconstriction; however, there is a lack of standardized guidelines to optimize nebulization therapy in this patient population. Different nebulizer types and interfaces can affect the efficiency of drug deposition, thereby affecting the therapeutic efficacy. Understanding these differences is essential to improve aerosol delivery strategies in clinical practice.

This in vitro study aimed to evaluate the drug deposition rates of different aerosol generators and interfaces to determine the most effective combination for spontaneously breathing tracheostomized patients. Specifically, we compared the performance of a jet nebulizer and a vibrating mesh nebulizer in combination with different delivery interfaces: a face mask, a tracheostomy mask and a T-piece connected directly to the tracheostomy tube.

The study used an in vitro model simulating a spontaneously breathing tracheostomized patient. Drug deposition rates were measured using a jet nebulizer (Cirrus™ 2, Intersurgical Beatmungsgeräte GmbH, Sankt Augustin, Germany) and a vibrating mesh nebulizer (Aerogen® Solo, Aerogen Ltd., Galway, Ireland). The aerosol was delivered with the help of a face mask, a tracheal mask and a T-piece. The lung deposition rate was quantified gravimetrically by analyzing salbutamol deposition in a filter placed at the simulated airway.

The vibrating mesh nebulizer demonstrated the highest drug deposition rate (19.32 ± 4.29%) when used with a T-piece, significantly outperforming the jet nebulizer, which achieved its highest deposition rate (12.33 ± 1.38%) with a face mask (p = 0.008). The mesh nebulizer also achieved a higher deposition rate than the jet nebulizer when a tracheostomy mask was used (p = 0.023 with 1 l O₂/min supplementary flow, p < 0.001 with 8 l O₂/min).

The results suggest that the use of a vibrating mesh nebulizer connected directly to the tracheostomy tube via a T-piece can improve aerosol delivery efficiency in spontaneously breathing tracheostomized patients. The T‑piece functions as a small reservoir when a vibrating mesh nebulizer is used without additional oxygen supply, improving the deposition efficiency. Conversely, jet nebulizers require a continuous oxygen/air flow for operation; this can result in significant drug loss when used with a T-piece due to the continuous release of aerosol through the distal T‑piece opening. These findings are consistent with previous studies highlighting the benefits of mesh nebulizers in mechanically ventilated patients but extend this knowledge to spontaneously breathing tracheostomized individuals. Further clinical research is required to validate these in vitro results and to assess their impact on patient outcomes, secretion clearance and treatment efficacy in real-world settings.