A simple in vitro method for the evaluation of an ultrasonic nebulizer for drug delivery to intubated, ventilated patients and the effect of nebulizer and ventilator settings on the uptake of fluid from the nebulizer chamber

Inhaled Antibiotics for Gram-Negative Respiratory Infections

Gram-negative organisms comprise a large portion of the pathogens responsible for lower respiratory tract infections, especially those that are nosocomially acquired, and the rate of antibiotic resistance among these organisms continues to rise. Systemically administered antibiotics used to treat these infections often have poor penetration into the lung parenchyma and narrow therapeutic windows between efficacy and toxicity. The use of inhaled antibiotics allows for maximization of target site concentrations and optimization of pharmacokinetic/pharmacodynamic indices while minimizing systemic exposure and toxicity. This review is a comprehensive discussion of formulation and drug delivery aspects, in vitro and microbiological considerations, pharmacokinetics, and clinical outcomes with inhaled antibiotics as they apply to disease states other than cystic fibrosis. In reviewing the literature surrounding the use of inhaled antibiotics, we also highlight the complexities related to this route of administration and the shortcomings in the available evidence. The lack of novel anti-Gram-negative antibiotics in the developmental pipeline will encourage the innovative use of our existing agents, and the inhaled route is one that deserves to be further studied and adopted in the clinical arena.

In vitro study and semiempirical model for aerosol delivery control during mechanical ventilation

The object of this study was to evaluate in vitro the influence of various ventilatory parameters on the delivery of synchronized nebulization of terbutaline during mechanical ventilation and to determine a semiempirical model to control the quantity of aerosol delivered into the patient's lung. An ATOMISOR NL9 M jet nebulizer (La Diffusion Technique Francaise, France) was filled with terbutaline (Bricanyl, Astra-Zeneca, Sweden) and connected to the inspiratory line of a Horus ventilator (Taema, France). Nebulization was synchronized with the inspiratory phase. We assessed at the end of the endotracheal tube the quantity of terbutaline (terbutaline mass output) and the volume median diameter (VMD) by diffraction-laser method. There was a negative correlation between terbutaline mass output and inspiratory air flow ( r =-0.95, p <0.0001) and between VMD and inspiratory air flow ( r =-0.96, p <0.0001). Moreover, positive end-expiratory pressure levels between 0 cm and 8 cm of water did not significantly change the terbutaline output mass ( p =0.22). Total nebulization time and terbutaline mass output calculated by the mathematical model showed good agreement with experimental data. In conclusion, our semiempirical model allows calculation of the duration of the nebulization required to deliver a given mass of terbutaline into patient lungs.