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The authors have adjusted a jet nebulizer to a mechanical ventilator (Servo Ventilator, Siemens) to deliver an aerosol to rats. They aimed to clarify whether a modified jet nebulizer generating particles with a mass median aerodynamic diameter of 2 microm would be effective and safe in intubated ventilated rats. Fluorescent microspheres (diameter: 1.0 microm) were aerosolized to verify qualitatively and quantitatively intrapulmonary deposition. Particle deposition fraction was 3.8% (1.3%) of the delivered dose (median [interquartile range]). There was no evidence for any adverse event as assessed from heart rate, mean arterial pressure, PaO2 and PaCO2 before, during, and after nebulization. No pulmonary tissue trauma was detected histologically.

After a single short term inhalation of monodisperse cobalt compound aerosols with preselected physical and chemical parameters the long term retention in beagle dogs is determined measuring their radioactive Co-57 label by a gamma camera. Additionally the major clearance pathways are estimated by excretion analyses. The biological variability of the lung retention is small but it depends clearly on the physiochemical properties of the inhaled aerosol particles. The predominant clearance mechanism in the lung is a moderate dissolution process depending on the specific surface area of the particles. So cobalt oxide particles with an adjustable solubility in the lung can be used for studies of distinct dissolution processes in the lung. Using a gamma camera the dynamics of particle accumulation in the tracheobronchial lymph nodes and the subsequent clearance are analysed on single dogs.

Administration of drugs via the airway is increasingly practiced in ICU- and surgical patients. For this purpose, aerosols may be produced by either jet nebulization or ultrasonic droplet generation. In mechanically ventilated patients, aerosol delivery is often insufficient. The influence of the ventilatory pattern on nebulizer efficacy is poorly understood. In the present in vitro study we determined the efficacy of a new ultrasonic nebulizer in delivering aerosolized epoprostenol using defined ventilator settings. We determined aerosol delivery rates, the aerosol droplet size distribution and the impact of the connection tubing on drug delivery, applying adult and infant ventilation patterns. Aerosol production rates ranged from 0.28 to 0.57 ml per minute. Using an adult ventilator setting volume controlled ventilation (CMV) led to a higher aerosol production rate than pressure controlled ventilation (PCV) at identical tidal volumes and mean airway pressures (0.57 ml/min,CMV vs 0.39 ml/min, PCV). With an infant ventilator setting, nebulizer rates were lower than those found for the adult ventilator setting, but did not differ substantially between CMV and PCV mode (0.29 ml/min, CMV vs 0.28 ml/min, PCV). Aerosol delivery rates distal to the endotracheal tube changed according to aerosol production rates (adult mode: 0.18 ml/min, CMV vs 0.10 ml/min, PCV; infant mode: 0.03 ml/min, both CMV and PCV). In the infant ventilation mode, a higher percentage of the aerosol was trapped in the catheter mount as compared to the adult ventilation mode. Mass median droplet diameters for each of the four ventilator settings were almost identical (4.63 to 5.09 micron) and smaller than indicated in the product specifications (8 micron). Delivery rates and sizes of droplets delivered by the new ultrasonic nebulizer SUN 345(R) agree well with previously reported data from comparable settings using diverse nebulizer devices.