PRESSURIZED AEROSOL VERSUS JET AEROSOL DELIVERY TO MECHANICALLY VENTILATED PATIENTS - COMPARISON OF DOSE TO THE LUNGS

The purpose of this study was to compare deposition of aerosol to the lung from a metered-dose inhaler (MDI) and aerosol holding chamber and from a jet nebulizer in ventilator-dependent patients. Twenty-one patients were entered into the study, all receiving assisted ventilation and inhaled bronchodilators because of airflow limitation. The average age was 68 yr; there were 10 men and 11 women. The patients were randomized to receive either 4 puffs (800 μg) of radiolabeled fenoterol by MDI of 1.75 ml (1,750 μg) of radiolabeled fenoterol solution by nebulizer. Imaging of lung fields was made by a portable scintillation camera at 5-min intervals during the study. Results showed that 20 patients completed the study, 9 receiving fenoterol by MDI, and 11 by jet nebulizer. Four were exluded from analysis because of previous pneumonectomy, two from each group. Lung deposition measured as a percent of given dose from either system was 5.65 ± 1.09 (mean ± SEM) for MDI plus extension chamber and 1.22 ± 0.35 for jet nebulizer (p < 0.001). Therefore, this trial shows significantly greater efficiency of aerosol deposition to the lung in ventilator-dependent patients when using an MDI plus aerosol holding chamber than when using a jet nebulizer.