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 micrograms) of radiolabeled fenoterol by MDI of 1.75 ml (1,750 micrograms) 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 excluded 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 less than 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.
"Several factors may affect respiratory tract deposition of bronchodilator drugs delivered by a MDI during mechanical ventilation. In vitro studies [14*,15,16,17,18,19,20,21,22] have shown that aerosol deposition is influenced by the ventilator mode and settings, heat and humidification of inspiratory gas, density of inhaled gas, size of endotracheal tube, and method of connecting the MDI in the ventilator circuit. "
[Show abstract][Hide abstract] ABSTRACT: The delivery of bronchodilators with metered-dose inhaler (MDI) in mechanically ventilated patients has attracted considerable interest in recent years. This is because the use of the MDI has several advantages over the nebulizer, such as reduced cost, ease of administration, less personnel time, reliability of dosing and a lower risk of contamination. A spacer device is fundamental in order to demonstrate the efficacy of the bronchodilatory therapy delivered by MDI. Provided that the technique of administration is appropriate, MDIs are as effective as nebulizers, despite a significantly lower dose of bronchodilator given by the MDI.
Critical Care 02/2000; 4(4):227-34. DOI:10.1186/cc698 · 4.48 Impact Factor
[Show abstract][Hide abstract] ABSTRACT: An aerosol is defined as a suspension of solid or liquid particles in a gas. Most aerosols in clinical practice are polydisperse, that
is to say, the contained particles vary greatly in diameter.
A dust is a suspension of solid particles in a gas. Dust particles are irregular.
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