Subject(s)
Aerosols/administration & dosage , Humans , Nebulizers and Vaporizers , Particle Size , TemperatureABSTRACT
The regional deposition patterns of inhaled hygroscopic aerosols obtained in vivo in the studies of Phipps et al. (P. R. Phipps, I. Gonda, D. L. Bailey, P. Borham, G. Bautovich, and S. D. Anderson. Am. Rev. Respir. Dis. 139: 1516, 1989; and P. R. Phipps, I. Gonda, S. D. Anderson, D. L. Bailey, and G. Bautovich. Eur. Respir. J. 7: 1474-1482, 1994) and Chan et al. (H.-K. Chan, P. R. Phipps, I. Gonda, P. Cook, R. Fulton, I. Young, and G. Bautovich. Eur. Respir. J. 7: 1483-1489, 1994) by using single-photon-emission computerized tomography (SPECT) are compared with the regional deposition predicted by the hygroscopic lung deposition model of Finlay and Stapleton (W. H. Finlay and K. W. Stapleton. J. Aerosol Sci. 26: 655-670, 1995). Three pairs of saline aerosols are considered: isotonic with small [2.6-microns mass median aerodynamic diameter (MMAD), geometric standard deviation (GSD) 1.4] vs. large (5.5-microns MMAD, GSD 1.7) droplets; hypotonic (0.3% NaCl) vs. hypertonic (4.5% NaCl) with 3.7- to 3.8-microns MMAD (GSD 1.4), and hypotonic vs. hypertonic (3.7- to 3.8-microns MMAD, GSD 1.5-1.8) with reduced number of droplets per cubic centimeter. For each of the three pairs of aerosols, no significant difference (P > 0.05) was found between the in vivo and computational results for either the mean value or the variance of the difference in peripheral to central deposition. Thus it appears that theoretical calculations can be used to predict the pattern of lung deposition of hygroscopic aerosols in populations of normal subjects.
Subject(s)
Aerosols , Lung/diagnostic imaging , Lung/metabolism , Tomography, Emission-Computed, Single-Photon , Administration, Inhalation , Chelating Agents , Humans , Hypotonic Solutions , Models, Biological , Particle Size , Pulmonary Alveoli/metabolism , Saline Solution, Hypertonic , Technetium Tc 99m Pentetate , Tissue DistributionABSTRACT
A methodology for determining the regional dosages delivered to the respiratory tract by a jet nebulizer is presented and applied to the DeVilbiss PulmoNeb disposable nebulizer delivering a 2.5 ml nebule of Ventolin (1 mg/ml salbutamol sulphate). Results are obtained both with tapping of the nebulizer, which enhances nebulizer performance, and without tapping. The nebulizer output is characterised by measuring the total mass and the mass of solids leaving the nebulizer per minute, and performing a control volume analysis of the nebulizer. Particle size distributions are determined by phased Doppler anemometry. Deposition probabilities are calculated using a semi-empirical model for the deposition of hygroscopic aerosol particles in healthy adult Caucasian males. Deposition probabilities are then converted to regional dosages using the measured nebulizer output characteristics. The regional dosages (% of initial dose in nebulizer) of Ventolin delivered to the extrathoracic, bronchial, and alveolar regions of the respiratory tract are 0.248 +/- 0.005 mg (9.9%), 0.034 +/- 0.001 mg (1.4%), and 0.071 +/- 0.002 mg (2.8%) respectively when the nebulizer was tapped during operation, and 0.184 +/- 0.005 mg (7.4%), 0.025 +/- 0.001 mg (1.0%), and 0.052 +/- 0.002 mg (2.1%) when tapping was not used. This methodology provides a well controlled and rapid means of comparing the effectiveness of different nebulizers for use in aerosol therapy.
