Chest
Volume 92, Issue 6, December 1987, Pages 991-994
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In vitro Comparison of DeVilbiss Jet and Ultrasonic Nebulizers

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Output, droplet size (by laser instrument), and nebulization time have been compared in vitro for eight individual ultrasonic nebulizers (DeVilbiss Pulmosonic) and eight individual jet nebulizers (DeVilbiss 646), the latter operated by compressed air at flows of 6 and 12 L/min. A solution of hypertonic (7 percent) saline was nebulized. The ultrasonic nebulizer retained a higher “dead” volume of solution on completion of nebulization (p<0.05), but the increase in saline concentration was less marked than for the jet (p<0.01). The mass of NaCl released as aerosol was similar for the ultrasonic and for the jet at 6 L/min but was increased for the jet at 12 L/min (p<0.05). There was a fivefold interindividual variation in output for the ultrasonic. Droplet mass median diameters for the ultrasonic (mean 5.4 µm) were slightly lower than those for the jet at 6 L/min (mean 6.0 µm, p<0.05) but were higher than those for the jet at 12 L/min (mean 3.7 µm, p<0.01). The ultrasonic emitted virtually no droplets <2 µm diameter and may be unsuitable for applications requiring high yields of fine particles for delivery to the peripheral lung regions.

Section snippets

METHODS AND MATERIALS

Eight individual DeVilbiss Pulmosonic (ultrasonic) nebulizers and eight individual DeVilbiss 646 (jet) nebulizers supplied by the manufacturers during 1985 and 1986 were tested. In order to vent aerosol from the ultrasonic nebulizer, the medication chamber was flushed with air at 25 L/min. The jet nebulizers were driven by compressed air from a cylinder at 6 L/min and 12 L/min; these flows correspond approximately to those generated by the weakest and most powerful compressors currently

RESULTS

The initial solution masses averaged 4.33 g (283 mg NaCl), 4.34 g (284 mg NaCl), and 4.24 g (277 mg NaCl) for the ultrasonic and for the jet nebulizer operated at 6 and 12 L/min, respectively.

DISCUSSION

Bronchodilators, sodium cromoglycate, corticosteroids, and many other drug solutions may be aerosolized by jet or ultrasonic nebulizers. The hypertonic saline solution used in this study is sometimes used as a placebo, but may itself have expectorant properties.13 Previous observations from our laboratory5, 6, 7 suggest that the changes in droplet size brought about by alterations in air flow rate through jet nebulizers and the increase in drug concentration with time are similar both for

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  • Cited by (0)

    This work was supported by a grant from the Cystic Fibrosis Research Trust of the United Kingdom.

    Manuscript received December 30; revision accepted April 6.

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