Two different mechanisms of aerosol generation can be distinguished in nebulizers: Systems requiring compressed air or ultrasonic nebulizers. In compressor systems using gas containers or pneumatic pipes aerosol is generated through the venturi effect. It must be noted that the mass median aerodynamic diameter (MMAD) is dependent on device construction as well as the pressure generated. Matching nebulizers with associated air compressors is necessary to assure optimal efficiency of drug delivery.
Ultrasonic nebulizers produce aerosol by mechanical oscillations, which separate particles from the surface of the drug liquid. Here the particle size depends on the oscillation frequency. Exposure to ultrasonic waves may destroy complex molecules like proteins.
Nebulizers require minimal patient cooperation and coordination but are cumbersome and time-consuming to use. In average inhalation requires about 5-10 minutes to apply a sufficient amount of drug. However dose application is relatively inexact. Since nebulizers are effective with normal tidal breathing they are especially useful for patients, who are not able to cooperate: infants and small children, intubated patients or patients in emergency situations. Additionally nebulizers can be used to apply drugs or drug combinations unavailable in commercially distributed hand held devices.
Voshaar T, Berdel D, Buhl R, Fischer J, Gessler T, Haidl P, Heyder J, Köhler D, Kohlhäufl M, Lehr CM, Lindemann H, Matthys H, Meyer T, Olschewski H, Paul KD, Rabe K, Raschke F, Scheuch G, Schmehl T, Schultze-Werninghaus G, Ukena D, Worth H. Empfehlungen f¨r die Auswahl von Inhalationssystemen zur Medikamentenverabreichung. 2001. Pneumologie; 55: 579-586
COURSE OF PARTICLES USING A NEBULIZER
-video to be updated-
This animated model shows the aerosol flow generated by a nebulizers into the upper respiratory tract.