The invention relates to a small-volume nebulizer with a valve system to provide lung physiotherapy during airway therapy with small-volume nebulizers. The valve system may be incorporated into a small-volume nebulizer. The small-volume nebulizer may be pre-filled with at least one unit-dose of medicine and hermetically sealed until use. The nebulizer may be sealed at the top with a removable cap that may be detached at the time of use and replaced with a patient connector. Likewise, the nebulizer may be sealed at the bottom with a bottom cap that is replaced with a gas source at the beginning of a therapeutic aerosol treatment.