Abstract: A therapeutic respiratory apparatus is used to provide a continuous dosage of an aerosolized medicament to a patient. Pressurized carrier gas, which may be a mixture of oxygen and air, is supplied to a nebulizer which contains a reservoir of the liquid medicament. The aerosolized medicament is then delivered to a collapsible chamber which serves to store the aerosol between inhalations by the patient. Upon inhalation, the peak demand for the aerosolized mixture is drawn from the collapsible chamber, which is caused to collapse, so as to be reduced in its volume. A one-way valve prevents gas exhaled by the patient from being urged into the collapsible chamber. The exhalation gas is vented into the ambient air via exhaust valves in a mask, which may be an oxygen mask, coupled to the collapsible chamber.