These small hand-held devices propel or send needed medicine directly to the lungs by combining medicine and a propellent (such as HFA or hydrofluoroalkane). But, the medicine only works if the MDI is used in the proper way. It is important to inhale while you press down on the MDI canister (Refer to the insert provided by the manufacturer of the medication in the packaging). Most MDIs (except for MAXAIR (pirbuterol), QVAR, or Combivent Respimat, and all dry powedered inhalers) can be used with valved holding chamber or spacer. Adding a valved holding chamber or spacer device to an MDI provides many benefits to the patient no matter their age or ability. WVAEPP recommends that all individuals regardless of age should have a spacer or valved holding chamber when using an inhaler.