Does it really matter what volume to exhale before using asthma inhalation devices?

Correct use of inhalation devices is one essential component of optimal management of asthma. Several longstanding controversies regarding specific steps to correct use of metered dose inhalers (MDI) include the lung volume when the MDI should be actuated. As a primary objective, literature was reviewed examining this one step in MDI use. Results from six of nine investigations support the need to gently exhale either to functional residual capacity (FRC) or residual volume (RV) before MDI actuation. Literature is also summarized regarding the need to exhale to FRC or RV before inhaling from MDI plus valved holding chambers or other extension devices and from dry powder inhalers. Numerous studies indicate that many patients as well as health care professionals either do not know or forget to exhale to RV or FRC before inhaling asthma medications. Both patients and health care professionals need education to help ensure correct use of MDI and other asthma inhalation devices, including instruction to first exhale gently to RV or FRC before inhaling the medication.