APSD of Metered Dose Inhalers (MDIs)

The APSD testing of MDIs is typically performed at a flow rate of 28.3 L/min when using an ACI or 30 L/min when using an NGI. For Breath Actuated MDIs (BAIs) a Breath Actuation Controller may also be used to generate a time delay. However, it must be noted that when add-on devices such as spacers or valved holding chambers (VHCs) are used, the APSD characteristics may be substantially altered from what is emitted when the MDI is used alone and must be assessed appropriately.