What distinguishes a holding chamber from a regular spacer?

A holding chamber is distinctive from a standard spacer primarily because it is equipped with a one-way inspiratory valve. This valve allows medication to be delivered efficiently to the lungs during inhalation while preventing the backflow of exhaled air into the chamber. This design enhances drug delivery efficacy by allowing the patient to inhale the medication at their own pace and ensuring that more of the inhaled medication reaches the airways instead of settling in the device.

Conversely, regular spacers do not typically feature a one-way valve, which can lead to suboptimal inhalation techniques and reduced medication delivery. Other options such as having a filter, being intended for nebulizer solutions, or being designed for single-use do not accurately describe the fundamental function or design difference that characterizes a holding chamber.