What is the purpose of using a spacer with an MDI (metered-dose inhaler)?

Using a spacer with a metered-dose inhaler (MDI) significantly improves the delivery of medication to the lungs. The primary function of a spacer is to hold the aerosolized medication for a brief period after it is released from the inhaler, allowing the patient to inhale it more effectively. When medication is sprayed from an MDI, it can often form large droplets that may not reach the smaller airways in the lungs.

The spacer facilitates the conversion of these droplets into a finer mist and gives the user additional time to inhale the medication deeply and slowly, optimizing lung deposition. This is particularly beneficial for individuals who may have difficulty coordinating the act of pressing the inhaler and inhaling simultaneously, such as young children or the elderly.

While the use of a spacer could lead to a more efficient medication delivery, it does not decrease the overall dose delivered or prevent wastage of medication to any significant extent. It also does not serve the primary purpose of making inhalation easier, although it indirectly supports proper inhalation technique, enhancing the overall effectiveness of the therapy.