What is the purpose of using a spacer with a metered-dose inhaler?

Using a spacer with a metered-dose inhaler enhances medication delivery to the lungs. This device helps to optimize the inhalation of aerosolized medication by allowing particles to disperse in the chamber before they are inhaled. When using a metered-dose inhaler alone, a significant portion of the medication may be deposited in the mouth and throat rather than reaching the lungs, where it is needed most. The spacer improves coordination between pressing the inhaler and inhaling the medication, which can lead to more effective delivery, especially in patients who may have difficulty using the inhaler correctly on their own.

The other choices do not accurately reflect the purpose of a spacer. Using a spacer does not reduce the frequency of inhaler use; rather, it helps ensure that the medication is delivered more effectively on each use. There is no intentional increase in inhaler's resistance, and while spacers can help with inhalation technique, they do not serve as a monitoring tool for a patient's inhalation rate. Thus, enhancing medication delivery is the primary and intended purpose of using a spacer with a metered-dose inhaler.