What does a metered dose inhaler (MDI) do?

A metered dose inhaler (MDI) is specifically designed to administer medication directly to the lungs, which is essential for conditions such as asthma and chronic obstructive pulmonary disease (COPD). By effectively delivering rescue medications, an MDI allows for rapid relief from acute respiratory distress by targeting the airways directly. This is crucial because it enables the medication to work quickly and efficiently at the site of action, which is the respiratory system, rather than having to go through the digestive system as oral medications would.

In contrast, the other options pertain to entirely different functions. One option relates to the delivery of oral medications, which does not apply to an MDI as it is not an oral delivery method. Another option mentions measuring lung capacity, which is typically performed with a spirometer, not an MDI. Lastly, while tracking medication usage is important, an MDI does not inherently collect this data; instead, it serves a pharmacological purpose by delivering medication. Thus, the role of the MDI as a tool for effectively administering rescue medications stands out as its primary and correct function.