Definition of Metered-dose inhaler

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Metered-dose inhaler: Abbreviated MDI. A device that delivers a measured amount of medication as a mist the patient can inhale. A MDI consists of a pressurized canister of medication in a case with a mouthpiece. MDIs are portable, efficient and convenient. People with asthma, chronic obstructive pulmonary disease (COPD), chronic bronchitis, and emphysema.