Final answer:
Nitrous oxide is the inhalant that is used as a medication, typically for inhalation anesthesia in medical settings and delivered using an anesthesia machine.
Step-by-step explanation:
Of the inhalants listed, nitrous oxide is the one used as an actual medication. Nitrous oxide is commonly used in combination with other volatile anesthetics like desflurane, isoflurane, and sevoflurane for inhalation anesthesia. These compounds are less flammable compared to diethyl ether, which was earlier used and has now been replaced due to safety concerns and for being highly flammable. It's crucial to note that nitrous oxide is delivered using an anesthesia machine which composes a mixture of oxygen, anesthetics, and ambient air, delivering it to the patient safely during medical procedures.