INI-CET 2022 — Anesthesiology

Question 1: Arrange the following anesthetic agents based on their potency Nitrous oxide Halothane Isoflurane Methoxyflurane

• A. Methoxyflurane > Halothane > Isoflurane > Nitrous oxide (Correct Answer)
• B. Methoxyflurane > Nitrous oxide > Halothane > Isoflurane
• C. Methoxyflurane > Isoflurane > Halothane > Nitrous oxide
• D. Halothane > Isoflurane > Nitrous oxide > Methoxyflurane

Explanation: ***Methoxyflurane > Halothane > Isoflurane > Nitrous oxide*** - Anesthetic potency is inversely related to its **MAC (Minimum Alveolar Concentration)** value. A lower MAC value indicates higher potency. - The MAC values for these agents are: Methoxyflurane (0.16%), Halothane (0.75%), Isoflurane (1.15%), and Nitrous oxide (104%), which directly corresponds to this order of potency. *Methoxyflurane > Nitrous oxide > Halothane > Isoflurane* - This order incorrectly places nitrous oxide as more potent than halothane and isoflurane. **Nitrous oxide** has a very high MAC (104%), indicating low potency. - **Halothane** and **isoflurane** have significantly lower MAC values (0.75% and 1.15%, respectively), making them much more potent than nitrous oxide. *Methoxyflurane > Isoflurane > Halothane > Nitrous oxide* - This order incorrectly places **isoflurane** as more potent than halothane. **Halothane** has a MAC of 0.75%, while **isoflurane** has a MAC of 1.15%. - Therefore, halothane is more potent than isoflurane, making this sequence incorrect. *Halothane > Isoflurane > Nitrous oxide > Methoxyflurane* - This order incorrectly places **halothane** as the most potent and **methoxyflurane** as the least potent among the listed agents. - **Methoxyflurane** has the lowest MAC (0.16%), making it the most potent, while **nitrous oxide** has the highest MAC (104%), making it the least potent.