Arrange following inhalational anesthetic agents according to increasing MAC values i) Isoflurane ii) Desflurane iii) Sevoflurane iv) Halothane
**Core Concept**
MAC (Minimum Alveolar Concentration) values are used to express the potency of inhalational anesthetic agents. It is defined as the concentration of the anesthetic in the lungs that is required to prevent movement in 50% of patients in response to a painful stimulus. Lower MAC values indicate more potent agents.
**Why the Correct Answer is Right**
MAC values for the given inhalational anesthetic agents are as follows:
- Isoflurane: 1.17%
- Desflurane: 6%
- Sevoflurane: 2%
- Halothane: 0.75%
The correct order from lowest to highest MAC value is: Halothane, Isoflurane, Sevoflurane, Desflurane. This is because Halothane is the most potent and Desflurane is the least potent among these agents.
**Why Each Wrong Option is Incorrect**
**Option A:** Halothane, Sevoflurane, Isoflurane, Desflurane - This option is incorrect because Halothane has a lower MAC value than Sevoflurane.
**Option B:** Sevoflurane, Isoflurane, Halothane, Desflurane - This option is incorrect because Sevoflurane has a higher MAC value than Isoflurane.
**Option C:** Isoflurane, Halothane, Sevoflurane, Desflurane - This option is incorrect because Halothane has a lower MAC value than Isoflurane.
**Option D:** Desflurane, Sevoflurane, Isoflurane, Halothane - This option is incorrect because all the options except Desflurane have lower MAC values.
**Clinical Pearl / High-Yield Fact**
When choosing an inhalational anesthetic agent, consider the MAC value as a guide to the required concentration and the potency of the agent. A lower MAC value indicates a more potent agent, which may require closer monitoring to avoid over-sedation or respiratory depression.
**Correct Answer:** D. Desflurane, Sevoflurane, Isoflurane, Halothane