Question
Meyer Overton rule relates potency of an anesthetic to
| A. |
Solubility in blood |
| B. |
Solubility in lipid |
| C. |
Blood- gas partition coefficient |
| D. |
Minimum Alveolar Concentration |
Show Answer
|
Correct Answer » D Explanation |
 |
- MAC is defined as the alveolar concentration of an inhalational anesthetic at which 50% of patients do not move in response to a standard surgical stimulus.
- It is the standard clinical measure of anesthetic potency.
- According to the Meyer–Overton rule:
- Higher lipid solubility → Greater potency → Lower MAC.
- Lower lipid solubility → Lower potency → Higher MAC.
- Therefore, potency is inversely proportional to MAC.
- In examination practice, when MAC is given as an option, it is considered the best answer because it directly represents anesthetic potency.
Why Other Options are Incorrect
A. Solubility in blood
- Blood solubility determines the speed of induction and recovery, not anesthetic potency.
- Lower blood solubility results in faster induction and emergence.
B. Solubility in lipid
- This is the original Meyer–Overton correlation.
- However, among the given options, MAC is the accepted clinical measure of anesthetic potency and is the expected examination answer.
C. Blood–gas partition coefficient
- Reflects blood solubility.
- Determines onset and recovery of anesthesia.
- Does not determine potency.