Minimum Alveolar Concentration (MAC) is an important measure in inhalational anaesthesia. Which of the following DECREASES MAC?
- A Hyperthermia
- B Concurrent opioid administration ✓
- C Chronic alcohol use (tolerance)
- D Hypernatraemia
Correct answer: B. Concurrent opioid administration
Explanation
MAC (the alveolar concentration preventing movement in 50% of patients exposed to a surgical stimulus) is decreased by factors that reduce CNS activity: increasing age, hypothermia, acute ethanol intoxication, concurrent opioids, alpha-2 agonists, pregnancy, and hypoxia/hypotension. Opioids reduce MAC significantly (opioid-sparing effect), allowing lower inhalational agent concentrations. Hyperthermia and chronic alcohol use (CNS tolerance) increase MAC.
Reference: KD Tripathi, Essentials of Medical Pharmacology, 8th ed.
High-yield for: NEET PGINI-CETNExTFMGEUSMLEPLABMRCP
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