Compared with the MAC of isoflurane in a healthy young adult, the MAC of isoflurane in a healthy 3-month-old full-term infant is:
- A Approximately 30% lower, reflecting immature neuronal development
- B Approximately 30% higher, since MAC peaks around 6 months of age before declining ✓
- C Identical, because MAC is age independent between birth and adulthood
- D Nearly double, because neonates have higher cerebral metabolic rates
Correct answer: B. Approximately 30% higher, since MAC peaks around 6 months of age before declining
Explanation
MAC rises after birth, reaches a maximum at roughly 6 months of age, and then declines steadily with advancing age, falling about 6% per decade in adults. Thus an infant requires a higher alveolar concentration than a 40-year-old. Option A reverses the relationship, option C ignores the well-documented age dependence used in MAC reduction tables, and option D states a magnitude never observed clinically.
Reference: Miller's Anesthesia, 9th ed.
High-yield for: NEET PGINI-CETNExTFMGEUSMLEPLABMRCP
Written and medically reviewed by the StethoPrep medical team.