What are the MAC (minimum alveolar concentration) values for sevoflurane, isoflurane, and desflurane?

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MAC Values for Volatile Anesthetics

The MAC values for these three volatile anesthetics in healthy adults (approximately 40 years old) are: sevoflurane 2.1%, isoflurane 1.15-1.28%, and desflurane 6.0-7.25%. 123

Standard MAC Values by Agent

Sevoflurane

  • Adults (40 years): 2.1% 1
  • Adults (general): 1.71% 4
  • Children (3-5 years): 2.49% 5
  • Elderly (mean age 71 years): 1.48% 6

Isoflurane

  • Adults (26 years): 1.28% in 100% oxygen 2
  • Adults (44 years): 1.15% in 100% oxygen 2
  • Adults (64 years): 1.05% in 100% oxygen 2

Desflurane

  • Adults (18-30 years): 7.25% 7
  • Adults (31-65 years): 6.0% 7
  • Elderly (≥65 years): 5.17% 7

Age-Related MAC Reduction

MAC decreases progressively with age for all three agents. This is a critical clinical consideration:

  • Sevoflurane: MAC in elderly patients (71 years) is approximately 70% of adult values 6
  • Desflurane: MAC in geriatric patients (≥65 years) is approximately two-thirds that of younger adults 3
  • Isoflurane: Shows similar age-related decline, with MAC at 64 years being 82% of the value at 26 years 2

Effect of Nitrous Oxide

When 60-70% nitrous oxide is added, MAC values are substantially reduced:

  • Sevoflurane: Reduced by 61.4% (from 1.71% to 0.66%) with 63.5% N₂O 4
  • Isoflurane: MAC becomes 0.56% in 70% N₂O (from 1.28% in oxygen alone) 2
  • Desflurane: Reduced to 1.67% with 60% N₂O (from 5.17% in oxygen alone) in elderly patients 7

Clinical Monitoring Implications

When using volatile anesthetics, maintain end-tidal anesthetic concentration (ETAC) >0.7 age-adjusted MAC during maintenance to reduce risk of awareness. 8 Enable audible alarms for low ETAC (<0.7 age-adjusted MAC) as recommended by the Association of Anaesthetists 88.

Important Caveats

  • MAC values represent the concentration preventing movement in 50% of patients; the ED95 (preventing movement in 95% of patients) is approximately 20-25% higher than MAC for all three agents 654
  • These values assume healthy, unpremedicated patients without opioids or other adjuvants
  • Individual patient factors (comorbidities, medications, surgical stimulation) will modify actual anesthetic requirements
  • Monitors should have age-adjusted MAC alarm capability rather than requiring manual calculation for each patient 8

References

5
Research

Minimum alveolar concentration of sevoflurane in children.

British journal of anaesthesia, 1992

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This information is intended for healthcare professionals. Any medical decision-making should rely on clinical judgment and independently verified information. The content provided herein does not replace professional discretion and should be considered supplementary to established clinical guidelines. Healthcare providers should verify all information against primary literature and current practice standards before application in patient care. Dr.Oracle assumes no liability for clinical decisions based on this content.