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The minimum alveolar concentration (MAC) of sevoflurane with and without nitrous oxide in elderly versus young adults

R J Fragen1, K L Dunn

  • 1Department of Anesthesia, Northwestern University Medical School, Chicago, IL 60611, USA.

Journal of Clinical Anesthesia
|August 1, 1996
PubMed
Abstract

Insights

The minimum alveolar concentration (MAC) of sevoflurane decreases with age and the addition of nitrous oxide (N2O). This study confirms sevoflurane MAC is similar across populations, with N2O reducing it by approximately 50%.

Area of Science:

  • Anesthesiology
  • Pharmacology
  • Geriatric Medicine

Background:

  • Minimum alveolar concentration (MAC) is a key measure of anesthetic potency.
  • Sevoflurane is a widely used volatile anesthetic.
  • Age and co-administered agents like nitrous oxide (N2O) can influence anesthetic requirements.

Purpose of the Study:

  • To determine the MAC of sevoflurane in younger (18-35 years) and elderly (≥70 years) non-Asian patients.
  • To evaluate the effect of 65% nitrous oxide (N2O) on sevoflurane MAC in these age groups.

Main Methods:

  • Randomized open-study design utilizing the Dixon up-down method.
  • Sevoflurane MAC was determined in 27 young and 26 elderly ASA status I and II patients.
  • Measurements included end-tidal sevoflurane, N2O, and O2 concentrations.

Main Results:

  • The MAC of sevoflurane in O2/air was 2.6% for younger patients (mean age 25) and 1.45% for elderly patients (mean age 76).
  • 65% nitrous oxide reduced sevoflurane MAC by approximately 50% in both age groups.
  • Results were consistent with previous findings in diverse populations.

Conclusions:

  • Increasing age and the co-administration of nitrous oxide significantly decrease sevoflurane MAC.
  • The MAC of sevoflurane in elderly patients is lower than in younger adults.
  • Sevoflurane MAC reduction by age and N2O is comparable to other volatile anesthetics.

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