Addition of Nitrous Oxide and Its Effects on Depth of Anesthesia (N20)

The study hypothesizes that adding 60% nitrous oxide to a steady state sevoflurance or propofol anesthetic will lead to a decrease in both BIS and Entropy indices during a constant level of surgical stimulus

Nitrous oxide is a widely used general anesthetic pas. It is often used in addition to a second, more potent agent. BIS and Entropy are depth of anesthesia monitors in clinical use. There are conflicting reports about the usefulness of these monitors when nitrous oxide is used as a part of the anesthetic regimen. While some studies demonstrate a decrease in BIS and Entropy, this study aims to investigate the effects of adding nitrous oxide to a sevoflurane or a propofol based anesthetic on BIS and Entropy indices.

• Deep Sedation
• Anesthesia, General

• Drug: nitrous oxide
  Addition of 60% nitrous oxide for 20 minutes duration, then back to 1:1 oxygen/air mixture.
  Other Name: laughing gas
• Device: BIS Monitor
  BIS Monitor electrodes placed on forehead
  Other Name: Anesthesia depth monitor
• Device: Entropy Monitor
  Entropy monitor electrodes placed to forehead
  Other Name: Anesthesia depth monitor

• Active Comparator: 1
  Sevoflurane based general anesthesia
  Interventions:

  • Drug: nitrous oxide
  • Device: BIS Monitor
  • Device: Entropy Monitor
• Active Comparator: 2
  Propofol based general anesthesia
  Interventions:

  • Drug: nitrous oxide
  • Device: BIS Monitor
  • Device: Entropy Monitor

Inclusion Criteria:

• Ages 18 to 55yrs
• ASA status less than and equal to 2

Exclusion Criteria:

• Surgery on head and neck
• ASA greater than 3
• Contraindication to nitrous oxide
• Pregnant women
• History of dementia and stroke, or other organic brain disorder
• Prisoner
• Ear surgery