Why does nitrous oxide dissolution in the volatile agent cause transient changes in vaporizer output when nitrous oxide enters or leaves the vaporizing chamber?

Why does nitrous oxide dissolution in the volatile agent cause transient changes in vaporizer output when nitrous oxide enters or leaves the vaporizing chamber?

• A. Output increases when N2O enters
• B. Output decreases when N2O enters
• C. Output remains unchanged by N2O dissolution
• D. Output decreases when N2O leaves

Answer: (B)

When a volatile anesthetic is delivered through a vaporizer, its output depends on the balance between the liquid in the chamber and the vapor that enters the gas stream. Nitrous oxide readily dissolves into the liquid anesthetic. As N2O enters the vaporizing chamber, it pulls some of the liquid anesthetic into the dissolved phase. This momentary transfer reduces the amount of anesthetic that can volatilize into the gas phase, so the concentration delivered to the breathing circuit drops transiently. Once equilibrium is reestablished, the vaporizer output recovers toward the baseline. If nitrous oxide later leaves the chamber, the dissolved anesthetic is released back into the gas phase, causing another transient change, typically an increase in output.

When a volatile anesthetic is delivered through a vaporizer, its output depends on the balance between the liquid in the chamber and the vapor that enters the gas stream. Nitrous oxide readily dissolves into the liquid anesthetic. As N2O enters the vaporizing chamber, it pulls some of the liquid anesthetic into the dissolved phase. This momentary transfer reduces the amount of anesthetic that can volatilize into the gas phase, so the concentration delivered to the breathing circuit drops transiently. Once equilibrium is reestablished, the vaporizer output recovers toward the baseline. If nitrous oxide later leaves the chamber, the dissolved anesthetic is released back into the gas phase, causing another transient change, typically an increase in output.