Final answer:
The vaporizer output and delivered concentration of volatile anesthetics decrease when oxygen is replaced with nitrous oxide due to changes in gas density and viscosity, which affect the vapor pressure and the amount of anesthetic picked up by the carrier gas.
Step-by-step explanation:
The vaporizer output and the delivered concentration of volatile anesthetics decrease when the carrier gas is changed from oxygen to nitrous oxide due to the carrier gas effect. Volatile anesthetics like desflurane, isoflurane, and sevoflurane are often combined with nitrous oxide in an anesthesia machine to create a breathable mixture. When oxygen is replaced with nitrous oxide, the physical properties of the gases change the dynamics of evaporation and delivery. Nitrous oxide has a higher density and lower viscosity compared to oxygen, which affects the vapor pressure of the anesthetic agent within the vaporizer and hence lowers the saturation vapor pressure. This results in less anesthetic being picked up by the carrier gas, thus reducing the concentration delivered to the patient.