Which volatile anaesthetic agent requires high vapor pressure handling via a temperature-controlled vapouriser?

• A. Sevoflurane
• B. Isoflurane
• C. Desflurane
• D. Nitrous oxide

Answer: (C)

Desflurane has the lowest boiling point among common volatile anaesthetics, so at room temperature it already has a very high vapor pressure. Because of this, delivering a precise concentration would be very sensitive to ambient temperature if a standard ambient-temperature vapouriser were used. To keep the output stable, the vapouriser for desflurane is heated and thermostatically controlled, ensuring the amount delivered matches the dialed setting regardless of room conditions. Sevoflurane and isoflurane, with higher boiling points, don’t require this heating to the same extent and can be reliably delivered with conventional vapourisers. Nitrous oxide is a gas at room temperature and is not handled by a liquid, temperature-controlled vapouriser, so it’s not the agent that requires this type of heating.