Which statement about desflurane and vapourisers is true?

• A. All volatile agents require temperature controlled vapourisers
• B. Nitrous oxide uses the same mechanism
• C. Sevoflurane has the highest vapor pressure
• D. Desflurane must be delivered via a temperature controlled vapouriser

Answer: (D)

The key idea is how vapor pressure and temperature control affect delivering volatile anaesthetics. Desflurane has an exceptionally high vapor pressure that rises with temperature, so to deliver a precise, stable inspired concentration it must be heated and temperature‑regulated in a dedicated vapouriser. That temperature‑controlled design keeps the output consistent regardless of ambient conditions, which is essential for desflurane’s accurate delivery. Nitrous oxide is delivered as a gas and does not require a traditional vapouriser, so its mechanism is different. Sevoflurane does not have the highest vapor pressure—desflurane does—so that statement isn’t correct.