Which gas is nicknamed 'laughing gas'?

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

Answer: (B)

Nitrous oxide earns the nickname because, at clinical concentrations, it often produces a quick, mild euphoric effect that can include laughter. Its onset is rapid and recovery is fast because it has low blood-gas solubility, so it takes effect quickly and wears off quickly. This makes it a useful analgesic and anxiolytic adjunct that can be titrated and combined with oxygen or other anesthetics during induction. The other inhaled anesthetics listed are more potent hypnotics used for maintenance of anesthesia and don’t produce that characteristic light, giggly sensation. In veterinary practice, nitrous oxide is typically used with oxygen as part of balanced anesthesia rather than as the sole agent, due to its weaker anesthetic potency and the need to avoid hypoxia.