Prolonged surgery cannot be undertaken with nitrous oxide alone.

The two main disadvantages which limit the use of nitrous oxide as an anaesthetic agent are :

1. Low anaesthetic potency.
2. It produces hypoxia.

At the maximum safe concentration of 85%, it cannot achieve the surgical stage of anaesthesia. But since it possesses many good properties such as non-explosive, non- irritant, pleasant smell, marked analgesia and rapid induction, which make it a valuable basal anaesthetic to be supplemented by other more potent agents.