Which medical gas is used primarily for sedation during medical procedures?

Nitrous oxide is primarily used for sedation during medical procedures due to its unique properties. It is a colorless, sweet-smelling gas that acts as a weak anesthetic and is commonly applied in various healthcare settings, including dentistry and minor surgical procedures. Its ability to provide analgesia (pain relief) and sedative effects makes it particularly advantageous.

When nitrous oxide is inhaled, it quickly enters the bloodstream and the brain, inducing a state of relaxation and euphoria, which can help alleviate anxiety and discomfort during medical interventions. This fast-acting sedative property is why it is often referred to as "laughing gas" due to its euphoric effects.

In contrast, the other gases listed serve different functions in medical practice. Oxygen is crucial for respiratory support but does not possess sedative properties. Helium is primarily used in respiratory therapy for conditions involving airway obstruction, but it does not have sedative effects. Carbon dioxide can be used in certain surgical procedures, especially in laparoscopy, but it does not provide sedation. This specialization of nitrous oxide makes it the preferred choice for sedation in various medical contexts.