Which gas is commonly used to treat singultus, more commonly known as hiccups?

The gas that is commonly used to treat singultus, or hiccups, is carbon dioxide. The rationale behind this is that carbon dioxide can stimulate the diaphragm and thus may help alleviate the involuntary contractions that cause hiccups. When carbon dioxide is administered, it can create a sensation that interrupts the hiccup reflex, providing relief from the condition.

Other options, such as oxygen, helium, and nitrous oxide, are not typically employed in the treatment of hiccups. Oxygen is necessary for respiration but does not have a specific effect on the hiccup reflex. Helium, while it can change the pitch of a person’s voice when inhaled, does not address the underlying causes of hiccups. Nitrous oxide is often used for its sedative and analgesic properties, but it is not a recognized treatment for hiccups either. Therefore, carbon dioxide stands out as the effective option for this particular condition.