Which gas is typically used for emergency resuscitation?

Oxygen is typically used for emergency resuscitation due to its essential role in human respiration and its ability to support life. In emergency situations, ensuring that a patient receives adequate oxygen can prevent brain injury and other complications related to hypoxia (lack of oxygen). Oxygen supplementation can help restore normal blood oxygen levels quickly, which is crucial during cardiopulmonary resuscitation (CPR) or when treating conditions such as choking, drowning, or respiratory distress.

The other options listed are not suitable for emergency resuscitation. Carbon dioxide is a byproduct of respiration and can be harmful in excess, while nitrogen is inert and does not support life. Helium, while used in certain medical applications, does not provide the necessary oxygen for survival and can complicate breathing if administered without oxygen content. Thus, oxygen is the vital gas required in emergency resuscitation scenarios.