Which gas flowmeter is always positioned last or rightmost on the anesthesia machine?

• A. Nitrous oxide
• B. Air
• C. Oxygen
• D. Carbon dioxide

Answer: (C)

The oxygen flowmeter is always positioned last or rightmost on the anesthesia machine due to several critical safety and functional reasons. Oxygen is the essential gas that supports life and is used to maintain patient safety during procedures under general anesthesia. By placing it last in the sequence of gas flowmeters, it ensures that the patient receives the highest concentration of oxygen after any other gases, such as nitrous oxide, air, or carbon dioxide, have been mixed or delivered.

This arrangement not only maximizes the delivery of oxygen to the patient but also helps in preventing hypoxia, which can occur if a user inadvertently administers a lower concentration of oxygen in an emergency situation. In the event of a malfunction or confusion over the gas flow, having oxygen positioned at the end of the sequence ensures that it is the last to be altered or cut off in a critical moment, allowing it to serve as the primary gas sustaining the patient's respiration. Thus, the placement of flowmeters is a well-considered design choice prioritizing patient safety and effective anesthetic delivery.