In the sequence of flowmeters on an anesthesia machine, which gas should be positioned last?

The sequence of flowmeters in an anesthesia machine is critical for ensuring safety during anesthesia delivery. In this context, oxygen is positioned last in the sequence of flowmeters because it is essential for patient safety.

Oxygen is the most critical gas of all those used in an anesthesia machine; it supports life and needs to be delivered in sufficient quantities to the patient. By positioning it last, it ensures that if there is a leak or an issue with another gas flow, the oxygen supply will still be intact and can be delivered effectively. This arrangement minimizes the risk of a hypoxic mixture, where non-oxygen gases could dilute the oxygen concentration.

This safety measure is important in preventing situations where a patient could inadvertently receive a mixture with insufficient oxygen levels, which could lead to serious complications. Additionally, positioning oxygen last allows for easier adjustments and control over the oxygen flow, ensuring immediate responses to any changes in the patient's needs during anesthesia.

Other gases, while important for their respective effects in anesthesia, do not have the same critical importance as oxygen, which is why they are placed before it in the flow meter sequence.