Which setting primarily controls the oxygen concentration delivered to a patient?

The correct choice is FiO2, which stands for the fraction of inspired oxygen. This setting is crucial because it directly dictates the percentage of oxygen delivered to the patient during mechanical ventilation. In most clinical scenarios, increasing the FiO2 can enhance the oxygen saturation in the blood, especially in patients who have respiratory distress or conditions that affect gas exchange.

Understanding the role of FiO2 is vital for managing patients effectively. If a patient is not receiving sufficient oxygen, adjusting the FiO2 upwards can provide immediate improvement in their oxygenation status. Therefore, in any ventilation strategy, ensuring the correct FiO2 is essential for optimizing respiratory support and maintaining adequate oxygen levels in the body's tissues.